Performance-Guaranteed Adaptive Asymptotic Tracking for Nonlinear Systems With Unknown Sign-Switching Control Direction

This article presents a performance-guaranteed ad- aptive asymptotic tracking control scheme for a class of nonlinear systems with unknown sign-switching control direction. By introducing the periodic sliding mode technique and equivalent control- based adaptive mechanism, the proposed control approach ensures that the sliding mode surface is reached in finite time, and thus, the asymptotic stability is achieved rather than only signals boundedness. Simultaneously, the tracking performance is strictly guaranteed inside the preassigned performance bounds even when the unknown control coefficients switch to the opposite direction. The effectiveness of the proposed control law is verified by numerical simulations.