Discrete sliding mode control with FIR output feedback sliding surface

Abstract

In this paper, two discrete sliding mode controllers (DSMC) are proposed for systems with time delay. A first order low pass finite impulse response (FIR) function of output error is taken as a sliding surface for designing first DSMC. While in the second DSMC, a sliding surface is selected as a function of first sliding surface. The design procedure is based on discrete time state space model of the system. The stability conditions of proposed controllers are derived using Lyapunov approach. The parametric uncertainty is also taken into account while designing the controllers. The results obtained from both DSMCs are compared to show the betterment of the second DSMC over the first DSMC. The chattering occurred in first DSMC is significantly reduced in second DSMC. Simulation examples are included to show the performance of proposed controllers.