Calibration method for 3D cameras, calibration plate, and calibration program for 3D cameras

Abstract

Calibrate the 3D camera fixed to the robot's hand. [Solution] A method for calibrating a three-dimensional camera, comprising the steps of: arranging a calibration plate 40 provided with three or more reference points and a two-dimensional code representing the relative positions of the reference points; an imaging step of acquiring a calibration plate image by imaging the calibration plate with a three-dimensional camera 30 fixed to the hand 22 of a robot 20; a calibration data acquisition step of acquiring calibration data which is a set of the coordinates of the reference points on the calibration plate image and information regarding the orientation of the hand at the time of imaging; and performing the imaging step and the calibration data acquisition step three or more times with the position of the three-dimensional camera changed, and calculating the mounting position and orientation of the three-dimensional camera on the hand from the series of calibration data.

Description

Technical Field

[0001] The present invention relates to a method for calibrating the position and orientation of a three-dimensional camera fixed to a robot hand.

Background Art

[0002] In a camera used as a vision sensor of a robot, internal parameters and external parameters are obtained by calibration in order to correct image distortion by calculation or calculate the distance to a workpiece. The internal parameters are camera-specific parameters, such as focal length, optical center, pixel scaling factor, and lens distortion coefficient. The external parameters are parameters that do not depend on the camera itself and give the position and orientation of the camera. In a stereo camera, by obtaining the external parameters of two cameras, the positional relationship between the two cameras, that is, the baseline length and the angle formed by the optical axes, can be known, and three-dimensional coordinates can be calculated using the parallax from the left and right images.

[0003] The calibration operation of the camera can be performed by a known method. A grid pattern is often used for the calibration plate used for calibration. For example, Patent Document 1 discloses an example of such a calibration plate. The calibration plate is imaged from several directions, and the internal parameters and external parameters are obtained, for example, by the method described in Non-Patent Document 1.

[0004] When a stereo camera is fixed and used in a work area when performing various operations on a workpiece with a robot, calibration is performed with the stereo camera fixed. The obtained external parameters indicate the position and orientation of the stereo camera in the coordinates of the work area. Thereby, conversion from the camera coordinate system based on the stereo camera to the base coordinate system based on the robot base becomes possible. Therefore, when imaging a workpiece with a stereo camera fixed in a work area, by calculating the position in the camera coordinate system from the position of the workpiece on the image and further converting it to the base coordinate system, it becomes possible to perform various operations on the workpiece with the robot.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-030807 [Non-patent literature]

[0006] [Non-Patent Document 1] Roger Y. Tsai and Reimar K. Lenz, "A New Technique for Fully Autonomous and Efficient 3D Robotics Hand / Eye Calibration", IEEE Trans. on Robotics and Automation, Vol.5, No.3, 1989, pp.345-358 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] When a stereo camera is fixed to a robot's hand, the stereo camera moves with the hand's movement. Generally, stereo cameras are calibrated at the factory for the internal parameters of the two cameras and their relative positions, i.e., the baseline length and the angle formed by the optical axes. However, to determine the position of the workpiece in the base coordinate system, it is necessary to accurately determine the mounting position and orientation of the stereo camera on the hand. Specifically, it is necessary to calculate the transformation matrix from the camera coordinate system to the hand coordinate system, which is based on the hand.

[0008] The present invention has been made in consideration of the above, and aims to provide a calibration method for a three-dimensional camera fixed to a robot hand, for determining the mounting position and orientation of the three-dimensional camera to the hand. [Means for solving the problem]

[0009] The calibration method for a three-dimensional camera of the present invention comprises the steps of: arranging a calibration plate provided with three or more reference points and a two-dimensional code representing the relative positions of the reference points; an imaging step of acquiring a calibration plate image by imaging the calibration plate with a three-dimensional camera fixed to the hand of a robot; a calibration data acquisition step of acquiring calibration data which is a set of the coordinates of the reference points on the calibration plate image and information regarding the orientation of the hand at the time of imaging; and a step of performing the imaging step and the calibration data acquisition step three or more times with the position of the three-dimensional camera changed, and calculating the mounting position and orientation of the three-dimensional camera on the hand from the series of calibration data.

[0010] To determine the mounting position and orientation of the 3D camera on the hand, we specifically need to find the transformation parameters from the camera coordinate system, which is based on the 3D camera, to the hand coordinate system, which is based on the hand.

