Auto-disturbance-rejection control of servo systems with output backlash

Backlash is one of the factors severely limiting the performance of the servo systems. In order to eliminate the influences of the backlash nonlinear characteristics, a two-step compensation method is proposed. The first-step compensation adopts backlash inverse model as the primary tools and can eliminate the effects of the backlash on the control performance to a certain extent. Thereafter, an auto-disturbance-rejection controller (ADRC) is introduced to realize the second-step compensation of the backlash. Thus, the residual compensation errors of the backlash can be compensated precisely by the ADRC. Compared with the previous studies, the method of this paper can improve the compensation accuracy a lot and can be implemented easily in engineering. Simulation results indicate that the method presented above is feasible.