Research on Fluctuation External Disturbance Suppression of Permanent Magnetic Levitation Platform

In this paper, a permanent magnet levitation platform with variable flux path mechanism for ultra-clean transport scenarios is presented, and a fractional-order PID centralized control strategy is designed to suppress fluctuating external disturbances. Firstly, the mechanisms of variable flux path and magnetic force regulation are introduced, and the four units support configuration, measurement scheme and feedback control principle of the levitation platform are explained. Then, the mathematical model of the levitation platform is established, and a centralized control strategy along with the fractional-order PID algorithm is designed to achieve stable levitation in three degrees of freedom. Subsequently, experiments are conducted to evaluate the stable levitation performance of the system, including initiation levitation and dynamic response to load variations. The experimental results demonstrate that the fractional-order PID centralized controller achieves smooth start-up with reduced overshoot, superior robustness under mass loading/unloading. Finally, the sinusoidal current is applied to the electromagnetic coil to generate vertically fluctuating disturbance force, simulating linear motor-induced disturbances acting on the levitation platform. Under fluctuating disturbance conditions, the fractional-order PID controlled levitation platform exhibited rapid suppression of air gap fluctuations and significantly reduced vibration amplitudes across all degrees of freedom. Compared with standard PID, the fractional-order PID controller achieved faster stabilization without residual oscillations, maintaining smoother pitch and roll responses. These results highlight the superior capability of fractional-order PID centralized control strategy in attenuating low-frequency fluctuating external disturbances and preserving platform stability.