SMC with linear dynamic compensator design: Performance margins approach

In this work, the performance of the real sliding mode is characterized with the notion of performance margins under the assumption that the real sliding motion presents a limit cycle with acceptable amplitude and acceptable frequency. The performance of sliding mode controllers, in real sliding motion, is improved by means of the addition of linear compensators in cascade connection with the plant. The applied compensators are phase lead controllers which modify the frequency response of the plant in order to meet the required performance margins adding robustness to the system. Bode diagram interpretation of performance margins is presented for the first time allowing the utilization of SMC combined with the classical methodology of linear compensator design where it is possible shape the Bode diagram in order to obtain desired values of performance margins. Examples supporting the proposed idea are presented.