Switching control design based on state feedback for unstable plants

Linear control design was adopted for unstable controlled plant, whose property was influenced by the unstable pole value. Therefore, design results can not satisfy the requirement of disturbances rejection and robustness. A effective nonlinear control design method, which combined effectively with state feedback control and PI-PD switching control, was proposed in the paper. Considered synthetically stability and dynamic property of controlled plant, which combined with magnetic suspension controlled experiment in order to gradually improve the controller. Finally, PI-PD (Proportion Integration- Proportion Differentiation) switching control based on PI-PD switching control was taken as a nonlinear control design method which could make magnetic suspension controlled system stabilize suspension. The method decreased steady state error, eliminated stick slip phenomenon of control action with stable tracking, and improved the robustness of the system.