Musculoskeletal Static Workspace Analysis of the Human Shoulder as a Cable-Driven Robot

The workspace analysis of cable-driven parallel manipulators has been widely studied, where the cables have been considered as ideal force generators. Due to the differences in actuation dynamics, workspace analysis has not been previously conducted for musculoskeletal systems. In this paper, static workspace analysis is performed on the human shoulder with a Hill-type physiological muscle model. The key characteristic of physiological muscles is that its ability to produce force is dependent on its length. Such type of workspace analysis on musculoskeletal systems as cable-driven manipulators is proposed for the first time. The generated shoulder workspace is validated by comparing the range of motion to that from benchmarks of human data. The significance of considering physiological muscles is demonstrated by comparing the musculoskeletal workspace with that of systems with ideal force generators. The novel formulation provides a new computational approach to perform workspace analysis for a wider range of engineered and biological systems.