Human factors and ergonomics

The study on cognitive workload is a field of research of high interest in the digital society. The implementation of 'Industry 4.0' paradigm asks the smart operators in the digital factory to accomplish more 'cognitive-oriented' than 'physical-oriented' tasks. The Authors propose an analytical model in the information theory framework to estimate the cognitive workload of operators. In the model, subjective and physiological measures are adopted to measure the work load. The former refers to NASA-TLX test expressing subjective perceived work load. The latter adopts Heart Rate Variability (HRV) of individuals as an objective indirect measure of the work load. Subjective and physiological measures have been obtained by experiments on a sample subjects. Subjects were asked to accomplish standardized tasks with different cognitive loads according to the 'n-back' test procedure defined in literature. Results obtained showed potentialities and limits of the analytical model proposed as well as of the experimental subjective and physiological measures adopted. Research findings pave the way for future developments.

Keywords: Cognitive load , Heart rate variability , Information theory model , NASA-TLX , Smart operators

This work proposes an innovative method for evaluating usersâ™ engagement, combining the User Engagement Scale (UES) questionnaire and a facial expression recognition (FER) system, active research topics of increasing interest in the humanâ"computer interaction domain (HCI). The subject of the study is a 3D simulator that reproduces a virtual FabLab in which users can approach and learn 3D modeling software and 3D printing. During the interaction with the virtual environment, a structured-light camera acquires the face of the participant in real-time, to catch its spontaneous reactions and compare them with the answers to the UES closed-ended questions. FER methods allow overcoming some intrinsic limits in the adoption of questioning methods, such as the non-sincerity of the interviewees and the lack of correspondence with facial expressions and body language. A convolutional neural network (CNN) has been trained on the Bosphorus database (DB) to perform expression recognition and the classification of the video frames in three classes of engagement (deactivation, average activation, and activation) according to the model of emotion developed by Russell. The results show that the two methodologies can be integrated to evaluate user engagement, to combine weighted answers and spontaneous reactions and to increase knowledge for the design of the new product or service.

Keywords: 3D simulator , CNN , Deep learning , Facial expression recognition , Human-computer interaction , User engagement scale , User-centered design

Due to its versatility, virtual technology is being widely employed in different domains, from industry to amusement. The possibility to adopt this technology in early product/service design is going to bring positive effects such as the reduction of costs associated with the production of physical prototypes and the generation of a more effective knowledge of users' feedback. This study proposes a preliminary methodology to evaluate users' engagement in interacting with a virtual environment that consists of the integration between a self-report method (the user engagement scale questionnaire) and a method based on facial expression recognition. Results reported in this paper show that the two methodologies generate different types of knowledge which can be used to fit users' needs and expectations. Even if focused on a specific case study, i.e., the evaluation of the engagement in a virtual learning environment, this paper aims to propose a methodology that can be applied to all kinds of virtual products.

Keywords: FER (facial expression recognition) , Product life cycle , Self-reports , Student engagement , Virtual learning environment

This paper introduces a motion analysis system based on a network of common RGB cameras, which provides the measurement of various angles considered for postural assessment, in order to facilitate the evaluation of the ergonomic indices commonly used for the determination of risk of musculoskeletal disorders of operators in manufacturing workplaces. To enable the tracking of operator postures during the performed tasks, the system exploits the multi person keypoints detection library “OpenPose”. The proposed system has been validated with a real industrial case study regarding a washing machine assembly line. Results suggest how the proposed system supports ergonomists in risk assessment of musculoskeletal disorders through the OCRA index.

Keywords: Assembly line , Ergonomic assessment , Manufacturing , Motion capture , OCRA index , Posture analysis

Very often historical buildings used as museums are characterized by rooms completely covered with decorations (e.g. frescoes, inlay, etc.) rich in details and symbolic contents. Providing adequate information to the visitors to allow them to fully appreciate the artworks is of paramount importance in this context. X-reality technologies have the potential to provide an effective response to the need to combine the educational mission of museums with the ability to involve visitors emotionally, allowing the public to learn new knowledge in a playful way. This study introduces a Museum Guide System, based on Dynamic Projection, to increase the involvement of visitors to the Studiolo by Federico da Montefeltro at Urbino, minimizing technology intrusiveness by ensuring a complete fusion of digital contents with the physical environment. The system is able to track the visitors, to detect their profile and to offer information and multimedia contents tailored to the characteristics of the audience (e.g., children, adults).

