International Journal of Human Factors Modelling and Simulation (9 papers in press)
Design and development of a game-engine based simulator specialized on ships evacuation
by George Kougioumtzoglou, Anastasios Theodoropoulos, Georgios Lepouras
Abstract: Modern ships have become larger in scale and function, and their complexity has increased considerably. This brings up many difficulties in evacuation and rescue when an emergency occurs. Therefore, effective evacuation and risk methods should be predicted and applied to design, safety training, and education. We have developed a Three-Dimensional Ship Evacuation Simulator (SES) facilitating the impersonation of evacuees by computer-controlled autonomous bots (agents) that perform risk assessment and continuously calculate route conditions, communicate with neighboring occupants, determine bottleneck points, and select the best evacuation routes. In this study, we introduce the simultaneous participation of human users and computer-controlled bots as evacuees in gamified multiplayer scenarios by the runtime spawning of 3D elements such as fire and smoke. SES is a game-engine based simulator with several benefits such as flexible technology and economic feasibility. We believe that realistic and valid results can be obtained by applying SES in evacuation simulation.
Keywords: Lightweight Simulator; Passenger Ship; Evacuation Simulation; Evacuation Model; Crowd Simulation; Human-Computer Interaction; Virtual Engineering; Intelligent agent.
Estimation of body surface area coverage by garment items: different approaches using mesh base modelling
by Gunther Paul
Abstract: Digital Human Modelling can be applied to determine skin exposure to sun as a factor in modelling risk of skin cancer. To determine body area covered by clothing (BSAC), a variety of garment data must be overlaid with the human model. Two approaches, one based on creation of clothing using MakeHuman add-ons in Blender, and the other based on the import of data are exemplified. Results are compared with data from Zhang . We found that a scalable library of garment elements, assembled to typical apparel is a feasible way to model clothing. We conclude that valid BSAC could be determined.
Keywords: Digital Human Modelling; DHM; Body surface area coverage by clothing; BSAC; skin cancer; MakeHuman.
The assessment of injury risk in the healthcare sector via integrating motion tracking techniques with digital human modeling ergonomic tools
by Xiaoxu Ji, Justo Hernandez, Emily Schweitzer, Wilson Wang, Davide Piovesan
Abstract: An advanced fusion technology has been investigated to evaluate the injury risk in the healthcare sector by integrating a motion tracking system with digital human modeling (DHM) ergonomic tools. The proposed approach greatly overcomes the time-consuming process to create a full-body dynamic simulation where the DHM postures are set manually. This study provides a new method to evaluate the lumbar forces and physical demands for individuals during healthcare operations. In this study, we analyzed the effect of key anthropometric and biomechanics variables on the low back loadings, such as body weight, body height, trunk and hip angular displacements, as well as genders. The relationship of such variables to the lumbar spine forces may provide insights on the occurrence of musculoskeletal disorders during patient handling tasks. The outcomes of this study can directly result in the design of better assistive device and workstation as well as the development of enhanced injury prevention programs.
Keywords: injury assessment; injury prevention; healthcare; patient handling task; ergonomics; physical demands; Xsens motion tracking; JACK Siemens; digital human modeling; lumbar spine; compressive force; shear force.
Special Issue on: IEA2021 Exoskeletons – Human-Centred Modelling, Simulation and Implementation
DHM Supported Assessment of the Effects of using an Exoskeleton during Work
by Francisco Garcia Rivera, Dan Högberg, Maurice Lamb, Estela Perez
Abstract: Recently, exoskeletons have been gaining popularity in many industries, primarily for supporting manual assembly tasks. Due to the relative novelty of exoskeleton technologies, knowledge about the consequences of using these devices at workstations is still developing. Digital human modelling (DHM) and ergonomic evaluation tools may be of particular use in this context. However, there are no standard integrations of DHM and ergonomic assessment tools for assessing exoskeletons. This paper proposes a general method for evaluating the ergonomic effects of introducing an exoskeleton in a production context using DHM simulation tools combined with a modified existing ergonomic assessment framework. More specifically, we propose adapting the Assembly Specific Force Atlas tool to evaluate exoskeletons by increasing the risk level threshold proportionally to the amount of torque that the exoskeleton reduces in the glenohumeral joint. We illustrate this adaptation in a DHM tool. We believe the proposed methodology and the corresponding workflow can be helpful for decision-makers and stakeholders when considering implementing exoskeletons in a production environment.
Keywords: digital human modelling; assessment; ergonomics; exoskeleton; assembly specific force atlas.
Study on multivariate analysis of anthropometric measures for upper body exoskeletons using archetypal analysis.
by Julia Riemer, Sascha Wischniewski
Abstract: The accurate fit of upper body exoskeletons is of importance for an efficient physical user support. However, theres a lack of multivariate data and adjustment ranges for proper upper body exoskeleton design. Therefore, the aim of this paper is to provide exoskeleton design-relevant body parameters of men and women as an input to suitable adjustment range for shoulder and back exoskeletons. We identified relevant body parameters for back and shoulder exoskeletons and calculated the upper and lower bounds for males and females by applying the archetypal analysis on a large anthropometric dataset from Mecklenburg-Vorpommern, Germany. Based on the archetypes, we identified minimum and maximum limits for males and females. These limits were checked for their accommodation level for the original as well as a weighted dataset, representing data for the whole of Germany. In addition, we compared the results of the limits with one dimensional percentile values. The results showed an accommodation for the identified multivariate limits between 87-94% for the different exoskeleton types and gender groups.
