Human factors and ergonomics

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

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

Postpartum haemorrhage (PPH) is an obstetric emergency causing nearly one-quarter of maternal deaths worldwide, 99% of these in low-resource settings (LRSs). Uterine balloon tamponade (UBT) devices are a non-surgical treatment to stop PPH. In LRSs, low-cost versions of UBT devices are based on the condom balloon tamponade (CBT) technique, but their effectiveness is limited. This paper discusses the experimental study to assess the usability and performance of a medical device, BAMBI, designed as an alternative to current CBT devices. The testing phase involved medical and non-medical personnel and was focused on testing BAMBI's usability and effectiveness compared to a standard CBT solution. We collected measures of the execution time and the procedure outcome. Different training procedures were also compared. Results show a significant preference for the BAMBI device. Besides, medical and non-medical subjects reached comparable outcomes. This aspect is highly relevant in LRSs where the availability of medical personnel could be limited

Keywords: Maternal mortality , Medical device , Patient safety , Sustainable development goals , Usability , User-centered design , Uterine balloon tamponade device

The advent of Industry 4.0 necessitates substantial interaction between humans and machines, presenting new challenges when it comes to evaluating the stress levels of workers who operate in increasingly intricate work environments. Undoubtedly, work-related stress exerts a significant influence on individuals' overall stress levels, leading to enduring health issues and adverse impacts on their quality of life. Although psychological questionnaires have traditionally been employed to assess stress, they lack the capability to monitor stress levels in real-time or on an ongoing basis, thus making it arduous to identify the causes and demanding aspects of work. To surmount this limitation, an effective solution lies in the analysis of physiological signals that can be continuously measured through wearable or ambient sensors. Previous studies in this field have mainly focused on stress assessment through intrusive wearable systems susceptible to noise and artifacts that degrade performance. One of our recently published papers presented a wearable and ambient hardware-software platform that is minimally intrusive, able to detect human stress without hindering normal work activities, and slightly susceptible to artifacts due to movements. A limitation of this system is its not very high performance in terms of the accuracy of detecting multiple stress levels; therefore, in this work, the focus was on improving the software performance of the platform, using a deep learning approach. To this purpose, three neural networks were implemented, and the best performance was achieved by the 1D-convolutional neural network with an accuracy of 95.38% for the identification of two levels of stress, which is a significant improvement over those obtained previously.

Keywords: deep learning , sensors , smart systems , stress detection , workers' health

The 4.0 revolution is leading to increasingly automated, flexible, and intelligent manufacturing systems that require greater complexity to manage during maintenance and process control. In this context the optimization of the human-machine interaction plays a crucial important role in the design of modern industrial systems. Virtual Reality (VR) offers realistic simulation environments where users can be involved to replicate specific human tasks, detecting and solving problems before they occur. The paper proposes a human-centric digital design methodology that integrates VR technologies with human data analysis tools to support the design or redesign of complex industrial systems. Different wearable devices have been used to collect data about physical and mental user conditions to provide an early assessment of the operators' workload, while comparing different design solutions into the virtual space. An industrial use case related to the redesign of packaging automated machines was used to validate the proposed method and tools: a preliminary correlation between physiological parameters and machines interactions was found.

Keywords: digital simulation , ergonomics and human factors , Human data analysis , Human-centred design , Virtual Reality

In the era of Industry 4.0, the importance of human-robot collaboration (HRC) in the advancement of modern manufacturing and automation is paramount. Understanding the intricate physiological responses of the operator when they interact with a cobot is essential, especially during programming tasks. To this aim, wearable sensors have become vital for real-time monitoring of worker well-being, stress, and cognitive load. This article presents an innovative dataset (SenseCobot) of physiological signals recorded during several collaborative robotics programming tasks. This dataset includes various measures like ElectroCardioGram (ECG), Galvanic Skin Response (GSR), ElectroDermal Activity (EDA), body temperature, accelerometer, ElectroEncephaloGram (EEG), Blood Volume Pulse (BVP), emotions and subjective responses from NASA-TLX questionnaires for a total of 21 participants. By sharing dataset details, collection methods, and task designs, this article aims to drive research in HRC advancing understanding of the User eXperience (UX) and fostering efficient, intuitive robotic systems. This could promote safer and more productive HRC amid technological shifts and help decipher intricate physiological signals in different scenarios.

