Abstract: Background and objective: Many diseases of the spine require surgical treatments that are currently performed based on the experience of the surgeon. The basis of this study is to deliver an automatic and patient-specific algorithm able to come to the aid of the surgeons in pedicle arthrodesis operations, by finding the optimal direction of the screw insertion, the maximum screw diameter and the maximum screw length. Results: The paper introduce an algorithm based on the reconstructed geometry of a vertebra by 3D-scan that is able to identify the best introduction direction for screw and to select, from commercial and/or personalised databases, the best screws in order to maximize the occupation of the bone while not intersecting each other and not going through the walls of the pedicle and the bounds of the vertebral body. In fact, for pedicle arthrodesis surgery, the incorrect positioning of the screws may cause operating failures, an increase in the overall duration of surgery and, therefore, more harmful, real-time X-ray checks. In case of not availability on market, the algorithm also suggests parameters for designing and manufacturing an ‘ad hoc’ solution. The algorithm has been tested on 6 vertebras extracted by a medical database. Furthermore, the algorithm is based on a procedure through which the surgeon can freely choose the entering point of the screw (based on his/her own experience and will). A real patient vertebra has been processed with almost 400 different entering point, always giving a feedback on the possibility to use the entering point (in case of unavailability of a good trajectory) and on the individuation of the right trajectory and the choose of the better screws. Conclusions: In very recent bibliography, several papers deal with procedure to screw’ trajectory planning in arthrodesis surgery by using Computer Aided surgery systems, and some of them used also modern methodologies (KBE, AI, Deep learning, etc.) methods for planning the surgery as better as possible. Nevertheless, no methodologies or algorithm have been still realized to plan the trajectory and choose the perfect fitting screws on the basis of the patient-specific vertebra. This paper represents a wind of novelty in this field and allow surgeons to use the proposed algorithm for planning their surgeries. Finally, it allows also the easy creation of a customized surgical template, characterized by two cylindrical guides that follow a correct trajectory previously calculated by means of that automatic algorithm generated on the basis of a vertebra CAD model for a specific patient. The surgeon will be able to set the template (drilling guides) on the patient's vertebra and safely apply the screws.

Keywords: Neurosurgery | Optimal insertion direction | Pedicle arthrodesis | Spine surgery | Standard screw | Surgical planning | Surgical Template

Abstract: In this study, a new methodology for designing and creating a custom-made template for maxillofacial surgery has been developed. The custom-made template can be used both for cutting and repositioning of the mandible arches for executing a BSSO (bilateral sagittal split osteotomy) treatment. The idea was developed in order to give the possibility of using a custom-made template with standard plates, thus reducing long times, high costs and low availability of custom-made plates; this represents the proof of novelty of the proposed template, based on a well-established methodology. The methodology was completely developed in the CAD virtual environment and, after the surgeons’ assessment, an in-vitro experiment by a maxillofacial surgeon was performed in order to check the usability and the versatility of the system, thanks to the use of additive manufacturing technologies. When computer-aided technologies are used for orthognathic surgery, there are significant time and cost savings that can be realised, as well as improved performance. The cost of the whole operation is lower than the standard one, thanks to the use of standard plates. To carry out the procedures, the proposed methodology allows for inexpensive physical mock-ups that enable the BSSO procedure to be performed.

Keywords: computer-aided surgery | low-cost procedure | orthognathic | standard plate | surgical template

Abstract: A car seat’s function is to support, protect, and make passengers and drivers feel comfortable during a trip. A more uniform pressure distribution and a larger contact area usually provide less discomfort. Consequently, the seat pan’s material and geometry play an essential role in the design process. A shaped pad was opportunely designed and realized, starting from the pressure distributions between the buttocks and the seat pan; pressure data were acquired during an initial experiment involving 41 people, representing a wide range of percentiles. The shaped pad was compared with a standard one by building a special seat with an interchangeable internal pad and testing the standard and the new seat; the second experiment involved 52 people that tested both seats. The tests were conducted to assess comfort (33 subjects were asked to be seated for 1 min each) and discomfort (19 subjects were asked to be seated for 15 min each); during the tests, pressure distribution and contact area data were gathered. The results showed that, for both tests, about 80% of the participants, among which 100% of the female sample, preferred the shaped seat pan pad. Even if the material was exactly the same, the shaped pad seemed to be softer, more comfortable, and more suited to the body’s shape than the standard one. The design methodology was demonstrated to be very useful for granting a more uniform pressure distribution and a wider contact area, i.e., higher comfort and less discomfort.

Keywords: car seat | design for comfort | experimental design | interface pressure

Abstract: Falls at height are among the major causes of fatal accidents at work, especially in the construction sector. Maintaining balance while performing a tool with both hands generates physical efforts and mental loading that needs to be managed for workers’ safety and health. The purpose of the study is to compare perceived (dis)comfort (overall and localized), the ergonomic risk, and the perceived effort through the acquired postures that subjects assumed during the execution of simple and common tasks both on a ladder and on the ground. 26 subjects were asked to perform four tasks in both conditions: top screwing, frontal screwing, object picking from the bottom forward, and object picking from the bottom sideways. Subjective and objective data were gathered for assessing subjective experience (discomfort and effort, perceived) and ergonomic risk. Results highlighted few ergonomic risk differences among “on ladder” and “on ground” tasks, while subjective data reveal significant differences in different scenarios. Furthermore, the knees and neck areas are the most critical ones.

Keywords: discomfort | ergonomics | hand tools | ladder | working at height

Abstract: As vehicles have become more complicated, Human-Machine Interaction (HMI) is becoming crucial. Nowadays, HMI is a substantial element in autonomous vehicles (AVs). Numerous studies are lately being published regarding significant parameters of AVs which can affect HMI. Hence, it is imperative to have a comprehensive prospect, to improve people's acceptance of AVs. In AVs, the driver's role will change to a passenger, however, it can be switched in some special situations. This work is divided in two parts: the first study has mapped from 299 papers in this area and found the most impressive concerns of people in using AVs. Various researchers’ approach has shown a dramatic shift from physical parameters to psycho-emotional ones; as results, trust and comfort are ranked first and second in the reviewed articles, respectively. The second part is dedicated to the explanation of methodology, the synthesis of findings and the perspectives about the future scenarios. Key findings and some insightful observations on the future of this approach are discussed in this section of the article. As a conclusion, we developed a novel model named 3p consisting of personal, psycho-emotional, and physical parameters, which states the current trend of momentous features affecting HMI in AVs.

Keywords: Comfort | Design model | Human-Autonomous Vehicle Interaction | Trust | User Experience

Abstract: As vehicles have become more complicated, Human-Machine Interaction (HMI) is becoming crucial. Nowadays, HMI is a substantial element in autonomous vehicles (AVs). Numerous studies are lately being published regarding significant parameters of AVs which can affect HMI. Hence, it is imperative to have a comprehensive prospect, to improve people’s acceptance of AVs. In AVs, the driver’s role will change to a passenger, however, it can be switched in some special situations. This work is divided in two parts: the first study has mapped from 299 papers in this area and found the most impressive concerns of people in using AVs. Regarding the researchers’ expertise and aim(s), each study has investigated the interactions between human and vehicle from a specific facet. In general, it can be claimed that a dramatic shift from physical parameters to psycho-emotional ones can be observed in recent years. The results showed that trust and comfort are ranked first and second in the reviewed articles, respectively. The second part is dedicated to the explanation of methodology, the synthesis of findings and the perspectives about the future scenarios. Finally, a novel model named 3p is proposed which includes personal, psycho-emotional, and physical parameters, and states the current trend of momentous features affecting HMI in AVs.

Keywords: Comfort | Design model | Human-Autonomous Vehicle Interaction | Trust | User experience

Abstract: In current times, it is common to hear about interactive tours and virtual museums to visit places which are sometimes inaccessible or difficult to access. Additionally, the conservation and maintenance of certain structural and historical works need to be preserved by digitizing their three-dimensional geometry, obtaining 3D models faithful to the reality that can become parametric with the help of mesh and point cloud processing software. In this specific case, this process of obtaining a 3D model from point clouds obtained by 3D scanning techniques will supply digital information of the Cabo de Palos Lighthouse. This monument is part of the architectural and cultural heritage of the Murcian municipality of Cartagena, built in 1865, on the Levante coast in south-eastern Spain. In order to create a digital model faithful to the real one, which is called a digital twin, the three main steps of reverse engineering are carried out: 3D scanning, solid modelling after mesh processing and revision of the resulting geometry; for each of them, the use of different technological equipment, technical tools and different computer programs that guarantee the necessary quality for the reproduction of the 3D model sought is foreseen.

Keywords: Conservation | Construction | Digital twin | Historical heritage | Laser scanner

Abstract: The development of cutting-edge technologies in the industrial sector has led to the demand for increasingly specific tools in the optimization of efficiency problems. The automotive sector is the one that makes the most use of these technologies, such as, among all, Virtual Reality (VR) and Augmented Reality (AR). A virtual reality tool is inserted as a guide tool for the user in drawing as quickly as possible the key information for optimizing the process. This research work fits into this context, the goal of which was the implementation of an immersive platform for carrying out accurate measurements within an entirely virtual automotive environment. A VR system of this type allows to check the dimensional and shape tolerances of car components, performing measurement, with high precision and in real time, in a custom-made virtual environment, in which it is possible to simulate the presence of a myriad of components and test their mutual interaction. A comparative test was carried out, obtained by varying the graphical and geometrical model in the VR settings, in order to evaluate the level of usability and the degree of efficiency of a tool for measuring distances between objects in a virtual reality environment, depending on the system parameters. The validation of a measurement instrument in VR is part of an increasingly current technological context in which the need to optimize the time-cost curve embraces the need for increasingly accurate results.

Keywords: Assembly training | Tolerance measurements | Virtual reality

Abstract: This paper elaborates on the modeling and control of an Unmanned Aerial Vehicle (UAV) for delivery purposes, thereby integrating computer-aided design, multibody dynamic modeling, and motion control analysis in a unified framework. The UAV system designed in this study and utilized for item delivery has a quadcopter structure composed of four arms connected to a central trunk. In this investigation, the proposed design of the delivery drone is systematically modeled employing the multibody approach, while SIMSCAPE MULTIBODY is the software used for performing the dynamic analysis and for devising the final design of the control system. To this end, starting from the CAD model designed using SOLIDWORKS, the control system of the quadcopter is developed by performing dynamic simulations in the MATLAB/SIMULINK environment. Additionally, another fundamental contribution of this paper is the analytical derivation of the nonlinear set of algebraic constraint equations peculiar to the present multibody system, which characterizes the kinematics of the delivery drone and describes the relative angular velocity imposed between two rigid bodies as nonholonomic constraints. Furthermore, as discussed in detail in this paper, the choice of the propulsion system and the design of the individual components heavily depends on the structural and functional needs of the UAV under study. On the other hand, the control system devised in this work is based on cascaded Proportional-Integral-Derivative (PID) controllers, which are suitable for achieving different maneuvers that are fundamental for the motion control of the delivery drone. Therefore, the final performance of the UAV system is a consequence of the regulation of the feedback parameters that characterize the PID controllers. In this respect, the paper presents the refining of the parameters characterizing the PID controllers by using both an internal MATLAB tool, which automatically tunes the controller gains of single-input single-output systems, and by observing the resulting transient behavior of the UAV system, which is obtained through extensive dynamical simulations. The set of numerical results found in this investigation demonstrates the high performance of the dynamical behavior of the UAV system designed in this work.

