REDUCING FLEXIBLE BASE VIBRATIONS THROUGH LOCAL REDUNDANCY RESOLUTION

Future space systems will use teleoperated robotic systems mounted on flexible bases such as the Shuttle Remote Manipulator System. Due to d ynamic coupling, a major control issue associated with these systems i s the effect of flexible base vibrations on the performance of the rob ot. If uncompensated, flexible vibrations can lead to inertial trackin g errors and an overall degradation in system performance. One way to overcome this problem is to use kinematically redundant robots. Thus, this article presents research results obtained from locally resolving kinematic redundancies to reduce or damp flexible vibrations. Using a planar, three-link rigid robot example, numerical simulations were pe rformed to evaluate the feasibility of three vibration damping redunda ncy control algorithms. Results showed that compared to a zero redunda ncy baseline, the three controllers were able to reduce base vibration by as much as 90% in addition to decreasing the required amount of jo int torque. However, similar to locally optimizing joint torques, exce ssive joint velocities often occurred. To improve stability, fixed wei ght, multi-criteria optimizations were performed. (C) 1995 John Wiley & Sons, Inc.