US 2011/0238221 A1Published application

Position control device

AssigneeOkuma Corporation

InventorsYuji Kawazu, Tomohisa Kameyama

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Abstract

For full-closed position control, there is provided a position control device capable of suppressing occurrence of stick-slip which occurs during a feed operation performed in a very low speed region. An adder 5 and an adder 24 add an output obtained by multiplying an actual speed deviation El by a proportional gain Pl, an integral component Tl of the actual speed deviation which is obtained by inputting the actual speed deviation El to an integral compensator 25, an output obtained by multiplying a motor speed deviation Em by a proportional gain Pm, and an integral component Tim of the motor speed deviation which is obtained by inputting the motor speed deviation Em to an integral compensator 9, and the result is output as a torque feedback command Tfb. Here, each of the integral compensator 25 and the integral compensator 9 has a coefficient changer capable of changing a coefficient to vary from 0 to 1 in order to adjust an integral gain Kl and an integral gain Km in accordance with a value of a speed feedforward command Vr or a speed command Vc. By setting the integral gain Kl to be large to increase the response speed of switching from static friction torque to kinetic friction torque in a very low speed region in which the influence of a lost motion is small, occurrence of stick-slip is suppressed.

Claims2

Dependent claims

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.

9 more elements

Dependencies are inferred from the claim text.