WORK APPARATUS AND CALIBRATION METHOD FOR THE SAME

• US 20100161125A1
• Filed: 12/17/2009
• Published: 06/24/2010
• Est. Priority Date: 12/24/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Aoba, Masato, Tate, Shunta
• Granted Patent: US 8,588,974 B2
• Time in Patent Office: Days
• US Class Current: 700/254
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G05B 19/401 characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/37009 Calibration of vision system, camera, adapt light level
• CPC Class Codes: G05B 2219/37423 Distance, gap between tool and surface sensor
• CPC Class Codes: G06T 1/00 General purpose image data processing

Abstract

A work apparatus sets a virtual target point on an image plane in an imaging apparatus, and obtains a plurality of coordinate values of a moving unit at which a work reference point of a work unit and the virtual target point are caused to match in an image captured by the imaging apparatus. Further, the work apparatus obtains, in the image, coordinate values of the moving unit at which a position of light projection by a distance information obtaining unit and the virtual target point are caused to match, and a plurality of pieces of distance information obtained from the distance information obtaining unit at those coordinate positions. Then, the work apparatus calculates, based on the plurality of coordinate values and the plurality of pieces of distance information obtained through the above processing, a calibration parameter for the moving unit and the distance information obtaining unit.

Claims

1. A calibration method for a work apparatus comprising a moving unit configured to move a work unit to a work position, a distance information obtaining unit placed on the moving unit and configured to move together with the work unit, and an imaging apparatus fixed independently from the moving unit, the method comprising:

a first obtaining step of setting a virtual target point on an image plane in the imaging apparatus, and obtaining a plurality of coordinate values of the moving unit at which a work reference point of the work unit, and the virtual target point are caused to match on an image captured by the imaging apparatus;

a second obtaining step of obtaining, in the image, a plurality of coordinate values of the moving unit at which a position of light projection by the distance information obtaining unit and the virtual target point are caused to match; and

a calculating step of calculating, based on the coordinate values obtained in the first obtaining step and the second obtaining step, a calibration parameter for the moving unit and the distance information obtaining unit.

2. The method according to claim 1,

wherein the work reference point is a position at which the work unit performs work, and is a point that moves together with the distance information obtaining unit when the moving unit moves the work unit.

3. The method according to claim 1,

wherein in the first obtaining step, the work unit is moved by the moving unit to a plurality of states in which the work reference point matches the virtual target point on the image.

4. The method according to claim 1,

wherein in the second obtaining step, the work unit is moved by the moving unit to a plurality of states in which the light projection position matches the virtual target point on the image, and distance information is obtained by the distance information obtaining unit in the plurality of states, and

wherein in the calculating step, the calibration parameter is calculated based on the coordinate values and the distance information obtained in the first obtaining step and the second obtaining step.

5. The method according to claim 1,

wherein the calibration parameter are an optical-axis direction of the distance information obtaining unit, and a relative position of the distance information obtaining unit and the work reference point.

6. The method according to claim 1,

wherein in the first obtaining step, a plurality of pairs of a coordinate value of the work reference point in the image, and a coordinate value of the moving unit at that time are obtained, and based on the obtained plurality of pairs of coordinate values, a plurality of coordinate values of the moving unit at which the work reference point is caused to match the virtual target point on the image are estimated.

7. The method according to claim 6,

wherein in the first obtaining step, based on the plurality of pairs of coordinate values, a coordinate value of the moving unit, at which the work reference point matches the virtual target point on an image is estimated using a least-square method.

8. The method according to claim 4,

wherein in the second obtaining step,

a plurality of pairs of a coordinate value of the position of light projection by the distance information obtaining unit in the image, and a coordinate value of the moving unit at that time are obtained, and based on the obtained plurality of pairs of coordinate values, a plurality of coordinate values of the moving unit at which the light projection position is caused to match the virtual target point on the image are estimated, and

the moving unit is moved to each of the estimated plurality of coordinate values, and distance information is obtained by the distance information obtaining unit.

9. The method according to claim 8,

wherein in the second obtaining step, from the plurality of pairs of coordinate values, a coordinate value of the moving unit at which the light projection position matches the virtual target point on the image is estimated using a least-square method.

10. The method according to claim 4,

wherein in the first obtaining step, a straight line that connects the obtained plurality of coordinate values is obtained by approximation by principal component analysis, and a coordinate value to be used in the calculating step is obtained based on the straight line, and

in the second obtaining step, a straight line that connects the obtained plurality of coordinate values is obtained by approximation by principal component analysis, a coordinate value to be used in the calculating step is obtained based on the straight line, and distance information to be used in the calculating step is distance information obtained from the distance information obtaining unit when the moving unit was moved to the coordinate value to be used in the calculating step.

12. A computer-readable storage medium storing a computer program for causing a computer to execute the calibration method for the work apparatus according to claim 1.

11. A work apparatus comprising a moving unit configured to move a work unit to a work position, a distance information obtaining unit placed on the moving unit and configured to move together with the work unit, and an imaging apparatus fixed independently from the moving unit, the work apparatus comprising:

a first obtaining unit configured to set a virtual target point on an image plane in the imaging apparatus, and to obtain a plurality of coordinate values of the moving unit at which a work reference point of the work unit and the virtual target point are caused to match in an image captured by the imaging apparatus;

a second obtaining unit configured to obtain, in the image, a plurality of coordinate values of the moving unit at which a position of light projection by the distance information obtaining unit and the virtual target point are caused to match; and

a calculation unit configured to calculate, based on the coordinate values obtained by the first obtaining unit and the second obtaining unit, a calibration parameter for the moving unit and the distance information obtaining unit.