NULL-SPACE DYNAMICS-BASED CONTROL OF REDUNDANT MANIPULATORS IN REDUCING IMPACT

This paper presents an impact control algorithm for reducing the poten tially damaging effects of interaction of redundant manipulators with their environments. In the proposed control algorithm, the redundancy is resolved at the torque le vel by locally minimizing joint torque, s ubject to an operational space dynamic formulation which maps the join t torque set into the operational forces. For a given pre-impact veloc ity of the manipulator, the proposed approach involves generating join t space trajectories throughout the motion near the contact, which ins tantaneously minimizes the impulsive force which is a scalar function of the manipulator's configurations. This is done by using the null sp ace dynamics, which does not affect the motion of an end-effector. The comparative evaluation of the proposed algorithm with a local torque optimization algorithm without reducing impact is performed by compute r simulation. The simulation results illustrate the effectiveness of t he algorithm in reducing both the effects of impact and large torque r equirements. Copyright (C) 1997 Elsevier Science Ltd.