The implementation of plug-in repetitive control on the direct drive axis of a prototype GMF A500 robot is considered. Plug-in repetitive control was developed and implemented using an IBM AT. A multirate sampling algorithm was designed to reduce the memory requirements of repetitive control. A microcontroller board based on the Intel 8096 was designed so that plug-in repetitive control could be applied from a small unit embedded within the KAREL controller. In each application, experimental results show that the tracking error is smoothly absorbed in a few cycles.>

The analysis and experimental implementation of a discrete-time repetitive control scheme is presented. The repetitive control structure is designed to be easily implemented on any system without modification to the existing controller. Simulation and experimental results show that the repetitive controller in conjunction with a computed-torque control or a simple proportional-derivative control law achieves good tracking performance when the desired trajectory is periodic and the period is known.>

The model reference adaptive control of a two axis direct drive manipulator arm is presented. The two axes exhibit a significant dynamic interaction. The model reference adaptive controller is utilized in the velocity loop to adaptively decouple the dynamic interaction and to linearize the dynamics. The outer loop controller for positioning and tracking is designed based on the linear decoupled dynamics. The adaptive velocity loop controller as well as position loop controller are implemented digitally. The use of a series-parallel, as well as a parallel reference model is suggested in the adaptive velocity loop controller. The stability problems arising from the straightforward digital implementation of the continuous time algorithm are analyzed and a modification in the digital algorithm is introduced which guarantees the asymptotic stability of the system. Simulation and experimental results show a consistently superior performance of the manipulator under adaptive control.

This paper deals with a design of a digital servo controller for a robot manipulator with mechanical nonlinearities. The experimental system is a D.C. motor driven manipulator arm. A model to predict the nonlinear behavior exhibited by the experimental system and a nonlinear controller with Coulomb friction compensator are developed and tested. The effectiveness of the nonlinear controller is certified by designing a linear tracking controller based on this scheme. Experimental and simulated responses are given.