Keywords: Adaptive system , Digital Cultural Heritage , Dynamic projection , Museum Guide System , Spatial Augmented Reality

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

In recent years, driving simulators have been widely used by automotive manufacturers and researchers in human-in-the-loop experiments, because they can reduce time and prototyping costs, and provide unlimited parametrization, more safety, and higher repeatability. Simulators play an important role in studies about driver behavior in operating conditions or with unstable vehicles. The aim of the research is to study the effects that the force feedback (f.f.b.), provided to steering wheel by a lane-keeping-assist (LKA) system, has on a driver's response in simulators. The steering's force feedback system is tested by reproducing the conditions of criticality of the LKA system in order to minimize the distance required to recover the driving stability as a function of set f.f.b. intensity and speed. The results, obtained in three specific criticality conditions, show that the behaviour of the LKA system, reproduced in the simulator, is not immediately understood by the driver and, sometimes, it is in opposition with the interventions performed by the driver to ensure driving safety. The results also compare the performance of the subjects, either overall and classified into subgroups, with reference to the perception of the LKA system, evaluated by means of a questionnaire. The proposed experimental methodology is to be regarded as a contribution for the integration of acceptance tests in the evaluation of automation systems.

Keywords: Driving simulator , Lane keeping assist , Steering wheel torque

Designing highly usable and ergonomic control dashboards is fundamental to support the user in managing and properly setting complex machines, like trains, airplanes, trucks and tractors. Contrarily, control dashboards are usually big, intrusive, full of controls and not really usable for different users. This paper focuses on the re-design of an ergonomic and compact dashboard for tractor control, proposing an innovative methodology in line with human-centered design and ergonomics principles. The study started by shifting the focus from how a machine works to how a task has to be performed and how the user interacts with the machine. It uses virtual simulations and human performance analysis tools to support the concept generation and the detailed design, and to test the new idea with users in the virtual lab. Indeed, within the virtual environment, different configurations of controls can be tested, checking which controls are mostly used and measuring human performance indexes (i.e., postural comfort and mental workload) for each configuration. Virtual mannequins can be used to as "digital twins"to interact with virtual items and to calculate robust comfort indicators during task execution. The study adopted the proposed methodology to an industrial use case to develop a usable and compact armrest for a new tractor platform. The new armrest is smaller than the previous one (-30% in dimensions), more usable (keeping on board only frequent controls, better positioned), and more comfortable (it satisfies 95% of the population size). This new approach could be used also for the design of new products.

Keywords: Human Factors , Human-centered design , Usability , Virtual simulation

Successful interaction with complex systems is based on the system ability to satisfy the user needs during interaction tasks, mainly related to performances, physical comfort, usability, accessibility, visibility, and mental workload. However, the "real"user experience (UX) is hidden and usually difficult to detect. The paper proposes a Transdisciplinary Assessment Matrix (TAS) based on collection of physiological, postural and visibility data during interaction analysis, and calculation of a consolidated User eXperience Index (UXI). Physiological data are based on heart rate parameters and eye pupil dilation parameters; postural data consists of analysis of main anthropometrical parameters; and interaction data from the system CAN-bus. Such a method can be adopted to assess interaction on field, during real task execution, or within simulated environments. It has been applied to a simulated case study focusing on agricultural machinery control systems, involving users with a different level of expertise. Results showed that TAS is able to validly objectify UX and can be used for industrial cases.

Keywords: Ergonomics , Human Factors , Human-centered design , User eXperience (UX) , Workload

Transdisciplinarity is characterising numerous research areas, in which natural sciences are integrated with technical and social sciences, requiring mixed methodologies for achieving full sustainability. However, there is a lack of engineering methods and design tools able to effectively integrate the analysis of human performance and social impacts with technical issues during product and process design. In this context, digital manufacturing tools and virtual simulation technologies can be validly used to create interactive digital mock-ups where human-system interaction during manufacturing operations can be simulated to support product and process design. The paper proposes a mixed reality (MR) set-up to support human-centred product and process design, where systems and humans interacting with them are monitored and digitalised to easily evaluate the human-machine interaction, with the scope to have feedback for design optimisation. Such an approach is defined as trans disciplinary since it merges technical design issues and human perspectives to design products on the basis of effective human performance, with the goal to early detect design criticalities and improve the overall system design. Industrial use cases have been developed to demonstrate the validity of the proposed approach to support human-centred design of a tractor. Results have demonstrated potential improvements, in terms of time saving for design review and workers' training, reduction of physical prototypes for design validation, reduction of late design and engineering changes, reduction of ergonomic issues, and global positive impact on time-to-market.

