Affiliations: [a] State Key Lab of Digital Manufacturing Equipment & Technology, Huazhong University of Science & Technology, Wuhan, Hubei, China | [b] School of Mechanical & Electronic Engineering, Wuhan University of Technology, Wuhan, Hubei, China
Correspondence:
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Corresponding author: Xin Cheng, School of Mechanical & Electronic Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China. Tel.: +86 027 87651793; E-mail:chengx@whut.edu.cn
Note: [1] These authors contributed equally to this work.
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.
Keywords: Magnetically levitated planar actuators, dynamical decoupling, continuity of current, center of mass deviation, inverse transformation, acceleration feed-forward controller
