Disturbance Observer-Based Filter Backstepping Control with Low Speed Crawling for AC Servo System

When the running speed of AC servo system is below a critical value, the position will alternate among stasis, slide, and speed fluctuations, which is called low speed crawling. For the non-linear feature of the AC servo system, the position controller and the speed controller are designed by backstepping control method. Due to the impact of friction torque, load disturbance and parameter perturbation at the extremely low speed, the disturbance observer is introduced on the basis of the backstepping control to observe the disturbances and feed forward compensation in real time, so as to further improve the dynamics and anti-interference ability of the system. While adding a filter to avoid the increasing complexity in calculating the analytic derivatives of the virtual control in conventional backstepping method and the calculating inflation problem. The experimental results show that the disturbance observer-based filter backstepping control (DOB-FBC) with low speed crawling for AC servo system has better robustness and it can effectively weaken the low speed crawling adverse influence on the performance of the servomotor running at low speed while meeting the system performance index. © 2019, Electrical Technology Press Co. Ltd. All right reserved.