Keywords: delivery drone | holonomicandnonholonomic constraints | MATLAB/SIMULINK | multibody dynamics | PID control | SIMSCAPE MULTIBODY | SOLIDWORKS | UAV system

Abstract: Driver posture and micro movements are main indicators of his attention and situation awareness, as well as of his capability to suddenly take control if necessary. Therefore, the real-time detection of wrong postures is essential to mitigate the risk of accidents. In this work we want to show that, by using a custom Convolutional Neural Network (CNN) for image processing, a very accurate driver posture recognition system can be realized by using a limited number of pressure sensors, grouped in a small carpet placed only on the seat of the driver, regardless of its shape. Data from the sensor carpet are converted in images reproducing the different pressure regions of the driver's body, so that the CNN can extract features and classify 8 postures with an average accuracy of 98.81% in real-time. According to the edge computing paradigm, the CNN implements an end-to-end classification by exploiting a quantization scheme for weights and binarized activations to reduce the number of required resources and allow a compact and low-power HW implementation on a small FPGA. When implemented with a Xilinx Artix 7 FPGA, the CNN consumes less than 7 mW of dynamic power at an operation frequency of 47.64 MHz. Such frequency is compatible with a sensor Output Data Rate (ODR) of 16.50 kHz, fundamental in critical applications, requiring a continuous monitoring and real-time action. Results of a 130 nm CMOS standard cells synthesis have also been reported.

Keywords: Driver safety | Neural Network | Posture recognition | Real-time image processing

Abstract: The aim of this study is to provide an example of a methodology to simulate human–machine interaction in human centric design approach for performing ergonomics and (dis)comfort analyses. It consists of gathering data from the real world, creating a virtual model of the environment and a digital human model, and finally simulating interactions with artefacts and human body-parts motions in different software applications. Firstly, motion capture has been carried out using a low-cost motion-capture system with markers and cameras, then data acquired have been processed using Python© and MATLAB© codes to extract useful information about the movements. This information has been processed to recreate the movements in a virtual environment using DELMIA™ and Unreal Engine™. Both methods proved their reliability in testing reachability, but the comparison showed that Unreal Engine™ appears much more realistic in manikin and movements’ simulations than DELMIA™.

Keywords: Car Seat | Comfort | DELMIA | Ergonomics | Reachability | Unreal Engine | Virtual Environment

Abstract: Orthognathic surgery allows broad-spectrum deformity correction involving both aesthetic and functional aspects on the TMJ (temporo-mandibular joint) and on the facial skull district. The combination of Reverse Engineering (RE), Virtual Surgery Planning (VSP), Computer Aided Design (CAD), Additive Manufacturing (AM), and 3D visualization allows surgeons to plan, virtually, manipulations and the translation of the human parts in the operating room. This work’s aim was to define a methodology, in the form of a workflow, for surgery planning and for designing and manufacturing templates for orthognathic surgery. Along the workflow, the error chain was checked and the maximum error in virtual planning was evaluated. The three-dimensional reconstruction of the mandibular shape and bone fragment movements after segmentation allow complete planning of the surgery and, following the proposed method, the introduction of both the innovative evaluation of the transversal intercondylar distance variation after mandibular arch advancement/set and the possibility of use of standard plates to plan and realize a customized surgery. The procedure was adopted in one clinical case on a patient affected by a class III malocclusion with an associated open bite and right deviation of the mandible with expected good results. Compared with the methods from most recent literature, the presented method introduces two elements of novelty and improves surgery results by optimizing costs and operating time. A new era of collaboration among surgeons and engineer has begun and is now bringing several benefits in personalized surgery.

Keywords: 3D-modelling | computer-aided surgery | methodology | orthognathic surgery | rapid manufacturing | surgical template

Abstract: The COVID-19 virus proliferated from its first emergence to a global phenomenon becoming a pandemic as declared by the World Health Organization on 11th March 2020. This sanitary emergency obliged people to suddenly face several changes in their way of life due to imposed countries’ lockdown and social distancing. One of these rapid changes involved schools and universities and, consequently, students and professors: with the sudden lockdown of universities and colleges worldwide, they had to turn the traditional “in presence” classes into online courses. A published survey among Italian academic staff and students allowed to identify and highlight the factors that affect ergonomics of workstation (learning and teaching workplace), postural and environmental comfort and teaching/learning effectiveness. This paper would like to give guidelines to set the right home environment and the timing of learning/teaching activities to improve global comfort, both for students and teachers, and improve learning effectiveness. Thirty-Five Master Degree students were involved in the experiment during the second-semester lessons (during Italian lockdown) and were asked to fill questionnaires and check their learning outcomes by answering multiple-choice tests. Data were statistically processed, and results were used to create guidelines to set the learning home-environment at best, where and when possible.

Keywords: Comfort | eLearning effectiveness | Workplace design method

Abstract: The aviation industry is constantly making compromises when designing comfortable airplane cabins. Providing passengers with a pleasant acoustic environment without adding weight to the cabin structure is a field of tension that challenges cabin interior designers. The aim of this study was to investigate whether noise levels affect the comfort and physical discomfort experienced by airplane passengers, and whether control influences comfort perception. To this end, 30 participants experienced three conditions (silence, aircraft engine noise at 75 dB, and the same noise with the ability to use earplugs), and comfort and discomfort were measured using a questionnaire. It was concluded that aircraft engine noise negatively affected the airplane passengers' comfort experiences. Having the ability to control this noisy environment with earplugs resulted in the lowest reported physical discomfort.

Keywords: aircraft cabin noise | airplane seat | control | discomfort | passenger comfort

Abstract: In this paper, a very tiny HW design of a Quantized Fully Convolutional Neural Network is proposed which demonstrates that accurate Human Posture Recognition can be designed by exploiting only pressure sensors and keeping the computation close to the data sources, according to the edge computing paradigm. The custom design of the QFCN exploits a base-2 quantization scheme to achieve state-of-The-Art performances in terms of classification accuracy, together with a very reduced number of mapped physical resources and power consumption. Trained and validated on a public dataset for in-bed posture classification, the QFCN exhibits an accuracy up to 96.77% in recognizing 17 different postures. When prototyped on a Xilinx Artix 7 FPGA the design achieves less than 7 mW dynamic power dissipation and a maximum operation frequency of 26.6 MHz, compatible with an Output Data Rate (ODR) of the sensors of 9.13 kHz.

Keywords: Convolutional neural network | FPGA custom design | low-power digital design | Quantization scheme

Abstract: A custom HW design of a Fully Convolutional Neural Network (FCN) is presented in this paper to implement an embeddable Human Posture Recognition (HPR) system capable of very high accuracy both for laying and sitting posture recognition. The FCN exploits a new base-2 quantization scheme for weight and binarized activations to meet the optimal trade-off between low power dissipation, a very reduced set of instantiated physical resources and state-of-the-art accuracy to classify human postures. By using a limited number of pressure sensors only, the optimized HW implementation allows keeping the computation close to the data sources according to the edge computing paradigm and enables the design of embedded HP systems. The FCN can be simply reconfigured to be used for laying and sitting posture recognition. Tested on a public dataset for in-bed posture classification, the proposed FCN obtains a mean accuracy value of 96.77% to recognize 17 different postures, while a small custom dataset has been used for training and testing for sitting posture recognition, where the FCN achieves 98.88% accuracy to recognize eight positions. The FCN has been prototyped on a Xilinx Artix 7 FPGA where it exhibits a dynamic power dissipation lower than 11 mW and 7 mW for laying and sitting posture recognition, respectively, and a maximum operation frequency of 47.64 MHz and 26.6 MHz, corresponding to an Output Data Rate (ODR) of the sensors of 16.50 kHz and 9.13 kHz, respectively. Furthermore, synthesis results with a CMOS 130 nm technology have been reported, to give an estimation about the possibility of an in-sensor circuital implementation.

Keywords: Convolutional Neural Network | Human behavior | Low-power digital design | Posture recognition

Abstract: With the advent of future vehicles, passengers expect to travel in comfort, and the free leg space between facing-seats could be an issue due to the unsuitability for all people, according to their anthropometric variability. A previous investigation survey showed the need to increase the leg-space between facing seats and, if installed, to improve the surface of the table placed in between. So, four different distances between seat-pans front edges of facing seats have been set-up and tested (44 cm, 51 cm, 58 cm, 65 cm) with a table in between. 13 couples of participants with different heights took part to experiments. The aim was to investigate the relationship between facing-seat distances and passenger wellbeing in terms of postural comfort and social interaction. Postural comfort has been analysed through optical tracking (for postural angles overtime) and questionnaires (perceived comfort). Social interaction feelings have been investigated with questionnaires. Experiment results showed the suitable distance could be 51 cm keeping the same table surface; otherwise, the 65 cm one could be ideal changing the table surface. Relevance to industry: With the advent of autonomous driving, vehicle manufacturers and designers are working hard to define new paradigms of public transportation in terms of seat layout, passenger wellbeing and interiors’ design. This paper contributes to increasing the general knowledge on the effects of distance between facing seats on postural comfort and social interaction.

Keywords: Occupant comfort | Passenger satisfaction | Seats' layout | Social interaction | Vehicle seat

Abstract: Remaining seated for extended periods increases the risk health issues and discomfort perception. Consequently, the seat-pan design is crucial and could be mainly influenced by two factors: pressure distribution and seat contour. For seat pan discomfort, the lower average pressure is accompanied by less discomfort. Moreover, a seat contour with a large contact area is correlated with more comfort. Thus, a shaped cushion had been accurately designed (Virtual Prototype) and realized (Physical Prototype) aiming to translate the pressure distribution due to interaction between seat and buttock in a geometric shape, suitable for the international population (including P5 females and P95 males). With this shape, the pressure should be more uniform and lower, the contact area at interface bigger, and the perceived comfort higher. Both Virtual and Physical Prototype design had been described in this paper through a repeatable and straightforward approach. Also, experiments had been performed to validate the hypothesis through a comparison with a standard flat cushion. Results showed the goal of the design had been reached: the shaped cushion scored less pressure distribution and higher contact area than the flat cushion.

Keywords: Design methodology | Product modelling / models | Prototype manufacturing method | Surface modelling | User centred design

Abstract: This study aimed to analyse the discomfort threshold (that could be linked to sensitivity or sensation) of different regions in hand and elbow to support hand-held devices' design. Indeed, there are no studies regarding the hand and elbow discomfort threshold or sensitivity. To overcome these literature gaps, the discomfort threshold of hand and elbow were recorded at 24 spots by pushing a cylinder with a diameter of 10 mm until the participants reported not to be longer comfortable. Experiments were performed with 24 participants, 13 females and 11 males. The results showed the map of discomfort threshold (or sensitivity) for the hand and elbow. The olecranon, situated at the ulna's upper (proximal) end, one of the two bones in the forearm, could withstand more pressure than the elbow area surrounding it. The fingertips and the area close to the metacarpals were most sensitive (lower discomfort threshold).

Keywords: Discomfort | Human centred design | Localized contact | Pressure | Upper limbs

Abstract: A proper seat is crucial not only for preventing health issues but also for the (dis)comfort perception. In the design of a seat, the seat pan’s geometric shape, either in or under the cushion, plays a vital role as it constrains the deformation of the foam it supports. The contact area and pressure distributions between the foam and the human body, closely associated with (dis)comfort, are influenced by those constrained deformations. In this paper, using a comparative study, the aim is to determine if opportunely shaped seat pans are better than a standard flat pan regarding postural comfort and pressure distribution. Two cushions with the same type of foam but two different seat pans were used in the comparison. The first seat pan is the standard one used in current aircraft seats and the second is a shaped seat pan, which was designed following the mean buttock-thigh shape of an international population (including P5 females and P95 males). Twenty-two international participants (11 males and 11 females, with BMI between 16 and 30) took part in the blind experiment. Results indicated that the cushion with shaped seat pan performed better as it led to less postural comfort, a larger contact area and more uniform pressure distribution. Also, 64% of participants favored the cushion with the shaped seat pan as they felt it was more comfortable and suitable for the buttock shape.

