Improved Sliding Mode Control with Continuous Transition of Redefined Control Structures to Suppress Chattering

Abstract

Sliding Mode Control is a robust approach based on a variable structure controller inducing an exponential attractive behavior that has proved to be an effective design technique for complex electronic and electro-mechanical systems. However, discontinuous control is inherently related to the presence of parasitic dynamics excited by the switching action that induce high frequency oscillations around the Sliding Surface affecting the general performance of the closed-loop system. In this paper, the author, proposes an improved Sliding Mode controller that preserves the dynamic properties of the Sliding Mode but suppress the discontinuous control as the main cause of undesired dynamics inducing chattering. The proposed controller applies redefined design criteria concerning the introduction of the Sliding Surface as an intermediate control structure with an improved equivalent controller, and integrated to the others structures attracting the state to the Sliding Surface into a soft and continuous controller by a Fuzzy like algorithm (three structure continuous control to suppress the causes of parasitic dynamics inducing chattering is discussed in a companion paper also presented in this conference.) Performance of the closed-loop system is illustrated with numerical simulation using a Mass/Spring/Damper system as a generic plant and comparing the obtained results with those of the standard Sliding Mode Controller in its simplest version. The aim of this work is to provide control engineers of some ideas about basic concepts of the Sliding Mode Control to improve it as a design technique.