[0011] Preferably, in the above-described method for calibrating the three-dimensional camera, the two-dimensional code further represents the positional information of each of the reference points with respect to the two-dimensional code. This makes it easier to search for markers from the calibration plate image.

[0012] Preferably, in any of the above three-dimensional camera calibration methods, the reference point has a dot shape.

[0013] Preferably, in any of the above three-dimensional camera calibration methods, the number of reference points is 4 or more and 8 or less.

[0014] Preferably, in any of the above three-dimensional camera calibration methods, the imaging step and the calibration data acquisition step are performed five or more times with the position of the three-dimensional camera changed.

[0015] Preferably, in any of the above three-dimensional camera calibration methods, the two-dimensional code is a matrix-type two-dimensional code with a size of 4x4 or more and 8x8 or less, and the two-dimensional code has a code linked to the positional information of the reference points.

[0016] Preferably, in any of the above three-dimensional camera calibration methods, the three-dimensional camera is a stereo camera.

[0017] The calibration plate of the present invention has three or more reference points and a two-dimensional code that represents the relative positions of the reference points, and is used for calibrating a three-dimensional camera fixed to the hand of a robot.

[0018] Preferably, in the calibration plate described above, the reference point is located outside the two-dimensional code and along the outer circumference of the two-dimensional code.

[0019] The calibration program for the three-dimensional camera of the present invention instructs the robot and the three-dimensional camera to image one of the calibration plates three or more times with the position of the three-dimensional camera to acquire calibration plate images, acquires calibration data which is a set of the coordinates of the reference point on the calibration plate image and information about the orientation of the hand when the calibration plate image was taken, and calculates transformation parameters from the camera coordinate system based on the three-dimensional camera to the robot coordinate system based on the robot from the series of calibration data. Here, the robot coordinate system based on the robot includes the base coordinate system and the hand coordinate system. The robot knows the transformation parameters between coordinate systems based on each part of the robot and can convert between them. The transformation parameters also include transformation matrices and quaternions. [Effects of the Invention]

[0020] According to the stereo camera calibration method of the present invention, transformation parameters from the camera coordinate system to the hand coordinate system can be determined for a stereo camera fixed to the robot hand. Furthermore, since the two-dimensional code contains information about the relative positions of the reference points, the calibration plate can be easily managed. In addition, since the robot's control unit can perform the transformation from the hand coordinate system to the base coordinate system based on the robot's base, the position and orientation of the workpiece imaged by the stereo camera in the base coordinate system can be determined, making it possible to perform various operations on the workpiece with the robot.

Brief Description of the Drawings

[0021] [Figure 1] FIG. is a diagram showing a system for implementing a calibration method of a stereo camera according to an embodiment. [Figure 2] FIG. is a block diagram showing a functional configuration of a system for implementing a calibration method of a stereo camera according to an embodiment. [Figure 3] FIG. is a diagram showing an example of a calibration plate. [Figure 4] FIG. is a diagram showing another example of a calibration plate. [Figure 5] FIG. is a process flow diagram of a calibration method of a stereo camera according to an embodiment. [Figure 6] FIG. is a diagram for explaining the relationship between coordinate systems.

Mode for Carrying Out the Invention

[0022] An embodiment of a calibration method for a three-dimensional camera of the present invention will be described based on the drawings.

[0023] [[ID=|34]]In the present embodiment, for a stereo camera attached to the hand of a robot, the internal parameters of the two cameras and the baseline length and the angle formed by the optical axes indicating the positional relationship between the cameras are values calibrated at the time of factory shipment, and the attachment position and orientation of the stereo camera to the hand are calibrated. Hereinafter, the internal parameters and positional relationship of the two cameras may be collectively referred to as the internal parameters, etc. of the stereo camera. [[ID=|35]] [[ID=|36]]

[0024] [[ID=|37]] [[ID=|38]]Referring to FIG. 1, the calibration method for the three-dimensional camera of the present embodiment is implemented using a robot 20, a stereo camera 30, and a calibration plate 40. [[ID=|39]] [[ID=|40]]

[0025] [[ID=|41]] [[ID=|42]]The robot 20 is preferably an articulated robot. The robot 20 includes an arm 21 and a hand 22 and is controlled by a robot control unit 25. [[ID=|43]] [[ID=|44]]

[0026] [[ID=|45]] The stereo camera 30 is a three-dimensional camera. The stereo camera 30 is fixed to the hand 22 of the robot 20. The stereo camera 30 is calibrated at the factory, and its internal parameters are known. The stereo camera 30 is controlled by the camera control unit 35.

