Abstract: Approximately 50% of the adult global population is projected to suffer from some form of metabolic disease by 2050, including metabolic syndrome and diabetes mellitus. At the same time, this trend indicates a potential increase in the number of patients who will be in need of implant-supported reconstructions of specific bone regions subjected to inflammatory states. Moreover, physiological conditions associated with dysmetabolic subjects have been suggested to contribute to the severity of bone loss after bone implant insertion. However, there is a perspective evidence strengthening the hypothesis that custom-fabricated bioengineered scaffolds may produce favorable bone healing effects in case of altered endocrine or metabolic conditions. This perspective review aims to share a comprehensive knowledge of the mechanisms implicated in bone resorption and remodelling processes, which have driven researchers to develop metallic implants as the cobalt-chromium (Co-Cr) bioscaffolds, presenting optimized geometries that interact in an effective way with the osteogenetic precursor cells, especially in the cases of perturbed endocrine or metabolic conditions.

Keywords: 3D-printed scaffolds | cobalt-chromium (Co-Cr) bioscaffolds | customized medicine | endocrine metabolic and immune disorders | regenerative medicine | tissue engineering | translational medicine

Abstract: In this work, a procedure for modelling and simulating conformal biomimetic scaffolds for bone tissue engineering is presented. Starting from a three-dimensional biomedical model of a real human mandible presenting a severe damage, a conformal shape was modelled and filled with an irregular beam network mimicking human trabecular bone. The material considered for the realization of the scaffold was hydroxyapatite derived from fish industry by-products, a material that is highly biocompatible to human bone. Several simulations were conducted on a beam-based wireframe model by varying the radius of the trabeculae, until reaching a stiffness of the scaffold equal to that of human bone. This represents a good design practice to avoid the stress shielding effect on growing bone tissue and functionality losses during bone regeneration. The resulting porosity and the average pore size, which are fundamental properties to ensure a proper vascularization of the growing tissue, were measured and compared to literature data, showing an acceptable agreement. The proposed beam-based approach for modelling and simulating conformal irregular scaffolds appeared as an interactive, fast, and versatile procedure that can be applied in the design stage of conformal biomimetic scaffolds for bone tissue regeneration.

Keywords: Bone Tissue Engineering | CAD Modelling | Mechanical Simulation

Abstract: The Industry 5.0 paradigm emphasizes the importance of the operator’s well-being by seeing human-centricity as one of its cardinal principles. This enables a twofold benefit, improving the sustainability of the production process and enhancing performance. Improving performance and increasing operators’ safety is often related to cognitive load optimization. Confined spaces are working environments where elements of distraction, such as noise, can cause accidents with major, even fatal, consequences. Studies on the effects of noise on cognitive abilities present mixed results, and those concerning confined spaces are limited as they require an expensive experimental setup replicating the working scenario. Immersive Virtual Reality (IVR) technology enables overcoming this gap by replicating the experimental conditions in a synthetic environment. We exploited IVR to study noise’s impact on cognitive performance in confined spaces. We compared the impact of a stationary continuous noise source with an intermittent non-periodic one by administering the Stroop Color and Word Test. We also assessed the perceived cognitive effort by administering the modified noise-induced task load index questionnaire. We also compared the effects on the operator’s physiological activity through Heart Rate Variability (HRV) analysis. Results show that by keeping the equivalent noise level lower than 85 dB, noise has no statistically significant effects on cognitive performance and Heart Rate.

Keywords: Cognitive Performance | Heart Rate Variability | Noise Effects | Stroop Color and Word Test | Virtual Reality

Abstract: Cell adhesion is a phenomenon characterizing cell-environment interactions and affects cellular behavior. Cell-substrate adhesion is ensured by focal adhesions (FAs), which are multilayer protein complexes. External mechanical stimulus perceived by FAs is rapidly transmitted first to cytoskeleton load-bearing structures and finally to the nucleus thanks to an interlinked cellular architecture, thus inducing transcription mechanisms and changes in cell functionality. Prestress of cytoskeletal filaments allows mechanical information to be transferred along these stiffer transportation channels with respect to neighboring cell regions, thus avoiding the energy dissipation typical of soft matter. Peculiar items concerning adhesion mechanisms, i.e., stiffness inhomogeneity in cell architecture, and auto-supporting tension-based cell structure, can be effectively handled thanks to modeling strategies provided by finite element method (FEM), which represents a valid tool for simulating cell adhesion. With the aim of replicating experimental results and predicting cell behavior, useful guidelines for simulating cellular adhesion will be outlined in the proposed work.

Keywords: Cell Adhesion | Finite Element Method | Mechanotransduction

Abstract: This work aims to validate the “minimal AR” authoring approach in a real industrial assembly scenario. It focuses on optimizing visual assets in Augmented Reality (AR) work instructions. The design of AR assembly documentation is influenced by three main variables: work instructions, affordance (dependent on equipment components and operator capabilities), and AR signifiers (combination of visual assets with their properties). In this study, we fixed the instruction complexity while exploring the relationship between affordance and AR signifiers. First, we set up a focus group of 10 experts in AR technical documentation to extract guidelines for the design of minimal AR signifiers for assembly instructions with a variable affordance. Then, we validated these guidelines through an industrial case study involving 34 participants in four assembly tasks. We verified if the candidate minimal AR signifier, obtained using the proposed guidelines, corresponded to the minimal AR signifier established by users. The results showed that in 33% of the cases, users exploited the candidate minimal AR signifier to accomplish the task successfully. Beyond the minimal AR signifier, an additional one conveying the notification about the task success must always be provided to ensure failure by those operators with reduced capabilities. We also found that, in 29% of the cases, users needed less information than the candidate minimal AR signifier due to their higher capabilities. However, as expected, this condition leads users to make more errors than with the candidate minimal AR signifier. Moreover, the study confirms that AR signifiers with redundant information or attractive appearance, such as animated product models, are unnecessary to improve task comprehension. Still, animations could be beneficial in reinforcing understanding when object properties are difficult to detect.

Keywords: Assembly | Authoring | Industrial augmented reality | Minimal information | Visual asset | Work instruction

Abstract: The aim of the present work is to investigate the superplastic behaviour of a bilayer Ti6Al4V-ELI to numerically design a full custom prosthesis manufacturing process by means of SuperPlastic Forming (SPF); the bilayer was composed by: (i) a monolithic Titanium blank (cut by a rolled sheet); (b) a porous blank cut by a billet produced by Hot Isostatic Pressing (HIP) and subjected to a Solid State Foaming (SSF) heat treatment. Experimental bulge tests aimed to evaluate the effects of both the initial porosity level of the HIPed layer and the temperature (850 and 900 °C) of the SPF process. The bilayer sample was deformed by a constant argon gas pressure and the time evolution of the dome height was recorded during the test in order to be used as target in the IA to determine the constants of the rheological model of the porous layer, being the behavior of the monolithic layer already known. A 2D FE model of the free inflation test was integrated in an automatic optimization procedure with the aim to minimize the error between the calculated and the acquired dome height vs time curve. Finally, the obtained material constants determined were used to design the SPF process by means of the numerical simulation, identifying as a case study a zygomatic full custom prosthesis. The initial porosity level resulted to poorly affect the superplastic behavior of the bilayer at 850 °C; on the contrary, when increasing the temperature up to 900 °C, an evident reduction of the forming time was obtained. Numerical simulations showed that at 900 °C it is possible to obtain the very complex geometry of the adopted case study in about 50000 seconds.

Keywords: Finite Element | Inverse Analysis | Material Characterization | Superplasticity | Ti Alloy

Abstract: The demand for ethically sourced and safe products has surged, prompting industries to adopt intricate traceability systems. Blockchain technology revolutionizes traceability by ensuring data integrity and transparency in supply chains. However, complexities within supply chains often obfuscate meaningful insights for consumers. This paper explores leveraging Augmented Reality to enhance Blockchain-based traceability systems. By integrating AR, consumers can seamlessly access traceability information through QR codes, presented via optimized 3D models. This immersive approach fosters trust by visually demonstrating product quality. The architecture combines QR codes, Vuforia markers, and Blockchain, ensuring data security and immutability.

Keywords: Computer systems organization | Distributed architectures | Security and privacy | Security services | Software and its engineering | Software design engineering

Abstract: This work aims to propose a virtual mirror as a tool for an Augmented Reality (AR) interface in support of operators who perform maintenance tasks, especially in blind areas with component occlusion. In the literature, it is still not clear what is the best AR solution to help workers perform maintenance tasks with occluded components. Thus, we designed an AR interface with a virtual mirror that can assist workers in identifying occluded components thanks to an additional workspace viewpoint. While physical mirrors are commonly employed in maintenance tasks to address blind spots, virtual mirrors are not yet widely adopted. Therefore, our study intends to design and evaluate a virtual mirror that simulates workers’ behavior using a real one in maintenance tasks. We planned a user study to compare the real and virtual mirrors in a real maintenance context. We conducted a performance evaluation with 20 users. Findings indicated no statistically significant differences between the virtual and physical mirrors regarding completion time, accuracy, and cognitive load. Our solution makes it possible to replace a real mirror providing the same user performance but with the advantage of being able to place it without space limitations and observe additional information exploiting AR.

Keywords: Augmented Reality | Blind Area | Maintenance | Occlusion | Virtual Mirror

Abstract: Dental tool positioning is a challenging manual operation that requires precise 5DOF positioning of the drill -rotation around the tool is not influential- minimal error can result in grave consequences such as nerve and bone damage. Augmented Reality (AR) can help to assist tool positioning, but the widgets proposed in the literature are quasi-static, commonly using virtual 3D cylinders or lines to be visually collimated and eventually supported by color change. We draw our inspiration from the photographic viewfinder and propose a novel Virtual Stigmometer Widget (ViSti) to convey tool positioning error magnitude to the dentist. The widget slightly blurs the view and gradually focuses it while approaching the target (i.e., implant drilling position) till it is perfectly collimated. We conducted a within subjects experiment (N = 30) to compare our widget with the golden standard in 32 positioning tasks. NASA-TLX results demonstrated that our widget reduces frustration (−43%), and mental demand (−19%), and the user perceives a better performance (+8%). However, the expected tradeoff is effort (+34%), and physical (+33%) temporal demand (+4%). Our widget demonstrated to have a potential usage for dentistry and in further fields where 5DOF precision is crucial.

Keywords: 5DOF manipulation | Augmented Reality | Dental Implantology | Human Centered Design | Stigmometer

Abstract: In recent years, Augmented Reality (AR) has been effectively proposed as a tool to support workers in manual procedural tasks in industry, such as assembly and maintenance. It is very common for workers to deal with complete equipment in maintenance. Then, instructions may refer to components located in blind areas, i.e., visually occluded by part of the equipment. Displaying in-situ AR instructions in such blind areas requires handling occlusions; otherwise, side-by-side instructions can be exploited. In the literature, it is still unclear which solution better leverage workers’ performance in maintenance tasks accomplished in blind areas. Thus, we designed three AR presentation modes to convey maintenance instructions in a real machine: 3D in-situ rendered with X-ray technique; 3D side-by-side on a CAD model replicating the blind area; 2D side-by-side on a virtual mirror. We conducted a user study comparing these three presentation modes with a 2D drawing extracted from the original maintenance documentation of the machine. The performance of 42 participants was evaluated in terms of completion time, accuracy, and cognitive load. The results revealed that both in-situ and 3D side-by-side presentation modes perform better than 2D drawing. Specifically, the in-situ presentation mode outperforms the 3D side-by-side mode in terms of completion time. The side-by-side virtual mirror does not improve performance with respect to 2D drawing, then it needs to be redesigned for effective use in AR maintenance interfaces.

Keywords: Augmented reality | Blind area | Industrial operator support | Maintenance | Occlusion | Work instructions

Abstract: In this work, we present a technique to simplify the authoring of Augmented Reality Technical Documentation, allowing technical writers with limited knowledge in Augmented Reality (AR) to produce this new type of documentation in their companies. Contrarily to Traditional Technical Documentation, AR offers the opportunity to provide the exact amount of information needed through a careful design of the AR interface. However, in the literature, there are no established techniques to break work instructions down into elemental pieces of information and define how to convey this information through visual assets in AR. In this work, we proposed identifying the information contained in work instructions of technical documentation, extending the method of “Therbligs,” already used in the literature to describe assembly tasks. First, we defined six classes of information types: identity, location, order, way-to, notification, and orientation. Then, we showed how to use these information types to break down the work instructions of an assembly manual used as a case study. We found that the six information types were enough to analyze the complete manual. The second contribution of this work is the proposal of the most suitable visual asset and its properties for each information type. This goal was accomplished through a technical discussion in a focus group with ten experts in the design of AR technical documentation.

Keywords: Augmented reality | Authoring | Information presentation | Technical documentation | Work instructions

Abstract: Hydraulic hammers, also known as breakers and peckers, are utilized in a wide variety of applications for the demolition of a structure and breaking rocks into smaller sizes. These tools and equipment are extremely sensitive and operate in harsh environments. As a result, there is a widespread requirement for remote control and monitoring of equipment and machines. Thus, Remote monitoring of industrial equipment such as hydraulic hammers has become an important part of Industry 4.0 and Internet of Things technologies. This paper presents the design and development of an Internet of Things (IoT) device (data logger) to improve the usage and performance of hydraulic hammers based on remote monitoring by implementing sensors for data collection, analysis, and management. It is expected that with the design of the platform and optimal sensor placement, huge data (Big Data) will be obtained from the vibration, machine operation time, oil pressure, temperature, and oil flow of the hydraulic hammer, based on operation conditions and type of material. Extracting this information and analysis of huge data generated by the Data logger directly from the hydraulic hammer during operation provides unique prior information and can be useful to adjust process planning, the possibility to implement predictive maintenance, and provide standard technical information for different modes of the Hydraulic hammer.

Keywords: Industry 4.0 | Internet of Things (IoT) | Predictive maintenance | Remote monitoring | Wireless Sensor Network (WSN)

Abstract: Confined spaces cause fatal and serious injuries that tragically recur with similar dynamics every year. A survey carried out on the Italian territory by the National Institute for Insurance against Accidents at Work on the years from 2001 to 2019 shows that a total of 184 accidents occurred in confined spaces mostly because workers were poorly informed and trained, the risk assessment lacking, and that the provisions of the law were not respected. Often fatal events affect those involved in the primary incident and those who intervene in an attempt to assist. Consequently, it is necessary to apply a proper training process and extend it to all those involved in operations both inside and next to confined spaces. Traditionally, the training approach consists of classroom lectures and simulations in real environments. However, real simulation scenarios are costly and time-consuming as real scenarios training simulations require expensive purpose-built physical simulators. To overcome these limitations, we designed and implemented an Immersive Virtual Reality based platform to support and enforce the traditional confined space safety training approach. Finally, we defined an experimental validation procedure.

