DYNAMIC CONTROL OF MULTI-STRUCTURE ROBOT SYSTEMS AT THE MANIPULATION OBJECT LEVEL

ABSTRACT The paper discusses basic methodologies developed within the operational space framework for the analysis and control of robot systems involving combinations of serial and in-parallel mechanical structures. First, we present the fundamentals of the operational space framework and describe the unified approach for motion and active force control of manipulators. For serial structures such as a macro/-manipulator, the effective inertial characteristics of the combined system are shown to be dominated by the inertial properties of the micro-manipulator. This result is the basis for the development of a new approach for dextrous dynamic coordination. In this approach, the combined system is treated as a single redundant manipulator. The dexterity is achieved by minimizing the deviation from the neutral (mid-range) joint positions of the micro-manipulator. In the case where several arms, i.e. in-parallel structures, are involved in the manipulation of object, the multi-effector/object system is treated as an augmented object representing the total masses and inertias perceived at some operational point actuated by the total effector forces acting at that point. This model is used for the dynamic decoupling, motion, and active force control of the system using a criterion based on the minimization of the total actuator joint force activities.