Computationally inexpensive fault tolerant control of uncertain non‐linear systems with non‐smooth asymmetric input saturation and undetectable actuation failures

Abstract

This study investigates the tracking control problem of strict-feedback systems with parametric uncertainties and asymmetric non-smooth saturation as well as actuation faults. By combining a well-defined smooth function with a Nussbaum-type function, robust adaptive and fault-tolerant control scheme is developed, which, as compared with most existing methods, exhibits several attractive features such as, capable of dealing with strict feedback systems with time-varying unknown control gain and parametric uncertainties; able to cope with asymmetric and non-smooth input saturation without requiring the prior knowledge of bound of input saturation; able to accommodate unexpected actuation faults; and structurally simple and computationally inexpensive. The proposed control schemes can guarantee all of the signals in the closed-loop system are semi-globally uniformly ultimate bounded. Finally, a simulation experiment is utilised to demonstrate the feasibility of the proposed design approach.