From Knowledge to Leverage: How to Use Musculoskeletal Simulation to Design Exoskeleton Concepts

Background: An exoskeleton and its wearer form a mutually dependent biomechanical system, where design choices for the exoskeleton can affect the wearer in complex and often unforeseeable ways, and this makes exoskeleton design challenging. Advanced simulation methods provide an insight into the consequences of design choices, but such analysis is usually employed towards the end of the design process. This paper demonstrates an option for musculoskeletal simulation to be used already in the conceptual design phase. Methods: We present the workflow by means of an example of box lifting. We show that the mathematical algorithm underlying the solution of the redundant equilibrium equations in musculoskeletal modeling has a structure that can be exploited to gain information about ideal actuator forces for an exoskeleton supporting the selected work task. Results: Based on the identified forces, passive or active actuators can be selected, and control strategies can be devised. Conclusions: We conclude that this methodology can save design cycles and improve exoskeleton development.