Application of active disturbance rejection to tracking control of a fast tool servo system

This paper addresses the design and implementation of a digital tracking controller for a fast tool servo to drive the cutting tool to machine workpieces with noncircular cross section in a lathe. The main idea of the controller lies in its actively rejecting disturbance while maintaining the simplicity and intuitiveness of existing PID approach. The proposed active disturbance rejection controller (ADRC) mainly consists of an extended state observer (ESO) and a nonlinear proportional derivative controller. The ESO is uniquely designed to estimate the unknown system dynamics and external disturbance, and compensate in each sampling period. Both simulation and experimental results demonstrate the ADRC concept and its validity