OPTIMAL CONTROL OF CHATTER VIBRATIONS OF A MOTOR SPINDLE WITH INTEGRATED ELECTROMAGNETIC ACTUATOR

摘要

In times of increasing demands on production profitability it is obliging to investigate the limiting parameters of production processes. In case of milling the limiting factor nowadays no longer is the rotational speed and power but often the spindle and tool vibrations resulting from unstable machining processes. In this paper a motor spindle with integrated electromagnetic actuator and eddy current position probes near the front bearings is under consideration. This actuator allows the application of radial forces on the spindle without physical contact. Thereby it is possible to damp and reduce the radial vibrations of the spindle. The milling process can be stabilized at spindle speeds and axial depths of cut, where without active control chatter vibrations would occur. In this paper the whole procedure of implementing active vibration control on the motor spindle is described. It covers the identification of the plant, the fitting of parametric models, and design of a Kalman observer and LQG controller. Finally the combined observer and controller are discretised and implemented on the test rig. The identification of the plant with active controller proves the intended effect of the controller on the spindle dynamics.