EXTENDED IMPEDANCE CONTROL OF REDUNDANT MANIPULATORS BASED ON WEIGHTED DECOMPOSITION OF JOINT SPACE

In this work, impedance control approach based on an extended task spa ce formulation is addressed to control the kinematically redundant man ipulators. By defining a weighted inner product in joint space, a mini mal parameterization of the null space is achieved, and we can visuali ze the null space motion explicitly. Moreover, it is shown that carefu l choice of the weighting matrix gives physically consistent and inert ially decoupled dynamics. By augmenting this minimal null motion param eter with a forward kinematic relation, a new extended task space form ulation can be obtained. Based on this formulation, we propose two con trol methods, a kinematically decomposed impedance controller and an i nertially decoupled impedance controller, to control the motion of the end-effector as well as the internal motion expanding the conventiona l impedance control. We also show the relationship with the previous d ynamic controllers of a redundant manipulator. Some numerical simulati ons are given to demonstrate the performance of the proposed control m ethods. (C) 1998 John Wiley & Sons, Inc.