Fault Detection Observer Design for Nonlinear Steering Control Systems of Unmanned Surface Vehicles

This article studies the design of fault detection (FD) observers for nonlinear steering control (NSC) systems of unmanned surface vehicles (USVs) with steering machine faults. The considered NSC systems of USVs are characterized by discrete-time T-S fuzzy models with immeasurable states. First, a new fuzzy FD observer is constructed to handle the challenge caused by the introduction of membership functions (MFs) that are different from the ones in the system, in which the MFs in the FD are designed by scaling and biasing those of the T-S model. Different from the existing uncertainty restrictions between the MFs in the systems and those in the observers, the deterministic restrictions are constructed, and the MFs of the observer are directly constructed according to the ones of the system without calculation. Then, by employing Lyapunov function (LF), it is proved that the constructed FD observers can ensure the stability and desired performance of the systems. Finally, an NSC system model of USVs is given to verify the effectiveness of the presented technical solution.