Study of human motion generation based on redundancy of musculoskeletal structure: Analysis of potential generated by internal force for two-link system

The human body has a musculoskeletal system with the muscles which exist around the bones and joints. Taking notice of the structural characteristics that a human possesses inherently, this paper analyzes feedforward position control for the musculoskeletal system. The feedforward positioning does not need any sensory feedback by use of internal force balancing at a desired posture. Targeting a non-pulley musculoskeletal system with two links and six muscles, this paper clarifies mathematical conditions of the feedforward positioning to converge at a desired posture. In the analysis, muscular length is approximated by Taylor expansion. Based on quasi-statical approach, the convergent conditions are clarified. The verification of the conditions is conducted through simulation.