Design of optimal output sliding mode control for discrete-time systems and improving the response rate using the CNF method

In this paper, a new version of optimal discrete-time sliding mode control method for linear systems, without considering any constraints on the system structure or any limitations in dimension of the input vector is proposed. Moreover, to improve the transient response of the closed-loop system, the idea of CNF (composite nonlinear feedback) controller is utilized and the sliding surface is designed such that an arbitrary quadratic cost function is minimized. Since, in practice all state variables of the system may not be measurable, an output feedback method called FOS (fast output feedback), is used. The performance of the proposed algorithm is illustrated through analysis and simulation and the results are compared with two efficient methods: Discrete-time integral sliding mode and CNF composite with discrete-time integral sliding mode.