A Redefined Discrete Quasi - Sliding Mode Strategy

Variable structures with sliding mode control (SCM) are one of the best techniques for analyzing the dynamics of nonlinear systems, not only in continuous domain but also in discrete domain. This paper presents a redefined discrete quasi-sliding mode control strategy. The reaching law condition defined in the presently available technique is redefined in this paper. For systems with both time invariant disturbances and time variant disturbances the redefined strategy improves the convergence rate of the system dynamics in the reaching mode. Due this, the system response is smoother during the transition from reaching mode to sliding mode with reduced settling time and better quality criterion. These improvements are achieved at a lesser control effort compared to that required by the presently available techniques, thus improving the overall system efficiency. The proposed redefined strategy is applied to the systems with time-invariant and time-variant disturbances separately, and the results obtained demonstrate its effectiveness and improved efficiency.