THE MACRO MICRO MANIPULATOR - AN IMPROVED ARCHITECTURE FOR ROBOT CONTROL

A macro/micro manipulator system, consisting of a large (macro) robot carrying a small (micro) high-performance robot, has been proposed as a means of enhancing the functionality of a manipulator. The objective of the research presented in this paper was to investigate the inhere nt features in dynamic performance of such a system, and to evaluate i ts feasibility. The effect of a micromanipulator on the stability and performance of a robot system was investigated. it was found that a ma cro/micro manipulator is a stable and well-suited physical architectur e for endpoint control. A robust controller design based on physical e quivalence and impedance matching is proposed. It is shown that both e ndpoint position and force control bandwidths higher than the structur al frequencies of the robot can be achieved with minimal knowledge of the structure. A five degree-of-freedom micromanipulator that can acce lerate a 22 kg mass at 45 G was designed, fabricated, and attached to an experimental one-axis robot. Using this system, a force-control ban dwidth of 60 Hz (32 times higher than the first structural mode of the robot) was achieved against an environment that is five times stiffer than the robot structure. An endpoint position control bandwidth of 2 8 Hz (15 times higher than the first structural mode of the robot) was also achieved. This can improve endpoint accuracy, reduce cycle-time, and enhance the robot's capability to successfully interact with a la rge class of environments.