Position control of XY table in CNC machining center with non-rigid ballscrew

In a CNC machining center, each axis of an XY table is linked to a motor through a ballscrew. Since the stiffness of the ballscrew is finite, there exists a difference between the position of the table and the corresponding position of the motor. In the paper, a method is proposed to reduce the error of the table position without directly measuring the table position. The method consists of a torsional displacement feedback algorithm and an estimation method of the torsional displacement. The proposed method is tested in a CNC machining center and shows significant reduction in the error of the table position.