Disturbance‐Observer‐Based Fixed‐Time Prescribed Performance Control for Permanent Magnet Synchronous Motor Under Friction Disturbance

ABSTRACT This article proposes a fixed‐time prescribed performance controller with an adaptive disturbance observer to enhance disturbance rejection and dynamic performance in a permanent magnet synchronous motor (PMSM). Firstly, an adaptive control law designed using a fixed‐time prescribed performance function ensures transient behavior and steady‐state performance strictly adhere to preset boundary constraints. Secondly, a fixed‐time command filter resolves the repeated differentiation issue of virtual control signals in backstepping, while an error compensation signal further improves tracking accuracy. Friction effects and unknown load torque are treated as lumped disturbances, with a novel adaptive disturbance observer developed to suppress these disturbances, thereby improving system robustness. Finally, simulations and experiments validate the algorithm's effectiveness.