This article proposes a digital control strategy of the RST type combined with a PI regulator of a synchronous servomotor with permanent magnets supplied by a voltage inverter controlled by the vector PWM technique whose robustness of the regulators is studied by the µ-analysis technique, and the estimation of the mechanical quantities is carried out using an observer by the Kalman filter. This study presents a detailed theoretical analysis and the simulation and experimentation results obtained clearly show the effectiveness of the proposed control strategy.