Keywords: Human-Robot Collaboration , Human-Robot Interaction , Multimodal Dataset , Psychophysiological Signals , Stress Evaluation

The logistics industry involves various processes in the warehouse work environment on a daily basis, such as handling, storage, and packing. Therefore, workers are often engaged in manual activities such as pushing, pulling and lifting loads. These types of movements are repetitive and, together with adverse physical factors of the environment, they affect employees' health condition. The aim of this study is to test a proactive evaluation approach exploiting the potential of a professional virtual wall to simulate specific tasks performed in a warehouse to find the better solution in terms of working condition and productivity. The proposed framework includes the following steps: at first, it is required to design the virtual environment by means of 3D modelling tools; afterwards, simulation tests are performed by objectively assessing the physical working condition of the operator; finally, the valuable information are provided to improve the design of the workstation, based on the operator's ergonomics. The framework is modular and can be scaled to complex industrial environments.

Keywords: Ergonomics , Logistics , Virtual Reality , Virtual Wall

Nowadays the interest for improving methodologies to design customized external devices for the neck has considerably grown, considered that neck pathologies are widespread among the population. Their design for additive manufacturing starts by acquiring the body's part and, in order to achieve a satisfactory end result, the support of accurate reconstructed models from fast scans is relevant. At this aim, the availability of an average or statistical model could be potentially useful for reducing acquisition time and for upgrading low-resolution scans. This paper focuses on the application of a methodology for the creation of an average model of human neck. The method required the use of a set of scans, acquired by means of a structured light scanner, from which an accurate reconstruction of the neck surface was obtained. A number of healthy subjects of both genders was considered and the digital neck surfaces were used for creating an average digital model for males and for females. The methodology developed was based on mesh morphing and was applied to the sample considered with satisfactory results. The procedure is also suitable for the development of statistical models of the neck, that will cover future research

Keywords: Acquisition , Mesh morphing , Neck , Reverse Engineering

The paper presents a hybrid user-centred/simulation approach to populate the design specification. It presents an application in the field of exoskeleton design, with the final goal to support workers to carry out their professional tasks. More than 100 professionals (mostly health workers) participated in the survey. The qualitative requirements were extracted are then tested in simulation environments. The approach proved to generate meaningful results for product concept generation. Beyond the expectations, the simulation also showed more adequate product architectures.

Keywords: exoskeletons , product design , product planning , requirements management , user-centred design

The presented study investigates differences in engineering designers' CAD performance when modelling from two types of projections in technical drawings – isometric and orthographic. The results revealed significant differences in the percentage of correctly replicated components' size and shape, indicating better CAD outcomes when generating CAD models from the orthographic projection. In addition, a comparison of duration, as well as the number and type of sketch entities, sketch relations, and CAD features, showed that CAD modelling processes were similar in both conditions.

Keywords: computer-aided design (CAD) , design representation , performance indicators

Computational image aesthetics aims at determining what makes an image look pleasing. Assessing image aesthetics usually relies on the extraction of suitable image features related, for instance, to image composition (e.g. rule of third, depth of field), texture, shape and colour. It is widely accepted that colour, in particular, plays a major role in this context. The objective of this study was to investigate potential relationships between the most significant colours in an image (the colour theme, or palette) and the aesthetic rating. To this end we defined a procedure for colour palette extraction and its characterisation by a set of 21 hand-crafted features. Rank-based correlations between the features and manually-assigned aesthetic ratings were assessed by Spearman's correlation coefficient. Experimenting on a total of 4,647 images from the public dataset EVA we found that 12 features were significantly associated with image aesthetics, although the overall correlation strength was at best weak. In particular, perceived aesthetic rating correlated positively with saturation (indicating a slight preference for colourfulness) and negatively with colour temperature (suggesting a slight preference for warm colours). A significant positive correlation (but again weak) also emerged between perceived aesthetic and harmonic colour schemes

