Industrial workers' work-related musculoskeletal disorders (WMSD) cause muscle, tendon, and nerve injury. These injuries affect the health of the industrial worker. These injuries have an impact on the health of the industrial worker. The risk of WMSD in the workplace must be investigated and minimised. The risk level of WMSD is investigated using ergonomic risk assessment tools. The objective of this study is to observe recent advancements in the ergonomic risk assessment of industry workers between 2007 and 2022. The literature was collected from standard ergonomic publications by searching abstracts and titles for keywords such as 'ergonomic risk assessment methods', 'ergonomic evaluation', 'ergonomic intervention', and 'musculoskeletal disorders (MSD) '. Over the last 15 years, recent developments in the ergonomic risk assessment of industry workers have been reviewed. Each risk assessment tool described above is essential in determining the risk of MSD among employees.
The simulation of maintenance activities is deployed within the industry to assess maintainability and human factors in preliminary aircraft architecture and design review. The use of augmented reality (AR) associated with a physical mock-up could be an alternative to other existing complementary simulations (virtual reality, physical mock-up alone). This paper introduces the first experiment with this hybrid simulation and the results of its performance. Through experimentation, we tested the ability of this solution to improve the design using the participants' feedback. This hybrid solution reduces the lead time in the development and decision process. It reduces the cost of the mock-up using only the basic shape of the model and tangible interfaces for the user. AR increases the details of the model, allows multiple configuration review and fosters collaboration between designers and project stakeholders.
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) optimisation-based contact forces; 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 forces 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.
A repeatable evaluation of human-exoskeleton kinematics is needed to assess an exoskeleton's impact on worker biomechanics and safety. Standard measurement methods and metrics facilitate technology adoption and effective specification of the exoskeleton's 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 artefacts 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° to 2.7° and within 1.3° to 3.1° for the exoskeleton joint angle (50th to 99th percentile). To apply the measurement of the test artefacts rigid body position and orientation, two potential metrics, human-exoskeleton fit and stability, were implemented based on the exoskeleton-human alignment offset and the stability of the exoskeleton frame.
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.
The accurate fit of upper body exoskeletons is of importance for an efficient physical user support. However, there's 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. 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.
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.
Digital human modelling can be applied to determine skin exposure to sun as a factor in modelling risk of skin cancer. To determine body surface 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 (Shah and Luximon, 2019). 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.
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 Nm-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 shelves (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.
