Detection time for deterministic and stochastic systems with unknown inputs

This paper investigates the detection and diagnosis of actuator faults by using an Unknown Input Observer (UIO).The proposed UIO design guarantees robust residual generation through decoupling the disturbances effects from the faults ones. The discrimination between the faults and the effects of uncertain signals and perturbations on the residues minimizes the duration of fault detection for deterministic systems. Then these results were extended to the general case of stochastic linear systems by using an optimal observers for systems with unknown disturbances and noise. A simulation is done on an aeronautic model to illustrate the theoretical development.