Adaptronic gantry machine tool with piezoelectric actuator for active error compensation of structural oscillations at the tool centre point

In modern high dynamic gantry type machine tools rotary motors for feed axes have been replaced by linear direct motors. Thus, the limiting parameter in terms of the dynamic response is now the mechanical structure itself. Current design wisdom to improve the cutting accuracy is to increase the rigidity of essential machine components. This detrimentally results in either higher masses to be moved or sophisticated reinforcements being applied to the cross-arm or both. The adaptronic gantry concept proposed in this paper overcomes the need for stiffer machine structures but incorporates a light weight cross-arm. The occurring cross-arm’s structural oscillations are actively compensated by means of an additional piezo actuator that is attached between the cutting head, that moves along the cross-arm, and the tool. The piezo command is obtained from an observer that utilises additionally sensed acceleration information.