Although the automation level is high within the automotive industry, there are still a large number of manual tasks, especially is the final assembly of the vehicle. Overhead assembly operations is an example of a problematic manual task that can cause workers to develop musculoskeletal disorders in the shoulder complex. Exoskeletons may be a solution to reduce the risk for developing musculoskeletal disorders from the work tasks. This study evaluates and compares how the use of three different passive upper body exoskeletons affects the range of motion (ROM) of workers at overhead assembly tasks. An experiment consisting of three tasks was set up in order to analyze the differences between the models. Seventeen subjects were involved in the study. Interviews, observations, videos and motion capture recordings were the methods of collecting data. The results show agreement from all the subjects that the exoskeletons help the worker at this specific assembly operation. The results also show that different exoskeleton models cause different levels of ROM reductions. The subjects’ opinions about how the different exoskeletons influence the ROM corresponds with the analysis of the motion capture data. Positive and negative aspects of each exoskeleton from a ROM and an implementation point of view are discussed. In general, the results indicate that the exoskeleton models can be applicable for the type of work tasks studied. However, the exoskeletons would benefit from further development in order to decrease ROM limitations and therefore cover a larger number of different manual assembly tasks.
Recent developments in commercial virtual reality (VR) hardware with embedded eye-tracking create tremendous opportunities for human subjects researchers. Accessible eye-tracking in VR opens new opportunities for highly controlled experimental setups in which participants can engage novel 3D digital environments. However, because VR embedded eye-tracking differs from the majority of historical eye-tracking research, in both providing for relatively unconstrained movement and stimulus presentation distances, there is a need for greater discussion around methods for implementation and validation of VR based eye-tracking tools. The aim of this paper is to provide a practical introduction to the challenges of, and methods for, 3D gaze-tracking in VR with a focus on best practices for results validation and reporting. Specifically, first, we identify and define challenges and methods for collecting and analyzing 3D eye-tracking data in VR. Then, we introduce a validation pilot study with a focus on factors related to 3D gaze tracking. The pilot study provides both a reference data point for a common commercial hardware/software platform (HTC Vive Pro Eye) and illustrates the proposed methods. One outcome of this study was the observation that accuracy and precision of collected data may depend on stimulus distance, which has consequences for studies where stimuli is presented on varying distances. We also conclude that vergence is a potentially problematic basis for estimating gaze depth in VR and should be used with caution as the field move towards a more established method for 3D eye-tracking.
This paper presents a solution that integrates a smart textiles system with virtual reality to assess the design of workstations from an ergonomics point of view. By using the system, ergonomists, designers, engineers, and operators, can test design proposals of workstations in an immersive virtual environment while they see their ergonomics evaluation results displayed in real-time. The system allows its users to evaluate the ergonomics of the workplace in a pre-production phase. The workstation design can be modified, enabling workstation designers to better understand, test and evaluate how to create successful workstation designs, eventually to be used by the operators in production. This approach uses motion capture together with virtual reality and is aimed to complement and integrate with the use of digital human modelling (DHM) software at virtual stages of the production development process.
DHM tools have been widely used to analyze and improve vehicle occupant packaging and interior design in the automotive industry. However, these tools still present some limitations for this application.Accurately characterizing seated posture is crucial for ergonomic and safety evaluations. Current human posture and motion predictions in DHM tools are not accurate enough for the precise nature of vehicle interior design, typically requiring manual adjustments from DHM users to get more accurate driving and passenger simulations. Manual adjustment processes can be time-consuming, tedious, and subjective, easily causing non-repeatable simulation results. These limitations create the need to validate the simulation results with real-world studies, which increases the cost and time in the vehicle development process.Working with multiple Swedish automotive companies, we have begun to identify and specify the limitations of DHM tools relating to driver and passenger posture predictions given predefined vehicle geometry points/coordinates and specific human body parts relationships. Two general issues frame the core limitations. First, human kinematic models used in DHM tools are based on biomechanics models that do not provide definitions of these models in relation to vehicle geometries. Second, vehicle designers follow standards and regulations to obtain key human reference points in seated occupant locations.However, these reference points can fail to capture the range of human variability. This paper describes the relationship between a seated reference point and a biomechanical hip joint for driving simulations. The lack of standardized connection between occupant packaging guidelines and the biomechanical knowledge of humans creates a limitation for ergonomics designers and DHM users. We assess previous studies addressing hip joint estimation from different fields to establish the key aspects that might affect the relationship between standard vehicle geometry points and the hip joint. Then we suggest a procedure for standardizing points in human models within DHM tools. A better understanding of this problem may contribute to achieving closer to reality driving posture simulations and facilitating communication of ergonomics requirements to the design team within the product development process.
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