Development of the PD/PI extended state observer to detect sensor and actuator faults simultaneously

This paper discusses about an observer based fault detection scheme to detect sensor and actuator faults simultaneously in LTI system. The proposed strategy is to add derivative action on the extended state observer (ESO) in addition to proportional-integral action, so that the structure of the proposed observer is PD/PI or called PD/PI-ESO. The derivative action is performed both in state estimation and fault estimation. This is to achieve fast state estimation as well as fast fault estimation. Furthermore, the effects of disturbance are attenuated by using the H_∞ performance approach. The observer gains are then determined based on Linear Matrix Inequalities (LMI) technique. Simulation results of a DC motor speed control system are presented to illustrate the effectiveness of the proposed method.