Unbalanced vibration suppressing for aerostatic spindle using sliding mode control method and piezoelectric ceramics

Abstract

The lubricating medium of the aerostatic spindle is gas, with relatively low rigidity, which is easy to cause rotor offset and additional vibration under the action of external load, thus affecting the processing accuracy of the spindle. To solve the problem of unbalanced vibration of the spindle, a new type of controllable radial aerostatic bearing is designed by combining piezoelectric ceramics, which use the inverse piezoelectric effect of piezoelectric ceramics to squeeze the air film to produce corresponding control force, and the radial unbalanced vibration of the spindle is suppressed. A bearing–rotor–piezoelectric ceramic coupling model was established, and the control method of feedforward combined with feedback was used to reduce the hysteresis characteristics of piezoelectric ceramics. On this basis, the sliding mode controller of the entire system, and through research, it is found that the sliding mode controller based on the extended observer has the best vibration suppression effect compared with other sliding mode controllers in the article; this research results can improve the rotation accuracy of the spindle system and the machining accuracy of ultra-precision machine tools.