Vibration control of a hybrid magnetic bearing using an adaptive sliding mode technique

Abstract

This paper presents a consideration of the nonlinear modelling and vibration control of a hybrid magnetic bearing (HMB). The dynamics of the system are highly nonlinear in nature and exhibit parameter uncertainty. A sliding mode controller (SMC), well known for its robustness against parameter variation and external disturbance attenuation, was used, in the form of an adaptive sliding mode controller (ASMC), chosen because the ASMC operates in the absence of knowledge of the upper bounds of the system uncertainty, and its tracking performances are guaranteed. The HMB–ASMC system was simulated with varying system parameters and the performance of the controller is discussed. A laboratory prototype of the HMB system was built and experiments were carried out with the ASMC controller, which was found to offer acceptable vibration characteristics and disturbance attenuation.