H∞Control for PMLSM Suspension Platform Based on PDFF

Permanent magnet linear synchronous motor (PMLSM) suspension system has the merits of no friction, high-speed, high response and so on, using the normal force achieve the mover suspension. The servo performance is affected by the nonlinear coupling between the horizontal trust and vertical normal force, parameters uncertainties and load disturbances. The feedback linearization method is used to achieve the dynamic decoupling of the PMLSM suspicion system and decoupling it Into two linear subsystems; to solve the conflict between disturbance restraint and fast tracking performance, increase the robustness and dynamic stiffness for system, H∞ speed controller based on PDFF and position proportional controller are designed. Simulation results show that the proposed control strategy guarantees the high speed and high precision positioning performance for horizontal axis; the good rigidity and stability for normal suspension length and the strong robustness against load disturbances and parameters variations for the two axes.