Abstract: Aiming at the problem that the control accuracy of the servo system decreases due to the failure of the three phase surface mount permanent magnet synchronous motor, a fractional order sliding mode fault tolerant control method based on online real time fault estimation is proposed. Firstly, a fault model of the drive motor is established; secondly, a fault observer based on the nonlinear disturbance observer is designed according to the fault model, which can estimate the fault information of the drive motor in real time online. In addition, based on the observation information of the observer, a fractional order sliding mode fault tolerant control method of the drive motor is proposed. Compared with the traditional sliding mode control method, the proposed sliding mode controller based on the fractional order theory improves the response speed and is smaller in steady state errors, and reduces the chattering phenomenon of traditional sliding mode controllers. Finally, simulations verify the feasibility and effectiveness of the proposed control method.

Key words: servo motor, fault, nonlinear disturbance observer (NDO), fault tolerant control, fractional order sliding mode control