Cascade plus Feedforward Control Strategy for Enhanced Regulation in Maglev System

The magnetic levitation (Maglev) is a highly nonlinear and unstable system. Hence, it requires advanced and effective control mechanism. In this work, a cascaded and feedforward control strategy is designed for Maglev. Internal model control (IMC)-based proportional-integral (PI) and proportional-integral-derivative (PID) controllers are designed for the inner and outer loops. The feedforward controller is designed as a proportional controller which is decided based on the desired equilibrium point. Guidelines for selecting the adjustable IMC parameters for inner and outer loops are provided. Experimentally obtained closed-loop responses of the Maglev setup are compared using three different control strategies: proposed cascaded with feedforward, feedback with feedforward and pure feedback. It is vindicated that the proposed cascaded with feedforward strategy outperforms the other two strategies in terms of quantitative error metric, integral square error (ISE) and tracking the desired setpoint (ball position).