A novel design for robust fault diagnostic observer

A new approach for the design of robust fault diagnostic observers is proposed in this article. The design is carried out through transformation of the system into its special coordinate basis (SCB) form, and with the aid of loop transfer recovery (LTR) like techniques. Furthermore, simple necessary and sufficient conditions for existence of perfect disturbance decoupled residual are presented. The proposed design approach offers computational simplicity and unifies approaches using eigenstructure assignment and unknown input observer design. Finally, an example dealing with sensor and actuator failure diagnosis of a vertical takeoff and landing- (VTOL) aircraft is given to illustrate the proposed approach.