This paper presents an approach for evaluating exoskeleton support concepts through biomechanical analyses on a musculoskeletal human model. By simplifying the support forces of an exoskeleton as external forces, different support concepts can be biomechanically evaluated for the respective use case without concrete design specifications of the exoskeleton. This enables an estimation of the resulting relief and strain on the human body in the early stages of exoskeleton development. To present the approach, the use case of working at and above head height with a power tool is chosen.
Repetitive overhead work with a heavy load increases the risk for work-related shoulder disorders. Occupational exoskeletons supporting arm elevation are potential solutions to reduce that risk by lowering the physical strains on the shoulder. Many studies have reported a reduction in shoulder stress in various overhead tasks by using such exoskeletons. However, the support demand can vary in each phase of motion as well as in each individual task. This paper presents a laboratory study with five participants to evaluate the influence of the support level of an active shoulder exoskeleton in different motion phases (e.g., arm lifting, screw-in, and arm lowering of two overhead tasks) to identify the potential optimization of support at each phase. Results show that the support level of the exoskeleton should be adapted to the motion phase of the two chosen tasks. A higher support force is desired for the screw phase compared to the arm lifting and lowering phases, and the support level needs to be reduced immediately for arm lowering after the screw phase. The time for switching the support levels can be recognized by the electric current of the screwdriver.
Unterstützungssysteme zeichnen sich durch eine erhöhte MenschMaschine-Interaktion aus. Diese Interaktion und ihre Auswirkungen haben große Bedeutung für die Entwicklung und Anwendung von Unterstützungssystemen und führen zu einer besonderen Herausforderung bei der Simulation entsprechender Systeme. Um diesen gerecht zu werden, wird ein Co-Simulationsmodell von Menschen, Exoskelett und Power-Tool entwickelt. Derartige Co-Simulationsmodelle ermöglichen bereits in der frühen Phase der Entwicklung der Unterstützungssysteme eine digitale Integration des Anwenders.
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