Work apparatus and calibration method for the same

• US 8,588,974 B2
• Filed: 12/17/2009
• Issued: 11/19/2013
• 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
• Primary Examiner(s): Jen, Ian
• Application Number:
  US12/641,246
• Publication Number:
  US 20100161125A1
• Time in Patent Office: 1,433 Days
• Field of Search: None
• US Class Current: 700/248
• 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 an apparatus comprising a work unit, a distance information obtaining unit configured to move together with the work unit, and an imaging apparatus fixed independently from the work unit, the method comprising:

an obtaining step of obtaining a first position of the work unit when a target point on an image plane in the imaging apparatus matches with a reference point of the work unit on the image plane and obtaining a second position of the work unit when the target point on the image plane matches with a position on which a light is projected by the distance information obtaining unit on the image plane; and

a calculating step of calculating a calibration parameter which calibrates a position of the reference point relative to the distance information obtaining unit based on the first and second positions of the work unit obtained in the obtaining step.

2. The method according to claim 1,

wherein the 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 work unit moves.

3. The method according to claim 1,

wherein in the obtaining step, the work unit moves to a plurality of states in which the reference point matches the target point on the image plane.

4. The method according to claim 1,

wherein in the obtaining step, the work unit moves to a plurality of states in which a position of the light projected by the distance information obtaining unit matches the target point on the image plane, 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 first and second positions and the distance information obtained in the 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 reference point.

6. The method according to claim 1,

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

7. The method according to claim 6,

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

8. The method according to claim 4,

wherein in the obtaining step,

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

the work unit moves 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 obtaining step, from the plurality of pairs of coordinate values, a coordinate value of the work unit at which the position of the light projected by the distance information obtaining unit matches the target point on the image plane is estimated using a least-square method.

10. The method according to claim 4,

wherein in the obtaining step, a straight line that connects the plurality of coordinate values obtained as the first position 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 obtaining step, a straight line that connects the plurality of coordinate values obtained as the second position 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 non-transitory 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. An apparatus comprising a work unit, a distance information obtaining unit configured to move together with the work unit, and an imaging apparatus fixed independently from the work unit, the apparatus comprising:

an obtaining unit configured to obtain a first position of the work unit when a target point on an image plane in the imaging apparatus matches with a reference point of the work unit on the image plane and obtain a second position of the work unit when the target point on the image plane matches with a position on which a light is projected by the distance information obtaining unit on the image plane; and

a calculation unit configured to calculate a calibration parameter which calculates a position of the reference point relative to the distance information obtaining unit based on the first and second positions of the work unit obtained by the obtaining unit.

13. A calibration method for an apparatus comprising a work unit, a distance information obtaining unit configured to move together with the work unit, and an imaging apparatus, the method comprising:

an obtaining step of obtaining a position of the work unit when a target point on an image plane in the imaging apparatus matches with a position on which a light is projected by the distance information obtaining unit on the image plane; and

a calculating step of calculating, a calibration parameter which calibrates a position of a reference point of the work unit relative to the distance information obtaining unit, based on the position of the work unit obtained in the obtaining step and a position of the work unit relative to the imaging apparatus, which is known.