Augmented Object and Reduced Effective Inertia in Robot Systems

The paper investigates the dynamic characteristics and control of robot systems involving combinations of parallel and serial mechanical structures, e.g. multiple manipulators and macro/micro-manipulators. A framework for the analysis and control of multiple manipulator systems with respect to the dynamic behavior of the manipulated object is developed. A multi-effector/object system is treated as an augmented object representing the total masses and inertias perceived at some operational point. This system is actuated by the total effector forces acting at that point. The allocation of forces is based on the minimization of the total joint actuator efforts. For serial structures, the effective inertial characteristics of a combined macro/micro-manipulator are shown to be dominated by the inertial characteristics of the micro-manipulator. A new approach for a dextrous dynamic coordination of such mechanisms based on treating the combined system as a single redundant manipulator while minimizing of the deviation from the neutral (mid-range) joint positions of the micro-manipulator is proposed.