Keywords: Confined spaces | Immersive Virtual Reality | Safety training | Usability | Work safety

Abstract: The study of predictive models describing the biological processes relating extra-cellular mechanical stimuli to structural responses of living cells, or even a differentiation, as in the case of mesenchymal stem cells (MSCs), is a relevant aspect in mechanobiology. A preliminary phase for these studies is the assessment of the mechanical behavior of whole living cells or their subcellular components, often performed by means of Atomic Force Microscopy (AFM). In this study we developed a numerical optimization framework aiming at matching the computed results obtained from a sequence of FEM simulations to an experimental AFM report curve associated to a MSC under investigation, in order to extract the elastic parameters of subcellular components and to assess how the mechanical response changes if the stress fibers network present in the interior of the cell is activated or not. By means of the proposed study, we extracted a set of Young’s moduli for the main subcellular components, which resulted comparable to the values computed by means of the Hertzian contact theory, and was also in good agreement with the related literature. By neglecting the effect of the tensioning pre-stress field induced by the stress fibers network, an underestimation of the Young’s moduli of subcellular components, up to a 15% in magnitude, was obtained.

Keywords: Finite element method | Mechanical simulation | Mechanobiology | Stem cells | Stress fibers

Abstract: A growing interest in creating advanced biomaterials with specific physical and chemical properties is currently being observed. These high-standard materials must be capable to integrate into biological environments such as the oral cavity or other anatomical regions in the human body. Given these requirements, ceramic biomaterials offer a feasible solution in terms of mechanical strength, biological functionality, and biocompatibility. In this review, the fundamental physical, chemical, and mechanical properties of the main ceramic biomaterials and ceramic nanocomposites are drawn, along with some primary related applications in biomedical fields, such as orthopedics, dentistry, and regenerative medicine. Furthermore, an in-depth focus on bone-tissue engineering and biomimetic ceramic scaffold design and fabrication is presented.

Keywords: bioceramics | biomaterials | bone tissue engineering | dentistry

Abstract: A fundamental outcome of bone tissue engineering is the regeneration of bone defects presenting large dimensions. A promising solution in biomedical practice is the implantation of biomimetic scaffolds, i.e. porous structures mimicking the natural shapes of healthy bone tissues, which are colonized by mesenchymal stem cells and that support the growth of the regenerating tissues, until the complete healing process is realized. This work presented a workflow for the geometrical modeling and the mechanical design of beam-based, bilayered, and conformal scaffolds, mimicking the human cortico-cancellous bone structure for filling a large dimension defect in the mandibular bone of an injured patient. An isotropic Voronoi topology built on a refined point set generated by a high-quality meshing algorithm was adopted for lattice generation, which led to an open-cell architecture characterized by full connectivity and uniform cell size. Such geometrical and structural features represent crucially important requirements for maximizing the osteointegration and the vascularization of the implanted scaffold. An irregular scaffold was modelled, including a cortical and a sponge layer. The beam radii of both layers were determined by matching the elastic properties of the corresponding bone tissues, thus minimizing the stress shielding effects. Interestingly, several scaffold properties deriving from the proposed procedure, such as the porosity and the pore size, were in good agreement with those reported in the literature.

Keywords: Biomimetic scaffolds | Bone tissue engineering | CAD modeling | Lattice structures | Mechanical simulation

Abstract: Despite the increasing degree of automation in industry, manual or semi-automated are commonly and inevitable for complex assembly tasks. The transformation to smart processes in manufacturing leads to a higher deployment of data-driven approaches to support the worker. Upcoming technologies in this context are oftentimes based on the gesture-recognition, − monitoring or–control. This contribution systematically reviews gesture or motion capturing technologies and the utilization of gesture data in the ergonomic assessment, gesture-based robot control strategies as well as the identification of COVID-19 symptoms. Subsequently, two applications are presented in detail. First, a holistic human-centric optimization method for line-balancing using a novel indicator–ErgoTakt–derived by motion capturing. ErgoTakt improves the legacy takt-time and helps to find an optimum between the ergonomic evaluation of an assembly station and the takt-time balancing. An optimization algorithm is developed to find the best-fitting solution by minimizing a function of the ergonomic RULA-score and the cycle time of each assembly workstation with respect to the workers’ ability. The second application is gesture-based robot-control. A cloud-based approach utilizing a generally accessible hand-tracking model embedded in a low-code IoT programming environment is shown.

Keywords: assembly | gesture-based control | Gesture-Based monitoring | manufacturingv

Abstract: The creation and management of content are among the main open issues for the spread of Augmented Reality. In Augmented Reality interfaces for procedural tasks, a key authoring strategy is chunking instructions and using optimized visual cues, i.e., tailored to the specific information to convey. Nevertheless, research works rarely present rationales behind their choice. This work aims to provide design guidelines for the localization of in-view and not occluded components, which is recurrent information in technical documentation. Previous studies revealed that the most suited visual cues to convey this information are auxiliary models, i.e., abstract shapes that highlight the space region where the component is located. Among them, 3D arrows are widely used, but they may produce ambiguity of information. Furthermore, from the literature, it is unclear how to design auxiliary model shapes and if they are affected by the component shapes. To fill this gap, we conducted two user studies. In the first study, we collected the preference of 45 users regarding the shape, color, and animation of auxiliary models for the localization of various component shapes. According to the results of this study, we defined guidelines for designing optimized auxiliary models based on the component shapes. In the second user study, we validated these guidelines by evaluating the performance (localization time and recognition accuracy) and user experience of 24 users. The results of this study allowed us to confirm that designing auxiliary models following our guidelines leads to a higher recognition accuracy and user experience than using 3D arrows.

Keywords: Augmented reality | Authoring | Auxiliary model | Localization

Abstract: Mixed Reality (MR) technology has gained popularity in the manufacturing industry over the last few decades. In the maintenance field, it helps workers in document analysis and decision-making during operations. While numerous studies have demonstrated the empirical benefits of MR, few have examined its applicability in a real industrial context. Among them, many focus on user performance. The novelty of our work is to evaluate mainly the acceptance of MR technology by experienced technicians using smart glasses for maintenance tasks in a real industrial context. We conducted a user study involving 7 workers who were asked to follow the instructions provided by an MR Technical Documentation (MRTD) developed considering authoring guidelines already validated in the literature but only in a laboratory context. The industrial operators performed both navigation tasks within the menu of the MRTD and a disassembly task, following the instructions displayed on the smart glass. The evaluation in the real working scenario showed that MRTD is highly appreciated by workers even if they have no previous experience with smart glasses. These results allow us to confirm the goodness of the design guidelines followed for the authoring of the MRTD.

Keywords: Industrial Operator Support | Mixed Reality | Smart Glasses | Technical Documentation | User Acceptance

Abstract: The biophilic design of virtual workplaces consists of introducing additional natural elements in the virtual environment (VE) with respect to those needed for the main task. It has received increasing attention in recent years, and an increasing number of studies are showing that exposure to biophilic elements in an immersive VE produces positive effects on human well-being. However, in the literature, there are no guidelines about the setting of the different variables of biophilic design in a VE. In this work, we investigated one of these variables, i.e., the effect of the animations of biophilic elements, formulating the following research question: how do animations of biophilic virtual elements affect user attention while performing a working task? We carried out an experiment in which users performed two levels of difficulty of the n-Back cognitive test in three VEs: two identical biophilic VE, one with all static elements and another one in which some of these elements were animated, and an additional empty VE used as a baseline. Performance measurements, eye-tracking measurements, and subjective measurements were collected from 24 users. We found that introducing animations of biophilic elements does not affect user performance in the cognitive task. Furthermore, we found that users’ gaze remains fixed on the main task for more than 94% of the time. However, the use of animations does not bring added value to users in terms of user experience, whereas it causes an increase in perceived distraction and mental effort.

Keywords: Animations | Biophilic Design | Positive Computing | Virtual Reality

Abstract: Background: Despite its relatively low lifetime prevalence, the health, social, and economic burden of Schizophrenia is very significant. In the last 10 years, several studies have analysed the economic burden of Schizophrenia, even if there is a lack of research that has considered the actual cost for the community as the result of each event in the patient's history. Objective: The present study aims to cover this gap by proposing a novel model to evaluate better the cost of Schizophrenia with real data from medical records. Methods: We applied (i) a ‘real life’ analysis of medical database to capture each event of the clinical history and healthcare that could have an economic impact; and (ii) a novel Activity-Based Costing model to quantify the overall annual economic burden of a patient with Schizophrenia treated by public mental health services. We carried out the study with 523 patients with a diagnosis of Schizophrenia in the Department of Mental Health of Bari, in the South of Italy. Results: Our results reveal an overall cost of €41.290 per patient with Schizophrenia per year. Almost half of the cost is due to rehabilitation. The second most important factor is instead related to disability and loss of productivity. Conclusions: We believe that the present approach represents the most effective method to properly estimate actual costs when real-life data are available compared with other studies mainly based on prevalence-based approaches.

Keywords: activity-based costing | cost of Schizophrenia | public mental health services

Abstract: In this work, we propose a Mixed Reality (MR) application to support laboratory lectures in STEM distance education. It was designed following a methodology extendable to diverse STEM laboratory lectures. We formulated this methodology considering the main issues found in the literature that limit MR’s use in education. Thus, the main design features of the resulting MR application are students’ and teachers’ involvement, use of not distracting graphics, integration of traditional didactic material, and easy scalability to new learning activities. In this work, we present how we applied the design methodology and used the framework for the case study of an engineering course to support students in understanding drawings of complex machines without being physically in the laboratory. We finally evaluated the usability and cognitive load of the implemented MR application through two user studies, involving, respectively, 48 and 36 students. The results reveal that the usability of our application is “excellent” (mean SUS score 84.7), and it is not influenced by familiarity with Mixed Reality and distance education tools. Furthermore, the cognitive load is medium (mean NASA TLX score below 29) for all four learning tasks that students can accomplish through the MR application.

Keywords: augmented and virtual reality | distance education and online learning | improving classroom teaching | mixed reality | mobile learning

Abstract: This work investigates the possibility of using a novel “minimal AR” authoring approach to optimize the visual assets used in augmented reality (AR) interfaces to convey work instructions in manufacturing. In the literature, there are no widely supported guidelines for the optimal choice of visual assets (e.g., CAD models, drawings, and videos). Therefore, to avoid the risk of having AR technical documentation based only on the author’s preference, our work proposes a novel authoring approach that enforces the minimal amount of information to accomplish a task. Minimal AR was tested through a simulated AR LEGO-based assembly task. The performance (completion time, mental workload, errors) of 40 users was evaluated with 4 combinations of visual assets in 4 tasks with an increasing amount of information needed. The main result is that visual assets with an excess of information do not significantly increase performance. Therefore, the location of a specified object should be “minimally” authored by an auxiliary model (e.g., a circle and an arrow). For identifying an object within a couple, color coding is preferred to using additional visual assets. If more than two objects must be identified, a drawing visual asset is also needed. Only when the orientation of a selected object must be conveyed, animated product models are required. These insights could be helpful for an optimal design of AR work instructions in a wide range of industrial fields.

Keywords: Authoring | Industrial augmented reality | Industrial metaverse | Minimal information | Visual asset | Work instruction

Abstract: Industrial Augmented Reality (iAR) has demonstrated its advantages to communicate technical information in the fields of maintenance, assembly, and training. However, literature is scattered among different visual assets (i.e., AR visual user interface elements associated with a real scene). In this work, we present a systematic literature review of visual assets used in these industrial fields. We searched five databases, initially finding 1757 papers. Then, we selected 122 iAR papers from 1997 to 2019 and extracted 348 visual assets. We propose a classification for visual assets according to (i) what is displayed, (ii) how it conveys information (frame of reference, color coding, animation), and, (iii) why it is used. Our review shows that product models, text and auxiliary models are, in order, the most common, with each most often used to support operating, checking and locating tasks respectively. Other visual assets are scarcely used. Product and auxiliary models are commonly rendered world-fixed, color coding is not used as often as expected, while animations are limited to product and auxiliary model. This survey provides a snapshot of over 20 years of literature in iAR, useful to understand established practices to orientate in iAR interface design and to present future research directions.

Keywords: Augmented reality | industry | reviews | user interfaces | visualization

Abstract: Industry 4.0 is characterized by great potential for innovation impacting the operator's role, increasingly engaged in smart activities of a decision-making nature. In such a working scenario, operators' working conditions can be effectively improved by applying a user-centered collaborative design approach. To this end, we developed a Virtual Reality-based multiplayer tool exploiting low-cost body tracking technology to evaluate ergonomic postural risk. The tool allows evaluating both in real-time and off-line the ergonomic postural risk according to the Rapid Upper Limb Assessment metrics. By applying this approach, a twofold advantage can be achieved. On the one hand, ergonomic experts can have an immersive three-dimensional visualization of postures even in off-line observations. On the other hand, it is possible to evaluate the ergonomics of workstations in the design phase by having the operator work on virtual mock-ups of workstations, thus allowing a sustainable approach to user-centered collaborative design.

Keywords: Collaborative design | Ergonomics | Kinect V2 | RULA | User-centered | Virtual Reality

Abstract: Although Virtual Reality Social Skills Training has proven its effectiveness in treating psychiatric disorders, this VR application field is still under-researched for two main reasons. The first one is the unavailability of low-cost VR technologies with sufficient computational capacity needed to render realistic Virtual Environments. The second one consists of the need for specialized VR application developers, usually far from the mental health research field. The recent diffusion of low-cost stereoscopic viewers and the introduction of easy and fast VR content authoring systems, such as Cinematic Virtual Reality (CVR), allow overcoming these limitations. CVR makes it possible to capture real scenes through 360 cameras, augment them with additional virtual objects, and finally immerse the user in these synthetic but highly immersive environments. We present the design and the features of the Entellect360 prototype -an innovative tool supporting the rehabilitation process of subjects affected by schizophrenia. It exploits CVR technology to create Virtual Environments aimed at the rehabilitation of psychiatric patients. The Entellect360 features allow for rehabilitation sessions and patient-performance data-collection even under conditions of social distancing. We also explain the experimental protocol and the validation procedure the prototype will undergo to assess its effectiveness.

Keywords: 360-degree virtual reality | Cognitive rehabilitation | Human-computer interaction | Mental health | Social skills training

Abstract: The introduction of the new generation of Head Mounted Displays (HMD) makes users’ experiences in Mixed Reality (MR) environments more engaging. However, these devices still have a limited field of view, which negatively affects the spatial localization process of virtual objects in the 3D environment. The literature presents several visualization techniques to address this issue, but they currently have several drawbacks, such as visual clutter, occlusion of the real scene, high user workload, and there is still no visualization technique that solves such issues definitively. Therefore, inspired by the gaming industry, we present CompassbAR a visualization technique for out-of-view objects. CompassbAR encodes the position of all out-of-view objects surrounding the user, in a 2D bar positioned at the top of the field of view. In addition, we propose a validation procedure and metrics that aim to evaluate the ability of the CompassbAR visualization technique to guide users towards the out-of-view objects.

