Parameter tuning and chattering adjustment of Super-Twisting sliding mode control system for linear plants

A simple procedure for tuning the parameters of the Super-Twisting (STW) second-order sliding mode control (2-SMC) algorithm, used for the feedback control of uncertain linear plants, is presented. When the plant relative degree is higher than one, it is known [10] that a self-sustained periodic oscillation takes place in the feedback system. The purpose of the present work is that of illustrating a systematic procedure for control tuning based on Describing Function (DF) approach guaranteeing pre-specified frequency and magnitude of the resulting oscillation. The knowledge of the plant´s Harmonic Response (magnitude and phase) at the desired chattering frequency is the only required prior information. By means of a simulation example, we show the effectiveness of the proposed procedure.