A fixed-time observer for discrete-time singular systems with unknown inputs

This paper is concerned with the fixed-time observer (FTO) design for discrete-time singular systems subject to unknown inputs. Firstly, the observer matching condition (OMC) and the strongly observability condition (SOC) are given. Then, a new FTO design framework with a reduced-order is given which is free from the influences of the unknown inputs. It is proven that the SOC together with the OMC guarantees the existence of a FTO which is able to provide an exact state estimation in an arbitrarily pre-defined time step. Another advantage of the FTO is that both the estimation accuracy and the convergence time step can be guaranteed regardless of whatever the initial values of the observer are. Finally, a numerical simulation validates the effectiveness of the proposed result. (C) 2019 Elsevier Inc. All rights reserved.