Keywords: Upper body exoskeletons; anthropometry; fitting parameters; archetypal analysis; ergonomic design.
A comparison of different methods for modelling the physical human-exoskeleton interface
by Divyaksh Subhash Chander, Max Böhme, Michael Skipper Andersen, John Rasmussen, Johannes Zentner, Maria Pia Cavatorta
Abstract: There are several methods to simulate the human-exoskeleton interface but there is insufficient evidence regarding the choice of the method. This work compares two rigid-body methods to simulate the interface: 1) optimization-based contact forces and 2) reaction forces at a point on the interface. Additionally, a method to kinetically align the human-exoskeleton joint axes is presented. A single subject tested an active lower limb exoskeleton in stair ascent. The biomechanical outputs were compared to a baseline model, where the measured assistive and ground reaction force were applied directly to the human model. Both methods showed negligible differences in knee compression force, knee flexion moment, and vastus lateralis activation. However, the ankle outputs showed some differences between the methods. Computationally expensive contact forces provided six-axis interface forces unlike reaction forces, which were limited to the number of constraints required by the exoskeleton. Future studies could compare rigid-body and viscoelastic models.
Keywords: Human-exoskeleton interface; interaction force; joint misalignment; musculoskeletal model; contact model; contact force.
Auditory Movement Feedforward for a Lower-Limb Exoskeleton Device (AIDER) to Increase Transparency
by Jing Qiu, Yilin Wang, Hong Cheng, Lu Wang, Xiao Yang
Abstract: A lower-limb exoskeleton (LLE) is a device intended to assist patients with spinal cord injury (SCI) with standing and walking in daily life. Due to the lack of proprioception in lower limbs, SCI patients wearing an LLE need the gait information feedforward from the human-exoskeleton system for walking safety. It is necessary, therefore, to explore how to improve the transparency of LLE systems to help the wearer get gait information from LLE. This study conducted several auditory prompt experiments to determine the most adaptive movement feedforward method to improve transparency for an exoskeleton called AIDER. The results indicated that auditory movement feedforward could remind wearers of the next motion state. Moreover, the subjects felt more secure with auditory movement feedforward than with no feedforward when wearing AIDER.
Keywords: lower-limb exoskeleton; spinal cord injury; transparency; movement feedforward; auditory prompt; AIDER.
Towards Standard Test Artifacts for Synchronous Tracking of Human-Exoskeleton Knee Kinematics
by Roger Bostelman, Ann Virts, Soocheol Yoon, Mili Shah, Ya-Shian Li-Baboud
Abstract: A repeatable evaluation of human-exoskeleton kinematics is needed to assess industrial exoskeletons impact on worker biomechanics and safety. Standard measurement methods and metrics facilitate technology adoption and effective specification of the exoskeletons intended use. This study assesses the feasibility and repeatability of a measurement method that enables synchronous tracking of human and exoskeleton kinematics using a set of lower-limb human motion capture test artifacts and exoskeleton motion capture plates. Experimental validation was conducted on 30 subjects. The inter-trial repeatability of the human knee joint angle was within 1.2 degrees to 2.7 degrees and within 1.3 degrees to 3.1 degrees for the exoskeleton joint angle (50th to 99th percentile). To apply the measurement of the test artifacts rigid body position and orientation, we propose two potential metrics, human-exoskeleton fit and stability, based on the human-exoskeleton alignment offset and the stability of the exoskeleton frame.
Keywords: motion capture repeatability; exoskeleton test methods; human motion capture test artifacts; human-exoskeleton interaction; standard measurement artifacts; synchronous human-exoskeleton tracking; knee kinematics; human-exoskeleton fit; human-exoskeleton stability; human-exoskeleton alignment.
Biomechanical investigation of a passive upper-extremity exoskeleton for manual material handling a computational parameter study and modelling approach
by Bo Eitel Seiferheld, Jeppe Frost, Mathias Krog, Sebastian Skals, Michael Skipper Andersen
Abstract: Passive upper-extremity exoskeletons may decrease the risk of developing work-related musculoskeletal disorders. This study examined how shoulder muscle forces and biomechanical loads in the glenohumeral and L4-L5 joint changed as different support torque (1.1-11.2 Nm) and angle settings (60-120°) of an exoskeleton were simulated during an overhead manual material handling task. Full-body kinematics of 15 grocery workers, who lifted a bread case (7.9 kg) onto shopping shelfs (145.5 cm), were captured on site. The kinematic data were used to drive a detailed human-exoskeleton model based on inverse dynamics. Generally, simulations with maximum torque combined with a peak angle setting between 75-105° reduced L4-L5 compression and anteroposterior shear forces, glenohumeral contact forces and shoulder flexor muscle forces. The exoskeleton therefore, seemed effective for reducing physical exposure during overhead handling. However, maximum torque with the lowest angle setting, 60°, increased musculoskeletal loading, suggesting that not adjusting the exoskeleton properly could be detrimental.
Keywords: musculoskeletal modelling; musculoskeletal diseases; exoskeleton device; lifting; manual material handling; computer simulation; biomechanics.