An experimental study on redundancy resolution scheme of postural configuration in human arm reaching with an elbow joint kinematic constraint

This paper studies the redundancy resolution strategy of the central nervous system (CNS) in selecting an arm posture during reaching motions. Based on the assumption that such governing rules are preserved against any joint constraint condition, an elbow joint DOF was fixed during the experiments with a light weight elbow brace. Two different coordinate systems are defined to interpret kinematics and dynamics of motion in a task-oriented space and an internal body space. The kinematic and dynamic contributions of the internal body frame on the task frame, is quantified by mappings. The experimental results show that the core principle of the CNS to determine the arm posture is to minimize the kinetic energy cost.