Keywords: Aesthetic rating , Colour , Image aesthetics , Visual perception

This work is aimed to set-up a methodology for foot shape prediction at different flexion angles, overcoming limitations encountered when different poses are required but a limited set of acquisitions can be performed. The basic idea was to identify a fitting law able to interpolate positions of foot anatomical landmarks, and then use this information to guide the deformation of an average foot shape. First of all, mesh correspondence between foot geometries was accomplished by an established procedure based on mesh morphing. Then Procrustes analysis was applied to the dataset to remove rigid motions and estimate the average shape. Two interpolation laws (linear and quadratic) were investigated and the best one in terms of prediction of 3D landmarks' coordinates was identified. Finally, shape geometries at any flexion angle were predicted performing a second mesh morphing guided by interpolated landmarks' displacements from the average shape. These analyses proved that a limited number of interpolation angles provides a prediction accuracy comparable to that obtained using all the angles available in the dataset. Moreover, predicted shapes have been compared to the actual scans in terms of root mean square error between corresponding nodes, obtaining a mean value of 4.03 ± 1.39 mm, in accordance with data reported in literature.

Keywords: Accurate geometric reconstruction , Foot model , Real-time acquisition , Statistical deformation model , Statistical shape model

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

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

Addressing sustainability challenges requires shifts in consumption patterns and lifestyles. Design for Sustainable Behavior (DfSB) aims to cultivate sustainable attitudes and behaviors through product-based interventions. However, there can be a disconnect between design strategy and its embodiment and sometimes conflicts between designers' intent and users' interpretation. This paper explores the role of metaphors in DfSB in terms of using metaphorical thinking during the design process and/or creating product metaphors in the final design. It begins by identifying barriers that prevent people from engaging in sustainable practices, such as human nature and ambiguity in design. It then examines the roles of metaphor in design and its key strengths in DfSB. Furthermore, the paper outlines three methods to generate metaphors in DfSB: (1) The source domain implies the target domain. (2) The source domain serves design goals and strategies. (3) Cross-domain mapping is based on embodied experience. In conclusion, the paper discusses potential issues surrounding its use in DfSB.

Keywords: Behavior change , Design for sustainable behavior , Metaphor , Metaphorical thinking , Product design , Sustainability communication

Nowadays, there is a pressing need to incorporate sustainable practices and promote environmental awareness. The fashion industry, characterized by resource-intensive consumption, significantly contributes to global sustainability threats. The authors proposed the adoption of Virtual Reality (VR) to design and develop the Fashion Footprint application, an experience aimed at enhancing sustainability awareness and fostering behavioral change. The findings suggest that VR technology is valuable in promoting sustainability awareness and driving positive behavioral shifts in the fashion industry.

Keywords: behavioural design , sustainability , virtual reality (VR)

This study explores the interplay between internal factors (e.g. personal values) and external factors (e.g. product framing and representation form) in shaping user perceptions, attitudes and behaviours towards products. A between-participants experiment (N = 52) was designed using deliberately an iconic product (Haribo gummy bears) to be presented either as image or a tangible item, as well as framed either positively or negatively. The aim is to examine the impact of these manipulated internal and external factors on users' evaluations and their subsequent behaviour. The effects of framing, and markedly negative framing, were considerably larger than those of forms of representations, whose role was limited for the studied product. However, the effect of framing on evaluations is amplified after interacting with the real product. Despite its significance, negative product framing cannot change behaviour as much as user personal values. These insights suggest designers pay attention to how products are portrayed to potential users. Particular attention should be paid to aligning products with the personal values of the target users since this turned as the main determinant for product appreciation. Hence, this research urges designers to pay attention to the fact that products have to resonate with users so to enhance their acceptance.

