Study of friction compensation in bi-axis servo system based on improved ADRC

In view of the friction nonlinearity and uncertain external disturbance in the bi-axis servo system,and based on the analysis of the contour error of the system and the cross-coupling idea,an improved second-order active disturbance rejection controller(ADRC) is applied in friction compensation.The inner and outer disturbance of the system as well as the friction can be observed and compensated by the high-gain extended state observer(ESO) of ADRC with strong robustness.And by adopting a new non-linear function,the system sensitivity to the friction can be overcome which is led to by the roughness of non-linear function in the nonlinear state error feedback of conventional ADRC.The simulation results indicate that the friction compensation can be carried out well based on this improved ADRC,so that the system has better robustness and higher contour machining precision.