Keywords: Comfort | Human-center-design | Pressure map | Seat-pan

Abstract: University students spend most of their time in a sitting position. Prolonged sitting on ill-fitted furniture and the resulting lousy posture is making students having different musculoskeletal disorders and is strictly related to students learning outcomes. This study aims to improve postural comfort of chairs placed inside the Science & Technology Library at the University of Salerno. A previous study about these library chairs showed that the lumbar area was the most suffering part while perceived (dis)comfort was dependent on time. Based on this, an ergonomic redesign and, consequently, manufacturing of the chair has been done. A perceived-comfort comparison between the library chair and the redesigned one has been performed. A statistical sample of 28 healthy students performed a 20-min experiment two times, alternatively on the library chair and the redesigned one. The 20-min experiment was divided into two 10-min tasks (“Reading & Writing” and “Laptop use”) to simulate a study day. The participants’ postures were acquired non-invasively using cameras and processed by Kinovea; questionnaires were used to rate the perceived subjective (dis)comfort. A procedure for improving an existing product through a comfort-driven redesign is proposed. Results showed the redesigned library chair lead on increasing postural comfort (particularly in the lumbar area) thanks to the new design and modifications.

Keywords: (dis)comfort | Design method | Postural comfort | Redesign | Student seat

Abstract: BACKGROUND: The sanitary emergency due to COVID-19 virus obliged people to face up several changes in their everyday life becauseWorld Health Organisation (WHO) guidelines and countries' Health Systems imposed lockdown of activities and social distancing to flatten the infection curve. One of these rapid changes involved students and professors that had to turn the traditional 'in presence' classes into online courses facing several problems for educational delivery. OBJECTIVES: This work aimed to investigate the factors that affected both teaching/learning effectiveness and general human comfort and wellbeing after the sudden transition from classrooms to eLearning platforms due to COVID-19 in Italy. METHODS: A workshop, involving students and experts of Human Factors and Ergonomics, has been performed to identify aspects/factors that could influence online learning. Then, from workshop output and literature studies, a survey composed of two questionnaires (one for students and one for teachers) has been developed and spread out among Italian universities students and professors. RESULTS: 700 people answered the questionnaires. Data have been analysed and discussed to define the most important changes due to the new eLearning approach. Absence of interactions with colleagues and the necessity to use several devices were some of the aspects coming out from questionnaires. CONCLUSIONS: The study shows an overview of factors influencing both teaching/learning effectiveness and general human comfort and wellbeing. Results could be considered as a basis for future investigation and optimization about the dependencies and correlations among identified factors and the characteristics of the products/interaction/environment during eLearning courses.

Keywords: comfort | COVID-19 | discomfort | human centred design | university lectures

Abstract: Various aspects related to comfort are described in this special issue. Some papers are focused on the environment, like smell, temperature, light, acoustics, space and some on an artefact touching the human, like the floor angle, the seat, a bed and light. However, in this special issue also topics like modelling and behavior get more attention.

Keywords: comfort | ICC2019 | main findings | model | Review

Abstract: BACKGROUND: Human-centred design asks for wellbeing and comfort of the customer/worker when interacting with a product. Having a good perception-model and an objective method to evaluate the experienced (dis)comfort by the product user is needed for performing a preventive comfort evaluation as early as possible in the product development plan. The mattress of a bed is a typical product whose relevance in everyday life of people is under-evaluated. Fortunately, this behaviour is quickly changing, and the customer wants to understand the product he/she buys and asks for more comfortable and for scientifically assessed products. No guidelines for designing a personalized mattress are available in the literature. OBJECTIVES: This study deals with the experience of designing an innovative product whose product-development-plan is focused on the customer perceived comfort: a personalized mattress. The research question is: which method can be used to innovate or create a comfort-driven human-centred product? METHODS: Virtual prototyping was used to develop a correlated numerical model of the mattress. A comfort model for preventively assessing the perceived comfort was proposed and experimentally tested. Mattress testing sessions with subjects were organized, and collected data were compared with already tested mattresses. Brainstorming and multi-expert methods were used to propose, realize, and test an archetype of a new mattress for final comfort assessment. RESULTS: A new reconfigurable mattress was developed, resulting in two patents. The mattress design shows that personalized products can be tuned according to the anthropometric data of the customer in order to improve the comfort experience during sleep. CONCLUSIONS: A 'comfort-driven design guideline' was proposed; this method has been based on the use of virtual prototyping, virtual optimization and physical prototyping and testing. It allowed to improve an existing product in a better way and to bring innovation in it.

Keywords: Comfort | design | innovation | mattress | personalized product

Abstract: BACKGROUND: In recent years, a growing interest in ergonomics and comfort perception in secondary schools and universities can be detected, to go beyond the UNI-EN regulations and understanding how practically improve students' perceived comfort during lessons. OBJECTIVE: This study aimed to analyse the (dis)comfort perceived by students while sitting in a combo-desk during lessons; it proposed a method for understanding and weighing the influence of postural factors on overall (dis)comfort. METHODS: Twenty healthy students performed a random combination of three different tasks in two sessions - listening, reading on a tablet and writing. Subjective perceptions were investigated through questionnaires, in which the expected and the overall comfort were evaluated; postural angles were gathered by processing photos through Kinovea® software and were used for the virtual-postural analysis, using a DHM (Digital Human Modelling) software; statistical analysis was used to investigate the influence of subjective comfort of each body part on the overall perceived comfort. RESULTS: The statistical correlations were used to perform an optimization problem in order to create a general law to formulate the overall comfort function, for each task, as a weighted sum of the comfort perceived in each body part. The test procedure, additionally, evaluated the influence on comfort over time. The results showed how the upper back and the task-related upper limb are the most influencing factors in the overall comfort perception. CONCLUSIONS: The paper revealed a precise and straightforward analysis method that can be easily repeated for other design applications. Obtained results can suggest to designers easy solution to re-design the combo-desk.

Keywords: combo-desk | Perceived (dis)comfort | school activities | school seat | students wellbeing

Abstract: BACKGROUND: According to ergonomic researches regarding a good sitting posture, it is essential to ensure a natural back-curve in order to prevent musculoskeletal disorders. A brief observation among the Scientific Technology Library inside the University of Salerno showed that students used to complain about neck and lumbar pain, especially after a study day. OBJECTIVE: On the light of this background, a sitting posture comfort analysis had been performed on chairs inside the library to check the critical factors that influence the postural comfort and, consequently, the learning. METHODS: A prolonged sitting posture, that is common during the daily study activity, had been simulated with fifteen volunteer students performing 1-hour tests (divided into four 15-minutes tasks). Subjective perceptions had been gathered through questionnaires rating on a 5-point Comfort scale, both the expected comfort at the beginning of the experiment and the Localized Postural Comfort at the end of each task have been investigated. Then, postural angles had been gathered through photographic acquisition and Kinovea®. CaMAN software had been used to calculate the objective (dis)comfort indexes. Finally, subjective and objective data had been statistically processed and compared. RESULTS: Lumbar area scored the lowest perceived comfort while the perceived comfort was independent of participants and tasks, but dependent on time. CONCLUSIONS: After this comfort-driven analysis, critical factors of the chair-design were checked, and a proposal for a future re-design was hypothesized.

Keywords: Comfort | library | office seat | postural comfort-driven redesign | students

Abstract: BACKGROUND: Selecting the most suitable questionnaire(s) in comfort research for product design is always a challenge, even for experienced researchers. OBJECTIVE: The objective of this research is to create a list of Preferred Comfort Questionnaires (PCQ) for product design to help researchers in the selection of questionnaires for comfort research. METHODS: Fifteen questionnaires that are often used in comfort research for product design were selected as candidate questionnaires. During the Second International Comfort Congress (ICC 2019), 55 researchers and practitioners working in the field of comfort joined together in a workshop to rate these questionnaires individually as well as rank them in groups based on their experience. The criteria of rating and ranking included easiness to answer, easiness for data interpretation, time needed to complete, the need for prior training, as well as mapping the applicable design phases and field of application. RESULTS: The elicited responses related to each questionnaire were analyzed. For comfort research in five proposed application fields and four design phases, the preferred questionnaires were highlighted and categorized into four categories: preferred questionnaire, suitable for less prior training, suitable for fast completion and generally applicable, which led to a list of PCQ for product design. CONCLUSION: We expect that the PCQ list can be used as a useful instrument to help researchers in selecting questionnaires for comfort research in product design.

Keywords: Comfort | discomfort | product design | questionnaire | research

Abstract: BACKGROUND: Nowadays, the ergonomic study of the driving position is a critical aspect of automotive design. Indeed, due to the rising needs on the market, one focus for car industries is to improve the perceived comfort related to the cars' interior. Driving a car for a prolonged time could cause complaints in some body-regions, especially in the lumbar-sacral area. Thus, special lumbar-sacral supports for driver seat has been proposed for reducing this kind of complaints. OBJECTIVE: Development of two virtual and physical models of lumbar-sacral support for improving both the lumbar/sacral and overall perceived comfort while driving. METHODS: Two prototypes of lumbar/sacral support have been realized: the first one was integrated into the seat, and the second one was shaped as a removable pillow (removable support). Fifty participants were asked to rate the perceived comfort in lab tests performed on a seating-buck by comparing three configurations (5 min each): a standard seat, seat with the removable support, seat with integrated support. Subjective data (by questionnaires) and objective data (interface pressure between backrest and driver) have been acquired and statistically processed. In addition, real driving tests have been performed to test the actual performance of the removable support in term of perceived comfort comparing it with the standard seat. RESULTS: Statistical correlations between subjective and objective data showed interesting results in comfort improvement through the adopted solutions. Real driving tests showed an improvement in comfort perception with the lumbar-sacral support towards the standard seat. CONCLUSIONS: Thanks to the virtual prototyping and the application of previous knowledge, coming from literature and experience, a solution for improving the overall comfort and reduce the lumbar/sacral pain while driving has been developed, tested, and assessed.

Keywords: body-shaped pillow | Car seat comfort | lumbar-sacral support | seat design

Abstract: The most common type of spine instrumentation is the pedicle screw fixation. The recent literature shows how customized drilling templates help surgeons to perform the surgery better. This work aims to validate the design of a customized template for inserting lumbar pedicle screw via a procedure based on rapid prototyping and reverse engineering techniques and to show the benefits. The novelties of this template are its low-invasive sizes, its design based on a patented algorithm, which calculates the sizes of the screws and the optimal insertion direction, the engage/disengage system, and the adaptability to every kind of surgeon's kit. Accuracy of pedicle screw location, surgery duration, and X-ray exposition have been used to evaluate the performances of the template. Mono-centric in vivo trial was performed. Twenty patients (8 women and 12 men) were enrolled randomly corresponding to sixty vertebrae treated with spinal arthrodesis (30 with and 30 without templates). Accuracy of the screw positioning and reduction in both surgery duration and patients' exposure to X-rays achieved excellent results because the time spent on the insertion of pedicle screws via the surgical template was cut down by about 63%, while the number of X-ray shots was reduced by about 92%. The proposed template performed better than the standard approach and could be helpful both for skilled and novice surgeons.

Keywords: Lumbar spinal arthrodesis | Screw location optimisation | Spine surgery | Surgical template | X-ray minimisation

Abstract: In recent years, comfort seat design has received widespread attention from researchers. One of the factors that could contribute to comfort is the thermal influence due to the interaction between the human and the seating surface, for which literature is limited. In this paper, a laboratory experimental setup was used to detect and analyse the temperature changes at interface between seated subjects and a sensorized automotive seat. Acquired temperatures were processed in order to identify a mathematical model for describing the temperature changes at the interface. The main target of the study was the identification of the most sensitive areas of the human body to temperature variation while seated and its effect on local and overall perceived thermal comfort. Statistical analysis showed that the effects of temperature were most perceived in the “Upper Body” (UB) and less in the “Lower Body” (LB). The shoulders, the sides of the back, the back and the buttocks were most sensitive to temperature changes at the interface. Differences have been highlighted also between male and female subjects. Relevance to industry: The identification of the most sensitive areas of the human body to temperature variation, while seated, and the identification of the logarithmic model for describing the temperature changes should allow seat designers to define targets and strategies in developing cooling and heating systems for car seats, taking into account, in a preventive evaluation, the most probable perceived thermal comfort.

