FPGA-Based Real-Time Wrench Model of Direct Current Driven Magnetic Levitation Actuator

Magnetic levitation actuators (MLAs) are increasingly employed in the modern high-precision manufacturing industry. Since the current-wrench transformation matrix is calculated inaccurately in the controller, the existing MLA finds it hard to undertake high-precision multi-degrees-of-freedom (DOF) movement in the large stroke. A high-fidelity real-time model is required to design better controllers for MLAs. This paper proposes a universal FPGA-based real-time wrench model (RTWM); meanwhile an MLA capable of translation and rotation in the horizontal plane is employed as the modeling object. To obtain the high accuracy with excellent generality, the force and torque distribution is solved through the magnetic node, coordinate transformation, and Gaussian quadrature. The corresponding calculation components are developed on the field-programmable gate array (FPGA) by exploiting the fully pipelined arithmetic and parallel architecture processing. Utilizing the high level synthesis tool, the final register transfer level structure is optimized adequately to reduce the time and hardware overhead. In the experiment, the RTWM of the proposed MLA and an existing MLA from the literature are obtained together to highlight the generality, and the computational accuracy is compared with the finite element method (FEM) software Comsol Multiphysics and a boundary element method software package Radia, respectively. The results show that the relative deviation is less than 2% choosing the FEM results as benchmark.