Position control apparatus for identifying low-frequency disturbance

Patent metadata

Field	Value
Publication number	US-10386252-B2
Application number	US-201414464820-A
Country	US
Kind code	B2
Filing date	Aug 21, 2014
Priority date	Aug 26, 2013
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

A position control apparatus is provided that can perform accurate nonlinear compensation control immediately after the apparatus is activated. At a time of acceleration, a signal amplification ratio is calculated and designated for each signal vector element based on information related to acceleration/deceleration at a starting time and the structure of a signal vector that is determined for a target plant, and as a result, a signal vector for which the strength of linear independence is increased is generated. Because the strength of the linear independence condition of the signal vector is increased, the speed of convergence of identification for a low-frequency disturbance element, such as a gravitational torque or a sliding-mode load torque, can be increased.

First claim

What is claimed is:

1. A position control apparatus, which identifies a characteristic parameter for a target plant that is a mechanical plant to be controlled, and additionally performs compensation control based on the identified characteristic in accordance with a characteristic for the target plant, comprising:
a nonlinear element calculation unit for calculating, based on the identified characteristic parameter, a torque compensation value that is to be added to a torque command value;
a driver for driving a servo motor of the target plant by power generated in accordance with a final torque command value that is obtained by adding the torque compensation value to the torque command value;
a ξ max detector, configured to output a maximum absolute element, based on a structure of a signal vector of the target plant and predesignated information related to acceleration/deceleration, for each column vector of a signal matrix in which signal vectors obtained during acceleration of the target plant are arranged in a direction of rows in a time series manner;
a signal matrix gain operation unit configured to calculate a signal amplification ratio for each column vector of the signal matrix based on at least the maximum absolute element;
a signal vector amplification/generation unit configured to form, based on individual elements of the signal vector and the signal amplification ratio, an identification signal vector that is to be applied for parameter identification calculation; and
an adaptive loop operation unit for identifying a characteristic parameter for the target plant based on the identification signal vector and the final torque command value.

2. The position control apparatus according to claim 1 ,
wherein the signal matrix gain operation unit calculates the signal amplification ratio based on a reference signal amplification ratio and the maximum absolute element, and
wherein the reference signal amplification ratio is determined by performing a plant response simulation to calculate motions of the position control apparatus and the target plant performed during a period in which an axial movement command is being issued, an identification response simulation to calculate an identified parameter by employing the identification signal vector, which is obtained based on both the signal amplification ratio designated by referring to the reference signal amplification ratio and the results of the plant response simulation, and a correction process for correcting the reference signal amplification ratio in accordance with a convergence characteristic of results of the identification response simulation, and by repeating the plant response simulation, the identification response simulation, and the correction process until it is determined that the convergence characteristic is satisfactory.

3. The position control apparatus according to claim 1 , in combination with a servo motor of the target plant operatively connected with and adapted to be driven by the driver by power generated in accordance with the final torque command.

4. A system comprising:
a target plant serving as a component of a numerical controlled machine;
a servo motor configured to drive the target plant;
a detector configured to detect a position of the target plant as a detection position;
a position control apparatus, which identifies a characteristic parameter for a the target plant, and performs compensation control on the target plant based on the identified characteristic parameter in accordance with a characteristic for the target plant, the position control apparatus comprising:
a nonlinear element calculation unit for calculating, based on the identified characteristic parameter, a torque compensation value that is to be added to a torque command value;
a driver for driving a the servo motor by power generated in accordance with a final torque command value that is obtained by adding the torque compensation value to the torque command value;
a ξ max detector, configured to output a maximum absolute element, based on a structure of a signal vector of the target plant and predesignated information related to acceleration/deceleration, for each column vector of a signal matrix in which signal vectors obtained during acceleration of the target plant are arranged in a direction of rows in a time series manner;
a signal matrix gain operation unit configured to calculate a signal amplification ratio for each column vector of the signal matrix based on at least the maximum absolute element;
a signal vector amplification/generation unit configured to generate, based on the detection position detected by the detector and an acceleration of the target plant obtained by performing differentiation on the detection position twice, a signal vector including the detection position and the acceleration as elements, and configured to form, based on the signal vector and the signal amplification ratio, an identification signal vector that is to be applied for parameter identification calculation; and
an adaptive loop operation unit for identifying a characteristic parameter for the target plant based on the identification signal vector and the final torque command value.

5. The system according to claim 4 , wherein
the signal matrix gain operation unit calculates the signal amplification ratio based on a reference signal amplification ratio and the maximum absolute element, and
the reference signal amplification ratio is determined by performing a plant response simulation to calculate motions of the position control apparatus and the target plant performed during a period in which an axial movement command is being issued, an identification response simulation to calculate an identified parameter by employing the identification signal vector, which is obtained based on both the signal amplification ratio designated by referring to the reference signal amplification ratio and the results of the plant response simulation, and a correction process for correcting the reference signal amplification ratio in accordance with a convergence characteristic of results of the identification response simulation, and by repeating the plant response simulation, the identification response simulation, and the correction process until it is determined that the convergence characteristic is satisfactory.

Assignees

• Okuma Machinery Works Ltd

Inventors

• Eguchi Satoshi

Classifications

• G01L3/242 Primary

  by measuring and simultaneously multiplying torque and velocity · CPC title

• G05B19/404 Primary

  characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia (G05B19/19, G05B19/41 take precedence) · CPC title

• G01L3/02 Primary

  Rotary-transmission dynamometers · CPC title

• G05B2219/49185

  Position error compensation as function of position of slide, control bearing pressure · CPC title