Keywords: Comfort evaluation | Seat design | Temperature | Thermal comfort | Thermal sensitivity

Abstract: Generally, comfort may be defined as the “level of well-being” perceived by humans in a working environment. The state-of-the-art about the evaluation of comfort/discomfort shows the need for an objective method to evaluate the “effect in the internal body” and “perceived effects” in main systems of comfort perception. Some medical studies show that each human joint has its own natural Rest Posture in which human muscles are completely relaxed or at the minimum strain level. Basing on this assumption, in other studies postural comfort curves for each Degree of Freedom of human upper and lower-limbs joints have been studied and CaMAN software has been developed to have a direct interface with these curves. In this paper, the upper limbs’ postural comfort curves have been compared with the results gained by the biomechanics virtual simulation built on ANYBODY Software. A detailed study has been conducted on the upper body muscular activation during upper limbs movement with and without load. Postures have been analysed both by ANYBODY and CaMAN in order to correlate the postural (dis)comfort perception with the calculated muscular activity.

Keywords: ANYBODY software | Human Man Interface simulation | Postural comfort

Abstract: This paper gives an overview of the relevance of the comfort concept, its definitions, boundary conditions, and stakeholders. Current comfort theories are presented and reflected on, both in their applicability and testing methodology. Questionnaires commonly used to study comfort and discomfort are also reviewed. An example of a comfort lab is introduced in its functionality and tools, which can be useful as a benchmark for others studying comfort.

Keywords: Comfort | Comfort modelling | Discomfort | Product design

Abstract: The percentage of passengers that prefer travelling in groups is increasing. In most vehicles, passengers sit side by side and need to turn their body to be engaged in the conversation with their fellow travellers. However, rotating the body could lead to discomfort which influences conversation quality. The aim of this research is to study the effect of seat configuration on the (dis)comfort experience, conversation quality and posture. Experiments in which participants were asked to talk to each other while sitting at the same distance (1 m) were conducted in four seating arrangements (with seat-belts on), where the angle between the forward directions of two seats were positioned at 0° (side by side), 22.5°, 90° and 120° (almost opposite each other), respectively. Optical tracking has been deployed and the collected data were processed with MatLab® to acquire postural angles over time. Questionnaires were also used to evaluate the perceived (dis)comfort and the quality of the conversation. Experiment results indicate that the 120° configuration scored the best in the overall comfort and the quality of conversation, but only slightly better than the 90° configuration. Practitioner summary: Seating side by side is not optimal to have a comfortable conversation with your seatmate. To improve comfort and quality of conversation in future vehicles, we tested four seating arrangements analysing the effect of seat layout on (dis)comfort experience. Statistical analysis of objective and subjective data shows the optimal configuration for a comfortable conversation. Abbreviation: LPD: localized postural discomfort; PDF: probability density function; OCRA: occupational repetitive action.

Keywords: Comfort | conversation quality | seat layout | seating arrangement | vehicle design

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: The purpose of this study is to research if a headrest benefits the comfort of the passenger and lowers muscle activity in the neck when sitting in a reclined (slouched)posture while watching in flight entertainment (IFE)in an aircraft business class seat. No significant differences in muscle activity in the musculus sternocleidomastoid and musculus trapezius pars descendant were found between the conditions with headrest and without headrest. A significant difference in expected comfort rating was found. Subjects indicated they expect to experience more comfort with a headrest when watching IFE for a duration of two movies during a long-haul flight. This study also found a significant difference in posture. In the condition without headrest the head was more upright compared to the condition with headrest. The lack of significant difference in muscle activity and the significant difference in posture may indicate that humans tend to look for a head position that is neutral, in the sense of minimal muscle effort. This study shows that the use of a headrest may benefit the comfort experience of the passenger during flight. However, further research is necessary on the design of the headrest and the long-term effects of head support on comfort, discomfort, muscle activity and fatigue for watching IFE in a slouched posture.

Keywords: Aircraft seat | Comfort | EMG | Headrest | Neck angle | Posture | TV

Abstract: Background: The integration of computer-aided design/computer-aided manufacturing (CAD/CAM) tools and medicine is rapidly developing for designing medical devices. A novel design for a 3D-printed patient-specific surgical template for thoracic pedicle screw insertion, using a procedure based on reverse engineering, is presented. Methods: The surgeon chooses the entry point on the vertebra. The optimal insertion direction and the size of the screws are defined via an algorithm on the basis of a patient-specific vertebra CAD model. The template features an innovative shape for a comfortable and univocal placement and a novel disengaging device. Results: Three spinal fusions were performed to test the template. Excellent results were achieved in terms of the accuracy of the screw positioning, reduction in surgery duration, and number of X-rays. Conclusions: A novel design for a customized, 3D-printed surgical template for thoracic spinal arthrodesis was presented, and improvements in terms of precision, duration, and safety were achieved without changing the standard procedure.

Keywords: 3D imaging | additive manufacturing | bone | computer-assisted surgery | imaged guided surgery | in vivo | modelling | pedicle screw fixation | screw direction optimization | spine | surgical template | thoracic | thoracic spinal arthrodesis | X-ray minimization

Abstract: This research aims to study the effect of seat and/or backrest rotation on comfort and quality of conversation. Different sitting arrangements were tested to study the effect of the seat layout on: 1) (dis)comfort experience; 2) conversation quality and 3) postures. Two seats were arranged in different angles (0° 45° 90° and 180°) at the same distance (1 m) and participants were asked to talk to each other. The participants’ postures were acquired by using cameras and markers on the participants’ body. Questionnaires were used to rate the perceived (dis)comfort and quality of conversation. Results show that 90° configuration scored the best both in overall comfort and quality of conversation; while the 0° configuration scored the lowest in both ratings. A strong correlation was established between high comfort and good quality of conversation.

Keywords: Comfort | Communication | Quality of conversation | Sitting arrangement

Abstract: Computer aided technologies (CAT) are becoming an indispensable instrument to design, improve and manufacture new products and services. Digital human modelling (DHM) systems allow to simulate the Human-artifact interface and to evaluate, in early step of design process, the ergonomic performances of new products or workplaces. In particular, for products that have to be used in a “constrained” workplace, different tasks and activities are associated with different postures. The aim of this study is to investigate the influence of anthropometric characteristics and expectations on the postural comfort perception through the CAT/DHM systems, while using four office devices: desktop computer, laptop computer, tablet and smartphone. A statistical sample of healthy students was selected and their anthropometric characteristics were measured. The postures assumed by the participants were gathered in a not-invasive way by cameras. The angular detection was performed directly on snapshots by using Kinovea® software. Human joints’ an-gles were used for the virtual-postural analysis, through DELMIA® software. The evaluation of postural comfort was obtained in two ways: CaMAN® software developed by the researchers from the Department of Industrial Engineering in Salerno (Italy) was used to calculate the objective comfort indexes while an appropriate questionnaire, given to subjects during the devices usage, was used to evaluate the subjective com-fort indexes. The results of analyses show a difference between subjective and objective postural comfort indexes for all the devices: this difference has been associated to the expectations.

Keywords: Comfort evaluation | Computer aided technologies | Expectations | Not-invasive postural analysis | Office devices

Abstract: BACKGROUND: Several comfort perception models have proposed an objective method to evaluate 'effects in the internal body' and 'perceived comfort'. Postural comfort is one aspect of comfort/discomfort perception, and this current work adds to existing knowledge toward a more objectified posture evaluation for comfort. OBJECTIVE: The authors have used the concept of Range of Rest Posture (RRP), as proposed by Apostolico et al. The study focused on the identification of RRP within the Comfort Range of Motion (CROM) for lower limbs. METHODS: The proposed method is based on extensive experimental work involving 114 healthy individuals (59 males and 55 females) ranging from 20 to 40 years old. The age range was narrowed to avoid an age-clustering of results due to inhomogeneity of the statistical sample. Data were processed using statistical methods for identifying the RRP in the experimental CROM. Several Maximum Level of Comfort (MLC) positions were found within the RRP. RESULTS: RRPs for lower limbs of men and women have been identified and can be used for virtual comfort assessment. CONCLUSIONS: This paper shows a method to evaluate in a more objective way the subjective postural comfort perception and results allow researchers to improve models for the virtual preventive comfort assessment.

Keywords: Comfort evaluation | lower limbs joints | range of motion | rest posture

Abstract: The aim of this work is to define a new method that helps researchers to analyze perceptions of (dis)comfort in dynamic conditions. Recent studies pay considerable attention to body movements, mobility, and stability to measure comfort or discomfort when seated. Most of these discuss the relations between subjective comfort/discomfort and objective measurements (e.g. body pressure distribution, body movement and EMG) for short- and medium-term sitting. The present analysis took place in a classroom of the Industrial Engineering Department at the University of Salerno. The participants included 25 students (12 females and 13 males), who were observed during classroom hours. The students were invited to sit at a combo-desk and were free to perform different combinations of movements while writing and listening. These activities required that they adapt their body movements, as the combo-desk was fixed to the floor. A pressure pad was used to detect pressure at interface and center of pressure's changes, allowing for the bodies' motion data to be recorded. The aim was to identify the correct threshold to be used for movement detection and to investigate correlations between the number of movements and the perceived (dis)comfort. The study also identifies those body parts that have the greatest effect on (dis)comfort perception.

Keywords: Body movements | Center of pressure | Classroom seat | Comfort | Discomfort | Pressure map | School furniture

Abstract: Currently, the word ‘comfort’ is often used in relation to the marketing of products such as chairs, cars interiors, clothing, hand tools and even airplane tickets. In this field of research, the aim of this study is to investigate the influence of spinal posture on postural (dis)comfort perception; the test case is the analysis of the interaction between humans and vending machines for purchasing food or beverages. A statistical sample of 20 healthy students (subjects) performed the required tests, with each participant asked to take a product from three different vending machines (snacks, drinks and coffee). The subjects' postures were acquired non-invasively using cameras; software and instruments for virtual prototyping were used for posture analysis and interaction modelling, both questionnaires (subjective) and comfort-analysis software (objective) were used to rate the perceived (dis)comfort. The results obtained from simulations and questionnaires were compared, and a method to weigh the effect of the perceived spinal discomfort on overall postural (dis)comfort was proposed. These results reveal a good correlation between subjective perception and objective evaluation obtained through simulations, confirming the validity of the proposed method.

Keywords: Comfort evaluation | Information fusion | Non-invasive postural analysis | Spine discomfort | Vending machines

Abstract: The most advocated schemes of comfort perception have proposed an objective method to evaluate “effects in the internal body” and “perceived effects”—the state of the art for comfort/discomfort evaluation. Postural comfort is one aspect of comfort/discomfort perception, and this current work adds to existing knowledge toward a more objectified posture evaluation for comfort. The authors have used the concept of Range of Rest Posture (RRP), as proposed by Apostolico et al. [1], useful for comfort evaluation. The study focused on the identification of RRP within the Comfort Range of Motion (CROM) for these human joints in the lower limbs: hip, knee, and ankle. The proposed method is based on extensive experimental work involving 114 healthy individuals (59 males and 55 females) ranging from 20 to 40 years old. The age range was narrowed to avoid an age-clustering of results due to inhomogeneity of the statistical sample. The experimental data were processed using statistical methods for identifying the RRP in the experimental CROM. Several Maximum Level of Comfort (MLC) positions were found within the RRP. These positions were among the most important information in the comfort evaluation analyses.

