Abstract:

According to the problem of static friction disturbances in the direct current (DC) servo system of CNC, a servo control method based on friction model compensation after the parameter identification of the static friction model using Genetic Algorithm (GA) is proposed. Firstly, according to the friction characteristics of the DC servo systems, a friction model is built, then the friction compensation into the feedback control structure of the servo systems to obtain the position error of the servo motor is introduced. GA is adopted to identify the parameters of the friction compensation model, and to make the quantity of the friction compensation approximates to the practical friction disturbance unceasingly, so that the influence of friction on the servo systems is eliminated. In order to verify the effect of parameter identification, a comparison is  made between the traditional PD control and the PD control based on friction compensation. The simulation results show that the latter can eliminate the flat phenomenon in position tracing caused by the static friction and achieve the desired tracking effect. Therefore, this method has strong ability to compensate the friction interference and can achieve precise control of the DC servo systems.

Key words: DC servo system；genetic algorithm；parameter identification；friction compensation；PD control