Variable structure controller based on extended state observer for the position control of servo system

Considering the characteristics of the servo system, such as disturb, nonlinearity and high inertia, variable structure controller(VSC) based on extended state observer(ESO) is designed for the aim of quick, stable and high-accuracy controlling process. The disturbances and high-order factors are estimated and compensated using ESO. The dynamic compensation reduces the motion system to approximately a triple integrator which can be easily controlled using VSC. And because ESO provides a high-frequency path for the dynamic state which is not modeling, the chatter of VSC is reduced. Through the test in the servo test system, it is shown that this controller is superior to the engineering PID and general VSC.