Disturbance observer-based fault-tolerant control for a class of additive faults

This chapter is devoted to the design of a class of fault-tolerant controllers for a class of linear systems with additive faults. The states and the allowed class of faults are first studied in the context of linear systems with unknown inputs; in this context, the structural properties of the system are studied to determine the conditions that should satisfy the faults to be estimated. Then, using a high-order, sliding mode-based observer, both the states and the dynamic effect of the faults are estimated. The fault tolerance of a baseline controller is enhanced by the feedback injection of the estimated fault. An illustrative example is proposed at the end of the chapter, where a fault-tolerant control is designed for the roll autopilot of a missile. The simulations show the effectiveness of the proposed methodology.