[0027] A three-dimensional camera can be any three-dimensional visual sensor that can add depth information to image information, and even if it consists of multiple housings and is not physically integrated, it is acceptable as long as it is controlled in conjunction with each other. Preferably, the three-dimensional camera is a stereo camera. Alternatively, preferably, the three-dimensional camera is a visual sensor that has a projector attached to a stereo camera or monocular camera for projecting patterns. Examples of stereo cameras include Basler's rc_visard series and Kurabo Industries Ltd.'s Kurasense series. An example of a camera with a projector attached to a monocular camera is IDS's Encenso S series. Examples of cameras with a projector attached to a stereo camera include Intel's RealSense D435, D455 and IDS's Encenso X series.

[0028] Referring to Figure 2, the robot control unit 25 comprises a robot calculation unit 26, a robot memory unit 27, and a robot communication unit 28. The robot control unit 25 controls the entire robot 20, including the arm 21 and the hand 22. The robot calculation unit 26 performs various calculations, such as calculating joint variables to make the arm 21 assume a required posture or to make the hand 22 reach a target position. The robot memory unit 27 stores various parameters necessary for the robot's operation. The robot communication unit 28 communicates with the outside world, such as communicating with the camera communication unit 38 of the camera control unit 35.

[0029] The camera control unit 35 comprises a camera calculation unit 36, a camera storage unit 37, and a camera communication unit 38. The camera control unit 35 controls the stereo camera 30 and also provides functions necessary for calibrating the stereo camera. The camera calculation unit 36 ​​analyzes images captured by the stereo camera 30 to calculate the distance to each point on the image and executes programs necessary for calibrating the stereo camera 30 to perform various calculations. The camera storage unit 37 stores various data necessary for calculations performed by the camera calculation unit, as well as the progress of the calculations. The camera storage unit 37 also stores internal parameters of the stereo camera 30 and the stereo camera calibration program. The camera communication unit 38 communicates with external devices, such as the robot communication unit 28. Note that the functions of the camera control unit 35 may be shared among multiple physically separate devices.

[0030] Referring to Figure 3, the calibration plate 40 has a two-dimensional code 43 and four reference points, dots 42a, 42b, 42c, and 42d, on a smooth, flat plate 41. Hereafter, dots 42a to 42d will be collectively referred to as dot 42.

[0031] The dot 42 is a solid circle. The shape of the dot is not limited to a circle, but it is preferable to be circular because it makes it easier to calculate the centroid on the image even when imaging from an oblique angle. The number of dots 42 can be 3 or more, but preferably 4 or more, because it improves the accuracy of calibration. On the other hand, the number of dots 42 is preferably 8 or less, because many reference points are not needed to determine the mounting position and orientation of the stereo camera 30 to the hand 22, and the effect of improving accuracy will plateau if there are too many dots. The arrangement of the dots 42 is not particularly limited. The relative positions of the dots must be precisely determined, but each dot can be arranged in any way.

[0032] The reference points on the calibration plate are not limited to dots; for example, as shown in Figure 4, the reference points may be the intersections 47 (47a to 47d) of the lines constituting the grid 46, as in the calibration plate 45. In this case as well, the number of intersections 47 should be three or more, preferably four or more and eight or less. Furthermore, the arrangement of the intersections 47 is not particularly limited.

[0033] Various known two-dimensional codes 43 can be used. The two-dimensional code 43 contains information about its own orientation. Preferably, the two-dimensional code 43 has a rectangular shape. Rectangles also include squares. Furthermore, preferably, a matrix-type two-dimensional code is used. This is because it is easier to determine the orientation and detect the position of the code compared to other two-dimensional codes such as multi-row systems.

[0034] The two-dimensional code 43 represents the relative positions of the dots 42. The relative positions of the dots 42 refer to information indicating how each dot is positioned on the calibration plate 40. The relative positions of the dots 42 can be expressed, for example, by the distance and direction from one dot to another dot, with one dot and an arbitrary direction as the reference. The two-dimensional code may have the relative positions of the dots themselves, or it may have a code associated with the relative positions of the dots. In other words, the two-dimensional code may directly represent the relative positions of the dots, or it may indirectly represent them by having information associated with the relative positions of the dots. The code may be a number such as 0, 1, or 2. In this case, the relative positions of the dots can be stored in the camera memory unit 37, etc., and the corresponding relative positions of the dots can be read out by comparing them with the code represented in the two-dimensional code 43 and used for calculations in the camera calculation unit 36.

