Tracking Control for Nonlinear Fully Actuated Systems with Multiple Disturbances Using Dual-Disturbance Observer

This paper considers a tracking control problem of nonlinear fully actuated systems (FASs) with multiple disturbances. A trapezoidal integral proportional-integral (TIPI) control based on dual-disturbance observer (DDO) is presented to address this problem. Concretely, a discrete-time FAS model of dynamic systems with multiple disturbances is provided as a foundation for the control design. For the multiple disturbances, the DDO including two high-order disturbance observers (HODOs) is designed to implement the accurate estimations under a less conservatism condition for full compensation. Then, the original nonlinearities can be eliminated by means of full actuation feature to obtain a linear constant system with the desired closed-loop performances. Further, a TIPI control is used to raise the computational accuracy for realizing the tracking control with satisfactory performance and simple design. A sufficient condition is derived to analyze the bounded stability and tracking performance of the closed-loop systems. A simulation of an inverted pendulum is provided to verify the feasibility of the DDO-based TIPI control.