Robust high-speed positioning servo system based on disturbance observer

A robust servo system is important for the performance improvement of motion control systems in several industrial applications. An ideal position servo system should accelerate the rotor to its rated speed by applying maximum acceleration torque, and it should decelerate the rotor by applying the maximum deceleration torque. The position servo system should stop at the target position without overshoot. When the position reference profile of the conventional position servo system is not ideal, there are two problems in achieving the ideal high-speed positioning response. One is the windup phenomenon caused by the saturation of the PI speed regulator. The other problem is the slow deceleration response near the target position that is due to the error input of the position servo system becoming small. In order to overcome these problems, this paper proposes a new robust high-speed positioning servo system based on a disturbance observer. The proposed system corrects the integrator value of the PI speed regulator by using the torque current reference estimated by the disturbance observer. The experimental results show that the proposed robust high-speed positioning servo system has a quick and stable position response.