Design of unknown input integral sliding‐mode discrete observer for linear systems

Abstract

This paper considers the problem of the observer design to estimate the state and reconstruct the unknown inputs for linear discrete‐time systems in the presence of uncertainties. By appropriate use of system transformation and the integral term in the sliding‐surface design, we propose a novel output injection term in its structure to achieve convergence of the sliding‐manifold. The dimension of the designed observer is independent of the number of additive uncertainties in the model of the plant. A numerical simulation demonstrates the design procedure and compares the proposed observer with the standard proportional integral observer (PIO) design.