Dynamical decoupling and feed-forward control for magnetically levitated planar actuators

Abstract

This paper concerns the dynamical decoupling and feed-forward control of magnetically-levitated planar actuators (MLPAs) with moving coils when the moving stage's center-of-mass (CM) deviates from the geometric center (GC). Based on the direct wrench-current decoupling, the factors that affect the continuity of current are emphatically analyzed for a more stable current control, and the propulsion works at CM is converted at GC with Newton-Euler dynamic equation. By inverting the system dynamics, 6 degrees-of-freedom (DOF) individual control is realized and the system is simplified from MIMO to SISO. Based on the decoupling, an acceleration feed-forward controller with PID control is designed. By studying the coupling parameter relating to feed-forward inputs and white noise, the acceleration amplification coefficient is achieved and the PID parameters will be optimized based on comparing the actual variance with the minimum achievable variance. Last, the simulation results indicate that the feed-forward compound controller applying to MLPAs system has a better performance than the general PID controller.