Keywords: Head-mounted display | Mixed Reality | Visualization techniques

Abstract: Mixed Reality (MR) could help students in the understanding of complex concepts as well as increase their motivation in the learning process. In this work, our aim is to propose a MR application for the support of engineering students in the understanding of assembly drawings of complex machines. We presented the application of our design methodology for this case study. Then, based on the results of a user study with a sample of students, we tried to improve the usability and the user experience of the MR application, proposing an updated version. The usability of the revised application was in the range “good-excellent” (mean SUS score 77.0). We also presented the lessons learned in this case study, that can be a starting point for a renewal of consolidated didactic processes aiming at future application of MR in other STEM courses.

Keywords: Augmented and virtual reality | Distance education and online learning | Improving classroom teaching | Mixed Reality | Mobile learning

Abstract: In this work, a Coarse-Grained Lattice Spring Model to characterize the mechanical behavior of human mesenchymal stem cells subjected to nanoindentation measurements is presented. The model simulated the action of adhesive structures acting on cells, necessary for attaching them to a substrate, and a nanoindentation process, performed by means of an atomic force microscope with a spherical tip. Cells were hypothesized to behave as elastic materials and the model included several subcellular components such as cell cortex and cytoskeleton. The lattice spring model was integrated within an optimization algorithm that iteratively compared the force-indentation curve numerically predicted to the data experimentally obtained, until a best fit condition was reached. The computed mechanical properties of the cell were compared to those obtained via the Hertz contact theory and finite element modelling, showing a good agreement. The proposed lattice spring model appears as a promising tool that can be used, with a very low computational cost, to characterize cell materials and other biological materials.

Keywords: Cell mechanical properties | Lattice spring models | Nanoindentation | Stem cells

Abstract: Numerous computer-based therapies have been designed for cognitive-behavioral interventions to support children with Autism Spectrum Disorder (ASD) in recent years. Among these technologies, Augmented Reality (AR) offers unique educational benefits because it provides children with direct guidance on their learning tasks. In this work, we propose “AR-brickhouse,” an AR application to support ASD children during LEGO therapy. It combines the benefits derived from AR technology and the LEGO tangible user interface with caregivers’ involvement. The novelty of our system concerns the improvement of ASD children’s basic skills such as positioning in space; focusing on tasks; acquisition of concepts of shape, color, and size. A preliminary user study involved eight ASD children and twelve therapists from a real medical center. Our results suggest that the proposed system is easy for therapists and allows children to improve the aforementioned basic skills. In fact, they were able to accomplish LEGO assembly tasks with better accuracy and in less time than traditional LEGO therapy.

Keywords: Augmented Reality | Autism Spectrum Disorder | LEGO assembly | Play therapy

Abstract: Sailing navigation is an activity that requires acquiring and processing information from the surrounding environment. The advancement of technology has enabled sailboats to have an increasing number of onboard sensors that make sailing more user-friendly. However, data provided by these sensors are still visualized on 2D digital displays that imitate traditional analog interfaces. Although these displays are strategically placed on the sailboat, the user needs to divert attention from the primary navigation task to look at them, thus spending a significant amount of cognitive resources. AR-based technologies have the potential to overcome these limitations by displaying information registered in the real environment, but there are no studies in the literature for validating the effectiveness of this technology in the field of sailing. Thus, we designed a head-mounted display AR-based interface to assist users in monitoring wind data to avoid user diversion from the primary task of sailing. We conducted a user study involving 45 participants in an Immersive Virtual Reality simulated environment. We collected objective and subjective measures to compare the AR-based interface with a traditional data visualization system. The AR-based interface outperformed the traditional data visualization system regarding reaction time, cognitive load, system usability, and user experience.

Keywords: Augmented reality | Cognitive load | Human–computer interaction | Nautical | Sailing | User study

Abstract: In the future, many activities will be carried out in the Metaverse: hybrid offices and video-based education are just some examples. The way research is carried out could change, too. In this context, this work investigates the possibility of simulating Augmented Reality (AR) user studies on information presentation in a virtual environment. Organizing an industrial setup is complex; thus, most studies are executed in laboratories. However, lab experiments present limitations, e.g., the number and variety of participants and the availability of facilities. User studies may also be carried out by exploiting simulated AR, as an initial step for the Metaverse, where people are connected regardless of their location. This alternative could be used to carry out experiments on AR information presentation to solve common issues, such as the lack of physical equipment to perform component location tasks and the long time required to collect a large sample of users. Indeed, researchers could propose CAD models with information that simulates the same visual realism achieved with true AR. Moreover, multiple tests could be conducted in parallel by not relying on a limited amount of physical equipment per user. In this work, we developed and evaluated a desktop-simulated testing environment (DSTE) to conduct AR information presentation experiments remotely. We applied it in a pilot user study, revealing that the proposed DSTE was effective for the related research goals. Furthermore, 40 participants reported a positive user experience. The evaluation confirms that using a DSTE is promising for collecting and analyzing data from a wide range of people.

Keywords: AR simulation | industrial metaverse | information presentation | user interaction | user study

Abstract: The choice of furniture in a retail store is usually based on a product catalog and simplistic product renderings with different configurations. We present a preliminary field study that tests a Multi-Sensory In-Store Virtual Reality Customer Journey (MSISVRCJ) through a virtual catalog and a product configurator to support furnishings sales. The system allows customers to stay immersed in the virtual environment (VE) while the sales expert changes the colors, textures, and finishes of the furniture, also exploring different VEs. In addition, customers can experience realistic tactile feedback with in-store samples of furniture they can test. The journey is implemented for a furniture manufacturer and tested in a flagship store. Fifty real customers show positive feedback in terms of general satisfaction, perceived realism, and acceptance. This method can increase purchase confidence, reduce entrepreneurial costs, and leverage in-store versus online shopping.

Keywords: customer journey | furniture | in-store | industrial design | multisensory | retailing | virtual reality

Abstract: Objectives: This study aims to evaluate the acceptability of Cinematic VR technology as a novel therapeutic approach supporting Social Skills Training (SST) rehabilitation interventions among patients with schizophrenia. Materials and Methods: We developed an innovative cinematic VR-based platform as a support system for SST rehabilitation of independent living skills and evaluated its acceptance among psychiatric patients in terms of usability, user experience, and use performance. Ten voluntary participants were enrolled in the study. The study inclusion criteria consisted of age 18-65 years, lack of moderate and severe intellectual disability, no substance use disorder, and schizophrenia spectrum disorder pathology according to DSM V. We administered post treatment questionnaires and developed the platform to capture relevant data automatically. Results: Patients rated usability and user experience from good to excellent. We also observed an improvement in the use performance. Conclusions: Cinematic Virtual Reality based applications showed good acceptability among patients with schizophrenia. This result supports further efforts in evaluating its effectiveness as a novel therapeutic approach supporting SST rehabilitation interventions.

Keywords: Cinematic virtual reality | Schizophrenia rehabilitation | Social skills training | Task performance | Usability | User experience

Abstract: Drill tool positioning in dental implantology is a challenging task requiring 5DOF precision as the rotation around the tool axis is not influential. This work improves the quasi-static visual elements of the state-of-the-art with a novel Augmented Collimation Widget (ACW), an interactive tool of position and angle error visualization based on the gestalt reification, the human ability to group geometric elements. The user can seek in a quick, pre-attentive way the collimation of five (three positional and two rotational) error component widgets (ECWs), taking advantage of three key aspects: component separation and reification, error visual amplification, and dynamic hiding of the collimated components. We compared the ACW with the golden standard in a within-subjects (N=30) user test using 32 implant targets, measuring the time, error, and usability. ACW performed significantly better in positional (+19%) and angular (+47%) precision accuracy and with less mental demand (-6%) and frustration (-13%), but with an expected increase in task time (+59%) and physical demand (+64%). The interview indicated the ACW as the main preference and aesthetically more pleasant than GSW, candidating it as the new golden standard for implantology, but also for other applications where 5DOF positioning is key.

Keywords: Augmented Reality | augmented tool | dental implantology | gestalt principles | spatial orientation | visualization design

Abstract: Immersive Vimial Reality (IVR) training offers the capability to industrial workers to acquire skills and address complex tasks by immersing them in a safe and controlled virtual environment (VE). However, in the literature, IVR training is mainly based on principles of standardization and efficiency without considering the operators' well-being. A novel design approach consists of the introduction in the VE of Positive Computing to improve workers' well-being by applying the Biophilia hypothesis. In this work, we explored the possibility of introducing biophilic elements in a VE training scenario that would support psychological well-being and human potential. However, the introduction of virtual elements not related to the training task may distract operators, impairing their performance. We selected as a training scenario the assembly of a real truck engine. It is accomplished in a workstation, and operators do not interact with the surrounding VE. Therefore, we placed the training area into four different types of VEs: 3D Minimal (MIN), 3D Minimal Biophilic enriched (MIN+BIO), 3D Realistic (REAL), and 3D Realistic Biophilic enriched (REAL+BIO). We compared the MIN and REAL scenarios with the respective biophilic enriched scenarios. The performance of 40 participants was evaluated in terms of completion time, object fixation time, training task accuracy, knowledge accuracy, cognitive load, and user experience. The results revealed that introducing biophilic elements in a VR training environment attracts users' attention in the idle phase of the training. In contrast, they keep concentrating on the task without worsening their performance during the task accomplishment

Keywords: Biophilia Hypothesis | Industrial Training | Positive Computing | Virtual Reality

Abstract: My thesis work is focused on the creation of guidelines for the authoring of the next-generation Industrial Augmented Reality Technical Documentation. The research project aims to provide clear recommendations to optimize the template presentation related to the instruction authoring in an industrial context focusing attention in assessing the real economic impact that AR can offer for companies. This optimization not only will improve the operators' performance by providing them with more easily interpretable information, but also will reduce developers' computational costs to companies in both programming and 3D modeling. Finally, the outcomes obtained will provide guidelines that can make the authoring of AR technical documentation accessible even to technical writers who are not particularly skilled in AR.

Keywords: Authoring | Industrial Augmented Reality | Information Presentation | Interaction paradigms | Mixed/augmented reality | Technical Documentation | Visualization design and evaluation methods | Work Instructions | [Human-centered computing]: Human computer interaction (HCI) | [Human-centered computing]: Visualization

Abstract: As noise is a pervasive element of work environments, it could affect workers' performance and wellbeing. In particular environments, such as confined spaces, noise could represent an even greater disruptor because reverberation effects amplify exposure levels and could affect cognitive abilities. The study of the effects of noise has mixed results in the literature and was scarcely investigated with reference to this application scenario. Nowadays, Immersive Virtual Reality (IVR) can simulate in a realistic way the working conditions in these environments and consequently simplify the investigations in this field that otherwise would be expensive and difficult to implement for safety reasons. In this work, we verify the ability of a current high-end IVR system to reproduce the acoustic conditions of a confined space realistically, and we evaluate the effects on user cognitive performance and user-perceived workload of a noise source typical of these industrial working environments.

Keywords: immersive virtual reality | N-back test | noise effects | NOISE-TLX | user experience | user performance

Abstract: The definition of an innovative category of implantable devices, characterized not only by a fully customization but also by improved osteoconductive and functionalized bioactive surfaces, needs to be supported by a systematic approach. In the present work, a new human-machine interface based on the Mixed Reality (MR) is proposed and focused on the implantation of a fully customized prosthesis. By means of an informal and exploratory focus group (i.e., without using a structured questionnaire), the limitations belonging to the current procedure were highlighted and a first list of user needs was subsequently defined. The MR interface was then considered to be the most suitable solution to match the gathered requirements. However, the doctors proposed also to develop a desktop interface for a finer and easier manipulation of 3D models. The proposed MR application offers several advantages from the possibility to display 3D anatomical structures and 3D models of custom prostheses in an immersive environment to the optimized communication and data exchange among the players (medical staff, doctors and engineers). A mock-up of the MR applications is presented in this work to show the results of the design stage, before the deployment of the application.

Keywords: Collaborative Network | Fully Custom Implants | Immersive Environment | Mixed Reality

Abstract: The industrial transition to the 4.0 paradigm defines new scenarios in which the operator plays a central role within the industrial ecosystem. Thanks to the enabling technologies of Industry 4.0, it is possible to effectively improve operators' working conditions by applying the Human-Centered approach. Nowadays, one of the main challenges is to reduce work-related musculoskeletal disorders resulting from ergonomically incorrect working conditions in order to prevent the occurrence of occupational diseases. To this end, we developed a software tool that leverages a low-cost D-RGB camera (Kinect v2) to track the human body and an Augmented Reality (AR) visualization system based on Microsoft HoloLens 2. The tool assesses postural ergonomic risk in real-time according to the Rapid Upper Limb Assessment (RULA) metric. The proposed AR application allows a three-dimensional visualization of postures, which can be observed directly superimposed on the operator's body in the real scene. This approach aims to optimize the understanding of postures by creating a link between real information (operator's body) and virtual information (virtual skeleton, RULA score, and angles) by providing a simple and immediate user interface for ergonomists.

Keywords: Augmented Reality | Ergonomics | Hololens 2 | Human-Centered | Kinect v2 | RULA

Abstract: This study investigates the use of augmented reality technology (AR) in the field of maritime navigation and how researchers and designers have addressed AR data visualisation. The paper presents a systematic review analysing the publication type, the AR device, which information elements are visualised and how, the validation method and technological readiness. Eleven AR maritime solutions identified from scientific papers are studied and discussed in relation to previous navigation tools. It is found that primitive information such as course, compass degrees, boat speed and geographic coordinates continue to be fundamental information to be represented even with AR maritime solutions.

Keywords: augmented reality | data visualisation | human-computer interaction | maritime

Abstract: The procedure commonly adopted to characterize cell materials using atomic force microscopy neglects the stress state induced in the cell by the adhesion structures that anchor it to the substrate. In several studies, the cell is considered as made from a single material and no specific information is provided regarding the mechanical properties of subcellular components. Here we present an optimization algorithm to determine separately the material properties of subcellular components of mesenchymal stem cells subjected to nanoindentation measurements. We assess how these properties change if the adhesion structures at the cell-substrate interface are considered or not in the algorithm. In particular, among the adhesion structures, the focal adhesions and the stress fibers were simulated. We found that neglecting the adhesion structures leads to underestimate the cell mechanical properties thus making errors up to 15%. This result leads us to conclude that the action of adhesion structures should be taken into account in nanoindentation measurements especially for cells that include a large number of adhesions to the substrate.

Keywords: Cell cortex | Cell mechanics | Cytoskeleton | Finite element method | Focal adhesion | Stress fibers

Abstract: Today’s sailing visualization instruments struggle to cope with the increasing number of onboard sensors, automation, artificial intelligence, and the high dy-namism of the crew. Current solutions scatter multiple displays all over the boat, both inside and outside, potentially reducing usability and increasing costs. This work presents a systematic review of augmented reality (AR) as an integral solution for sailing data visualization, which revealed four scientific papers and eight commercial products. We analyzed the publication type, the AR hardware, what and how information is presented using AR, the validation method (if present), and the technological readiness. We defined the technical requirements needed for the AR device for sailing and distinguished a first generation of commercial solutions based on head-up displays from a second one based on proper augmentation with stereo head-mounted displays. The displayed information elements are limited in number and are commonly 2-D graphics (e.g., text and symbols) with a screen-relative frame of reference (as opposed to body-or world-relative). The most visu-alized elements are heading (10) followed by wind direction (8), boat speed (7) compass (7), and wind speed (7). We also found that most of the solutions lack critical evaluation. We conclude that AR has the potential to integrate sailing data from different systems and to improve accessibility, situation awareness, and safety for a large group of users. However, the main limitations are the lack of AR head-mounted displays suitable or adaptable for sailing conditions, an extensive exploration of 3-D interface elements, and an adequate number of usability studies in the scientific literature.