[0035] By including positional information between the dots 42 in the two-dimensional code 43, it becomes unnecessary to manage the dot arrangement of each calibration plate, even when selecting and using one from multiple calibration plates with different dot arrangements. Furthermore, recognizing the two-dimensional code 43 from the captured image of the calibration plate 40 is easier than recognizing each dot 42, which is another advantage of providing the two-dimensional code 43 on the calibration plate 40.

[0036] Preferably, the two-dimensional code 43 further represents the positional information of each dot 42 relative to the two-dimensional code 43. The positional information of each dot 42 relative to the two-dimensional code 43 indicates where each dot is located on the calibration plate 40 in relation to the two-dimensional code 43 itself. This makes it easier to search for dots on an image of the calibration plate.

[0037] The positional information of each dot 42 relative to the two-dimensional code 43 can be expressed as absolute positional information in terms of distance and direction to each dot, based on a point in the two-dimensional code and a direction defined by the shape of the two-dimensional code, for example, based on a corner or center of the two-dimensional code and one side of the matrix-type two-dimensional code. Alternatively, for example, in the arrangement shown in Figure 3, the positional information can also be expressed as relative positional information, such as each of the four dots existing in one of the four quadrants centered on the two-dimensional code, or being on the diagonal of the two-dimensional code. The two-dimensional code 43 may have the positional information of each dot relative to the two-dimensional code itself, or it may have a code associated with such positional information. The code may be a number such as 0, 1, or 2. Also, for one calibration plate, one code may be associated with the combined positional information of the dots relative to each other and the positional information of each dot relative to the two-dimensional code.

[0038] If the two-dimensional code 43 is of matrix type, it is even more preferable that the vertical and horizontal dimensions are 4 or more and 8 or less, respectively. Here, the vertical and horizontal dimensions do not include the outer frame formed in black, but refer to the number of cells painted black or white inside the frame that represent information. The two-dimensional code 43 in Figure 3 is 4x4. Two-dimensional codes with dimensions of 4x4 to 8x8 have the advantage of being easily recognizable when captured by a stereo camera, although they can directly represent less information. Furthermore, if the information includes the relative positions of the dots and a code linked to the position information of each dot relative to the two-dimensional code, the limited amount of information that can be directly represented is not a problem.

[0039] Next, the transformation matrix of the target coordinate system for the calibration method of the stereo camera in this embodiment will be described.

[0040] First, the transformation between the two coordinate systems can be expressed by the following equation.

number

[0041] Referring to Figure 6, the calibration method for the stereo camera in this embodiment determines the mounting position and orientation of the stereo camera 30 on the hand 22. Specifically, a transformation matrix is ​​calculated as a transformation parameter between the camera coordinate system (Xc, Yc, Zc) based on the stereo camera 30 and the hand coordinate system (Xh, Yh, Zh) based on the hand 22 of the robot 20. The camera coordinate system is usually set with the optical center of the stereo camera as the origin. The hand coordinate system is usually set with the base end of the hand as the origin.

[0042] When the calibration plate 40 is imaged, the position of the dot 42 on the image is determined by the relative positions of the actual calibration plate and the stereo camera at the time of imaging. Using the internal parameters of the stereo camera 30 set at the factory, etc., a transformation matrix from the calibration plate coordinate system (Xb, Yb, Zb) based on the calibration plate can be calculated from the position of the dot on the image. The calibration plate coordinate system can be taken with any point on the calibration plate as the reference. On the other hand, the transformation matrix from the base coordinate system (Xr, Yr, Zr) based on the base 23 of the robot 20 to the hand coordinate system can be calculated using the parameters set by the calibration of the robot 20. The robot parameters are stored in the robot memory unit 27, and the robot calculation unit 26 can calculate the transformation matrix each time according to the robot's posture.

[0043] Here, the camera coordinate system and hand coordinate system move according to the robot 20's posture, but the calibration plate coordinate system and base coordinate system do not change with the robot's posture. Furthermore, the positional relationship between the calibration plate coordinate system and the base coordinate system does not change even while a series of images of the calibration plate are taken while changing the position of the stereo camera. Therefore, the transformation matrix from the camera coordinate system to the hand coordinate system can be calculated by solving the system of equations obtained from the series of images. The specific calculation process can be carried out in accordance with the method described in Non-Patent Document 1. However, the internal parameters of the stereo camera are not updated, and calibration is performed only in terms of position and orientation.

