A model-free control system based on the sliding mode control method with applications to multi-input-multi-output systems

Abstract

In this paper, a model-free sliding mode control technique for linear and nonlinear uncertain multi-input multi-output (MIMO) systems is proposed. The developed method does not require a mathematical model of the dynamic system. Instead, the controller relies on state measurements and estimates of the error between previous and current control inputs to stabilize the system. Knowledge of the system's order, shape of the control input matrix, and control gain bounds, if non-unitary, are the only variables required to develop the controller. Lyapunov's stability criterion is used in the derivation process to ensure closed-loop asymptotic stability. High frequency chattering, often observed with the sliding mode control method, is eliminated using a smoothing boundary layer. Simulations are performed on a nonlinear two mass-spring-damper system and a quadrotor model to examine the performance of the proposed control law.