Keywords: human factors , human-centered design , transdisciplinary engineering , Virtual manufacturing , virtual reality (VR)

In the context of smart factories, where intelligent machines share data and support enhanced functionalities at a factory level, workers are still seen as spectators rather than active players (Hermann, Pentek, & Otto, 2017). Instead, Industry 4.0 represents a great opportunity for workers to become part of the intelligent system; on one hand, operators can generate data to program machines and optimize the process flows, on the other hand they can receive useful information to support their work and cooperate with smart systems (Romero et al., 2016). Diversely from machines, humans are naturally smart, flexible and intelligent, so putting the operators in the digital loop can bring more powerful and efficient factories. The paper aims at defining a theoretical human-centered framework for Operator 4.0, and testing its feasibility and impact on companies, thanks to the integration of human factors in 4.0 computerized industrial contexts. The proposed framework is based on data collection about the workers' performance, actions and reactions, with the final objective to improve the overall factory performance and organization. Data are used to assess the workers' ergonomics performance and perceived comfort and to build a proper knowledge about the human asset of the factory, to be integrated with the knowledge derived from machine data collection. The framework is cased on the adoption of an Operator 4.0 monitoring system, which consists of an eye tracking and a wearable biosensor, combined to a proper protocol analysis to interpret data and create a solid knowledge. Virtual prototypes are used to make the workers interact with the digital factory to conveniently simulate the human–machine interaction (HMI) in order to avoid bottlenecks at the shop floor, to optimize the workflows, and to improve the workstations' design and layout. The study represents a step toward the design of human-centred industrial systems, including human factors in the digital twin. The research approach has been successfully tested on an industrial case study, developed in collaboration with CNH Industrial, for the re-design of assembly workstations.

Keywords: Digitization , Human factors , Industry 4.0 , Mixed reality , Operator 4.0

This paper presents an approach for monitoring exercises of hand rehabilitation for post stroke patients. The developed solution uses a leap motion controller as hand-tracking device and embeds a supervised machine learning. The K-nearest neighbor methodology is adopted for automatically characterizing the physiotherapist or helper hand movement resulting a unique movement pattern that constitutes the basis of the rehabilitation process. In the second stage, an evaluation of the patients rehabilitation exercises results is compared to the movement pattern of the patient and results are presented, saved and statistically analyzed. Physicians and physiotherapists monitor and assess patients' rehabilitation improvements through a web application, furthermore, offer medical assisted rehabilitation processes through low cost technology, which can be easily exploited at home. Recorded tracked motion data and results can be used for further medical study and evaluating rehabilitation trends according to patient's rehabilitation practice and improvement.

Keywords: Hand rehabilitation , K-nearest neighbor , Leap motion controller

A 3D sketching system is presented for transforming an ideation to an actual CAD model using Human Computer Interaction (HCI). The system uses a Leap motion controller to capture human gestures, and translated them by a recognition model. The pinch and pull gestures are used to represent actions for flexible manipulations on control points coordinates of NURBS surfaces. The continuous motion of the designers hands is converted to morphological/geometrical and mathematical values. Both cases of single and dual hands are developed, offering the designer a variety of resolution tools to convey their ideas and creativity.

Keywords: 3D sketching , Human Computer Interaction Design , Leap Motion controller , NURBS surfaces

Driving safety is recognized as critical for young people by institutions, insurances and research. The ability to manage such a complex activity as driving is still developing through adolescence and in early adulthood. The present research investigates the human factors in the driver-car interaction. The experimental method assesses the visual-motor coordination capabilities of future drivers, also in relation to their life styles. The results show that a frequent but good quality physical activity improves visual-motor coordination.

Keywords: Broc String , Distance Rock test , Human factors , Motor Efficiency Test , Peripheral Wall Chart , Visual-Motor coordination

Today, a wide range of domains encompassing, e.g., movie and video game production, virtual reality simulations, augmented reality applications, make a massive use of 3D computer generated assets. Although many graphics suites already offer a large set of tools and functionalities to manage the creation of such contents, they are usually characterized by a steep learning curve. This aspect could make it difficult for non-expert users to create 3D scenes for, e.g., sharing their ideas or for prototyping purposes. This paper presents a computer-based system that is able to generate a possible reconstruction of a 3D scene depicted in a 2D image, by inferring objects, materials, textures, lights, and camera required for rendering. The integration of the proposed system into a well-known graphics suite enables further refinements of the generated scene using traditional techniques. Moreover, the system allows the users to explore the scene into an immersive virtual environment for better understanding the current objects\' layout, and provides the possibility to convey emotions through specific aspects of the generated scene. The paper also reports the results of a user study that was carried out to evaluate the usability of the proposed system from different perspectives.

