Method and device for calibrating robot measuring stations, manipulators and associated optical measuring devices

• US 6,615,112 B1
• Filed: 04/01/2002
• Issued: 09/02/2003
• Est. Priority Date: 06/26/1999
• Status: Expired due to Term

• Current Assignee: KUKA Roboter GmbH (Midea Group Co., Ltd)
• Original Assignee: Kuka Schweissanlagen GmbH (Midea Group Co., Ltd)
• Inventors: Roos, Eberhard
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): MARC, MCDIEUNEL
• Application Number:
  US10/019,345
• Time in Patent Office: 519 Days
• Field of Search: 700/230, 700/259, 700/254, 700/247, 700/251, 700/252, 700/262, 700/264, 318/568.1, 318/568.11, 318/568.14, 901/9, 901/42, 901/47, 702/94, 702/163, 702/86, 702/95, 396/54, 396/55, 396/233, 348/207.99, 348/208.8, 348/208.14
• US Class Current: 700/254
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G01B 21/04 by measuring coordinates of points
• CPC Class Codes: G01B 21/042 Calibration or calibration artifacts G01B3/30, G01B9/02072 take precedence
• CPC Class Codes: G01B 3/30 Bars, blocks, or strips in which the distance between a pair of faces is fixed, although it may be preadjustable, e.g. end measure, feeler strip
• CPC Class Codes: G05B 19/4015 going to a reference at the beginning of machine cycle, e.g. for calibration
• CPC Class Codes: G05B 2219/37068 Setting reference coordinate frame
• CPC Class Codes: G05B 2219/39024 Calibration of manipulator
• CPC Class Codes: G05B 2219/40613 Camera, laser scanner on end effector, hand eye manipulator, local
• CPC Class Codes: G05B 2219/45061 Measuring robot
• CPC Class Codes: G05B 2219/50026 Go to reference plane, cube

Abstract

A method and device is provided for multistage calibration of multiple-axis measuring robots (6) and associated optical measuring devices (10), especially 3D sensors, in a measuring station (1) for workpieces (2), preferably the bodyshells of motor vehicles. Calibration occurs in a measuring cascade comprising at least three calibrating steps, whereby the optical measuring device (10) and the operating point (28) thereof, the manipulator (6) and the axes thereof and the allocation of the manipulator (6) with respect to the workpiece (2) are successively calibrated. The calibration device (47) includes a control and a calibration system (27) for the operating point (28), a calibration body (15) for the axes of the manipulator and a calibration device (12) for the allocation of the manipulator with respect to the workpiece.

Claims

1. A process for calibrating multiaxial measuring robots and a carried optical 3D sensor measuring device, within a said measuring station for vehicle body shells, the process comprising calibration taking place in a measuring cascade comprising:

calibrating the optical measuring device with the optical measuring device working point;

calibrating the measuring robot with the measuring robot axes; and

subsequently calibrating the assignment of the measuring robot to the workpiece.

2. A process in accordance with claim 1, wherein the optical measuring device working point at the measuring robot is calibrated using an accurately positionable testing device with a reference sample, the sample being temporarily positioned in the area of the working point and is caused to overlap the working point by a relative movement in relation to the optical measuring device with the reference sample being subsequently measured to determine the space coordinates of the working point.

3. A process in accordance with claim 2, wherein for the recalibration of the optical measuring device the testing device belonging to is brought into position with the reference sample fixed in the desired position of the working point, and the agreement between the desired and actual positions is checked, wherein the optical measuring device is adjusted for correcting possible deviations or the reference sample and measured again to determine the space coordinates of the working point.

4. A process in accordance with claim 1, wherein the measuring robot with the robot axes is calibrated at a calibrating body with at least one measuring mark with a flat, rotationally symmetrical contour, wherein the measuring mark is approached with the optical measuring device from different directions and with different axis orientations of the measuring robot.

5. A process in accordance with claim 1, wherein the measuring robot for calibrating the robot assignment to the workpiece approaches and measures with the optical measuring device one or more the calibration marks at the workpiece and/or at the workpiece holder and/or at least at one mark carrier with a known position.

6. A process in accordance with claim 1, wherein a measuring coordinate system, in which the measurements are performed, is spanned at calibration marks.

7. A process in accordance with claim 6, wherein partial work spaces are generated during the calibration in the area of the calibration marks and in the area of measuring points on the workpiece.

8. A process in accordance with claim 1, wherein the measuring robot and/or the workpiece are moved relative to one another during the measuring in the normal measuring operation, wherein a calibration of the measuring robot is performed at the calibration marks after the movement before the next measurement.

9. A calibrating device for a multistep calibration of a multiaxial measuring robot and a carried 3D sensor optical measuring device, within a measuring station for the vehicle body shell workpieces, the device comprising:

a testing device for calibrating a working point of the optical measuring device;

a calibrating body for calibrating the robot axes; and

a calibrating device for the calibration of the assignment of the measuring robot to the workpiece.

10. A calibrating device in accordance with claim 9, wherein the testing device has a holder for the temporary positioning of a reference sample in the area of the working point and an adjusting device for monoaxial or multiaxial relative adjustment between the reference sample and the optical measuring device.

11. A calibrating device in accordance with claim 9, wherein the holder is arranged detachably on a frame of the optical measuring device with an accurately positioned fastening.

12. A calibrating device in accordance with claim 9, wherein the adjusting device has at least as many adjusting axes as the optical measuring device has measuring axes, wherein the adjusting axes are directed corresponding to the measuring axes.

13. A calibrating device in accordance with claim 9, wherein the holder has a bent shape, wherein the adjusting device has one or more adjusting carriages associated with the adjusting axes.

14. A calibrating device in accordance with claim 9, wherein the reference sample is designed as a hole in a sample plate.

15. A calibrating device in accordance with claim 9, wherein the sample plate is designed as an adjusting carriage and has a fixing device.

16. A calibrating device in accordance with claim 9, wherein the calibrating body is arranged in the vicinity of the measuring robot and has at least one measuring mark with a rotationally symmetrical flat contour.

17. A calibrating device in accordance with claim 9, wherein the measuring marks are designed as small circular plates or openings.

18. A calibrating device in accordance with claim 9, wherein the measuring marks are arranged at a plurality of the individual upright and/or horizontal mark holders at the calibrating body and have an alternatingly different orientation.

19. A calibrating device in accordance with claim 9, wherein the calibrating device has one or more calibration marks at one or more stationary mark carriers arranged in a known position close to the workpiece and/or at a workpiece holder and/or at the workpiece.

20. A calibrating device in accordance with claim 9, wherein a plurality of the calibration marks are arranged in a group with a defined spatial distance from one another.

21. A calibrating device in accordance with claim 9, wherein the calibration marks have a flat circular contour and are designed as openings, small leaves or color marks.

22. A calibrating device in accordance with claim 9, wherein the measuring robot and/or the workpiece are arranged movably with at least one additional travel axis on at least one linear unit.