Robust output feedback tracking control for a class of perturbed systems using NDOB and nonlinear continuous predictive control

This paper presents a new robust output feedback tracking control scheme for a class of higher-order uncertain systems. Since traditional nonlinear continuous predictive control requires accurate system model as well as full system states to synthesize a controller, a composite control methodology is adopted in the proposed scheme. Specifically, the nonlinear disturbance observer (NDOB) is used to estimate the lumped uncertainty and the unmeasured system states in an integrated manner while the nonlinear continuous predictive control regulates the system states to track the desired reference signal asymptotically. Detailed stability analysis is also presented for the closed-loop nonlinear observer-controller structure through two steps. Then, the obtained results are applied to missile autopilot design to track the desired angle-of-attack signal. Finally, numerical simulations with some comparisons are provided to demonstrate the effectiveness of the proposed formulation.