Keywords: Augmented reality | Data visualization | Human-computer interaction | Nautical instruments | Sailing

Abstract: The knowledge of the mechanical properties is the starting point to study the mechanobiology of mesenchymal stem cells and to understand the relationships linking biophysical stimuli to the cellular differentiation process. In experimental biology, Atomic Force Microscopy (AFM) is a common technique for measuring these mechanical properties. In this paper we present an alternative approach for extracting common mechanical parameters, such as the Young's modulus of cell components, starting from AFM nanoindentation measurements conducted on human mesenchymal stem cells. In a virtual environment, a geometrical model of a stem cell was converted in a highly deformable Coarse-Grained Elastic Network Model (CG-ENM) to reproduce the real AFM experiment and retrieve the related force-indentation curve. An ad-hoc optimization algorithm perturbed the local stiffness values of the springs, subdivided in several functional regions, until the computed force-indentation curve replicated the experimental one. After this curve matching, the extraction of global Young's moduli was performed for different stem cell samples. The algorithm was capable to distinguish the material properties of different subcellular components such as the cell cortex and the cytoskeleton. The numerical results predicted with the elastic network model were then compared to those obtained from hertzian contact theory and Finite Element Method (FEM) for the same case studies, showing an optimal agreement and a highly reduced computational cost. The proposed simulation flow seems to be an accurate, fast and stable method for understanding the mechanical behavior of soft biological materials, even for subcellular levels of detail. Moreover, the elastic network modelling allows shortening the computational times to approximately 33% of the time required by a traditional FEM simulation performed using elements with size comparable to that of springs.

Keywords: Atomic force microscopy | Cell material characterization | Elastic network model | Meshless methods

Abstract: This research investigates the application of positive computing principles to Virtual Reality (VR) training scenarios where the Virtual Environment (VE) has not a direct influence on operator learning. We propose to place the 3D models of the only objects needed for the task in a VE consisting of 360° panoramas of natural environments. We made a preliminary evaluation of the user experience which showed that the hedonic quality is significantly higher with this VE than a 3D modeled empty room. However, we also observed a reduction of the pragmatic quality, due to potential distractions. Thus, further research is needed to demonstrate the efficacy of our positive computing approach in training against a traditional one based on the faithful 3D reproduction of the real environment.

Keywords: Industrial Training | Positive Computing | Virtual Reality

Abstract: The research presented in this contribution aims to investigate user preferences about how to convey information in Industrial Augmented Reality (IAR) interfaces to the user. Our interest is focused on the opinion of potential technical writers of IAR documentation for assembly or maintenance operations. Authoring of IAR interfaces imply a choice among various visual assets, that is influenced by the information type and the AR display used. There are no specific standards in the literature to follow and it is challenging to extract guidelines from the literature. This study gathers preferences of 105 selected users that have knowledge about IAR issues, graphical user interfaces (GUI) designing, and assembly/maintenance procedures. The results of this survey show a great preference for 3D CAD models of components (product model) for almost all the information types. However, some alternative visual assets have also been proposed, such as video and auxiliary models. Contrary to common practices in industry, text was the least preferred visual asset. The insights from this research can help other IAR technical writers in the authoring of their interfaces.

Keywords: Graphic Interface | Industrial Augmented Reality | Manual Assembly | Visual Asset

Abstract: Sailing is a multidisciplinary activity that requires years to master. Recently this sustainable sport is becoming even harder due to the increasing number of onboard sensors, automation, artificial intelligence, and the high performances obtainable with modern vessels and sail designs. Augmented Reality technology (AR) has the potential to assist sailors of all ages and experience level and improve confidence, accessibility, situation awareness, and safety. This work presents our ongoing research and methodology for developing AR assisted sailing. We started with the problem definition followed by a state of the art using a systematic review. Secondly, we elicited the main task and variables using an online questionnaire with experts. Third, we extracted the main variables and conceptualized some visual interfaces using 3 different approaches. As final phase, we designed and implemented a user test platform using a VR headset to simulate AR in different marine scenarios. For a real deployment, we witness the lack of available AR devices, so we are developing one specific headset dedicated to this task. We also envision the possible redesign of the entire boat as a consequence of the introduction of AR technology.

Keywords: Augmented Reality | Human Computer Interaction | Nautical | Sailing | Yacht

Abstract: Since its beginning at the end of 2019, the pandemic spread of the severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) caused more than one million deaths in only nine months. The threat of emerging and re-emerging infectious diseases exists as an imminent threat to human health. It is essential to implement adequate hygiene best practices to break the contagion chain and enhance society preparedness for such critical scenarios and understand the relevance of each disease transmission route. As the unconscious hand–face contact gesture constitutes a potential pathway of contagion, in this paper, the authors present a prototype system based on low-cost depth sensors able to monitor in real-time the attitude towards such a habit. The system records people’s behavior to enhance their awareness by providing real-time warnings, providing for statistical reports for designing proper hygiene solutions, and better understanding the role of such route of contagion. A preliminary validation study measured an overall accuracy of 91%. A Cohen’s Kappa equal to 0.876 supports rejecting the hypothesis that such accuracy is accidental. Low-cost body tracking technologies can effectively support monitoring compliance with hygiene best practices and training people in real-time. By collecting data and analyzing them with respect to people categories and contagion statistics, it could be possible to understand the importance of this contagion pathway and identify for which people category such a behavioral attitude constitutes a significant risk.

Keywords: Azure kinect | Body tracking | Hygiene best practices | Occupational safety | Pandemics containment | Safety training

Abstract: Despite the wide use of scaffolds with spherical pores in the clinical context, no studies are reported in the literature that optimize the micro-architecture dimensions of such scaffolds to maximize the amounts of neo-formed bone. In this study, a mechanobiology-based optimization algorithm was implemented to determine the optimal geometry of scaffolds with spherical pores subjected to both compression and shear loading. We found that these scaffolds are particularly suited to bear shear loads; the amounts of bone predicted to form for this load type are, in fact, larger than those predicted in other scaffold geometries. Knowing the anthropometric characteristics of the patient, one can hypothesize the possible value of load acting on the scaffold that will be implanted and, through the proposed algorithm, determine the optimal dimensions of the scaffold that favor the formation of the largest amounts of bone. The proposed algorithm can guide and support the surgeon in the choice of a "personalized" scaffold that better suits the anthropometric characteristics of the patient, thus allowing to achieve a successful follow-up in the shortest possible time.

Keywords: Bone tissue engineering | Computational mechanobiology | Geometry optimization | Parametric CAD (Computer aided design) model | Python code

Abstract: This paper investigates the Augmented Reality (AR) technology with a novel approach based on patent research. We searched the USPTO for AR-related granted patents in the period 1993–2018, we selected and manually browse a total of 2,373, we classified them in five key technological classes i.e., display device, tracking, user interaction, application, and system, and we finally analyzed the results. The main contribution of this paper is the investigation of the technological trends, with outcomes that can be useful for researchers and developers for technical steering, but also for policymakers, managers and entrepreneurs for technology scouting and forecasting. Our study found that AR technological development has especially increased in the last decade. In particular, we evidenced a remarkable steady of 82 % annual growth rate of the number of granted patents after 2012. From geographical distribution, we found that North America is the leader (68 %); Asia (18 %) and Europe (13 %) are lagging behind despite dedicated Industry 4.0 policies actuated by the governments. Another nontrivial result is the incoherency between the owners of a high quantity of patents and those highly impacting. In fact, only Microsoft Corporation and Amazon Technologies are at the same time in the top 10 of the most patent-intensive organizations and the top 10 of highly impacting organizations. Moreover, the majority of the patents are owned by companies, albeit some of the highly impacting ones come from universities or research centers. These findings provide theoretical, managerial, and policy implications for future research activities in the AR domain.

Keywords: Application | AR systems | Augmented reality | Display device | Geographical distribution | Holograms | Human-machine interaction | Immersive technologies | Industry 4.0 | Interactive technologies | Patent analysis | Presence | Review | Technological innovation | Technological trend | Technology forecasting | Technology scouting | Tracking | User interaction | Visual overlay

Abstract: Technical documentation is evolving from static contents presented on paper or via digital publishing to real-time on-demand contents displayed via virtual and augmented reality (AR) devices. However, how best to provide personalized and context-relevant presentation of technical information is still an open field of research. In particular, the systems described in the literature can manage a limited number of modalities to convey technical information, and do not consider the 'people' factor. Then, in this work, we present a Context-Aware Technical Information Management (CATIM) system, that dynamically manages (1) what information as well as (2) how information is presented in an augmented reality interface. The system was successfully implemented, and we made a first evaluation in the real industrial scenario of the maintenance of a hydraulic valve. We also measured the time performance of the system, and results revealed that CATIM performs fast enough to support interactive AR.

Keywords: Augmented reality | Context-aware | Human-centered design | Human-computer interaction | Industrial | Information manager | Maintenance | Technical documentation

Abstract: In spite of the rather large use of the fused deposition modeling (FDM) technique for the fabrication of scaffolds, no studies are reported in the literature that optimize the geometry of such scaffold types based on mechanobiological criteria. We implemented a mechanobiology-based optimization algorithm to determine the optimal distance between the strands in cylindrical scaffolds subjected to compression. The optimized scaffolds were then 3D printed with the FDM technique and successively measured. We found that the difference between the optimized distances and the average measured ones never exceeded 8.27% of the optimized distance. However, we found that large fabrication errors are made on the filament diameter when the filament diameter to be realized differs significantly with respect to the diameter of the nozzle utilized for the extrusion. This feasibility study demonstrated that the FDM technique is suitable to build accurate scaffold samples only in the cases where the strand diameter is close to the nozzle diameter. Conversely, when a large difference exists, large fabrication errors can be committed on the diameter of the filaments. In general, the scaffolds realized with the FDM technique were predicted to stimulate the formation of amounts of bone smaller than those that can be obtained with other regular beam-based scaffolds.

Keywords: Biomaterials | Geometry optimization | Mechanobiology | Scaffold design | Tissue engineering

Abstract: Although the increasing use of automation in industry, manual assembly stations are still common and, in some situations, even inevitable. Current practice in manual assembly lines is to balance them using the takt-time of each workstation and harmonize it. However, this approach mostly does not include ergonomic aspects and thus it may lead to workforce musculoskeletal disorders, extended leaves, and demotivation. This paper presents a holistic human-centric optimization method for line balancing using a novel indicator the ErgoTakt. ErgoTakt improves the legacy takt-time and helps to find an optimum between the ergonomic evaluation of an assembly station and its balance in time. The authors used a custom version of the ErgoSentinel Software and a Microsoft Kinect depth camera to perform online and real-time ergonomic assessment. An optimization algorithm is developed to find the best-fitting solution by minimizing a function of the ergonomic RULA-value and the cycle time of each assembly workstation with respect to the worker's ability. The paper presents the concept, the system-setup and preliminary evaluation of an assembly scenario. The results demonstrate that the new approach is feasible and able to optimize an entire manual assembly process chain in terms of both, economic aspects of a well-balanced production line as well as the ergonomic issue of long term human healthy work.

Keywords: Assembly digitalization | Ergonomic assessment | Line balancing

Abstract: The enabling technologies of the Industry 4.0 program can support the smart factory of the future to face the challenges related to their sustainable growth. In particular, given the progressive ageing of the population, it is mandatory to develop systems able to preserve operators' wellbeing and to prevent the incidence of work-related musculoskeletal disorders. By exploiting a recently introduced low-cost sensor we developed and validated a reliable prototype for automatic assessment of ergonomic postural risk in the factory shopfloor. Encouraged by the results of the validation process, we enhanced the prototype functionalities. The tool will serve both as a monitoring system for the evaluation of postural risk and a training system for increasing operators' awareness. In this paper, we describe the design of the prototype and the enhanced functionalities of the final version, - the ErgoSentinel.

Keywords: Ergonomics | I4.0 | Kinect® V2 | Postural risk assessment | RULA | Sustainable work

Abstract: The aim of this study is to understand if the shape of a cell can affect the characterization process of the mechanical properties via nanoindentation measurements. The characterization of the cell material by atomic force microscopy, in fact, traditionally implements the Hertz contact theory that is based on hypotheses not satisfied in the contact Atomic Force Microscope tip/cell and that do not take into account the actual cell morphology. In previous experimental studies, the mechanical properties of colorectal cancer cells differently shaped (rounded or elongated cells) and sized were determined via nanoindentation measurements. Implementing the Hertz theory, the authors found that differences in mechanical properties exist between the different cell lines with different shape. At this point, the question that can be raised is the following. Is it possible to state that this difference depends on the differences intrinsically existing between the mechanical properties of the investigated cells? Or, this difference can be justified with the difference in cells shape? In other words, the differences seen with the Hertz theory can depend on the fact that the cell shape was not taken into account. To respond to this question, the nanoindentation process of the different colorectal cancer cells was simulated via the finite element method. The finite element models reproducing the cells morphology were integrated into a numerical optimization algorithm that cyclically perturbs the cell mechanical properties until the difference between the force-indentation curve retrieved numerically and that obtained experimentally becomes smaller than an a priori fixed ε value. Once this occurs, the optimization algorithm stops and gives in output the optimal cell material properties. Interestingly, we found that the mechanical properties obtained via the Hertz contact theory are significantly different with respect to those computed with the proposed approach. Furthermore, we found that the material properties of the rounded cells are intrinsically different with respect to those of the elongated ones. The proposed approach provides new insights on the cell mechanobiology and on the effect of cell shape on the specific tasks in cancer growth and invasion.

Keywords: Cell material characterization | Cell modelling | Cell shape

Abstract: Augmented Reality is considered one of the most promising technologies for Industry 4.0. Augmented Reality allows to display the needed information at the right time and to locate it in the desired space, superimposing it to the real world. In this way, it could simplify the work of industrial operators in a variety of tasks, from planning and commissioning to assembly and maintenance. Despite the growing research interest and efforts for the development of Augmented Reality applications and technologies for the industrial domain, Augmented Reality is still rarely used in real industrial procedures, often remaining at a conceptual level. In fact, developers fail to completely answer the actual needs of industries and workers because of a lack of knowledge of the context and the absence of guidelines to drive the design and development of Augmented Reality applications. One of the open issues is the choice of the proper visualization methods to display technical information in Augmented Reality, which is not trivial. Both the paper-based documentation, based on text and illustrations, and digital documentation, including CAD models and image or video-based tutorials, present different criticalities when adapted to the Augmented Reality technology. Other visual material has been developed specifically to be used in Augmented Reality, but it is difficult to use because of a lack of standards which are instead present for the former paper-based and digital documentation. In this work, we categorize and compare different Augmented Reality visual assets, illustrating their advantages and disadvantages and providing directions for future research.