Keywords: negative framing , positive framing , Product evaluation , representation form , user behaviour

n the design literature, creativity of products is recognized as a combination of novelty and usefulness. However, this mainly applies to the engineering field and within a community of experts. This study investigates how ordinary people understand creativity embodied in products. In an experiment with 70+ participants, 8 products and 5 metrics were dealt with. Novelty resulted as the main predictor of creativity. Usefulness turned to play a minor effect on perceived creativity. It emerged that usefulness has to make ordinary people like a specific product in order to link it to creativity.

Keywords: creativity assessment , design creativity , novelty , ordinary people , product design

Controls and prevention activities for musculoskeletal disorders are increasingly encouraged in the industrial context. Several ergonomic assessment techniques exist. However, they primarily focus on the biomechanical and postural load requirements of job tasks and rely on self-report and observational methods rather than direct measurements, which are often too intrusive. This study investigates whether a commercially available low-intrusive and low-cost wearable sensor can be utilised to assess muscular effort and fatigue, thereby improving decision-making in work and workstation design. For this purpose, the potential of the Myo™ armband has been explored. The electrical activity of the upper limbs (arm and forearm) was evaluated through 15 physically tasks (manual handling and assembly) conducted in laboratory conditions. Satisfactory results were obtained from the correlation and significance analysis, considering the EMG signal, the Borg scale, and the activity level (e.g., load, distance, n° of repetitions). Further experimentation was conducted to validate the proposed approach in a real production facility.

Keywords: Electromyography , Human-centered manufacturing , Muscle effort and fatigue , Physical ergonomics , Upper limbs , Work-related musculoskeletal disorders

Using custom-made physical cutting guides in maxillofacial surgery presents several drawbacks, mainly related to design, time, and costs. Even if the literature provides several Augmented Reality (AR) solutions, they mostly display cutting planes and static assistance for repositioning. This work proposes a Mixed Reality (MR) application, deployed on Microsoft HoloLens2, to guide the surgeon in maxillofacial osteotomies and repositioning through intuitive and interactive digital content. A holographic panel allows selecting between the osteotomy and repositioning modes. With the first one, the cutting lines and the drilling points for the fixation plates are overlaid on the patient's skull. With the second one, three different kinds of feedback simultaneously guide the surgeon toward the correct final bone placement, step-by-step, according to the real-time fragment displacement. The MR app was tested by seven inexperienced subjects using a 3D-printed skull. Satisfactory results were obtained for maxillary osteotomy (i.e., less than 1.5 mm deviations) and relocation (i.e., the accuracy is about 0.7 mm and 0.6°).

Keywords: Augmented Reality , Healthcare Design , HoloLens 2 , Maxillofacial Surgery , Mixed Reality

Seeing the innovative character of exoskeletal devices, it appears that there is yet progress to be made in adopting exoskeletons to industry, and to the different users' characteristics and needs. Their validation is mainly focused on technological aspects and seldom researchers presented methodological approaches including both physical and cognitive impact on operators, synergically with functional issues. This study proposes a multi-faced approach to investigate the impact of passive exoskeletons on functional and ergonomic aspects providing a preliminary experimental validation with an industrial task. The approach assesses the physical comfort, muscular fatigue, cognitive workload, and users' technological acceptance, to map the overall user experience (UX). Participants were monitored by a mechanomyogram (MMG) and a motion capture (MoCap) system and a UX questionnaire was administered. Results demonstrated the effectiveness of passive exoskeletons regarding the specific task being strictly related to a correct definition of the level of assistance for each user.

Keywords: Ergonomic assessment , Exoskeletons , Physical comfort , User eXperience

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