Abstract: This work deals with a novel procedure that can be used for reverse engineering (RE) of big and old boats’ hull through cheap and effective instruments. The procedure has been used to acquire dimensions and shapes of an offshore boat designed by Renato Levi in 1962, named “Ultima Dea”, commissioned by Gianni Agnelli. The research purpose is the development of a method that gives to designers and restorer an “easy to use” instrument for obtaining the 2D and 3D CAD models from a degraded physical object in order to check and re-design the parts to be restored. The study and the application allowed to develop an innovative procedure to set the right acquisition parameters for optimizing the RE output in terms of minimization of maximum error and mean geometric errors between physical object and virtual model, by using a one-shot RE operation and a completely off-line post-processing. This procedure ensures good timesaving, during acquisition, very high reliability level and lightness of CAD models, also being able to reconstruct worn down and spoiled parts (through ex-novo modelling). The procedure shows how the CAD-modelling step can be done directly on graphical models (without surfaces’ mathematics) while ensuring the appropriate level of detail and, contemporarily, improving the interoperability of used and developed software. This procedure is based on the use of well-known methodologies and instruments that usually are employed in architectural relief; finally, it allowed to model the boat’s hull for the redesigning of engine/electrical/services systems and to restore the boat completely.

Keywords: Polygon mesh modelling | Reverse engineering | Yacht design

Abstract: This paper analyse and compare the methods to detect and represent the human symmetry line. In the last years, the development of 3D scanners has allowed to replace the traditional techniques (marking based methods) with modern methodologies that, starting from a 3D valid discrete geometric model of the back, perform the posture and vertebral column detection based on a complex processing of the acquired data. The purpose of the paper is a critical discussion of the state of the art in order to highlight real potentialities and limitations of the most important methodologies proposed for human symmetry line detection.

Keywords: Anatomical landmarks | Back shape analysis | Posture prediction | Rasterstereography | Symmetry line

Abstract: Sitting still for extended periods of time can lead to physical discomfort and even serious health risks. Due to safety regulations, reducing passenger’ sitting time in aircrafts is not feasible. This paper presents the results of a laboratory study, in where an interactive airplane seat was compared with a current economy class seat. Participants used both seats for 3.5 h, and performed significantly more in-seat movements when using the interactive seating system. Furthermore, this interactive seat predominantly lead to significantly better comfort experiences and reduced discomfort experiences, however no significant differences have been found in self-reported localized musculoskeletal discomfort. Passengers indicated that they would prefer this interactive seat over a standard aircraft seat.

Keywords: Aircraft interior | Airplane seat | In-seat exercise | Passenger comfort

Abstract: The study of ergonomics and (dis)comfort is a major topic of interest to scientific literature since the introduction of ISO 11228. Over the past 30 years, researchers have attempted to understand the mechanisms underlying perceptions of (dis)comfort for a seated subject. Three main factors are recognized as paramount for the comfort performance of a seat: human body posture, pressure at interface, and load distribution on the contact area; this study investigates the relationships between them and examines their significance for (dis)comfort perception. Physiological factors are known to play a role in (dis)comfort perception, and we consider these as a consequence of the three main parameters above. An explanation is given for this hypothesis. Experimental tests were conducted using a school chair with a rigid seat pan and no armrests for reducing the number of factors of influence. Conclusions show the levels of correlation between acquired information and perceived (dis)comfort.

Keywords: Comfort | Posture | School furniture | Seating | User experience

Abstract: This work focuses on the modelling of the mechanical performance of cellulose acetate-graphene oxide nanocomposite membranes, produced by supercritical CO2 assisted phase inversion, using a set of algorithms able to build and integrate two different parametric variational 3D finite element (FE) models. These models simulate micro- and nano-level morphology of the nanocomposite using a multiscale approach. Microlevel is characterized by interconnected spherical pores; whereas, nanolevel is a composites whose filler is formed by graphene oxide sheets. Information about nanocomposite morphology, derived from electron scanning microscopy analyses, was used to build periodic representative volume elements. A numerical-experimental correlation was performed comparing FE model results with the experimental ones obtained by compression tests, at different weight percentages of graphene oxide with respect to the polymer loaded in the membrane. A good approximation of the experimental trend of Young modulus was obtained by FE simulations.

Keywords: Finite element analysis | Graphene oxide | Mechanical properties | Nanocomposite | Supercritical CO 2

Abstract: In this article, the authors propose a novel procedure for designing a customized 3D-printed surgical template to guide surgeons in inserting screws into the sacral zone during arthrodesis surgeries. The template is characterized by two cylindrical guides defined by means of trajectories identified, based on standard procedure, via an appropriate Computer-Aided-Design (CAD)-based procedure. The procedure is based on the definition of the insertion direction by means of anatomical landmarks that enable the screws to take advantage of the maximum available bone path. After 3D printing, the template adheres perfectly to the bone surface, showing univocal positioning by exploiting the foramina of the sacrum, great maneuverability due to the presence of an ergonomic handle, as well as a break system for the two independent guides. These features make the product innovative. Thanks to its small size and the easy anchoring, the surgeon can simply position the template on the insertion area and directly insert the screws, without alterations to standard surgical procedures. This has the effect of reducing the overall duration of the surgery and the patient's exposure to X-rays, and increasing both the safety of the intervention and the quality of the results.

Keywords: Computer-aided surgery | Orthopaedic device | Patient-specific guide | Rapid prototyping | X-ray minimization

Abstract: All over the world, and mainly in United States, since 1977 to 1991 the research centers of automotive companies have processed several statistical data on real accidents between vehicles and pedestrians taking care, obviously, to pedestrians' injury. In latest years, a research group of EEVC (European Enhanced Vehicle-Safety Committee) had realized some documents about "pedestrian test" procedures. In reference papers of period 1977 - 1997 and in EEVC documents, the scientists describe a proposed homologating test for child-head impact; it is represented by the impact of some standardized impactors on car bonnet, in order to evaluate the child-head injury as deceleration of its gravity center. Injury evaluation criteria is an energy criterion and is quantified by the HPC index (see below) calculated by acceleration resultant vector, measured by an accelerometer mounted in the head- impactor. Our research wants to propose a new potential-injury evaluation method based on virtual reconstruction of the surface that envelope all the deformation surfaces in internal part of the bonnet and on its rapid prototyping. This surface is so processed and rapid prototyped as a puzzle of shells with their support. This prototyped surface is super-imposed on the real under-bonnet layout of a car and allows to evaluate easily where and how much our deformed bonnet could hit the hard-parts of the engine layout. This paper shows the results of this research project.

Keywords: Additive manufacturing | Industrial benchmarking | Rapid prototyping | Vehicle design

Abstract: Rapid prototyping (RP) is a set of technologies that permits building a physical model directly from its design by implementing a single automatic process using a 3D model of the object to be printed. RP systems can be based on different Additive Manufacturing (AM) technologies, such as a Fused Deposition Modeling (FDM) machine that works by extruding and melting together fused plastic filaments, drawing the boundaries and filling the model thin layer by thin layer. Low-cost FDM 3d printers do not work well automatically but require of a calibration phase because the best configuration settings in the slicing software are unknown, and the number of parameters values that needs to be manually defined is very large. The scientific literature reports many interesting articles on this topic, describing how the process can be improved by choosing the correct values of various parameters. Internet websites such RepRap.org discuss 3D printers and ppost detailed FAQ sections where users described improvements in 3D printing with simple methods but with great effort in terms of costs and time. Yet not all questions are answered. This paper would introduces: a) a new method for the analysis of the slicing software parameters that can be done with easy models; b) a second method for improving the effects of the parameters that shows a higher influence in the signal-to-noise ratio analysis.

Keywords: Digital fabrication | FDM | NIST artifact | Rapid prototyping | RepRap

Abstract: Much research has been carried out in recent years to estimate perceived comfort levels for passengers in motor vehicles. This interest is in part due to the introduction of specific provisions (e.g. Law 81/08 in Italy). Another factor is the increased interest and attention of customers. These studies have concentrated in large part on driver position. However, this work describes an application of postural analysis of with results obtained via data acquired during the interaction between the passenger and the dashboard. Tests were carried out in the Virtual Reality Laboratory (VR Lab) at the University of Salerno using a physical mock-up of a passenger car seat involving a fully reconfigurable seating buck. The interior of a FIAT Grande Punto, MY 2013, was configured by setting the seating-buck parameters. Twenty participants were asked to sit in the car seat with their shoulders against the seatback. They were then asked to reach each of the dashboard buttons. To acquire the angles of the subject's joints, pictures were taken and processed using KINOVEA® software. Each subject was subsequently given a questionnaire to analyze subjective comfort perception for their neck, back, shoulders, arms, upper-arms and wrists. A virtual model of the front seat of a Fiat Grande Punto was developed in CATIA software environment, and each action involved in reaching a position and using a command was simulated using DELMIA® software. The anthropometric data for each subject was used to perform the virtual analyses. Reachability and visibility analyses - important factors in comfort perception - were carried out. CaMAN® software was used for the virtual assessment of upper-limb postural comfort. Statistical analyses were performed using SPSS® software to investigate potential correlations between:anthropometric data and comfort perceptions resulting from the questionnaires;anthropometric data and comfort indexes obtained by CaMAN® software;comfort indexes obtained by CaMAN® and from the questionnaires. The analyses showed a lack of strong correlations between anthropometric and comfort indexes calculated both by the questionnaires and by CaMAN®. Further analyses allowed us to understand the reasons for the weak correlation between the CaMAN and questionnaire results. Reachability was shown to strongly affect global comfort perception due to the perception of postural comfort. To understand the influence of reachability on global comfort perception, a new comfort perception function was developed, leading to some very interesting results.

Abstract: The preventive evaluation of perceived (dis)comfort during the early stages of the design process is still an open issue. In Car development process, all tasks that involve human operations have to be taken into account while thinking and developing new solutions. Fortunately, modern technologies like CAE (Computer Aided Engineering) and DHM (Digital Human Modeling), and some new simulation software, like AnyBody™ or Jack© by Siemens PLM, allow to investigate, through simulation, some of the aspects related to comfort perception in humans. In addition, the software named CaMAN®, developed at University of Salerno, allows the postural comfort evaluations of upper limbs. The questions to which this paper tries to give answers are: (1) Is it possible to correlate the simulated muscular activation with perceived (dis)comfort during a manual task? (2) How different are the subjective perceived (dis)comfort, rated by the Borg Scale and the (dis)comfort index calculated by software?.

Keywords: (Dis)comfort perception | Car-Subsystems development | Comfort driven design | Human factors | Muscular fatigue evaluation | Task analysis

Abstract: Many diseases of the spine require surgical treatments that are currently performed based on the experience of the surgeon. For pedicle arthrodesis surgery, two critical factors must be addressed: Screws must be applied correctly and exposure to harmful radiation must be avoided. The incorrect positioning of the screws may cause operating failures that lead to subsequent reoperations, an increase in the overall duration of surgery and, therefore, more harmful, real-time X-ray checks. In this paper, the authors solve these problems by developing a method to realize a customized surgical template that acts as a drilling template. The template has two cylindrical guides that follow a correct trajectory previously calculated by means of an automatic algorithm generated on the basis of a vertebra CAD model for a specific patient. The surgeon sets the template (drilling guides) on the patient’s vertebra and safely applies the screws. Three surgical interventions for spinal stabilization have been performed using the template. These have had excellent results with regard to the accuracy of the screw positioning, reduction of the overall duration of the intervention, and reduction of the number of times the patient was exposed to X-rays.

Keywords: Pedicle arthrodesis | Screw direction optimization | Spine surgery | Surgical template | X-ray minimization

Abstract: This work shows the practical application and the experimental validation of a procedure based on an algorithm, running in a finite element environment, able to operate inside a convex three-dimensional solid by replacing the continuous mass with an appropriate cancellous bone-inspired space frame sharing, with the solid, the border and organized for having the fibres oriented according to the boundary conditions. The purpose is to reach the maximum mechanical efficiency realizing a load adaptive space frame optimized in terms of weight. Young's moduli of a cubic virtual specimen were numerically estimated. Fifteen specimens were printed by a 3D printer using a titanium alloy. Numerical results were compared with experimental ones obtained by tensile tests. The simulation results confirmed the validity of the FEM “beam element-based” space frame.