Keywords: Augmented Reality | Graphical User Interface | Industry 4.0 | Technical documentation

Abstract: Schizophrenia poses a significant economic burden on the healthcare system as well as it has a significant impact on society at large. Reasons for such a high economic burden of schizophrenia include the frequent relapses and hospitalizations occurring in this disorder. We analyze the effectiveness of long-acting injectable antipsychotics (LAIs) compared to oral medications, in terms of “clinical process management” in a sample of patients with a diagnosis of schizophrenia spectrum disorder treated in community mental health centers. An observational, retrospective, mirror-image study was carried out to evaluate the effectiveness of LAIs compared to oral medications in terms of number of hospitalizations, emergency visits and planned visits on a 10-year period (from July 2007 to June 2017). Differences between first and second generation LAIs were also explored. Our findings show that hospitalization and emergency visits are significantly decreased with the use of LAIs, while planned visits are increased in patients treated with LAIs. Our results suggest that LAIs, in particular, second generation ones, reduce hospitalization rates and emergency visits, improving the economic burden of schizophrenia. Therefore, LAIs should be considered a cost-effective treatment in the management of schizophrenia under routine conditions.

Abstract: By combining load adaptive algorithms with mechanobiological algorithms, a computational framework was developed to design and optimize the microarchitecture of irregular load adapted scaffolds for bone tissue engineering. Skeletonized cancellous bone-inspired lattice structures were built including linear fibers oriented along the internal flux of forces induced by the hypothesized boundary conditions. These structures were then converted into solid finite element models, which were optimized with mechanobiology-based optimization algorithms. The design variable was the diameter of the beams included in the scaffold, while the design objective was the maximization of the fraction of the scaffold volume predicted to be occupied by neo-formed bony tissue. The performance of the designed irregular scaffolds, intended as the capability to favor the formation of bone, was compared with that of the regular ones based on different unit cell geometries. Three different boundary and loading conditions were hypothesized, and for all of them, it was found that the irregular load adapted scaffolds perform better than the regular ones. Interestingly, the numerical predictions of the proposed framework are consistent with the results of experimental studies reported in the literature. The proposed framework appears to be a powerful tool that can be utilized to design high-performance irregular load adapted scaffolds capable of bearing complex load distributions.

Keywords: finite element method | irregular and regular scaffolds | load adaptive algorithms | mechanobiological algorithms | robustness of optimized structures | structural optimization algorithms

Abstract: Due to the recent advances in technologies for gesture recognition, midair gestures can be considered the interface of the future in a large number of applications. However, designing effective interfaces with midair gestures is not an easy task because the design is application dependent and it must fulfill many requirements at the same time. Despite the availability of general guidelines in the literature, clear and well-established procedures for the optimal design of midair gesture-based interfaces are, to date, not available and remain an open issue. The main contribution of this paper is a user-centered modular framework, which integrates existing and novel methods. It supports the designer considering multiple aspects including ergonomics, memorability, and specific user requirements tailored to the application scenario. The framework involves three design steps and a final validation step, also supported by dedicated software. We tested with success the proposed framework in an industrial case study, where technicians must easily access technical information by browsing digital manuals during maintenance operations.

Keywords: Consumed endurance (CE) | ergonomics | gesture vocabulary | midair gesture interface | user-centered elicitation approach

Abstract: Blepharospasm (BSP) is an adult-onset focal dystonia with phenomenologically heterogeneous effects, including, but not limited to, blinks, brief or prolonged spasms, and a narrowing or closure of the eyelids. In spite of the clear and well-known symptomatology, objectively rating the severity of this dystonia is a rather complex task since BSP symptoms are so subtle and hardly perceptible that even expert neurologists can rate the gravity of the pathology differently in the same patients. Software tools have been developed to help clinicians in the rating procedure. Currently, a computerised video-based system is available that is capable of objectively determining the eye closure time, however, it cannot distinguish the typical symptoms of the pathology. In this study, we attempt to take a step forward by proposing a neural network-based software able not only to measure the eye closure, time but also to recognise and count the typical blepharospasm symptoms. The software, after detecting the state of the eyes (open or closed), the movement of specific facial landmarks, and properly implementing artificial neural networks with an optimised topology, can recognise blinking, and brief and prolonged spasms. Comparing the software predictions with the observations of an expert neurologist allowed assessment of the sensitivity and specificity of the proposed software. The levels of sensitivity were high for recognising brief and prolonged spasms but were lower in the case of blinks. The proposed software is an automatic tool capable of making objective ‘measurements’ of blepharospasm symptoms.

Keywords: Blepharospasm | Blepharospasm rating scale | Eye closure time | Focal dystonia | Neural network topology optimisation

Abstract: Augmented Reality (AR), is one of the most promising technology for technical manuals in the context of Industry 4.0. However, the implementation of AR documentation in industry is still challenging because specific standards and guidelines are missing. In this work, we propose a novel methodology for the conversion of existing “traditional” documentation, and for the authoring of new manuals in AR in compliance to Industry 4.0 principles. The methodology is based on the optimization of text usage with the ASD Simplified Technical English, the conversion of text instructions into 2D graphic symbols, and the structuring of the content through the combination of Darwin Information Typing Architecture (DITA) and Information Mapping (IM). We tested the proposed approach with a case study of a maintenance manual of hydraulic breakers. We validated it with a user test collecting subjective feedbacks of 22 users. The results of this experiment confirm that the manual obtained using our methodology is clearer than other templates.

Keywords: Augmented reality | Industry 4.0 | Maintenance support | Technical documentation

Abstract: Technical information presentation is evolving from static contents presented on paper or via digital publishing to real-time context-aware contents displayed via virtual and augmented reality devices. We present a Context-Aware Technical Information Management system (CATIM), that dynamically manages (1) what information as well as (2) how information is presented in an augmented reality interface. CATIM acquires context data about activity, operator, and environment, and then based on these data, proposes a dynamic augmented reality output tailored to the current context. The system was successfully implemented and preliminarily evaluated in a case study regarding the maintenance of a hydraulic valve.

Keywords: Aware information | Context | Industrial augmented reality | Technical information manager

Abstract: In this work, we present an Augmented Reality (AR) application for handheld devices that support operators in information retrieval tasks in maintenance procedures in the context of Industry 4.0. Indeed, using AR allows the integration of knowledge-based information, traditionally used by operators and mainly provided in the form of technical drawings, and data available from sensors on the equipment. This approach is suggested by companies, especially Small and Medium-sized Enterprises, that want a gradual introduction of Industry 4.0 technologies within their established practices. We implemented a prototype of the application for the case study of a milling plant. The application augments on a Piping and Instrumentation Diagram (P&ID) of the plant some virtual interactive graphics (hotspots) referenced to specific components drawn. Component data are retrieved, through a user interface, directly from the factory database and displayed on the screen. We evaluated the application through a user study aimed at comparing the AR application with the current practice, based on paper documentation, for an information retrieval task within a maintenance procedure. Results of the study revealed that AR is effective for this task in terms of task time reduction and usability. The AR application was tested both with a tablet and a smartphone, but results revealed that using tablet does not improve user performance in terms of task time, error rate, and usability.

Keywords: Augmented Reality | Industry 4.0 | Information retrieval | Maintenance | User evaluation

Abstract: In this work, we present an Augmented Reality framework for handheld devices that enhance users in the comprehension of plant information traditionally conveyed through printed Piping and Instrumentation Diagrams (P&ID). The proposed framework augments on the P&ID of a plant some virtual interactive graphics (hotspots) referenced to specific components drawn on the P&ID. In this way, it is possible to easily find all the components belonging to the same category (e.g., all the pumps). By tapping, on the tablet screen, on a single hotspot further multimedia information can be displayed: Technical data, 3D CAD model of the component, and 360° images of the plant section. The application is connected to the factory database where all the information associated with the plant components is stored. We used, as a case study, the cleaning section of a milling plant. With the tool presented in this work, technicians will be able to find information updated and in less time, so reducing the intervention time and increasing the accuracy of the operations. Furthermore, the cognitive load associated with the task of understanding the plant is highly reduced through the use of virtual information displayed using Augmented Reality.

Keywords: Augmented Reality | Industrial plant | Industry 4.0 | P&ID | Technical information

Abstract: Scaffolds are porous biomaterials that serve to replace missing portions of bone. Scaffolds must possess a proper geometry and hence have to be adequately designed to correctly undergo to the load and to favor the differentiation of the mesenchymal stem cells invading it, into osteoblasts. It is commonly known that scaffold geometry affects the quality of the regenerated bone creating within the scaffold pores. Scaffold properly designed trigger favorable values of biophysical stimuli that are responsible for the reactions cascade leading to the bone formation. In this paper an optimization algorithm is proposed that, based on mechano-regulation criteria, identifies the optimal geometry of scaffolds, i.e. the geometry that favors the formation of the largest amounts of bone in the shortest time. In detail, the algorithm, written in the Matlab environment, incorporates parametric finite element models of different scaffold types, a computational mechanobiological model and structural optimization routines. The scaffold geometry is iteratively perturbed by the algorithm until the optimal geometry is computed, i.e. the geometry that triggers the most favorable values of the biophysical stimulus which lead to the formation of mature bone. Mesenchymal stem cells were hypothesized to spread within the fracture domain and uniformly occupy the scaffold pores.

Keywords: Hexahedron unit cell | Mechanobiology | Rhombicuboctahedron unit cell | Unit cell geometry

Abstract: Enhancing the performance of scaffolds for bone regeneration requires a multidisciplinary approach involving competences in the fields of Biology, Medicine and Engineering. A number of studies have been conducted to investigate the influence of scaffolds design parameters on their mechanical and biological response. The possibilities offered by the additive manufacturing techniques to fabricate sophisticated and very complex microgeometries that until few years ago were just a geometrical abstraction, led many researchers to design scaffolds made from different unit cell geometries. The aim of this work is to find, based on mechanobiological criteria and for different load regimes, the optimal geometrical parameters of scaffolds made from beam-based repeating unit cells, namely, truncated cuboctahedron, truncated cube, rhombic dodecahedron and diamond. The performance, -expressed in terms of percentage of the scaffold volume occupied by bone-, of the scaffolds based on these unit cells was compared with that of scaffolds based on other unit cell geometries such as: hexahedron and rhombicuboctahedron. A very intriguing behavior was predicted for the truncated cube unit cell that allows the formation of large amounts of bone for low load values and of very small amounts for the medium-high ones. For high values of load, scaffolds made from hexahedron unit cells were predicted to favor the formation of the largest amounts of bone. In a clinical context where medical solutions become more and more customized, this study offers a support to the surgeon in the choice of the best scaffold to be implanted in a patient-specific anatomic region.

Keywords: Beam-based scaffolds | Bone tissue engineering | Diamond | Mechanobiology | Rhombic dodecahedron | Truncated cube | Truncated cuboctahedron | Unit cell

Abstract: One of the most effective strategies that can be adopted to make successful cultural heritage expositions consists in attracting the visitors’ attention and improving their enjoyment/engagement. A mid-air gesture-based Natural User Interface was designed, through the user-centric approach, for the navigation of virtual tours in cultural heritage exhibitions. In detail, the proposed interface was developed to “visit” Murgia, a karst zone lying within Puglia, very famous for its fortified farms, dolines, sinkholes, and caves. Including an “immersive” gesture-based interface was demonstrated to improve the user's experience thus giving her/him the sensation of “exploring” in a seamless manner the wonderful and rather adventurous sites of Murgia. User tests aimed at comparing the implemented interface with a conventional mouse-controlled one confirmed the capability of the proposed interface to enhance the user engagement/enjoyment and to make “more” natural/real, the virtual environment.

Keywords: Gesture vocabulary design | Natural user interface | User-centric approach | Virtual tour

Abstract: The evolution of technical documentation in the age of Industry 4.0 is going towards the use of visual manuals, in particular exploiting Augmented Reality (AR) technology. Traditional manuals are rich of text instructions that in AR applications are not advisable. In fact text occludes the real scene behind and it is an issue for the translation. For this reason, we propose to create and adopt a controlled and exhaustive vocabulary of graphical symbols, to be used in AR to represent maintenance instructions. In particular, in this work we identified the most frequent maintenance actions used in manuals, and converted them into graphical symbols. Then, we made an elicitation of the symbols designed and created different candidate vocabularies of symbols basing on the criteria found in literature of guessability and homogeneity. Moreover, the vocabularies had to respect two constraints: conflict set and reversibility. Finally, we identified the best of symbols and integrated this one in a real AR application for remote maintenance.

Keywords: Augmented Reality | Industry 4.0 | Maintenance

Abstract: In a context more and more oriented towards customized medical solutions, we propose a mechanobiology-driven algorithm to determine the optimal geometry of scaffolds for bone regeneration that is the most suited to specific boundary and loading conditions. In spite of the huge number of articles investigating different unit cells for porous biomaterials, no studies are reported in the literature that optimize the geometric parameters of such unit cells based on mechanobiological criteria. Parametric finite element models of scaffolds with rhombicuboctahedron unit cell were developed and incorporated into an optimization algorithm that combines them with a computational mechanobiological model. The algorithm perturbs iteratively the geometry of the unit cell until the best scaffold geometry is identified, i.e. the geometry that allows to maximize the formation of bone. Performances of scaffolds with rhombicuboctahedron unit cell were compared with those of other scaffolds with hexahedron unit cells. We found that scaffolds with rhombicuboctahedron unit cell are particularly suited for supporting medium-low loads, while, for higher loads, scaffolds with hexahedron unit cells are preferable. The proposed algorithm can guide the orthopaedic/surgeon in the choice of the best scaffold to be implanted in a patient-specific anatomic region.

Keywords: Computational mechanobiology | Morphology optimization | Rhombicuboctahedron | Scaffold unit cell

Abstract: Design of scaffolds for tissue engineering entails multi-disciplinary and multi-scale aspects. Since in vivo analysis of the tissue regeneration process is quite difficult in terms of selecting experimental protocols and requires considerable amount of time, a variety of numerical models have been developed to simulate mechanisms of tissue differentiation. The tremendous enhancement in computing power led researchers to develop more and more sophisticated models mostly based on finite element techniques and mechano-regulation computational models. In this article, we present an algorithm that combines the finite element model of an open-porous scaffold, a numerical optimization routine and a mechanobiological model. This algorithm has been utilized to determine both, the best scaffold geometry and the best load value (to apply on the scaffold) that allow the bone formation to be maximized.

