Integral barrier Lyapunov functions based sliding mode observer‐controller for nonlinear systems with performance constraints

This article presents an observer‐controller structure for nonlinear systems with external disturbances, uncertainties and performance constraints. Firstly, considering the unmeasurable state issue, a sliding mode observer is designed to estimate the unknown state. Then an integral barrier Lyapunov function (iBLF) is established to ensure that the observer estimation errors are held within the performance constraints. With the objective of utilizing iBLF, an equivalent output injection technique is adopted. Combining with backstepping technique, an observer‐controller scheme is given. The controller can hold all signals in the closed‐loop system bounded with the help of iBLF, and the tracking error will converge to a bounded tight set without violating the corresponding constraints. The effectiveness of the proposed strategy is clarified via a vessel heading control example.