Application of the preview compensation control method to large gap control in hybrid magnetic suspension

ABSTRACT Large-gap magnetic suspension is a conceptual design for experiments which can be used to investigate technical issues associated with magnetic suspension and accurate suspended-load control for large gaps. The traditional linear control strategy has significant limits to its control area, usually around the chosen operating points. With increase in the suspension gap, the nonlinearity and time delay of a system will become more serious. Additionally, the interaction of an estimation scheme and corresponding controller has not been fully examined in the literature. This paper examines a developed compound control method, Smith forecast compensation control with proportional-integral-derivative control (PID control) , as a means of advancing the achievable performance of magnetic suspension. We designed and built a laboratory testbed to determine the feasibility of utilizing proposed methods in these types of applications. The analytical results are supported by the simulations and experiments, showing our research approach to be fairly successful at providing satisfactory performance for motion control under conditions involving a large air gap.