Keywords: Bone tissue scaffold | Computational mechanobiology | Geometry optimization | Scaffold micro-architecture

Abstract: Background: New sources of stem cells in adult organisms are constantly emerging. Postnatal Mesenchymal Stem Cells (MSCs), are the most promising support to perform an effective regenerative medicine: such cells have the ability to differentiate into several lineages, such as osteoblasts and chondroblasts, providing novel strategies to improve different complex treatments, during bone regeneration. 3D-printed biomaterials can be designed with geometry aimed to induce stem cells to differentiate towards specific lineage. Objective: The interaction between stem cells easy to isolate and engineered 3D-printed scaffolds can translate the tissue bio-engineering into bone regenerative surgery. For those reasons, to better identify the complexity represented by the activities and responses of MSCs requires the advance of new target therapies which are not current in endocrine, metabolic and immune disorders and yet to be developed. Method: This topical review briefly focuses on the new approaches of translational medicine with the use of MSCs and scaffolds engineered with the aid of 3D-printing technology, highlights the osteogenic functions and addresses their applications across the breadth of regenerative medicine. Results: The application of bone constructs consisting of the engineered scaffold and MSCs as well as the aspects related to the optimal scaffold geometry that favours the best MSCs differentiation and the improvement of concepts as “sensing surface” were also discussed. Conclusion: Regenerative surgery is largely growing in the field of translational medicine. The use of new sources of MSCs and the improvement of new concepts of bio-engineered scaffolds will certainly be the next step of customized medicine.

Keywords: 3D-printed scaffolds | Customized medicine | Mesenchymal stem cells | Regenerative medicine | Tissue engineering | Translational medicine

Abstract: Thanks to the recent advances of three-dimensional printing technologies the design and the fabrication of a large variety of scaffold geometries was made possible. The surgeon has the availability of a wide number of scaffold micro-architectures thus needing adequate guidelines for the choice of the best one to be implanted in a patient-specific anatomic region. We propose a mechanobiology-based optimization algorithm capable of determining, for bone tissue scaffolds with an assigned geometry, the optimal value Lopt of the compression load to which they should be subjected, i.e. the load value for which the formation of the largest amounts of bone is favoured and hence the successful outcome of the scaffold implantation procedure is guaranteed. Scaffolds based on hexahedron unit cells were investigated including pores differently dimensioned and with different shapes such as elliptic or rectangular. The algorithm predicted decreasing values of the optimal load for scaffolds with pores with increasing dimensions. The optimal values predicted for the scaffolds with elliptic pores were found higher than those with rectangular ones. The proposed algorithm can be utilized to properly guide the surgeon in the choice of the best scaffold type/geometry that better satisfies the specific patient requirements.

Keywords: Computational Mechanobiology | Hexahedron Unit Cell | Numerical Optimization Algorithms | Printing of Biomaterials | Scaffolds for Bone Tissue Engineering

Abstract: Augmented reality (AR) is a key technology for the development of smart manufacturing. One of the main advantages of AR is that it can help workers to accomplish several tasks, making it possible the shift from mass production to mass customization. However, it is still not clear how these promises can be fulfilled in an industrial scenario. In particular, the question about which display solutions fit better the industrial constraints remains open. Based on the literature overview, laboratory experiments, and feedbacks from industrial companies, we supported the use of spatial augmented reality (SAR), designing a prototype intended to be used for manual working stations of the future smart factories. This work presents the evaluation of the effectiveness of conveying technical instructions with this SAR prototype as compared to paper manual. We run a within-subjects experiment with 16 participants to measure user task performance (completion times and error rates) and to collect subjective evaluation. We projected technical information on a motorbike engine during a seven-task maintenance procedure. Our results proved that SAR technology improves the operators’ performance with respect to a paper manual and that users well accept it. We found that SAR is more effective for difficult tasks than for simple ones and that the main advantage of SAR is related more to the reduction of error rates than to completion times. These results confirm the goodness of our design choices; then our prototype can be a valid candidate solution for a smart manufacturing application.

Keywords: Assembly | Industry 4.0 | Maintenance | Projection | Spatial augmented reality | Technical instructions

Abstract: This article explores what it takes to make interactive computer graphics and VR attractive as a promotional vehicle, from the points of view of tourism agencies and the tourists themselves. The authors exploited current VR and human-machine interface (HMI) technologies to develop an interactive, innovative, and attractive user experience called the Multisensory Apulia Touristic Experience (MATE). The MATE system implements a natural gesture-based interface and multisensory stimuli, including visuals, audio, smells, and climate effects.

Keywords: computer graphics | gesture controls | human-machine interface | multisensory virtual environment | natural user interfaces

Abstract: The evaluation of the exposure to risk factors in workplaces and their subsequent redesign represent one of the practices to lessen the frequency of work-related musculoskeletal disorders. In this paper we present K2RULA, a semi-automatic RULA evaluation software based on the Microsoft Kinect v2 depth camera, aimed at detecting awkward postures in real time, but also in off-line analysis. We validated our tool with two experiments. In the first one, we compared the K2RULA grand-scores with those obtained with a reference optical motion capture system and we found a statistical perfect match according to the Landis and Koch scale (proportion agreement index = 0.97, k = 0.87). In the second experiment, we evaluated the agreement of the grand-scores returned by the proposed application with those obtained by a RULA expert rater, finding again a statistical perfect match (proportion agreement index = 0.96, k = 0.84), whereas a commercial software based on Kinect v1 sensor showed a lower agreement (proportion agreement index = 0.82, k = 0.34).

Keywords: Ergonomics | Kinect v2 | RULA

Abstract: Text legibility in augmented reality with optical see-through displays can be challenging due to the interaction with the texture on the background. Literature presents several approaches to predict legibility of text superimposed over a specific image, but their validation with an AR display and with images taken from the industrial domain is scarce. In this work, we propose novel indices extracted from the background images, displayed on an LCD screen, and we compare them with those proposed in literature designing a specific user test. We collected the legibility user ratings by displaying white text over 13 industrial background images to 19 subjects using an optical see-through head-worn display. We found that most of the proposed indices have a significant correlation with user ratings. The main result of this work is that some of the novel indices proposed had a better correlation than those used before in the literature to predict legibility. Our results prove that industrial AR developers can effectively predict text legibility by simply running image analysis on the background image.

Abstract: Characterisation of the mechanical behaviour of cancer cells is an issue of crucial importance as specific cell mechanical properties have been measured and utilized as possible biomarkers of cancer progression. Atomic force microscopy certainly occupies a prominent place in the field of the mechanical characterisation devices. We developed a hybrid approach to characterise different cell lines (SW620 and SW480) of the human colon carcinoma submitted to nanoindentation measurements. An ad hoc algorithm was written that compares the force-indentation curves experimentally retrieved with those predicted by a finite element model that simulates the nanoindentation process and reproduces the cell geometry and the surface roughness. The algorithm perturbs iteratively the values of the cell mechanical properties implemented in the finite element model until the difference between the experimental and numerical force-indentation curves reaches the minimum value. The occurrence of this indicates that the implemented material properties are very close to the real ones. Different hyperelastic constitutive models, such as Arruda-Boyce, Mooney-Rivlin and Neo-Hookean were utilized to describe the structural behaviour of indented cells. The algorithm was capable of separating, for all the cell lines investigated, the mechanical properties of cell cortex and cytoskeleton. Material properties determined via the algorithm were different with respect to those obtained with the Hertzian contact theory. This demonstrates that factors such as: the cell geometry/anatomy and the hyperelastic constitutive behaviour, which are not contemplated in the Hertz's theory hypotheses, do affect the nanoindentation measurements. The proposed approach represents a powerful tool that, only on the basis of nanoindentation measurements, is capable of characterising material at the subcellular level.

Keywords: cell cortex | cell geometry | colon carcinoma | cytoskeleton | finite element method | nanoindentation | rough surface

Abstract: Due to the Industry 4.0 initiative, Augmented Reality (AR) has started to be considered one of the most interesting technologies companies should invest in, especially to improve their maintenance services. Several technological limitations have prevented AR to become an effective industrial tool in the past. Now some of them have been overcome, some others not yet by off-the-shelf technologies. In this paper, we present a solution for remote maintenance based on off-the-shelf mobile and AR technologies. The architecture of the application allows us to remotely connect a skilled operator in a control room with an unskilled one located where the maintenance task has to be performed. This application, which has been initially described in a previous work, has been improved on the basis of feedback received by industrial partners. We describe the important features we have added and the rationale behind them to make the remote communication more effective.

Keywords: Augmented Reality | Industry 4.0 | Remote Maintenance

Abstract: In this work, we proposed a method to reduce text in technical documentation, aiming at Augmented Reality manuals, where text must be reduced as much as possible. In fact, most of technical information is conveyed through other means such as CAD models, graphic signs, images, etc. The method classifies technical instructions into two categories: instructions that can be presented with graphic symbols and instructions that should be presented with text. It is based on the analysis of the action verbs used in the instruction, and makes use of ASD Simplified Technical English (STE) for remaining text instructions and let them easier to translate into other languages.

Keywords: Augmented Reality | Graphic symbols | Industry 4.0 | Simplified Technical English | Technical Documentation | Text reduction | Visual

Abstract: Blepharospasm is characterized by bilateral, synchronous, and symmetric involuntary orbicularis oculi muscle spasms leading to partial/total eyelid closure. We proposed a comprehensive method for assessing the severity of blepharospasm cases, based on expert observation of fixed-length video recordings and natural feature detection algorithms. The developed software detects involuntary spasms and blinks in order to evaluate BSP severity. In this work we have considered a new BSP severity scale to realize an objective evaluation of BSP severity.

Abstract: Endocanalar posts are necessary to build up and retain coronal restorations but they do not reinforce dental roots. It was observed that the dislodgement of post-retained restorations commonly occurs after several years of function and long-term retention may be influenced by various factors such as temperature changes. Temperature changes, in fact, produce micrometric deformations of post and surrounding tissues/materials that may generate high stress concentrations at the interface thus leading to failure. In this study we present an optical system based on the projection moiré technique that has been utilized to monitor the displacement field of endocanalar glass-fibre posts subjected to temperature changes. Measurements were performed on forty samples and the average displacement values registered at the apical and middle region were determined for six different temperature levels. A total of 480 displacement measurements was hence performed. The values of the standard deviation computed for each of the tested temperatures over the forty samples appear reasonably small which proves the robustness and the reliability of the proposed optical technique. The possible implications for the use of the system in the applicative context were discussed.

Keywords: Dental materials | Endocanalar post | Projection moiré | Thermal deformation | Thermal stress

Abstract: We present a novel interaction method for augmented industrial maintenance based on a "magic mirror" interface and virtual motion buttons. The system includes a video camera for object tracking, a video\depth camera for capturing user gestures, a projector for displaying technical instruction to the operator and a LCD monitor providing feedback of the virtual buttons. The operator can trigger maintenance commands by directional swift of the hands in regions sensitive to motion speed and direction. The main advantage of the presented interface is that it can work in realistic industrial conditions: (i) operators wearing gloves, (ii) operators handling tools, (iii) presence of moving machinery and personnel in the background. We measured the performances of the system with a laboratory test and we proved the feasibility with an automotive inspection test case. We calculated an average interaction time below 2 seconds and an error rate lower than 5%. However, we found some performances limitations if the operator is handling tools.

Keywords: Augmented reality | Computer assisted maintenance | Human computer interfaces | Motion buttons

Abstract: Recent Face Analysis advances have focused the attention on studying and formalizing 3D facial shape. Landmarks, i.e. typical points of the face, are perfectly suited to the purpose, as their position on visage shape allows to build up a map of each human being’s appearance. This turns to be extremely useful for a large variety of fields and related applications. In particular, the forensic context is taken into consideration in this study. This work is intended as a survey of current research advances in forensic science involving 3D facial landmarks. In particular, by selecting recent scientific contributions in this field, a literature review is proposed for in-depth analyzing which landmarks are adopted, and how, in this discipline. The main outcome concerns the identification of a leading research branch, which is landmark-based facial reconstruction from skull. The choice of selecting 3D contributions is driven by the idea that the most innovative Face Analysis research trends work on three-dimensional data, such as depth maps and meshes, with three-dimensional software and tools. The third dimension improves the accurateness and is robust to colour and lightning variations.

Keywords: 3D face | Fiducial point | Forensic | Landmarks | Reconstruction

Abstract: We present the design and a prototype of a projective AR workbench for an effective use of the AR in industrial applications, in particular for Manual Working Stations. The proposed solution consists of an aluminum structure that holds a projector and a camera that is intended to be mounted on manual working stations. The camera, using a tracking algorithm, computes in real time the position and orientation of the object while the projector displays the information always in the desired position. We also designed and implemented the data structure of a database for the managing of AR instructions, and we were able to access this information interactively from our application.

Abstract: We present a prototype system composed practically of an IR camera and a video projector with the purpose to create a device that projects the thermal map directly on the observed surface. The novelty of this work lies on the building of a portable tool, the development of software and the proposing of a calibration procedure to be used in industrial and construction sites from thermal inspectors.

Abstract: In this paper, we propose a forearm rehabilitation system based on a serious game in Augmented Reality (AR). We designed and developed a simplified AR arcade brick breaking game to induce rehabilitation of the forearm muscles. We record the electromyographic signals using a low cost device to evaluate the applied force. We collected and analysed data in order to find a relationship between the applied force and the difficulty of the game. This research focuses on the dehospitalization of subjects in the middle or final stages of their rehabilitation where the new technologies, like Virtual and Augmented Reality, may improve the experience of repetitive exercises. The results achieved prove that the force applied by the user to hit the virtual sphere with real cardboard cube is related to sphere speed. In a rehabilitation scenario the results could be used to evaluate the improvements analysing the performance history.

Keywords: Brick serious games | Rehabilitation | Virtual and Augmented Reality

Abstract: Functionally Graded Scaffolds (FGSs) are porous biomaterials where porosity changes in space with a specific gradient. In spite of their wide use in bone tissue engineering, possible models that relate the scaffold gradient to the mechanical and biological requirements for the regeneration of the bony tissue are currently missing. In this study we attempt to bridge the gap by developing a mechanobiology-based optimization algorithm aimed to determine the optimal graded porosity distribution in FGSs. The algorithm combines the parametric finite element model of a FGS, a computational mechano-regulation model and a numerical optimization routine. For assigned boundary and loading conditions, the algorithm builds iteratively different scaffold geometry configurations with different porosity distributions until the best microstructure geometry is reached, i.e. the geometry that allows the amount of bone formation to be maximized. We tested different porosity distribution laws, loading conditions and scaffold Young's modulus values. For each combination of these variables, the explicit equation of the porosity distribution law-i.e the law that describes the pore dimensions in function of the spatial coordinates-was determined that allows the highest amounts of bone to be generated. The results show that the loading conditions affect significantly the optimal porosity distribution. For a pure compression loading, it was found that the pore dimensions are almost constant throughout the entire scaffold and using a FGS allows the formation of amounts of bone slightly larger than those obtainable with a homogeneous porosity scaffold. For a pure shear loading, instead, FGSs allow to significantly increase the bone formation compared to a homogeneous porosity scaffolds. Although experimental data is still necessary to properly relate the mechanical/biological environment to the scaffold microstructure, this model represents an important step towards optimizing geometry of functionally graded scaffolds based on mechanobiological criteria.

