Fault diagnosis and self-restore fault-tolerant control for systems with state delays

Facing to a class of faults whose dynamic characteristics are known, but initial states and initial instants are unknown, fault diagnosis and self-restore fault-tolerant control are researched for linear systems with state delays. A novel observer-based approach to fault diagnosis is proposed, and a design approach to fault-tolerant control law is given. By introducing a special linear transformation, the time-delay systems are transformed into the delay-free ones. Then, the problem of fault diagnosis for time-delay systems is transformed into a problem of state observation for delay-free systems. By constructing a novel fault diagnoser which doesn´t need residual to embody faults, fault diagnosis is realized on-line. Finally, by using the results of fault diagnosis, a dynamic self-restore control law and a compensation law for output measurement values are designed, so that the states and the measured outputs of the system are isolated from faults. A simulation example is given to demonstrate the feasibility and validity of the proposed scheme.