A novel sth-order observer for linear system: Application to state and fault estimation of spacecraft control system

In this paper, a fault estimation problem for linear system is considered. A novel sth-order observer is proposed to cope with this problem. The advantages of the proposed observer are that (i) the observer matching condition is not required to be satisfied in practical systems, (ii) if the sth derivative of fault is unknown and/or unbounded and the (s + 1)th derivative of fault f (t) is naught or bounded, it can simultaneously estimate the state and fault. The sufficient existence condition of the proposed observer is given by a linear matrix inequality. In addition, a feasible method to obtain the design parameters is discussed. Finally, two numerical examples are presented to illustrate the effectiveness of the proposed method.