Keywords: 3-Dimensional printing | Directional orientation | Fibres | Finite element analysis (FEA) | Mechanical testing

Abstract: This work deals with the development, the application and the experimental validation of a procedure based on an algorithm, running in a finite element environment replacing the continuous mass of convex solids with a cancellous bone-inspired lattice structure showing curved beams oriented on the basis of the external forces, sharing with it border and boundary conditions. For the validation of the new lattice structure a cubic representative volume element, showing curved micro-beams, was chosen, implementing periodic boundary conditions. At the end, the algorithm created a. stl file to be printed by a 3D printer using an appropriate polymer. The numerical results were compared with experimental results obtained by compression tests. The experimental/numerical correlation confirmed the validity of the FEM “beam element – based” lattice structure that could be applied to different solid shapes.

Keywords: 3D printing | Directional orientation | Finite element analysis (FEA) | Mechanical testing | Microstructure

Abstract: This article focused on the study of the influence of morphological parameters on the mechanical performance (Young's modulus) of Cellulose Acetate-Graphene Oxide nanocomposites produced by Supercritical CO2 assisted phase inversion, by means of an algorithm managing two parametric variational 3D finite element (FE) models simulating micro- and nano-level of the nanocomposite. Micro-level showed interconnected spherical pores, while nano-level showed a dispersion of not fully exfoliated graphene sheets. 3D FE model exploited the periodic representative volume element (PRVE) concept and accounted for the nanocomposite morphology as determined from Field Emission Scanning Electron Microscopy (FESEM) experiments. Model predictions were compared with experimental results obtained by compression tests at different weight percentages of graphene oxide with respect to the polymer. Once validated, such a FE simulation procedure allows to know in advance which and how to vary the geometrical parameters during the nanocomposite production to improve its final mechanical performance.

Abstract: Abstract This paper proposes a review of the methods to detect and represent the human symmetry line. In the last years, the development of 3D scanners has allowed to replace the traditional techniques (marking based methods) with modern methodologies that, starting from a 3D valid discrete geometric model of the back, perform the posture and vertebral column detection based on a complex processing of the acquired data. The purpose of the paper is a critical d iscussion of the state of the art in order to highlight the real potentialit ies and the limitations still present of the most important methodologies proposed for human symmetry line detection.

Keywords: Anatomical landmarks | Back shape analysis | Posture prediction | Rasterstereography | Symmetry line

Abstract: The application of ergonomic principles to the design of processes, workplaces and organizations is not only a way to respond to legal requirements but also an indispensable premise for any company seeking to pursue a business logic. This paper shows a cheap and effective method to perform the ergonomic analysis of worker postures in order to optimize productivity and obtain the highest ergonomic ratings. Evaluations were performed for the 5°, 50° and 95° percentiles according to OCRA and NIOSH methods of biomechanical risk assessment. The results highlighted the need for improvements. A virtual simulation using DELMIA® software and the use of workers’ checklists drew attention to problems causing significant physical stress, as identified by ergonomic tools. An ergonomic/ comfort-driven redesign of the work cell was carried out, and CaMAN® software was used to conduct a final comfort-based analysis of the worst workstation in the work cell.

Keywords: Comfort rating | Ergonomic evaluation | NIOSH analysis | OCRA Index | Redesign

Abstract: In recent years, methods that allow for an objective evaluation of perceived comfort, in terms of postural, physiological, cognitive and environmental comfort, have received a great deal of attention from researchers. This paper focuses on one of the factors that influences physiological comfort perception: the temperature difference between users and the objects with which they interact. The first aim is to create a measuring system that does not affect the perceived comfort during the temperatures' acquisition. The main aim is to evaluate how the temperature at the human-mattress interface can affect the level of perceived comfort. A foam mattress has been used for testing in order to take into account the entire back part of the human body. The temperature at the interface was registered by fourteen 100 Ohm Platinum RTDs (Resistance Temperature Detectors) placed on the mattress under the trunk, the shoulders, the buttocks, the legs, the thighs, the arms and the forearms of the test subject. 29 subjects participated in a comfort test in a humidity controlled environment. The test protocol involved: dress-code, anthropometric-based positioning on mattress, environment temperature measuring and an acclimatization time before the test. At the end of each test, each of the test subject's thermal sensations and the level of comfort perception were evaluated using the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) scale. The data analyses concerned, in the first instance, correlations between the temperature at the interface and comfort levels of the different parts of the body. Then the same analyses were performed independently of the body parts being considered. The results demonstrated that there was no strong correlation among the studied variables and that the total increase of temperature at interface is associated with a reduction in comfort.

Keywords: Bedding systems | Comfort evaluation | Mattress | Objectifying comfort | Temperature | Thermal comfort

Abstract: Knowledge about the effects of primary factors on comfort level is useful in Human-Machine-Interface (HMI) design. The study and the mathematical modeling of these effects strongly depends on cross relations between the different kinds of comfort, the primary factors’ effects, and the modifiers’ actions. Starting from a sizeable bibliographic analysis, this paper describes a study, based on the axiomatic design approach, of the interactions between the results, factors, and modifiers in comfort/discomfort evaluation. The modifiers’ influence was determined by measuring the changes in information content. This study allowed us to validate and optimize our equation for the perceived “level of well-being” in order to better study the perception of comfort/discomfort in HMI.

Keywords: Axiomatic design | Comfort rating | Discomfort | Evaluation criteria | Perception

Abstract: In this paper we analyze the capabilities of a routine, based on Fuzzy logic, for elaborating a data set coming from a CMM (Coordinate Measuring Machine). We will show how to obtain, during holes measuring, the best measure, so that the approximation error is minimized. Moreover the CMM on-board software can elaborate these data and select the mathematical representation of the stored data, by identifying quotes, measures, axes, diameters, tolerances and so on. Information on measured parts is usually elaborated by an algorithm based on the least square squared error method, in order to evaluate the good shape of the hole; our purpose is to propose a new kind of approach, based on the Inferential Fuzzy system method, both to reduce the number of measured points, and to obtain the same accuracy. Our approach enables to measure the holes with a number of points lower than those usually needed for the CMM software. Thus time spent for obtaining a good measure is significantly reduced.

Keywords: Accuracy | Coordinate Measuring Machine | Fuzzy inference | Holes measurement | Precision

Abstract: Abstract: The aim of this work is to show a quick and simple procedure able to identify the geometrical parameters of the intervertebral disc that strongly affect the behavior of the FEM model. First, we allocated a selection criterion for the minimum number of geometrical parameters that describe, with a good degree of approximation, a healthy human vertebra. Next, we carried out a sensitivity analysis using the ‘Taguchi orthogonal array’ to arrive at a quick identification of the parameters that strongly affect the behavior of the Fem model.

Keywords: geometrical parameters | intervertebral disc | Spine | subject-specific finite element models | Taguchi method

Abstract: The evaluation of perceived comfort inside a car during the early stages of the design process is still an open issue. Modern technologies like CAE (Computer Aided Engineering) and DHM (Digital Human Modeling) already offer several tools for a preventive evaluation of ergonomic parameters for car drivers using detailed CAD (Computer Aided Design) models of car interiors and by a MBS (multi-body-system) solver for evaluating movements and interactions. Such evaluations are, nonetheless, not sufficient because the subjectivity of comfort perception is due to factors that are very difficult to evaluate in the early stage of design. Physical prototypes are needed and these are often too expensive to be realized. In the last 30 years, several researchers have tried to develop methods to objectivize comfort performance but most of these methods are based on questionnaires, market research, or physiological and biomechanical analyses, and need devices or interactions that modify perceived comfort. Recently, the authors of this study developed a software tool named CaMAN® for postural comfort evaluations of upper limbs. The software employs a static analysis of human joints in a working environment (the car cockpit is assumed to be a working environment). Some software, like AnyBody™, allows evaluations of the muscular efforts made during body actions. In the literature, it is possible to find several papers such as Na et al. [26] and Telfer et al. [40] that demonstrate a correlation between muscular effort and perceived comfort. Empirical evidence suggests that better comfort is related to lower muscular activity. This paper shows the results obtained from numerical and experimental analyses using AnyBody™ and CaMAN®. Simulations of the static and dynamic behaviors of a car driver using a steering wheel are performed. The results show the differences between preventive analyses of perceived comfort that are made with and without an applied load for a subject in the fiftieth percentile. This paper shows the results obtained from numerical and experimental analyses using AnyBody™ and CaMAN®. Simulations of the static and dynamic behaviors of a car driver using a steering wheel are performed. The results show the differences between preventive analyses of perceived comfort that are made with and without an applied load for a subject in the fiftieth percentile.

Abstract: In this work an hypothesis of modeling nanofibers network of Poly-L-lactide (PLLA) scaffolds loaded with hydroxyapatite (HA) nanoparticles, suitable for tissue engineering applications, is presented to investigate the mechanical properties by FEM analysis. Scaffolds were produced by Supercritical CO2 drying of polymeric gels. FEM modeling of nanoporous biomaterials involves computational problems such as: the reproduction of the nano-morphology by means of different techniques, such as molecular dynamics simulations that hardly lead to results adherent to the experimental evidence; the reverse engineering to extrapolate geometric information; the identification of a periodic representative volume element (RVE) to reach more coherent results and to reduce the simulation computational effort. Basic modeling assumptions are: a) polymer particles are small enough to exhibit Brownian motion; b) scaffold SEM images show that the porous structure consists of curved fibers that depart from punctiform nuclei realizing a space frame; c) scaffold experimental compressive tests show that the porous material behaves as a soft isotropic material. On the basis of these assumptions, a parametric algorithm that creates a cubic RVE, showing a nanofibers network and having the same porosity of the real material, has been written; RVE size has been optimized on the bases of its material isotropic degree measured by an ad hoc created iterative algorithm for generating a rod spaceframe; RVE mechanical behavior has been optimized by curving appropriately each fiber according to the experimental data and on the basis of SEM imaging diagnostic. Linear FEM simulations on mechanical behavior have given qualitatively and quantitative satisfactory results when compared to the experimental ones.

Abstract: Scaffolds have been produced by supercritical CO<inf>2</inf> drying of Poly-L-Lactid Acid (PLLA) gels loaded with micrometric fructose particles used as porogens. These structures show a microporous architecture generated by the voids left in the solid material by porogen leaching, while they maintain the nanostructure of the gel, consisting of a network of nanofilaments. These scaffolds have also been loaded with Hydroxyapatite (HA) nanoparticles, from 10 to 50% w/w with respect to the polymer, to improve the mechanical properties of the PLLA structure.Based on miscroscopic and mechanical considerations, we propose a parametric Finite Element Method (FEM) model of PLLA-HA composites that describes the microporous structure as a close-packing of equal spheres and the nanoscale structure as a space frame of isotropic curved fibers. The effect of HA on the mechanical properties of the scaffolds has been modeled on the basis of SEM images and by taking into consideration the formation of concentric cylinders of HA nanoparticles around PLLA nanofibers. Modeling analysis confirms that mechanical properties of these scaffolds depend on nanofibrous network connections and that bending is the major factor causing deformation of the network. The FEM model also takes into account the formation of HA multi-layer coating on some areas in the nanofiber network and its increase in thickness with HA percentage. The Young modulus tends to a plateau for HA percentages larger than 30% w/w and when the coverage of the nanofibers produced by HA nanoparticles reaches a loaded surface index of 0.14 in the FEM model.

