New approach to an adaptive robust motion controller combined with a disturbance observer

Abstract

Parameter adaptation and disturbance observer (DOB) have been considered as two contrastively different approaches in motion control problems. In the authors' previous work, the two techniques were merged into one control design with a theoretically guaranteed performance. A drawback of the method is that the controller has to be relatively complicated owing to the interactions between the two mechanisms. In this study, by exploiting the cascade features of backstepping design, the DOB is inserted into the position-loop which compensates for the velocity error that may not be suppressed to be sufficiently small by the adaptive mechanism owing to the presence of unparameterised uncertainties. This results in a much simpler controller since the two mechanisms are separated. Simulation results show that the proposed controller, while being much simpler than the authors' previously proposed controller, yields a comparable control performance.