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DE-112023006603-T5 - PARAMETER CORRECTION DEVICE

DE112023006603T5DE 112023006603 T5DE112023006603 T5DE 112023006603T5DE-112023006603-T5

Abstract

The present invention provides a parameter correction device that calculates a three-dimensional estimated position of a workpiece based on a sensor parameter and the position of a characteristic section in an image of the workpiece. The parameter correction device calculates a measured position of an element from the sensor and the workpiece based on the drive state of a motion device. The parameter correction device uses the motion device to move an element to a first and second position to capture images of the workpiece. The parameter correction device corrects the sensor parameter based on the amount of movement, which is based on the first and second measured positions, and the distance between a first estimated position and a second estimated position.

Inventors

  • TAKAHASHI YUUKI

Assignees

  • FANUC CORP

Dates

Publication Date
20260507
Application Date
20230912
Priority Date
20230912

Claims (12)

  1. A parameter correction device configured to correct a sensor parameter to calculate a three-dimensional position corresponding to a specific position in an image obtained by imaging a workpiece with a sensor, the parameter correction device comprising: a feature acquisition unit configured to acquire a feature section in the image of the workpiece; a unit for calculating the estimated position, configured to calculate an estimated position that is a three-dimensional position of the workpiece based on the position of the feature section in the image of the workpiece and the sensor parameter; a unit for calculating the actual measurement position, configured to calculate an actual measurement position that is a three-dimensional position of at least one element selected from a group of the sensor and the workpiece, based on a drive state of a motion device configured to move the at least one element; and a correction unit configured to correct the sensor parameter, wherein the feature acquisition unit is configured to capture the feature portion in an image obtained by mapping when the one element is located in a first position, and the feature portion in an image obtained by mapping when the one element is located in a second position, the estimated position calculation unit is configured to calculate a first estimated position when the one element is located in the first position, and to calculate a second estimated position when the one element is located in the second position, the actual measurement position calculation unit is configured to calculate a first actual measurement position when the one element is located in the first position, and a second actual measurement position when the one element is located in the second position, and the correction unit is configured to correct the sensor parameter based on a movement amount based on the first actual measurement position and the second actual measurement position, and a distance from the first estimated position to the second estimated position.
  2. Parameter correction device according to Claim 1 , wherein the correction unit is configured to calculate an error between the amount of movement based on the first actual measurement position and the second actual measurement position and the distance from the first estimated position to the second estimated position, and to correct the sensor parameter to minimize the error.
  3. Parameter correction device according to Claim 1 , further comprising a selection unit configured to select one or more parameters to be corrected from a plurality of parameters contained in the sensor parameter, wherein the correction unit is configured to correct the one or more parameters selected by the selection unit based on one or more images obtained by changing at least one position selected from a group of the first position and the second position and repeatedly imaging the number of times corresponding to the number of parameters selected by the selection unit.
  4. Parameter correction device according to Claim 1 , wherein the other element of the sensor and the workpiece is stationary, and the correction unit is configured to correct the sensor parameter based on the amount of movement between the first actual measurement position and the second actual measurement position.
  5. Parameter correction device according to one of the Claims 1 until 4 , further comprising an evaluation unit configured to evaluate the sensor parameter, wherein the evaluation unit is configured to evaluate the sensor parameter based on an error between the amount of movement based on the first actual measurement position and the second actual measurement position, and the distance from the first estimated position to the second estimated position.
  6. Parameter correction device according to one of the Claims 1 until 4 , further comprising a display control unit configured to control an image for display on a display element, wherein the correction unit is configured to calculate an error between the amount of movement based on the first actual measurement position and the second actual measurement position, and the distance from the first estimated position to the second estimated position, and the display control unit is configured to establish a relationship between the amount of movement based on the The first actual measurement position and the second actual measurement position are based on this, and the error is displayed on the display part.
  7. Parameter correction device according to one of the Claims 1 until 4 , further comprising: a display control unit configured to control an image for display on a display part; and an image estimation unit configured to estimate an image of the feature section when the one element is positioned at the second position, based on the image obtained by mapping the feature section when the one element is positioned at the first position, the sensor parameter, and a motion amount based on actual measurement positions, wherein the display control unit is configured to display the image of the feature section estimated by the image estimation unit in such a way that it is superimposed on the image obtained by mapping the feature section when the one element is positioned at the second position.
  8. Parameter correction device according to Claim 7 , wherein the sensor parameter includes a parameter relating to image distortion, and the image estimation unit is configured to estimate an image of the feature section including image distortion.
  9. Parameter correction device according to one of the Claims 1 until 4 , further comprising: an image estimation unit configured to estimate an image of the feature section when the one element is positioned at the second position, based on the image of the feature section obtained by mapping the feature section when the one element is positioned at the first position, the sensor parameter, and a motion amount based on actual measurement positions; and a score calculation unit configured to calculate a value indicating a degree of overlap between the image of the feature section estimated by the image estimation unit and the image of the feature section obtained by mapping when the one element is positioned at the second position.
  10. Parameter correction device according to Claim 4 , wherein the motion device is a robot, one element is the sensor, the other element is the workpiece, the sensor is attached to the robot or a hand attached to the robot, a change in the position and orientation of the robot causes a change in the position and orientation of the sensor, and the unit is configured to calculate the actual measurement position, to calculate an actual measurement position of the sensor based on the position and orientation of the robot.
  11. Parameter correction device according to Claim 4 , wherein the motion device is a robot, one element is the workpiece, the other element is the sensor, the workpiece is grasped by a hand attached to the robot, a change in the position and orientation of the robot causes a change in the position and orientation of the workpiece, and the unit is configured to calculate the actual measurement position, to calculate an actual measurement position of the workpiece based on the position and orientation of the robot.
  12. Parameter correction device according to one of the Claims 1 until 4 , where the sensor is a camera configured to capture a two-dimensional image, and the sensor parameter is a camera parameter comprising an extrinsic parameter and an intrinsic parameter.

