A quadratic boundedness approach to adaptive actuator fault estimation

This paper is concerned with the problem of designing adaptive actuator fault estimation scheme for linear discrete-time systems. The general methodology is focused on designing a robust fault estimation strategy with a quadratic boundedness approach which is used to guarantee the convergence of the proposed state and fault estimation scheme. The novelty of the proposed approach is that robustness is achieved through the unknown input decoupling while an unappealing effect of the undecoupled disturbances is suitably minimized. The proposed approach allows obtaining a feasible set of joined state and fault estimation error. Based on this knowledge, an adaptive threshold is obtained, which supports diagnostic decisions. The final part of the paper contains an illustrative example which confirms the effectiveness of the proposed approach.