Controller design for matrix second-order nonlinear plants based on requirements on tracking performance and disturbance rejection

In this paper, controller design for matrix second-order nonlinear plants based on requirements on tracking performance and disturbance rejection is addressed. The proposed controller is composed of a decoupling controller and a disturbance term observer. When designing the controller, a new tracking performance index is first defined, which reflects the desired modes of tracking errors of the closed-loop system. Based on this index, a decoupling controller with a disturbance term is derived. A disturbance term observer is then designed to estimate the disturbance term. In this research, Stability is proved for the closed loop system and it is shown that the speed and shape of response of the closed loop tracking error can be conveniently regulated with only two parameters; furthermore the closed loop system has strong disturbance rejection property. Good performance of the proposed controller is demonstrated by controlling a three-link nonlinear robot manipulator.