Enhanced Continuous Terminal Sliding Mode Position Control for PMSM Servo Systems Considering Speed and Current Constraints

In high-precision permanent magnet synchronous motor (PMSM) servo applications, it is essential to achieve both rapid and accurate positioning control while constraining the speed and current under multi-source disturbances. To achieve this objective, this paper proposes a composite control barrier function (CBF)-based enhanced terminal sliding mode control (TSMC) strategy. First, two finite-time generalized proportional integral observers (FTGPIOs) are designed for matched and unmatched disturbance estimation in PMSM servo systems. By capturing disturbances and their high-order derivatives, FTGPIOs deliver superior estimation accuracy, with finite-time convergence ensuring fast error reduction. Then, a disturbance-compensated finite-time TSMC approach is constructed for finite-time position tracking stability. Meanwhile, a disturbance-integrated robust CBF technique is designed for real-time optimization, effectively limiting speed and current deviations during positioning. Finally, the effectiveness of the proposed method is validated via rigorous stability analysis as well as comprehensive simulation and experimental comparisons.