Positioning control apparatus and machine tool provided therewith

A positioning control apparatus comprising:

• a moving body;
• a feed device having a guide mechanism for guiding the moving body in a predetermined feed-axis direction and a drive mechanism for moving the moving body;
• a structural body supporting the feed device;
• and
• a controller for controlling a moving position of the moving body with respect to a predetermined reference position by controlling an operation of the drive mechanism;
• wherein the positioning control apparatus has:
• a calculating section which calculates a displacement amount of the feed device in the feed-axis direction with respect to the reference position caused by displacement of the structural body, the displacement of the structural body occurring due to a reaction force which is against a force applied to the moving body when the moving body is moved by the feed device and which acts on the structural body through the feed device, and
• a compensating section which receives the displacement amount calculated by the calculating section and adds a modification amount for eliminating the displacement amount to a control signal for controlling the drive mechanism in the controller;
• and
• the calculating section calculates the displacement amount x of the feed device in the feed-axis direction with respect to the reference position caused by displacement of the structural body using a following equation:
• x=f/K−x″/ω2,
• where f is the force acting on the structural body and is also the reaction force against the force applied to the moving body, K is an elastic coefficient of the structural body, ω is a natural angular frequency of the structural body, and x″ is acceleration of the moving body.