Abstract: Complexity of scaffold geometries and biological mechanisms involved in the bone generation process make the design of scaffolds a quite challenging task. The most common approaches utilized in bone tissue engineering require costly protocols and time-consuming experiments. In this study we present an algorithm that, combining parametric finite element models of scaffolds with numerical optimization methods and a computational mechano-regulation model, is able to predict the optimal scaffold microstructure. The scaffold geometrical parameters are perturbed until the best geometry that allows the largest amounts of bone to be generated, is reached. We study the effects of the following factors: (1) the shape of the pores; (2) their spatial distribution; (3) the number of pores per unit area. The optimal dimensions of the pores have been determined for different values of scaffold Young’s modulus and compression loading acting on the scaffold upper surface. Pores with rectangular section were predicted to lead to the formation of larger amounts of bone compared to square section pores; similarly, elliptic pores were predicted to allow the generation of greater amounts of bone compared to circular pores. The number of pores per unit area appears to have rather negligible effects on the bone regeneration process. Finally, the algorithm predicts that for increasing loads, increasing values of the scaffold Young’s modulus are preferable. The results shown in the article represent a proof-of-principle demonstration of the possibility to optimize the scaffold microstructure geometry based on mechanobiological criteria.

Keywords: Mechano-regulation algorithm | Mechanobiology | Numerical optimization | Scaffold microstructure

Abstract: This paper presents a novel application of natural interaction techniques for technical documentation navigation in augmented reality maintenance. The objective is to provide technical information where and when needed in order to reduce the time spent in retrieving procedural data from manuals. The system integrates a video and depth camera for user gesture acquisition, a webcam for marker-based tracking and a see through head mounted display for digital information overlay. We designed a novel hand free gesture-based interface to access technical documentation while performing maintenance tasks. We implemented a specific flexible system to prototype natural interfaces using UML configurable state machines. It supports 2D and 3D content navigation, CAD assembly explosion, real time 3D sectioning and operation browsing. We differentiate the interaction metaphors for 2D documents and 3D CAD models in order to be intuitive and easy to learn. A case study and a user test demonstrated the feasibility and the good acceptance of the presented gesture interface.

Keywords: 3D hand gestures | Augmented reality | Digital technical documentation | Industrial maintenance | Natural interface

Abstract: A correct recognition of nonverbal expressions is currently one of the most important challenges of research in the field of human computer interaction. The ability to recognize human actions could change the way to interact with machines in several environments and contexts, or even the way to live. In this paper, we describe the advances of a previous study finalized to design, implement and validate an innovative recognition system already developed by some of the authors. It was aimed at recognizing two opposite emotional conditions (resonance and dissonance) of a candidate to a job position interacting with the recruiter during a job interview. Results in terms of the accuracy, resonance rate, and dissonance rate of the three new optimized neural networkbased (NN) classifiers are discussed. Comparison with previous results of three NN classifiers is also presented based on three single domains: facial, vocal and gestural.

Keywords: Facial/vocal/gestural features | Job interview | Neural networks and support vector machines | Nonverbal emotional recognition

Abstract: Augmented Reality is a promising technology for the product lifecycle development, but it is still not established in industrial facilities. The most relevant issues to be addressed relate to the ergonomics: avoid the discomfort of Head-Worn Displays, allow the operators to have free hands and improve data visualization. In this work we study the possibility to use projection-based Augmented Reality (projected AR), as optimal solution for technical visualization on industrial workbenches. In particular, text legibility in projected AR is difficult to optimize since it is affected by many parameters: environment conditions, text style, material and shape of the target surface. This problem is poorly addressed in literature and in the specific industrial field. We analyze the legibility of a set of colors prescribed by international standards for the industrial environments, on six widely used industrial workbenches surfaces. We compared the performance of 14 subjects using projected AR, with that using a traditional LCD monitor. We collected about 2500 measurements (times and errors) through the use of a test application, followed by qualitative interviews. The results showed that, as regards legibility, projected AR can be used in place of traditional monitors in most of the cases. Another not trivial finding is that the influence on legibility of surface irregularities (e.g., grooves, prominences) is more important than that of surface texturization. A possible limitation for the use of projected AR is given by the blue color, whose performance turned out to be lower than that of other colors with every workbench surface.

Keywords: Industrial applications | Spatial Augmented Reality | Text legibility | Visualization

Abstract: Text readability with augmented reality head-worn displays is critical and at present time, there are no standard guidelines to follow. The readability depends mainly on background lighting, display technology (i.e., OST: optical see-through or VST: video see-through), and text style (e.g., plain text, outline or billboard). In this work, we addressed the readability limits for industrial activities. We experimented the effects of two background illuminances levels (1,000 lx for very fine basic industrial tasks and 4,000 lx for fine machining), two commercially available head-worn display technologies, variable outline widths and contrast polarity of text. We analyzed the performance of 12 subjects by collecting about 3,400 measurements using a specific test application and followed by qualitative interviews. With high illuminances, VST performed better than OST, regardless of contrast polarity and outline width. We found that negative contrast polarity is preferable with VST, and that just a minimum outline (1 px) around black text is optimal. On the contrary, positive contrast polarity should be used with OST and outline is not effective. Therefore, we evaluated the usage limits of the OST by sampling its contrast sensitivity function.

Keywords: Augmented reality | Contrast sensitivity function | Industrial lighting | Optical see-through | Video see-through

Abstract: In the Industrie 4.0 vision, the creation of leading-edge options for interaction between people and technology occupies a key role. In this context, augmented reality (AR) is one of the most suitable solutions. However, it is still not ready to be effectively used in industry. A crucial problem is the legibility of text seen through AR head-worn displays (HWDs). AR interface designers have no standard guidelines to follow, especially for these devices. Literature and anecdotal evidence suggest that legibility depends mainly on background, display technology (that is, see-through optical or video HWDs), and text style (for example, plain text, outline, or billboard). Furthermore, there are constraints to consider in industrial environments, such as standard color-coding practices and workplace lighting. The authors examine aspects affecting text legibility with an emphasis on deriving guidelines to support AR interface designers. Their results suggest that enhancing text contrast via software, along with using the outline or billboard style, is an effective practice to improve legibility in many situations. If one text style is needed for both types of HWD, their results suggest that colored billboards (with neutral white text) are effective. When color coding is not mandatory, white text and blue billboard are more effective than other styles tested.

Keywords: augmented reality | computer graphics | head-worn displays | human-computer interface | Industrie 4.0 | mixed reality | style guides | usability engineering | vision I/O

Abstract: ABSTRACT: The paper describes an interactive Finite Elements Analysis (FEA) tool that aims to improve the learning of mechanical behavior of materials in industrial engineering schools. We implemented a “user in the loop” approach where students can explore the mechanical behavior of virtual specimens selected from a library of standard elements (cantilever beam, IPE beams etc.). The users can apply forces or displacements interactively by mouse or haptic device, and visualize and “feel” the structures stress configurations. We extended our previous work and compared this novel approach with respect to traditional FEA learning techniques. A test with twenty engineering students showed that learners following the interactive approach are faster in completing the given assignment showing a reduced error rate.

Keywords: engineering education | haptics | real-time finite element analysis | virtual reality

Abstract: We present an empirical study that evaluates the effectiveness of technical maintenance assisted with interactive augmented reality instructions. Our approach consists in an augmented visualization on a large screen and a combination of multiple fixed and mobile cameras. We used commercially available solutions. In our test, 14 participants completed a set of 4 maintenance tasks based on manual inspections of a motorbike engine. Tool selection, removal of bolts, and part dis\assembly, are supported by visual labels, 3D virtual models and 3D animations. All participants executed similar operations in two modalities: paper manuals and augmented instructions. Statistical analyses proved that augmented instructions reduced significantly participants' overall execution time and error rate. © 2013 Elsevier B.V. All rights reserved.

Keywords: Augmented reality | Computer aided task guidance | Large screen instruction | Maintenance

Abstract: Product maintenance is a service offered to customers which represents an interesting business for companies. Their interest is both providing a good service in terms of quality and at the same time cutting operational costs. In this view companies are seeking tools that enable them to reach both goals, among those offered by the rapidly evolving ICT sector. The paper describes an application based on augmented reality and mobile technologies aiming to support remote maintenance operations, and improve maintenance services that companies offer to their customers. The paper describes the main idea at the basis of the application, the requirements as well as its implementation. Finally a case study is presented.

Abstract: Augmented reality (AR) applications rely on robust and efficient methods for tracking. Tracking methods use a computer-internal representation of the object to track, which can be either sparse or dense representations. Sparse representations use only a limited set of feature points to represent an object to track, whereas dense representations almost mimic the shape of an object. While algorithms performed on sparse representations are faster, dense representations can distinguish multiple objects. The research presented in this paper investigates the feasibility of a dense tracking method for rigid object tracking, which incorporates the both object identification and object tracking steps. We adopted a tracking method that has been developed for the Microsoft Kinect to support single object tracking. The paper describes this method and presents the results. We also compared two different methods for mesh reconstruction in this algorithm. Since meshes are more informative when identifying a rigid object, this comparison indicates which algorithm shows the best performance for this task and guides our future research efforts.

Abstract: Efficient text visualization in head-worn augmented reality (AR) displays is critical because it is sensitive to display technology, text style and color, ambient illumination and so on. The main problem for the developer is to know the optimal text style for the specific display and for applications where color coding must be strictly followed because it is regulated by laws or internal practices. In this work, we experimented the effects on readability of two head-worn devices (optical and video see-through), two backgrounds (light and dark), five colors (white, black, red, green, and blue), and two text styles (plain text and billboarded text). Font type and size were kept constant. We measured the performance of 15 subjects by collecting about 5,000 measurements using a specific test application and followed by qualitative interviews. Readability turned out to be quicker on the optical see-through device. For the video see-through device, background affects readability only in case of text without billboard. Finally, our tests suggest that a good combination for indoor augmented reality applications, regardless of device and background, could be white text and blue billboard, while a mandatory color should be displayed as billboard with a white text message. © 1995-2012 IEEE.

Keywords: Augmented reality | optical see-through | style guides | video see-through | vision I/O

Abstract: The interaction metaphor, based on mouse, monitor and keyboard, presents evident limits in the engineering design review activities, when real and virtual models must be explored and compared, and also in "outside-the-office" environments, where the desk is not available. The presented research aims to explore a new generation of gesture-based interfaces, called "natural interfaces", which promise an intuitive control using free hands and without the desk support. We present a novel natural design review workspace which acquires user motion using a combination of video and depth cameras and visualizes the CAD models using monitor-based augmented reality. We implemented a bimanual egocentric pointer paradigm by a virtual active surface in front of the user. We used a XML configurable approach to explore bimanual gesture commands to browse, select, dis/assembly and explode 3D complex models imported in standard STEP format. Our experiments demonstrated that the virtual active surface is able to effectively trigger a set of CAD specific commands and to improve technical navigation in non-desktop environments: e.g. shop floor maintenance, on site quality control, etc. We evaluated the feasibility and robustness of the interface and reported a high degree of acceptance from the users who preferred the presented interface to a unconstrained 3D manipulation. © 2012 Springer-Verlag France.

Keywords: 3D manipulation | Augmented reality | CAD | Depth camera | Human computer interfaces | Natural interfaces

Abstract: We developed a wearable device to improve lower limb sport training. The presented system consists of a pair of spandex shorts which embed a processor unit, 2 accelerometers and 2 vibro motors. The accelerometers are located in proximity to the knees and measure tri-axial accelerations. We present a novel method to compute and correct asymmetry of lower limbs during training. The user performs an initial calibration phase which sets the accelerometer reference frames. While running, the system continuously refines the calibration using principal component analysis to take in account occasional shorts assessments. The system activates a corrective vibro feedback on the specific leg according to an asymmetry metric based on: (i) foot ground impact, (ii) phase error between legs, (iii) transversal knee movements. User tests demonstrated that the device is ergonomic to wear, easy to use and the corrective vibro feedback is appreciated during the training.

Keywords: Asymmetry correction | Lower limb rehabilitation | Sport training | Vibro feedback | Wearable training device

Abstract: The application of augmented reality in industrial environments requires an effective visualization of text on a see-through head-mounted display (HMD). The main contribution of this work is an empirical study of text styles as viewed through a monocular optical see-through display on three real workshop backgrounds, examining four colors and four different text styles. We ran 2,520 test trials with 14 participants using a mixed design and evaluated completion time and error rates. We found that both presentation mode and background influence the readability of text, but there is no interaction effect between these two variables. Another interesting aspect is that the presentation mode differentially influences completion time and error rate. The present study allows us to draw some guidelines for an effective use of AR text visualization in industrial environments. We suggest maximum contrast when reading time is important, and the use of colors to reduce errors. We also recommend a colored billboard with transparent text where colors have a specific meaning. © 2013 by the Massachusetts Institute of Technology.

Abstract: The paper describes a novel application of real-time finite element analysis controlled by a haptic device. The user can impose displacement constraints to a virtual structure using a probe and sense in real-time the response in terms of forces on her/his hand. In addition, conventional color map results are visualized on a desktop monitor. The application has been developed with the aim of simplifying the teaching of the mechanical behavior of materials in engineering schools by transforming the learning phase into an enactive process. A set of examples commonly used in the mechanical engineering courses have been implemented and tested. The paper describes and discusses the system implementation, the potentialities and the issues of such approach. Copyright © 2013 by ASME.

Abstract: Engineering 3D models become complex that paper drawings representation and monitor/mouse navigation on a computer-aided design (CAD) system is difficult and also frustrating. We present a novel interface paradigm for natural interactive visualization. It incorporates augmented reality enhanced engineering drawings and natural and tangible interfaces. We embedded ID markers on technical drawings to provide CAD data retrieval and tangible navigation. A user gets access to the CAD navigation functions using the drawing itself as a tangible device. In addition, CAD functions are triggered with gestures recognized by a video camera. We performed a pilot test assessment with industrial engineers. The results demonstrate the feasibility and the effectiveness of these techniques. © 2012 American Society of Mechanical Engineers.

Abstract: We present a novel approach to the early diagnosis of lung tumors that considers new malignancy indexes by using a metaball-based representation of this neoplasia. Starting from CT data we extract the suspected tumors represented as approximating metaballs and calculate malignancy indexes based on precise volume and surface irregularity evaluation. The mentioned approximation is performed resolving a constraint problem using a genetic algorithm whose objective function is a mathematical representation of the metaball. Compared to existing art, the metaball approximation provides a consistent reference surface for the evaluation of novel diagnosis parameters borrowed from engineering surface analysis. We have implemented the method in a demonstrator software and analyzed three different test cases. Copyright 2012 ACM.

Keywords: Biomedical computation | Genetic algorithm constrained optimization problem | GENOCOP III | Lung Tumor diagnosis | Surface analysis

Abstract: This work presents a novel Augmented Realty (AR) application to superimpose interactive Product Manufacturing Information (PMI) onto paper technical drawings. We augment drawings with contextual data and use a novel tangible interface to access the data in a natural way. We present an optimized PMI data visualization algorithm for CAD models in order to avoid model and annotation cluttering. Our algorithm ranks the model faces with technical annotations according to angle, distance, occlusion and area. The number of annotations visualized on 3D model is chosen following the cognitive perception theory to avoid information overload. We also extended the navigation metaphor adding the concept of tangible model navigation and flipping using the duplex drawing. As case studies we used annotated models from ASME standards. By using PC hardware and common paper drawings, this approach can be integrated at low-cost in existing industrial processes. Copyright © 2011 by ASME.

