Robust Observer-Based Fault Tolerant Tracking Control for Linear Systems with Simultaneous Actuator and Sensor Faults: Application to a DC Motor System

Abstract

This paper discusses the problem of observer-based sensor and actuator fault estimation for fault tolerant control systems subject to noise and disturbance. First, an extended state system is formulated by letting the sensor and actuator fault term be two auxiliary state vectors; then a single robust observer is constructed to achieve concurrent estimations of original system states and faults by using PI structure. Further, sufficient conditions for the robust stability of the proposed observer are formulated in terms of linear matrix inequalities (LMIs) that can be conveniently solved using LMI optimization techniques. Based on the idea of a corrective control law and a corrective measurement output, which have capability to compensate the presence of fault, the estimation results of the proposed observer are used to provide the fault tolerant control system without changing the existing nominal control law. Thus this approach can be applied to general control system. Finally, the validity and applicability of the proposed approach are shown by a numerical example of a DC motor system.