Keywords: Human-computer interaction , Image-based modeling , Scene and object modeling , Virtual reality

Products aimed at individuals with disabiliy could not match user requirements under conditions imposed by the user. Also, frequent modifications and adaptation are required to increase the match between user requirements and prototypes. The importance to test different solutions and gain a knowledge base is an important aspect as the time in trials and experimentation is still a limit of personalized devices. An experimentation is conducted to test a solution of hardware interface for an Augmentative and Alternative Communication System which implements visual feedbacks and visual tutorial in training phase. In this study, visual feedbacks demonstrate an improvement of performances due to three main effects: reducing training time through an interactive tutorial, improving automatic behaviour and limiting cognitive load. The prototypes are realized using open-source electronic boards and Additive Manufacturing to realize the housing. A usability test is performed to calculate metrics and benchmark solutions with and without visual aids. Measures of Lostness and Keystroke Level Model estimates the effectiveness of software interface and interaction of users with hardware and software interfaces.Also, this study can lead to the definition of an adaptive switch that modify its status in order to eliminate redundant operations and ineffective actions.Visual feedback has proven some advantages in training user and Additive Manufacturing enabled the study and lead the way for devices that are adaptive on software interface and control and personalized in the hardware interface.

Keywords: augmentative and alternative communication , biomedical devices , usability

The complexity of the interaction between user and computer can limit usability in products. When products are aimed at individuals with disability, the complexity increases the cognitive load and can reduce performances. The identification of interaction models and usability issues plays a role in product development as it enables designers to reduce this complexity. Methodology to identify lacking areas in products are required and permits to correct issues leading to an improvement of performances. A custom Augmentative and Alternative Communication system was developed for a student of the University of Naples Federico II. The user has complex communication needs and motor impairments and requires a personalized device to communicate. To promote an efficient interaction, hardware and software interfaces were personalized. Several studies were conducted: a usability evaluation, determination of the learning rate and Hardware/Software layout optimization were used to reduce the cognitive demands required by the system in its functioning. In this paper the HW layout optimization is investigated and strategies to reduce the cognitive load modifying order and position of the sensors of the input peripherals are provided.

Keywords: Augmentative and Alternative Communication , Human-Computer Interaction , Usability Testing

In a complex case of speech disorder, the communication is entrusted to systems equipped with a speech synthesizer. When the user has a motor disability, in addition, hardware and software interfaces are personalized to make technology more accessible. Interaction design methods can be applied to develop improved assistive systems and, particularly, for Augmentative and Alternative Communication (AAC). Interaction design methods and usability evaluation could have a positive impact in reducing product barriers and improving performances as the effort state associated to its use can be reduced. Minimizing cognitive and physical efforts through the development of new solutions and interface optimization can be challenging. A usability test and an interface optimization of a personalized AAC system developed for a student of the University of Naples Federico II with complex communication needs due to a traumatic injury and motor impairment are discussed to fix usability issues, highlight critical areas and design new prototypes.

Keywords: Augmentative and alternative communication , Biomedical devices , Disability , Interaction design , Learnability , Usability

Unfortunately, the affiliation of one of the authors “Salvatore Gerbino” was incorrect in the original publication, and the correct version is updated here.

This paper presents an interactive design method aimed at improving workplace health and safety. Human performances and anthropometric variability are carefully considered to make the workplace “robust” from a safety point of view. This topic is of increasing interest to industries that plan to make safer workplaces without renouncing to their productivity targets. A challenging issue concerns the evaluation of the effects of sources of anthropometric variability in the process by using just a small sample of real or digital humans. The adoption of a discretization technique helps to solve this problem and saving time and resources. Through real industrial case studies, the authors investigate the main ergonomic and safety issues faced during the development of both manual and human–robot hybrid workcells.

Keywords: Design methods , Digital human modelling , Human–robot interaction , Robust design , Virtual ergonomics , Virtual safety