Description

TECHNICAL AREA The present disclosure relates to a parameter correction device. STATE OF THE ART A conventional robot device is known that measures the position of a workpiece using an image obtained by a camera and performs operations based on the measured position. The robot device's controller can acquire an image obtained by imaging a feature section of the workpiece with the camera. The controller calculates the three-dimensional position of the workpiece from the image of the feature section, based on a previously created reference image of the feature section and a camera parameter. The controller then corrects an operating position described in a robot's operating program based on the three-dimensional position of the workpiece and controls the robot. The robot device can then correctly perform operations according to the actual position of the workpiece. Citation list Patent literature PTL 1: International Publication No. WO 2018/163450 A1PTL 2: Japanese unexamined patent publication no. JP 2023-69274 APTL 3: International Publication No. WO 2021/145280 A1 SUMMARY OF THE INVENTION TECHNICAL PROBLEM In a robotic device that corrects a robot's operating position based on an image obtained by a camera, it is necessary to determine a camera parameter in advance. If the accuracy of the camera parameter is high, the three-dimensional position of a workpiece calculated by the controller will also be accurate. A variety of parameters contained within the camera parameter can be determined through a process called calibration. During calibration, the controller uses a camera to image a calibration target where the positions of points are predefined. The controller can then generate the camera parameter based on the positions of the points in the image and their actual three-dimensional positions. However, after the robot setup has been used, the camera parameter can be corrected to ensure proper robot operation. In this case, it is necessary to re-prepare the calibration plate, and the problem arises that correcting the camera parameter error is time-consuming. Furthermore, the height of the calibration plate may differ from the height of the workpiece feature section actually being captured, and if the camera is performing a two-dimensional scan, an error may occur in the three-dimensional position of the workpiece, which is estimated from the camera image. Alternatively, if the contour or pattern of the workpiece is incorrectly set in a reference image, an error in the three-dimensional position of the workpiece may occur. The problem is that such an error is difficult to detect, and the parameter is even more difficult to correct. SOLUTION TO THE PROBLEM One aspect of the present disclosure is a parameter correction device configured to correct a sensor parameter to calculate a three-dimensional position corresponding to a specific position in an image obtained by imaging a workpiece with a sensor. The parameter correction device includes a feature acquisition unit configured to acquire a feature section in the image of the workpiece. The parameter correction device also includes a unit for calculating the estimated position, configured to calculate an estimated position that The parameter correction device includes a unit for calculating the actual measurement position, which is a three-dimensional position of at least one element selected from a group of the sensor and the workpiece, based on a drive state of a motion device configured to move that element. The parameter correction device also includes a correction unit configured to correct the sensor parameter. The feature acquisition unit is configured to acquire the feature section in an image obtained by mapping when the element is in a first position, and the feature section in an image obtained by mapping when the element is in a second position. The unit for calculating the estimated position is configured to calculate a first estimated position when the element is in the first position, and a second estimated position when the element is in the second position. The unit for calculating the actual measurement position is configured to calculate a first actual measurement position when one element is located at the first position, and a second actual measurement position when one element is located at the second position. The correction unit is configured to correct the sensor parameter based on a movement amount derived from the first and second actual measurement positions, and a distance between the first estimated position and the second estimated position. BRIEF DESCRIPTION OF THE DRAWINGS [ 1 ] 1 is a schematic diagram of a first robot arrangement according to one embodiment.[ 2 ] 2 is a block diagram of the robot arrangement according to the embodiment.[ 3 ] 3 is a perspective view of a workpiece according to the embodiment.[ 4 ] 4 is a schematic diagram to describe the distance from a camera to a feature section of a workpiece.[ 5 ] 5 is