Keywords: FEM modeling | Hydroxyapatite nanoparticles | Poly(L-Lactic Acid) nanofibers | Scaffold | Supercritical fluids

Abstract: The definitions of methods and tools used to evaluate how workers perceive the comfort during their activities remains an “open” problem at this time. Many researchers have dealt with that problem in the last twenty years, focusing their efforts primarily on the automotive sector and on VDT workstation comfort. This paper analyzes how workers position themselves at workstations used in industrial processes that sew together the edges of mattresses. The aim of the analysis is to determine whether workers can position themselves in ways that allow them to carry out activities in simple and economical ways. The Strain Index was used to identify the most critical and risky work phases in order to evaluate workers' risk of biomechanical overload. The OCRA checklist was used to evaluate the overall risk level associated with repeated completions of the total cycle of work and to develop a virtual-postural analysis to evaluate workers' perceived levels of discomfort. For the virtual-postural analysis, DELMIA® software was used to virtually model a workstation, and records of activities and the postures associated with various repetitive actions were gathered in a non-invasive manner with cameras and video cameras. CaMAN® software developed by the researchers from the Department of Industrial Engineering in Salerno (Italy) was used to calculate comfort indexes. An analysis of the comfort indexes was used to make as the basis for suggestions to correct workers' postures and for plans to redesign the workstations in order to improve ergonomics and allow workers to perceive them as more comfortable.

Keywords: Comfort evaluation criteria | Digital human modeling | Ergonomics | Non-invasive postural analysis | Redesign

Abstract: In Human-Machine Interface (HMI) design, several parameters have to be correctly evaluated in order to guarantee a good level of safety and well-being of users (humans) and to avoid health problems like muscular-skeletal disease. ISO Standards give us a good reference on Ergonomics and Comfort: ISO 11228 regulation; it deals with qualitative/quantitative parameters for evaluating Postural Ergonomics, using a "Postural Load Index", in push/pull, in manual loads' lifting and carrying and in repetitive actions; those parameters can represent the Ergonomics level of examined posture. While bibliographic references suggest different methods to make ergonomic evaluation like RULA, LUBA and REBA, the state of the art about comfort/discomfort evaluation shows the need of an objective method to evaluate "effect in the internal body" and "perceived effects" in several schemes of comfort perception like Moes', Vink & Hallback's and Naddeo & Cappetti's ones; postural comfort is one of the aspect of comfort/discomfort perception and this paper proposes a new quantitative method for evaluating this aspect of comfort, based on anthropometric parameters and upper limbs posture. The target of this paper is to present and test a "general purpose" method of comfort-measurement that can be applied to different industrial cases: in workspace environments, in automotive passenger compartments, in aeronautic cockpit or in industrial assembly lines. Relevance to industry: The method presented in this paper may allow industrial designers to provide an assessment of products' perceived comfort in the early stage of the product development process by making a posture-based quantitative evaluation; it also allows designers to make a comfort driven redesign of existing products' configuration for improving and innovating them.

Keywords: Comfort evaluation | Ergonomics | Industrial design | Postural analysis

Abstract: General comfort can be defined as the measure of the "level of wellbeing" perceived by humans when interacting with a working environment. The state of the art for comfort/discomfort evaluation shows the need for an objective method to evaluate both "effects on the internal body" and "perceived effects" when considering the perception of comfort. Medical studies show that each joint has its own natural resting posture. In this posture, our muscles are completely relaxed or at minimum levels of strain. The body's geometrical configuration corresponds to the natural resting position of arms/legs/neck etc. From this starting point, the authors experimented to develop and built postural-comfort curves for each degree of freedom (DOF) of upper-limb joints. These curves are regular, and do not show any kind of discontinuity. Software (CA-Man®) was developed to analyze different postures and calculate a postural comfort index for the entire upper body. This paper examines a postural comfort study that has been used to develop the MATLAB® Digital Human Model. Several routines for tracing trajectories while reaching for commands in a confined environment (e.g., a work table or a car-cockpit) were evaluated to obtain the maximum perceived postural comfort for each target point. Iso-comfort points were defined for each space, and iso-comfort surfaces were designed using an appropriate CAD system. An example of these routines is shown below. Iso-comfort surfaces can be also customized for different percentiles. This allows car-interior designers to have a virtual knowledge of the final perceived comfort when they decide, for example, on the positioning of a dashboard command.

Abstract: What are the new trends in research for comfort evaluation and the objective and predictive techniques for quantifying and qualifying comfort perception by humans? This paper has attempted to answer this question in a wide literature review, whereby it is possible to highlight many partial aspects that have been studied successfully. Just a few researchers [1–3] have studied the problem of comfort perception and evaluation under a wider point of view. Nevertheless, some aspects seem not to have yet been taken into account. In a previous paper, the authors extended the Vink–Hallbeck model to build a comfort perception/evaluation matrix in which four kinds of comfort related to different humans’ perception were studied and linked to the whole environment's characteristics. In the resultant perception-scheme and in the proposed “fusion rule” (for different kinds of perceived comfort/discomfort), one aspect that played a fundamental role in the final comfort/discomfort perception/evaluation was expectation. Expectation due to preconceived data (acquired or formed in the users’ minds) and the influence of the working environment, can act in terms of additive or subtractive factor in the comfort experience by altering the final comfort/discomfort perception and changing the subjective comfort/discomfort evaluation. This paper presents the results of expectation influence analysis on comfort evaluation. Using the placebo effect, authors conducted a wide experimental test with a wide sample of users, asking them to use and evaluate two identical mattresses that were dressed and described as two different products (the first one as a very cheap mattress and the second one as a high-level and expensive mattress). Differences between subjective evaluations have been statistically processed and correlated to anthropometric parameters to individuate and understand the role of expectation.

Keywords: Cognitive | Comfort evaluation | Expectations | Mattress | Physiological and environmental comfort | Postural

Abstract: Of primary importance in Axiomatic Design (AD) theory is Suh‘s first axiom, stating that the independence of functional requirements should be maintained throughout the design process. Para-complete logics, such as fuzzy logic, can be used to express the relationship between functional requirements (FRs) and design parameters (DPs) in AD. This is especially true in cases where this relationship can only be codified using linguistic variables. In fact, para-complete logics violate the principle of the excluded third party, allowing for the effects of changes in DP within the same FR to be considered partially independent of each other. Recently, a paper was published investigating changes in the concept of decoupled design when para-complete logics are applied to FRs-DPs link definition. Using an example case, this paper evaluated the impact of a designer‘s decoupling capability using composition rules for FRs, in order to make the design matrix diagonal or lower triangular by decoupling the effects of several DPs on different FRs using fuzzy formulation. -cut is a powerful instrument used to modify membership functions in order to approximate a non- optimized solution to an optimized one, by simply modifying the membership values. In this paper, we attempt to elaborate a simple optimization method based on a controlled approximation given by several values applied to different membership functions. We then introduce a new method to control and evaluate the amount of that approximation.

Keywords: Axiomatic design | Design approximation | Design optimization | Fuzzy set | Para-complete Logics

Abstract: In Axiomatic Design Approach, the first axiom, states that independence of functional requirements should be maintained throughout the design process. Para-complete logics, such as Fuzzy logic, represents a powerful instrument to express ―mathematical/functional‖ interaction between Functional Requirements (FRs) and Design Parameters (DPs). Para-complete logics violate the principle of the excluded third party, so that the effects of DPs’ changes on the same FR can be considered partially independent each other. Our paper investigates the changes in Decoupled Design’s concept when para-complete logics are applied in FRs-DPs matrix definition. Paper evaluates the impact of decoupling capability of designer using composition rules on FRs, in order to make the design matrix diagonal or lower triangular by decoupling effects of several DPs on different FRs using Fuzzy formulation.

Keywords: Axiomatic design | Design optimization | Fuzzy set | Para-complete logics

Abstract: In this paper we introduce and describe a new concept in human-measurements operation that seems to be very useful for comfort evaluation: the Range of Rest Posture (RRP). Our study is focused on the identification of RRP -inside the comfort range of motion (CROM)-for the following human joints: neck, shoulder, elbow, wrist and ankle. Method used is based on a wide experimental work on 85 healthy individuals (43 males and 42 females) ranging in age from 20 to 30 year. The main target of this work is the experimental definition of CROM and identification of RRP; Experimental data has been processed by statistical methods for identifying the best statistical distribution in order to fit experimental data. Main result is the identification of RRP in CROM of main human joints involved in upper and lower limbs movements. In RRP weve found several maximum level of comfort positions in human postures: those position seems to be one of the most important information in comfort evaluation analysis. The state of the art about comfort/discomfort evaluation shows the need of an objective method to evaluate effect in the internal body and perceived effects in Moes (Contemporary ergonomics. Taylor & Francis, London, 2005) and Vink and Hallback (Appl Ergon 43:271-276, 2012) scheme of comfort perception; postural comfort is one of the aspect of comfort/discomfort perception and this paper helps to put a piece in the puzzle of posture evaluation. On the basis of papers results, a comfort evaluation method can be developed using RRP, CROM and building a composition rule that takes into account also lumbar comfort and H-point. Our work does not use ROM and CROM values coming from literature because each of these values has been experimentally identified. © 2013 Springer-Verlag France.

Keywords: Comfort evaluation | Human joints | Range of motion | Rest Posture

Abstract: General comfort may be defined as the "level of well-being" perceived by humans in a working environment. The state-of-the-art about evaluation of comfort/discomfort shows the need for an objective method to evaluate the "effect in the internal body" and "perceived effects" in main systems of comfort perception. In the early phases of automotive design, the seating and dashboard command can be virtually prototyped, and, using Digital Human Modeling (DHM) software, several kinds of interactions can me modeled to evaluate the ergonomics and comfort of designed solutions. Several studies demonstrated that DHM approaches are favorable in virtual reachability and usability tests as well as in macro-ergonomics evaluations, but they appear insufficient in terms of evaluating comfort. Comfort level is extremely difficult to detect and measure; in fact, it is affected by individual perceptions and always depends on the biomechanical, physiological, and psychological state of the tester during task execution. These parameters cannot be modeled using software and instead have to be tested on physical models. A seating buck is often used to prototype a driver's seat, and virtual, mixed, and augmented reality devices help designers to improve ergonomics and comfort of a human-machine interface (HMI). In such environments, both postural and cognitive comfort can be evaluated, but often, testers' opinions are affected by devices, their interaction with designers, and especially, posture analysis systems. One solution to this kind of perception alteration can be found in non-invasive acquisition methods, such as acoustic, magnetic, or optical methods. Each has its own advantages and disadvantages, but all share the same characteristics: they are expensive and difficult to calibrate and use. This paper presents a new method for objectifying and evaluating postural and cognitive comfort levels based on human posture analysis and a questionnaire to evaluate cognitive performance. The posture acquisition method employs commercial low-cost cameras on tripods. The comfort evaluation methods, previously developed at the University of Salerno, are based on several experimental test campaigns, statistical processing, and biomedical studies. The method was tested in terms of reachability and usability for automotive drivers and was performed in a B-segment car (FIAT Grande Punto). A sensitivity analysis was performed to correlate the low resolution of the photographic acquisition with the consequent errors in the comfort evaluation. Posture acquisition errors were analyzed using DHM (DELMIA) software. Copyright © 2014 SAE International.

