Stability Analysis of a Class of Nonlinear Systems Using Discrete Variable Structures and Sliding Mode Control

This paper presents the application of discrete-time variable structure control with sliding mode based on the ‘reaching law’ method for robust control of a ‘simple inverted pendulum on moving cart’ a standard nonlinear benchmark system. The controllers designed using the above techniques are completely insensitive to parametric uncertainty and external disturbance. The controller design is carried out using pole placement technique to find state feedback gain matrix , which decides the dynamic behavior of the system during sliding mode. This is followed by feedback gain realization using the control law which is synthesized from ‘Gao’s reaching law’. The model of a single inverted pendulum and the discrete variable structure control controller are developed, simulated in MATLAB-SIMULINK and results are presented. The response of this simulation is compared with that of the discrete linear quadratic regulator (DLQR) and the advantages of sliding mode controller over DLQR are also presented Keywords—Inverted pendulum, Variable Structure, Sliding mode control, Discrete-time systems, Nonlinear systems.