STABLE JOINT TORQUE OPTIMIZATION FOR MULTIPLE COOPERATING REDUNDANT MANIPULATOR SYSTEM

In this paper, joint torque optimization for multiple cooperating redu ndant manipulators rigidly handling a common object is considered. Thi s work focuses on finding the optimal and stable distribution of the o perational forces of a multiple redundant manipulator system to the in dividual manipulators. Two joint torque optimization schemes(local joi nt torque minimization and natural joint motion) are formulated and co mpared. When a redundant manipulator with its joints free is driven by its tip, a naturally inducing joint motion can be called 'natural joi nt motion'. From the simulation results of a system of three cooperati ng redundant manipulators, the natural joint motion scheme is shown to be better than the local joint torque minimization scheme with regard to global torque minimization capability and the resulting stability of motion. However, in order to guarantee the stability, the null spac e damping method is required for the both schemes. The effectiveness o f the null space damping method is demonstrated by simulation. Additio nally, the condition for the distribution of the operational forces re quired to drive the given system along a natural joint motion trajecto ry is addressed.