Keywords: Augmented reality | PMI annotations | Technical drawing

Abstract: We present a novel self-calibrating wearable device to improve running training by active vibro feedback. The system consists of a pair of spandex shorts embedding: a processor unit, 2 three-axial accelerometers, 2 vibro motors, a SD card reader\writer module and a real time clock. Two supplementary wireless accelerometers are located on the shoes. We present an algorithm to compute gait asymmetry from the four sensors data. The main novelty is the auto calibration algorithm which uses principal component analysis on each sensor based on kinematic assumptions. The system provides two important advantages: data logging and real time active correction. The active correction is performed sending signals to the user in real time via vibrations cells (rumble feedback). The vibration signals are sent to the specific leg and its intensity is proportional to the entity of required correction. This training system for running can be very useful to athletes and to sport medicine in order to improve speed, posture, fatigue and reduce joints osteoarthrotic problems.

Keywords: Active posture correction | Running training | Vibro feedback | Wearable wireless device

Abstract: The main objective of this works is to develop a wearable device to improve sport training in lower limb. The system consists of a pair of spandex shorts which embed a processor unit, 2 accelerometers, 2 vibro motors, a SD card reader\writer module and a real time clock. The accelerometers are located in proximity to the knees and are used to measure in real time the tri-axial accelerations for each leg. We present a novel algorithm to compute asymmetry from the 3 axial sensor data. We propose two applications of the system: for real time active correction and for data logging. In the correction mode, adjustment signal are sent to the user during the training by vibrations. The vibration signal is sent to the specific leg and its intensity is related to the entity of required correction. The second application of the system is as datalogger. The device stores all the training data in a SD card. Those log files can be processed using a dedicated application on a PC. This information can be very useful for long term analysis. This novel approach to sport training is very useful to athletes and sport medicine doctor in order to improve posture, efficiency and performance, but it can be also useful in other medical appliances such as rehabilitation. © 2011 IEEE.

Keywords: posture correction | sport training | vibro feedback | wearable

Abstract: We present a novel framework for computer aided measurements which supports physicians during 3D virtual colonoscopy. We propose a four steps methodology: (i) segment colon regions, (ii) search for colorectal polyps by means of a supervised neural network architecture, (iii) 3D reconstruction of polyp geometry using a synthetic model and (iv) qualitative and quantitative geometrical analysis. Doctor can graphically visualize and inspect the surface and search for irregularities. This qualitative visual support is extended with mathematical tools which computes diagnostic indicators. The proposed tool was tested with two different data sets of polyps. The proposed approach can be an effective diagnostic tool to evaluate the degree of malignancy of the cancer. Due to its generality, the presented framework can be easily extended to search for other types of cancers. © 2011 IEEE.

Keywords: 2D segmentation | 3D rendering and 2D and 3D measurements | neural networks | polyps | Virtual Conolonoscopy

Abstract: Style sketches are an essential tool for the expression and the definition of the shape of industrial products. We present a novel wavelet approach for sketch segmentation and editing expressly addressed to the designer needs. Starting from a 2D curve drawn by a user with a graphics tablet, our algorithm converts it in a B-spline representation, detects the style features, allows interactive smoothing and continuous local and global editing. The novelty compared to the existing literature is the combination of: (i) unified wavelet approach to segmentation, smoothing and editing, (ii) support for endpoint C0 and C1 continuity constraints and (iii) implementation with an interactive pen-tablet interface. Our approach requires low memory footprints with time complexity linear in the number of control points. We validated the algorithm with synthetic and practical tests. © 2010 World Scientific Publishing Company.

Keywords: 2D interactive sketch | multi-level segmentation | multiresolution editing

Abstract: In this work we integrate augmented reality technology in a product development process using real technical drawings as a tangible interface for design review. We present an original collaborative framework for Augmented Design Review Over Network (ADRON). It provides the following features: augmented technical drawings, interactive FEM simulation, multimodal annotation and chat tools, web content integration and collaborative client/server architecture. Our framework is intended to use common hardware instead of expensive and complex virtual or augmented facilities. We designed the interface specifically for users with little or no augmented reality expertise proposing tangible interfaces for data review and visual editing for all the functions and configurations. Two case studies are presented and discussed: a real-time "touch and see" stress/strain simulation and a collaborative distributed design review session of an industrial component. © 2008 Elsevier Ltd. All rights reserved.

Keywords: 3D model annotation | Augmented reality | Collaborative design review | FEM data visualization

Abstract: Part modelling in a CAD environment requires a bi-manual 3D input interface to fully exploit its potentialities. In this research we provide extensive user tests on bi-manual modelling using different devices to control 3D model's rotation. Our results suggest that a simple trackball device is effective when the user task is mostly limited to rotation control (i.e. when modelling parts in a CAD environment). In our tests, performances are even better than those achieved with a specifically designed device. Since the task of rotating a CAD part often shows the need of flipping the controlled object, we introduce a non linear transfer function which combines the precision of a zero order control mode with the ability to recognise fast movements. This new modality shows a significant improvement in the user's performances and candidates itself for integration in next generation CAD interfaces. © 2008 Elsevier Ltd. All rights reserved.

Keywords: 3D input | Bimanual interaction | Human computer interface | Part modelling | VR CAD

Abstract: This paper presents a novel 'touch and see' approach for interactive leaching of dynamic stress/strain distribution in engineering education. Our Augmented Reality application visualizes Finite Element Method (FEM) results overlaid over the real model. The user can interactively change the boundary conditions of the simulation and then evaluate the stress distribution in real time. Marker based video tracking is used to measure displacements while COMSOL Multiphysics solves the structural FEM analysis. A cantilever test case has been implemented and evaluated We describe the optimization solutions needed to achieve real-time simulation and precise and stable tracking. The presented system demonstrates significant educational benefits making the student's experience more attractive and effective. © 2009 TEMPUS Publications.

Keywords: Active learning | Augmented Reality | FEM | Tangible interfaces

Abstract: We present a novel approach, called tangible digital master (TaDiMa), based on a flexible access to Product Lifecycle Management (PLM) database using a tangible/graphical user interface and augmented reality. We developed and tested a technical drawing template with automatically embedded markers for augmentation. We embedded the Mozilla FireFox engine into our annotation system for the integration of web 2.0 applications in the AR environment. We also extended the concept of web feed to PLM for notification of technical contents. We implemented a dynamic labelling management with view-driven filtering and placement. We also present a tangible management for layers visualization and users access by marked tokens. We validated the TaDiMa approach in a selection of possible scenarios for different PLM applications. The main benefit of the TaDiMa system is the easy and low-cost integration in the product lifecycle process. © 2009 Springer-Verlag.

Keywords: Industrial augmented reality | PLM | Tangible interfaces | Technical drawings and annotations

Abstract: We present a flexible framework for multimodal engineering applications using augmented reality. Our goal is to simplify the configuration procedures and to provide a higher grade of flexibility in multimodal interfaces. The system architecture is based on an extensible plug-in approach. A specific component has been designed to manage and synchronize the different multimodal inputs. A configurable XML based layer manages user preferences in a hierarchical way. We tested two engineering applications: a structural component re-design case and an industrial plant visualization. Industrial experts were positively impressed by the augmented visualization and by the usability of the interface. Most of them agree that the multimodal interface surpasses the desktop based interface.

Keywords: Augmented reality | Computer aided engineering | Multimodal interaction

Abstract: Large stereo displays and 3D input devices have proved significant productivity benefits in CAD, but they have also shown interaction weaknesses. We present a novel approach for pointing CAD entities with a 3D cursor on a wall-like stereoscopic display. We proved that the user error is affected by anisotropy, hence we present an enhanced snap tool called eSnap. This tool uses an elliptic metric for 3D cursor proximity. The provided results demonstrate a significant improvement in user performances and can be used as a guide for the development of user interfaces in emerging 3D displays. Copyright © 2008 Inderscience Enterprises Ltd.

Keywords: 3D input | CAD interaction | HCI | Large stereo displays | LSDs

Abstract: Multimodal interfaces are proved to increase the input\output bandwidth for a more efficient interaction in 3D activities. This work presents a novel framework designed to simplify the configuration procedures and to provide a high level of flexibility in multimodal interfaces. We propose an innovative system architecture to decouple input and output configuration from the application level and a multimodal engine designed to manage and synchronize the different inputs. The flexibility of the system is ensured by the use of a hierarchical XML-based configuration structure. This framework can be applied to test the advantage of multimodal interfaces in VRAD applications and provides tools to explore the synergy of different input\output techniques. © The Eurographics Association 2007.

Abstract: We have developed a pen device for CAD applications in virtual reality which provides novel features compared to existing systems. The SenStylus consists of a wireless pen designed to be ergonomically handled by the user for spatial interaction using a six degree of freedom optical tracking. In addition to the classic digital button(s) input, it provides analog multi-axial control, and a dual-rumble feedback output. We have integrated the device into an existing virtual reality CAD environment and extended the application functionalities with new devicespecific features. The SenStylus vibration feedback improves perception in the virtual world by controlling frequency, amplitude, and duration of the feedback, simulating a variety of responses during collisions and selection tasks. This capability enforces the visual depth sensitivity, which is critical when wo rking with complex CAD models. The multi-axial analog input provides a natural interaction paradigm to the user, thus simulating pen pressure and angle as in real world sketching and in real clay modeling. Dynamic tool-tip dimensioning and shaping are implemented as extra features. We present some applications to prove the added value of the SenStylus. The evaluation of the device received positive feedback by designers and engineers alike. The new features offered by this device can easily be extended to other VR applications using the API provided. Copyright UNION Agency - Science Press.

Keywords: 3D interaction | CAD | User interface hardware | Virtual reality

Abstract: Commonly, during the aesthetic design process, stylists sketch features called character lines over a simple and "uninteresting" geometry (e.g. a car bonnet) in order to confer personality, emotional feeling and style. This work presents an original interface paradigm for character line sketching in a virtual reality environment. Taking advantage of the 3D interface, the feature path, also called leading line, can be directly sketched on the initial surface by realtime projection. Afterwards, a semi-transparent section is selected along the path in a interactive way and then the feature profile is sketched on this plane according the user's intention. Subsequently, by moving the virtual pen forwards along the path, the character line is generated, on the contrary if the pen is moved backwards the feature is partially erased. The distance of the virtual pen from the leading line controls, in real time, the offsetting along the path of the feature which remains consistent in style and identity. Such a system has been proven to be a powerful tool for fast expression and evaluation of ideas, which can be, in subsequent design phases, integrated with detailed surfacing applications and prototyping.

Keywords: Constrained-based design | Curve and surface design | Feature-based design | Parametric modelling

Abstract: The definition of a restoration project for a historical-artistic building is a high-skill operation. The preliminary survey and the following graphic representation of the artefacts, in particular, are two critical phases for good final results. The representation techniques called vectorial, including also the analytic photogrammetry, are nowadays surpassed by the wide introduction of digital techniques like the digital photogrammetry because of to excellent reproduction and low cost. Our paradigm for building restoration starts with a three-dimensional model of an edifice extracted from a set of 2-dimensional image using specific Image Assisted Modelling software. This digital model represents the artefacts both in its metric and morphologic complexity. Basically the result is a fully three-dimensional wireframe model with dimensional information while the appearance features are defined as a collection of bi-dimensional textures attached to the faces of the model. The most innovative aspect is the possibility to simulate the restoration process in two separate streams. On one side it is possible to adjust the original textures using common bi-dimensional digital painting software or specific tools that allow the user to interact with a three-dimensional image. On the other side, virtual environments permit to modify the model defining the dimension according to the desiderate restoration goal. We propose a new restoration project paradigm that integrates these innovative tools where artists and engineers work together and interactively. The restoration process is visualized in a specific immersive virtual environment developed by the authors in the VR3lab at Polytechnic of Bari-Italy. This is definitively an efficient way for designers, control agencies and building companies to immediately evaluate different solutions.

Abstract: The definition of a restoration project for a historical-artistic building is a highskill operation. The preliminary survey and the following graphic representation of the artefacts, in particular, are two critical phases for good final results. The representation techniques called vectorial, including also the analytic photogrammetry, are nowadays surpassed by the wide introduction of digital techniques like the digital photogrammetry because of to exceIIent reproduction and low cost. Our paradigm for building restoration starts with a threedimensional model of an edifice extracted from a set of 2-dimensional image using specific Image Assisted Modelling software. This digital model represents the artefacts both in its metric and morphologic complexity. Basically the result is a fully 'three-dimensional wirefiame model with dimensional information while the appearance features are defined as a collection of bi-dimensional textures attached to the faces of the model. The most innovative aspect is the possibility to simulate the restoration process in two separate streams. On one side it is possible to adjust the original textures using common bi-dimensional digital painting software or specific tools that allow the user to interact with a three-dimensional image. On the other side, virtztal environments permit to modify the model defining the dimension according to the desiderate restoration goal. We propose a new restoration project paradigm that integrates these innovative tools where artists and engineers work together and interactively. The restoration process is visualized in a specific immersive virtual environment developed by the authors in the VR3lab at Polytechnic of Bari-Italy. This is definitively an efficient way for designers, control agencies and building companies to immediately evaluate different solutions.

Abstract: Virtual Environments (VEs) have the potential to revolutionize traditional product design by enabling the transition from conventional CAD to fully digital product development. The presented prototype system targets closing the "digital gap" as introduced by the need for physical models such as clay models or mockups in the traditional product design and evaluation cycle. We describe a design environment that provides an intuitive human-machine interface for the creation and manipulation of three-dimensional (3D) models in a semi-immersive design space, focussing on ease of use and increased productivity for both designer and CAD engineers.

Keywords: 3D sculpting | Computer aided geometric design (CAGD) | Immersive environments | Virtual reality

Abstract: In this paper we present a new technique for surface reconstruction of digitized models in three dimensions. Concerning this problem, we are given a data set in threedimensional space, represented as a set of points without connectivity information, and the goal is to find, for a Jxed number of vertices, a set of approximating triangles which minimize the error measured by the displacement from the given points. Our method creates near-optimal linear spline approximations, using an iterative optimization scheme based on simulated annealing. The algorithm adapts the mesh to the data set and moves the triangles to enhance feature lines. .4 t the end, we can use the approach to create a hierarchy of dtfferent resolutions for the model.

Abstract: We present a highly efficient, automatic method for the generation of hierarchical surface triangulations. Given a set of scattered points in three-dimensional space, without known connectivity information, our method reconstructs a valid triangulated surface model in a two-step procedure. First, we apply clustering to the set of given points and identify point subsets in locally nearly planar regions. Second, we construct a surface triangulation from the output of the clustering step. The output of the clustering step is a set of 2-manifold tiles, which locally approximate the underlying, unknown surface. We construct the triangulation of the entire surface by triangulating the individual tiles and triangulating the gaps between the tiles. Since we apply point clustering in a hierarchical fashion we can generate model hierarchies by triangulating various levels resulting from the hierarchical clustering step.

Keywords: Data Reduction | Hierarchical Clustering | Multiresolution Representation | Reverse Engineering | Surface Reconstruction | Triangulation