Abstract: The aim of this work is the realisation of an automatic generalised procedure for creating a parametric easily manageable and fully automatic FEM model to predict the mechanical properties of composites having cylinder-shaped reinforcing fibres characterised by a complex morphology. A three-dimensional finite element RVE (Representative Volume Element) has been realised by means of an original modified RSA algorithm (Random Sequential Adsorption algorithm) which allows to reproduce, with high degree of approximation, the intrinsic geometrical and statistic characteristics of the examined composite, directly influenced by the particular real forming process and, therefore, the phenomena which characterise the mechanical response of the materials constituting the therein coexisting phases. The implemented procedure is completely automatic, because it requires an external operator barely for the insertion of a minimum number of geometrical information in Input. This insertion pertains to the geometrical information concerning the composite to simulate and to the information about the mechanical properties of the coexisting phases. In Output the procedure provides directly, through a single run, the whole stiffness matrix calculated with two different numerical homogenisation tools, using periodic boundary conditions. The procedure allows a minimisation of the RVE dimensions which give acceptable scatters, thanks to an original "isotropic criterion" based on the minimisation of a particular function. It was also introduced a method of calibration of those Input data which may be affected by geometrical constraints, introduced to face the basic assumptions of the algorithm. The first release of this algorithm has been already implemented, in a previous published work, see Cricrì et al. (2012). Such a procedure results potentially much more versatile than most of the existing models; it is facilely adaptable to investigations beyond the mechanical characterisation and covers other areas of interest related to composites. © 2013 Elsevier B.V. All rights reserved.

Keywords: Fibres | Finite element analysis (FEA) | Modelling | Nanocomposites

Abstract: Main purpose of this work is to show how easy and economics an ergonomic/comfort based approach, in re-design a manual assembly workplace, can be; authors, using a new comfort/ergonomic evaluation criterion, analyzed a workstation and identified the critical issues under ergonomic/comfort point of view and finally gave several guidelines to re-design the workplace, implementing minor modification, and improve work-safety, work-quality and productivity. The postural analysis was performed by non-invasive and especially inexpensive methods, based on cameras and video-recorder use and by photogrammetric analysis; DELMIA® DHM software has been used to perform all simulations; comfort analysis was performed by the software developed by researchers of Departments of Industrial Engineering of Salerno: CaMAN®. The test case is an automatic assembly machine that has been modeled and used for virtual postural analysis. Main results of this work can be found in a very good numerical/experimental correlation between acquired/simulated postures and real ones, and on the powerful use of an objective comfort evaluation method, based on biomechanics and posture analysis, for giving to designers the guidelines to re-design a workplace and a work-cycle. This kind of approach seemed to be very powerful in re-designing the work-place and in re-scheduling the work time-sheet because it allowed to improve an ergonomic corrective action with minor costs for company. Obtained results demonstrated the validity of re-design hypotheses through the increase of all comfort indexes and the improvement of workstation/operator productivity. © (2014) Trans Tech Publications, Switzerland.

Keywords: Comfort evaluation criteria | Digital human modeling | Ergonomics | Not-invasive postural analysis | Re-design

Abstract: Mathematical modelling of human mandible and its temporomandibular joints (TMJs) is one of the most important steps for developing a powerful forecasting tool to analyse the stress/strain behaviour of a human masticatory system under occlusal loads. In this work the structural behaviour of a mandible with articular discs, undergoing a unilateral occlusion, is numerically analysed by means of both Finite Element Method (FEM) and Boundary Element Method (BEM). The mandible is considered as completely edentulous and its anisotropic and non-homogeneous bone material behaviour is modelled. The material behaviour of the articular discs was assumed to be either elastic or hyper-elastic. The loads applied to the mandible are related to the active muscle groups during a unilateral occlusion. The results of FEM and BEM analyses are presented mainly in terms of stress distribution on the mandible and on the articular discs. Due to the uncertainty in the determination of the biological parameters, a sensitivity analysis is provided, which demonstrates the impact of the variation of articular disc stiffness and TMJ friction coefficient on the mandible stress peaks and on the occlusal loads (for a given intensity of muscle loads). Moreover a comparison between the effectiveness of the BEM and FEM numerical approaches on this kind of problem is provided. © Citarella et al.

Keywords: BEM | FEM | Human mandible | Temporomandibular joint

Abstract: How can car designers evaluate device's position inside a car today? Today only subjective tests or "reach-ability" tests are made to assess if a generic user is able to reach devices, but it's no longer enough. The aim of this study is to identify an instrument (index) that is able to provide a numerical information about the discomfort level connected with a posture that is kept inside a car to reach a device, by this instrument it should be possible not only judge a posture, but also compare different solutions and get rapid and accurate evaluations. In the state of the art there are many indexes developed to evaluate postural comfort (like RULA, REBA and LUBA [3, 4, 5]) but none of them has been realized to evaluate postures' conditions that can be detected inside a car, so their evaluations cannot be acceptable. There are also many other studies (like Porter and Gyi, Krist, Grandjean, Rebiffe, Dreyfuss 2D and 3D) which deal with postural comfort inside car, but they have only assess neutral angles and ranges of comfort, so their evaluations are qualitative and discontinuous. For these reasons it has been realized a new instrument (implemented by our research group using Matlab™) to give the wanted numerical evaluation; it is based on an human scale manikin that can reproduce each user and each posture which can be introduced directly or imported from a digital human modeling (DHM) software (like JACK™ developed by U.G.S.), on discomfort functions (one for each degree of freedom of the manikin) and on a method (based on the distribution of the weights of the human body on the different joints) to aggregate them and return total discomfort values. © 2009 SAE International.

Abstract: In the current demanding global marketplace, ensuring that human fit, form and function are comprehensively addressed, is becoming an increasingly important aspect of design and, in particular, obliges the most important automotive industries to develop more flexible assembly lines and better methods for PLM solution. In the meantime, designers attempt to elaborate product development methodologies that conform health and safety standards while still maximizing the productivity. The aim of this work consists in developing a methodology based on preventive ergonomics and feasibility analyses of assembly tasks, simulating a work cell, in which acts a digital human model (manikin), in order to maximize human safety and performance and analyze manikin interaction in the virtual environment. In ergonomic analyses the OCRA protocol will be used, evaluating different involvement degrees of upper limb segments. The methodology is carried out by ergonomic tool of DELMIA software, using Digital Human Models technology. © 2008 International Federation for Information Processing.

Keywords: Digital human models | Ergonomic analysis | OCRA protocol | PLM solution

Abstract: In the last years the most important automotive OEM have given more importance to job organization and optimization in the plants for productivity and legal reasons. The continuous request to produce different new models in few years oblige OEM to develop more flexible assembly lines and better methods for job planning on the same lines. In the meantime, safety norms and product quality reasons request to improve working condition also according to international standards. In this paper, the authors show a new method for process design with the final goal to optimize assembly tasks. The method is based on the possibility to apply preventive ergonomics and feasibility analysis of the assembly task through a virtual simulation investigating general feasibility of the task and risks of muscle-skeletal pathologies from incongruous postures and movements. Using Digital Human Models (DHM) and Virtual Reality (VR) tools, it is possible to simulate manual assembly tasks in a very preliminary moment of the process development where designers and engineers have only virtual models to check assembly feasibility and to design the final bill of process. Through the use of virtual manikins, designers can vary workers movements to solve complex problems related to human movements and posture recognition bringing more realistic and reliable simulations to systematically investigate workplaces for a wide variety of users and operative solutions. On the methodological point of view, a special attention has been given to ergonomics evaluation methods that, usually, have an experimental nature and therefore specific adaptations are required to use them on digital humans in virtual environments. In the paper, the authors show an application of the new method to an interesting case study. The simulations suggest new solutions which bring to a more ergonomic and efficient task. Copyright © 2008 SAE International.

Abstract: A statistical approach based on the variance analysis allows to appraise the influence of the foam that covers leg impactors on results of the tests required by European New Car Assessment Program [EuroNCAP, Pedestrian Testing Protocol, Rel. 3.1.1, Gennaio, 2002] and ACEA (European Automobile Manufacturers Association) for the safety of the pedestrians in case of accident. Impactor used to evaluate the damage in pedestrian test is made by TRL and is quite similar to the structure of the human femur: it has a very complicated system to simulate the whole bone-flesh-skin apparatus and, in particular, has two layers of special Confor™ Foam CF45 Blue that has the same mechanical behaviour of human flesh; we have made a dynamic characterization of that foam at medium and high impact velocity; in order to simulate the whole leg impactor, in PamCrash environment, using the ESI formulation of the skin and using the results of characterization of all other elements with experimental tests. Experimental data coming from tests on foam have a medium value and dispersion around the mean; that dispersion can affect significantly the results of final simulation. So we have applied several statistical methods in order to optimize the final simulation results. This analysis is a part of a more complex design of experiment that analyse the difficulties when we simulate, using finite element method (FEM) simulation, the impact pedestrian-car. In problematic that is complex and not linearly influenced by many factors even a numerical simulation could be improved and optimised by statistic techniques. © 2005 Elsevier B.V. All rights reserved.

Keywords: Confor Foam | Design of experiment | Pedestrian safety

Abstract: In this paper the axioms, of axiomatic design, are extended to the non-probabilistic and repetitive events. The idea of information, in the classic theories of Fisher and Wiener-Shannon, is a measure only of probabilistic and repetitive events. The idea of information is broader than the probability. The Wiener-Shannon's axioms are extended to the non-probabilistic and repetitiveness events. It is possible the introduction of a theory of information for events not connected to the probability therefore for non-repetitive events. On the basis of the so-called Laplace's principle of insufficient knowledge, the MaxInf Principle is defined for choose solutions in absence of knowledge. In this paper the value of information, as a measure of equality of data among a set of values, is applied in axiomatic framework for data analysis in such cases in which the number of functional requirements (FRs) is greater than the design parameter's (DPs) one. As example is studied an application in which the number of DPs is lower then the number of FRs, and the coupled design cannot be satisfied. A typical example in which that happens is in the evaluation of the potential failure mechanisms, failure stresses, failure sites, and failure modes, given a product architecture, the comprising products and materials, and the manufacturing processes. In design analysis it is possible to hypothesise several causes that can affect the normal functionalities of some products/processes' parts and to individuate several possible effect that those causes can cause. In ideal analysis, each functional requirement (effect) must be linked to one design parameter (cause), and vice versa each design parameter can satisfy one (or more) functional parameter. From the system of equations it turns out that with the number of {FR} < {DP} it is possible to have only approximate solutions. In this situation the number of DPs is insufficient to achieve all the {FR} in exact mode. Respecting the following statements:In absence of solution is not possible compare anything: is needed at least a solution.Using mathematical transformations it is possible to obtain a marginal solution. Using the idea of information in metric space, in according with Maximum Entropy Principle of Jaynes it is possible to select as solution the distribution that maximise the Shannon entropy measure and simultaneously is consistent with the values of constraints. So this method allows to solve the Axiomatic framework and to reason for obtain the best design solution. © 2005 Elsevier B.V. All rights reserved.

Keywords: Axiomatic design | Entropy | Failure mode analysis | MaxInf | Non-probabilistic information | Probability

Abstract: In this paper, we analyse the design of a support plate for the accumulator of an electric motor vehicle. The support is an integral part of motor vehicle chassis. Therefore, geometrical configuration and boundary conditions require careful optimisation research of both function and structural behaviour, since lightness and dimension problems in the presence of dynamic stresses due to external factors have to be considered. Since these factors are complex and not homogeneous, the problem requires multi-criteria analysis. The presence of factors that are not precisely computable calls for fuzzy-logic application to optimisation problems, because fuzzy-logic is non-standard logic, particularly suitable for making choices in structural design. In plate optimisation, in fact, not numerically quantifiable characteristics such as a part's workability, numerically determinable structural values such as stresses and strains, and analytically calculable properties such as weight come into play. These four parameters become the domain of fuzzy membership functions, by which we will extract membership grade values (co-domain). Design variables (domain) are plate thickness, ashlar's number on the plate and stiffening ashlar's depth. In our research, we characterise fuzzy correlation between parameters and required characteristics in order to determine, according to non-standard logics, the best topological configuration which corresponds to the optimisation of individualised characteristics in conformity with design constraints. Results show value improvement in stress and strain in comparison with the not yet optimised plate and small reduction in workability, whereas the mass is almost the same. © 2002 Published by Elsevier Science B.V.

Keywords: Decision making | Fuzzy logic | Structural optimisation