Disturbance attenuation in robot control

We propose a model based disturbance attenuator (MBDA) with the conventional PD controller for robot manipulators. It is a generalization of the MBDA structure in Choi et al. (1999) and is applied to a robot manipulator which is nonlinear. This method does not require an accurate model of a robot manipulator and takes care of disturbances or modeling errors so that the plant output remains relatively unaffected by them. The output error due to the gravity or constant disturbance can be completely eliminated by this method in the same way as PID controllers. In addition, this can be easily implemented at a moderate computational cost. We apply this to a two-link robot manipulator and compare its performance with PD and PID controllers. Simulation results show that the proposed method is very effective in controlling robot manipulators.