Modeling and High-Precision Tracking Control of a Segmented Stator Permanent Magnet Linear Synchronous Motor

Permanent magnet linear synchronous motors are essential for industrial transport, offering the ability to independently transport multiple products using a single motor setup. This work considers a PMLSM with a segmented stator, where the individual segments have varying curvature, enhancing flexibility and enabling complex motor configurations. A highly accurate and computationally efficient mathematical model of the curved segments is developed, extending the straight segment model. It accounts for nonlinear effects such as saturation and cogging forces, and its accuracy is validated via test bench measurements. The control strategy employs a superimposed position controller and a subordinate indirect force control strategy. The force controller applies optimal currents derived from the model, utilizing the coils' multiple degrees of freedom to both generate the desired force and minimize ohmic losses. Shuttle positions are measured using anisotropic magnetoresistive sensors. This work proposes a user-friendly, cost-effective online calibration method based on iterative learning, significantly reducing measurement errors. Position tracking errors increase at segment transitions due to assembly and manufacturing tolerances that cannot be precisely modeled. To compensate for these model-plant mismatches, a learning-based feedforward force compensation is applied, ensuring high-precision tracking along the entire curvilinear track. Experiments confirm high-precision position tracking, improved motor efficiency, and robustness. The control strategy is further extended to multi-shuttle operation maintaining accurate, collision-free tracking even when shuttles operate in close proximity to maximize throughput.