[0044] Next, we will explain the specific procedure for calibrating the stereo camera, following the flowchart in Figure 5.

[0045] (S1) Arrangement of calibration plates First, the calibration plate 40 described above is prepared and placed near the location where the workpiece will be placed during operation by the robot 20. It is known that calibration accuracy is better when the angle between the calibration plate and the optical axis of the stereo camera is close to 90 degrees. The relative position information of the dots 42 on the calibration plate 40, and the position information of each dot 42 based on the two-dimensional code 43 are stored in the camera memory unit 37 in advance. The two-dimensional code 43 on the calibration plate 40 has a code linked to this information.

[0046] (S2) IO A stereo camera 30, fixed to the hand 22 of the robot 20, is used to image the calibration plate 40 and acquire an image of the calibration plate. The stereo camera is assumed to be factory-calibrated, and its internal parameters are stored in the camera memory unit 37.

[0047] (S3) Reading a 2D barcode The camera calculation unit 36 ​​recognizes the two-dimensional code 43 from the calibration plate image and obtains the position and orientation of the two-dimensional code. Next, it reads the codes associated with the relative position information of the dots 42 from the information represented in the two-dimensional code 43 and retrieves the relative position information of the dots from the camera storage unit 37. If the two-dimensional code 43 further represents the position information of each dot 42 relative to the two-dimensional code 43, it reads the codes associated with the position information of each dot relative to the two-dimensional code and retrieves the position information of each dot relative to the two-dimensional code from the camera storage unit 37. Recognition of the two-dimensional code and reading of the information can be performed by known methods.

[0048] (S4) Dot position reading If positional information for each dot 42 is obtained based on the two-dimensional code 43, the approximate position of each dot 42 can be determined from that positional information. Using this as a clue, the camera calculation unit 36 ​​recognizes the dots 42 on the calibration plate image and determines the precise coordinates of the centroid of the dots on the calibration plate image.

[0049] Calibrating the stereo camera 30 requires associating each dot 42a to 42d on two calibration plate images, left and right. When the position of the stereo camera 30 is changed and the calibration plate 40 is imaged, calibration plate images with different orientations are obtained. In this embodiment, by providing a two-dimensional code 43 on the calibration plate 40, the camera calculation unit 36 ​​can automatically perform the association of each dot based on the orientation of the two-dimensional code, rather than having an operator check the calibration plate image.

[0050] (S5) Reading hand posture The camera control unit 35 instructs the robot control unit 25 to transmit information regarding the posture of the hand 22, and receives information regarding the posture of the hand at the time of the image capture from the robot control unit. Information regarding the posture of the hand is, for example, a transformation matrix from the base coordinate system to the hand coordinate system at the time of image capture. Communication between the camera control unit 35 and the robot control unit 25 is conducted via the camera communication unit 38 and the robot communication unit 28.

[0051] (S6) Calibration data storage The camera control unit 35 stores the coordinates of the dot 42 on the calibration plate image and information regarding the orientation of the hand 22 at the time of imaging as a set in the camera storage unit 37 as the first calibration data.

[0052] The camera control unit 35 instructs the robot control unit 25 to change the position of the stereo camera 30, and steps S2 to S6 are repeated a predetermined number of times. Imaging must be performed at least three times. To improve the accuracy of calibration, it is preferable to further increase the number of imagings to five or more times. On the other hand, if the number of imagings is too large, the calibration work will take a long time and the effect of improving accuracy will plateau, so it is preferable to keep the number of imagings to 20 or less. When repeating imaging, the imaging position of the stereo camera should be moved to a degree in which the change in the position of the reference point can be significantly recognized on each image, and it is preferable to change the position within an angle of about ±30 degrees with respect to the imaging position of the central camera facing the calibration plate. This is because if the angle becomes too large, it becomes difficult to determine the centroid of the reference point from the image.

[0053] (S7) Calibration calculation Once calibration data sets for the number of imaging cycles have been obtained, the camera calculation unit 36 ​​solves a system of equations to obtain a transformation matrix from the camera coordinate system to the hand coordinate system.

[0054] With the above steps, the calibration of the stereo camera was completed, and the transformation matrix between the camera coordinate system and the hand coordinate system was obtained.

