Human-Like Reaching Movements of a Redundant Musculo-Skeletal System with Nonlinear Muscle Dynamics
Kenji TAHARA, Zhi-Wei LUO, Suguru ARIMOTO
This paper studies a sensory-motor control mechanism of human's reaching movements from the perspective of robotics aspect. By formulating the musculo-skeletal redundant system which takes into account a nonlinear muscle property obtained by some physiological understandings, we suggest that the human-like reaching movements can be realized by using only simple task-space feedback scheme together with the internal force effect which comes from mechanical property of muscles without any complex mathematical computation such as an inverse dynamics or some optimal trajectory derivation. Firstly, we introduce both kinematics and dynamics of a three-link serial manipulator with six single-joint muscles and three double-joint muscles model whose movements are confined within a horizontal plane. Secondly, the nonlinear muscle property, which comes from several physiological understandings based on Hill's muscle model, is taken into consideration and illustrated by some numerical simulations that the end-point of the manipulator can converge to the desired point smoothly using only simple task-space feedback scheme by considering the muscle property and internal forces induced by the redundancy of muscles, which makes it possible to modulate the damping factors in joint-space, even if the system owns both kinematic and dynamic redundancies. Then we discuss the effectiveness of our control scheme, and suggest it as one direction to study brain-motor control mechanism of human movements.