Local torque minimization of redundant manipulators with considering end-motion joint velocities

Local torque minimization has been considered an appealing redundancy resolution approach for redundant manipulators. To minimize the joint torques, the redundancy must be resolved at the acceleration level. Since the joint velocities were never considered, the proposed solutions have been plagued by performance instabilities due to the buildup of high joint velocities. Besides, the joint velocities at end of motion were never guaranteed to be zero in the former-proposed approaches. This is also a flaw of the former approaches, because the zero end-motion joint velocities are necessary in practical use. In this paper, we introduce a stable local torque minimization technique, with consideration of the end-motion joint velocities. By making the end-motion joint velocities to zero, the local torque minimization approach exhibits global characteristics and generates a stable arm motion. Computer simulations were executed on a three-link planar manipulator to demonstrate the effectiveness of the proposed local torque minimization technique