Patent ID: 8452425
Filing Date: 2013-05-28
Classification: G05B

Abstract:
1. A position control device for controlling a position of a feed shaft based on an output of a first position detector connected to a motor and an output of a second position detector connected to the feed shaft driven by the motor, the position control device comprising: a position calculator for outputting a speed feedback command obtained from a difference between a position command and the output of the second position detector; a position command differentiator for differentiating the position command to output a speed feedforward command; a first subtractor for outputting an actual speed deviation which is a difference between the speed feedforward command and an actual speed of the feed shaft obtained from the output of the second position detector; a first proportional calculator for performing proportional calculation of the actual speed deviation; a first integral compensator for integrating the actual speed deviation; a first adder for adding the speed feedforward command and the speed feedback command to output a speed command; a second subtractor for outputting a motor speed deviation which is a difference between the speed command and a motor speed obtained from the output of the first position detector; a second proportional calculator for performing proportional calculation of the motor speed deviation; a second integral compensator for integrating the motor speed deviation; and a second adder for adding an output of the first proportional calculator, an output of the second proportional calculator, an output of the first integral compensator, and an output of the second integral compensator to output a torque command, wherein each of the first and second integral compensators comprises a coefficient changer capable of changing a coefficient in accordance with the speed feedforward command or the speed command.