An improved adaptive robust motion controller combined with disturbance observer

Parameter adaptation and disturbance observer (DOB) have been considered as two contrastively different approaches in motion control problems. In our previous work [1], the two techniques were merged into one control design with theoretically guaranteed performance. A drawback of the method is that the controller has to be relatively complicated due to interference between the two mechanisms. In this paper, by exploiting the cascade features of backstepping design, the disturbance observer is inserted into the position-loop which compensates the velocity error that may not be suppressed to be sufficiently small by the adaptive mechanism. This results in a much simpler controller since the two mechanisms are separated.