Machine Tool Control with Additional Measurement for Increasing the Control System Dynamics

As a typical type of controller in the area of machine tools the classical cascade controller is used. It consists of several PI control loops and allows the position control of the machine tool. This type of controller is easy to be implemented and gives satisfactory results but only in the case that the sufficiently stiff machine tool is being controlled. If adverse is true the performance of the controller deteriorates. This is due to the fact, that the controller is limited by the structural properties of the machine tool. The bandwidth of the controller is restricted by the position of the first anti-resonant frequency of the machine tool. The control techniques overcoming this limitation have been extensively researched. As a result the control technique employing the additional measurement of TCP, the model-based predictive control and the Kalman filter is used and delivers the increased control system dynamics. The paper deals with the description of the proposed control concept and the practical methods for additional measurement together with the Kalman filter tuning are described. The evaluation of the proposed control concept is based on the experimentally measured data on the machine tool axis with significant flexibility.