Fuzzy robust fault-tolerant control for offshore ship-mounted crane system

Abstract

In this paper, a novel event-triggered fuzzy robust fault-tolerant control approach is designed to handle the offshore ship crane nonlinear system with actuator fault and external disturbance. The main objective of this study is to realize the tracking control ability of the outputs while saving the transmission resources, which is achieved by constructing the integrated adaptive sliding mode controller and event trigger mechanism. The fuzzy logic theory is used both in the observer and controller design processes to approximate the nonlinear unknown functions. First, the information of the crane system state, actuator fault, and lumped disturbance are acquired by designing a fuzzy composite observer. Then, a novel adaptive sliding mode controller is presented by using the estimated values. In the proposed control scheme, two adaptive parameters are contained to consider the disturbance elimination and to enhance the tracking performance. An adaptive law is also included to compensate for the fuzzy approximation error. Furthermore, a novel event-triggered controller is proposed to reduce the transmission load of the crane system while also maintaining the tracking ability of the crane system. The no Zeno phenomenon performance is analyzed and, finally, the application to the crane system is given to show the fault tolerance ability of the proposed method.