Robust and High-Precision Position Control of PMLSM-Driven Feed Servo System Based on Adaptive Fast Nonsingular Terminal Sliding Mode

Due to the removal of the mechanical transmission link, the utilization of a permanent magnet linear synchronous motor (PMLSM) as the feed actuator in computer numerical control (CNC) machine tools enables improved dynamic response performance. However, the presence of uncertainties, including parameter mismatch, nonlinear friction, and external disturbances, can significantly impair the position tracking accuracy of the PMLSM-driven feed servo system. To address this issue, this article proposes an adaptive fast nonsingular terminal sliding mode (AFNTSM) controller. The proposed AFNTSM controller synergistically combines the advantages of FNTSM, integral sliding mode, and adaptive estimation techniques, leading to effective achievement of the desired position tracking performance while suppressing control chattering. Unlike conventional methods, the adaptive estimation term eliminates the requirements for motor parameters and the upper bound information of the disturbances. In addition, a rigorous stability analysis is presented to prove the finite-time convergence and zero tracking error of the closed-loop system under the AFNTSM controller. The experimental results also demonstrate the superior tracking accuracy and robustness of the AFNTSM controller in comparison to both the FNTSM controller and conventional linear sliding mode (LSM) controller.