Adaptive Full-State-Constrained Control of Nonlinear Systems With Deferred Constraints Based on Nonbarrier Lyapunov Function Method

In this article, the problem of tracking control is considered for a class of uncertain strict-feedback nonlinear systems with deferred asymmetric time-varying full-state constraints. A novel adaptive robust full-state-constrained control scheme is developed. First, by introducing a novel shifting function, the original constrained system with any initial values is modified to a new constrained system, and the initial values of the modified constrained system remain 0. Then, to remove the feasibility condition caused by the barrier Lyapunov functions, the modified constrained system is further transformed into a new unconstrained system by a brand new nonlinear transformation. Furthermore, the tracking error system of the unconstrained system is constructed by using a new coordinate transformation, and a novel adaptive full-state-constrained control scheme is designed based on this error system through the backstepping recursion method and first-order filters. Finally, the resulting closed-loop system proves to be stable and numerical simulations are conducted to demonstrate the effectiveness of the developed control strategy.