[0055] In this embodiment, the internal parameters of the stereo camera 30 were calibrated at the time of shipment, and in the robot 20's working environment, only the mounting position and orientation of the stereo camera 30 on the hand 22 were determined when the stereo camera 30 was attached to the hand 22. The robot's working environment is not always suitable for calibration, and for example, it may not be possible to set the distance between the stereo camera and the calibration plate, or the intersection angle between the optical axis of the stereo camera and the calibration plate, to optimal values. If calibration is performed under such conditions and the internal parameters of the stereo camera are updated, the accuracy of distance measurement may actually decrease. Therefore, it is preferable not to update the internal parameters of the stereo camera, etc., by considering the factory-shipped values ​​obtained under more suitable calibration conditions as the correct values, and instead to calibrate only the mounting position and orientation of the stereo camera on the hand.

[0056] Furthermore, to calibrate only the mounting position and orientation of the stereo camera 30 to the hand 22, it is sufficient to have three or more sets of calibration data including the three-dimensional positions of three or more reference points placed on the same plane and the orientation of the hand 22, thus reducing the number of reference points on the calibration plate. This allows calibration work to be performed without problems even if the resolution of the stereo camera is low, and the time required for calibration work can be reduced.

[0057] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of its technical concept.

[0058] For example, the three-dimensional camera calibration method of the present invention can be used even when there are multiple three-dimensional cameras in a work area and multiple calibration boards are arranged for each three-dimensional camera, and each calibration board can be easily identified by the two-dimensional code on the calibration board. [Explanation of symbols]

[0059] 20 Robots 21 Arms 22 Hand 23 Base 25 Robot Control Unit 26 Robot Calculation Unit 27 Robot Memory Unit 28 Robot Communications Department 30 Stereo cameras (three-dimensional cameras) 35 Camera Control Unit 36 Camera Processing Unit 37 Camera memory unit 38 Camera Communications Department 40 Calibration plate 41 flat plate 42, 42a~42d Dots (reference points) 43 QR Code 45 Calibration plate 46 grid 47, 47a~47d intersection (reference point)

Claims

1. A step of arranging a calibration plate provided with three or more reference points and a two-dimensional code representing the relative positional information of the reference points, The process includes an imaging step in which a three-dimensional camera fixed to the robot's hand is used to image the calibration plate and acquire an image of the calibration plate, A calibration data acquisition step involves acquiring calibration data that includes the coordinates of the reference point on the calibration plate image and information regarding the orientation of the hand at the time of imaging, The imaging step and the calibration data acquisition step are performed three or more times with the position of the three-dimensional camera changed, and the mounting position and orientation of the three-dimensional camera to the hand are calculated from the series of calibration data. A calibration method for a three-dimensional camera having [specific features / features].

2. The aforementioned two-dimensional code further represents the positional information of each of the reference points based on the two-dimensional code. A method for calibrating a three-dimensional camera according to claim 1.

3. The aforementioned reference point has a dot shape. A method for calibrating a three-dimensional camera according to claim 1.

4. The number of reference points is 4 or more and 8 or less. A method for calibrating a three-dimensional camera according to claim 1.

5. The imaging step and the calibration data acquisition step are performed five or more times, with the position of the three-dimensional camera changed. A method for calibrating a three-dimensional camera according to claim 1.

6. The aforementioned two-dimensional code is a matrix-type two-dimensional code with a size of 4x4 or larger and 8x8 or smaller. The aforementioned two-dimensional code has a code linked to the positional information of the reference points, A method for calibrating a three-dimensional camera according to claim 1.

7. The aforementioned three-dimensional camera is a stereo camera. A method for calibrating a three-dimensional camera according to any one of claims 1 to 6.

8. It has three or more reference points and a two-dimensional code that represents the relative positions of the reference points, Used for calibrating a 3D camera fixed to a robot's hand, Calibration board.

9. The reference points are arranged along the outer circumference of the two-dimensional code. The calibration plate according to claim 8.

10. The robot and the three-dimensional camera are instructed to take images of the calibration plate described in claim 8 or 9 three or more times by changing the position of the three-dimensional camera, thereby acquiring an image of the calibration plate. Calibration data is obtained by combining the coordinates of the reference point on the calibration plate image and information regarding the orientation of the hand when the calibration plate image was captured. From a series of calibration data, the transformation parameters from the camera coordinate system based on the three-dimensional camera to the robot coordinate system based on the robot are calculated. Calibration program for 3D cameras.

Images