Robust Fault Detection for Switched Fuzzy Systems With Unknown Input

This paper investigates the fault detection problem for a class of switched nonlinear systems in the T–S fuzzy framework. The unknown input is considered in the systems. A novel fault detection unknown input observer design method is proposed. Based on the proposed observer, the unknown input can be removed from the fault detection residual. The weighted <inline-formula> <tex-math notation="LaTeX">${H_\infty }$ </tex-math></inline-formula> performance level is considered to ensure the robustness. In addition, the weighted <inline-formula> <tex-math notation="LaTeX">${H_{-}}$ </tex-math></inline-formula> performance level is introduced, which can increase the sensibility of the proposed detection method. To verify the proposed scheme, a numerical simulation example and an electromechanical system simulation example are provided at the end of this paper.