Manipulability-maximizing self-motion planning and control of redundant manipulators with experimental validation

For achieving optimal maneuverability, a performance index in the form of quadratic function is proposed and analyzed for the self-motion with manipulability maximization (SM³) of redundant manipulators. The corresponding SM³ scheme can automatically select the desirable configuration so that the manipulator is most flexible and best maneuverable. As joint-physical limits generally exist in an actual redundant manipulator, both joint-angle limits and joint-velocity limits are taken into consideration in the proposed SM³ scheme. For practical and protective purposes, a zero-initial-velocity constraint is also incorporated into the SM³ scheme to eliminate the large-initial-velocity weakness. The SM³ scheme can further be converted and unified into a quadratic program (QP). In addition, two very important bridge theorems are provided to guarantee that the QP can be solved by a numerical algorithm efficiently. By comparing with the scheme of the self-motion with middle-value approached (SM²VA), computer-simulation results based on five-link and seven-link robot manipulators demonstrate the effectiveness of the SM³ scheme. Furthermore, the experiment is conducted on an actual six degrees-of-freedom (six-DOF) push-rod-joint (PRJ) manipulator, which substantiates the effectiveness and physical realization of the proposed SM³ scheme.