Calibration device

Abstract

In one embodiment, a camera parameter calibration device comprises a feature detection unit that detects a feature portion of a calibration plate in an image obtained by imaging the calibration plate. The calibration device includes an identification unit that identifies the type of the calibration plate captured by a camera from a plurality of types of the calibration plate. The calibration device includes a parameter setting unit for setting a camera parameter on the basis of information related to the calibration plate identified by the identification unit. The feature portion is formed on the surface of the calibration plate together with a basic figure indicating a predetermined interval. The identification unit identifies the type of the calibration plate on the basis of the feature portion detected by the feature detection unit.

Description

Calibration device

[0001] The present disclosure relates to a calibration device.

[0002] Conventionally, robotic devices have been known that detect the position of a workpiece using an image captured by a camera and perform work based on the detected position of the workpiece. The robot's control device can acquire an image of a characteristic part of the workpiece captured by the camera. The control device calculates the three-dimensional position of the workpiece based on the position of the characteristic part in the image and the camera parameters. Because the control device can drive the robot based on the three-dimensional position of the workpiece, accurate work can be performed.

[0003] The camera parameters are parameters for calculating the positions of three-dimensional feature parts from the positions of feature parts in an image. The camera parameters include, for example, external parameters related to the position and orientation of the camera, and internal parameters related to the internal mechanism of the camera, such as lens distortion and dimensions of the light receiving element.

[0004] The multiple parameters included in the camera parameters can be determined through a calibration process. In the calibration process, for example, a camera captures an image of a calibration plate on which a dot pattern with predetermined dot spacing is formed. The calibration device can then calibrate the camera parameters based on the dot spacing calculated from the image of the dot pattern and the actual three-dimensional spacing of the dots.

[0005] JP 2022-30807 A JP 2021-67514 A JP 2014-128845 A JP 2018-122376 A

[0006] The diameter and spacing of the dots formed on the calibration plate for calibrating camera parameters depend on the environment in which the camera is used, the type of camera, the type of lens, and other factors. For example, to accurately calculate parameters related to lens distortion, it is preferable that the images of the dots are dispersed throughout the entire field of view of the camera. On the other hand, it is preferable to capture the dots large enough so that they can be correctly recognized.

[0007] There are multiple types of calibration plates with different dot diameters and spacing between dots. An operator can select the optimal calibration plate depending on the type of camera, etc. Here, information about the calibration plate, such as the spacing between dots, must be input by the operator into the calibration device each time the calibration plate is changed. Furthermore, if the operator inputs incorrect information, inaccurate camera parameters are generated, which can lead to an incorrect calculation of the position of the workpiece detected from the image of the workpiece. Furthermore, even if inaccurate camera parameters are generated, it is difficult for the operator to notice that the camera parameters are inaccurate.

[0008] One aspect of the present disclosure is a calibration device that calibrates camera parameters for detecting the position of an object from an image captured by a camera. The calibration device includes a feature detection unit that detects feature portions of a calibration plate in an image captured of the calibration plate. The calibration device includes an identification unit that identifies the type of calibration plate imaged by the camera from multiple types of calibration plates. The calibration device includes a parameter setting unit that sets camera parameters based on information about the calibration plate identified by the identification unit. The feature portions are formed on the surface of the calibration plate together with a basic figure that indicates a predetermined interval. The identification unit identifies the type of calibration plate based on the feature portions detected by the feature detection unit.

[0009] 1 is a schematic diagram of a robot system according to a first embodiment. FIG. 2 is a block diagram of a robot system according to the first embodiment. FIG. 3 is a plan view of a first calibration plate according to the first embodiment. FIG. 4 is a plan view of a second calibration plate according to the first embodiment. FIG. 5 is a plan view of a third calibration plate according to the first embodiment. FIG. 6 is a plan view of a first calibration plate according to the second embodiment. FIG. 7 is an enlarged view illustrating the diameter of dots and the spacing between dots. FIG. 8 is a plan view of a second calibration plate according to the second embodiment. FIG. 9 is a plan view of a third calibration plate according to the second embodiment. FIG. 10 is a plan view of a calibration plate according to the fourth embodiment. FIG. 11 is a plan view of a fifth calibration plate according to the second embodiment. FIG. 12 is a plan view of a sixth calibration plate according to the second embodiment. FIG. 13 is a plan view of a first calibration plate according to the third embodiment. FIG. 14 is a plan view of a calibration plate according to the fourth embodiment.

[0010] 1 to 5, a calibration device and a robot system including the calibration device according to a first embodiment will be described. The robot system of this embodiment detects the position of a workpiece based on an image captured by a camera.

[0011] Fig. 1 is a schematic diagram of a robot system equipped with a calibration device according to this embodiment. Fig. 2 is a block diagram of the robot system according to this embodiment. Fig. 1 shows a state in which a calibration operation of camera parameters 62 of a camera 6 is performed. Referring to Figs. 1 and 2, a robot system 3 according to this embodiment detects the position of a workpiece placed on a stand 34 based on an image captured by the camera 6, and grasps and transports the workpiece to a predetermined position.

[0012] The robot system 3 includes a robot device. The robot device includes a hand 5 as a work tool for gripping a workpiece, a robot 1 for moving the hand 5, and a control device 2 for controlling the hand 5 and the robot 1. The robot system 3 also includes a stand 34 on which the workpiece is placed.

[0013] The hand 5 in this embodiment is a work tool that grips and releases a workpiece. The work tool attached to the robot 1 is not limited to this form, and any work tool can be used depending on the work to be performed by the robot system 3. For example, a spray gun for painting a workpiece and a welding torch for welding can be used as the work tool.

[0014] The robot 1 of this embodiment is an articulated robot including multiple joints 18. The robot 1 includes an upper arm 11 and a lower arm 12. The upper arm 11 is supported by the lower arm 12. The lower arm 12 is supported by a swivel base 13. The swivel base 13 is supported by a base 14. The robot 1 includes a wrist 15 connected to the end of the upper arm 11. The wrist 15 includes a flange 16 to which the hand 5 is fixed. The components of the robot 1 are configured to rotate around a predetermined drive axis. The robot 1 is not limited to this configuration, and any robot that can change the position and posture of a work tool can be used.

[0015] The robot 1 of this embodiment includes a robot driving device 21 having a driving motor that drives components such as the upper arm 11. The hand 5 includes a hand driving device 22 that drives the hand 5. The hand driving device 22 of this embodiment drives the hand 5 by air pressure. The hand driving device 22 includes an air pump and a solenoid valve for supplying compressed air to a cylinder.

[0016] The control device 2 includes a control device main body 40 and a teaching pendant 26 for an operator to operate the control device main body 40. The control device main body 40 includes an arithmetic processing device (computer) having a CPU (Central Processing Unit) as a processor. The arithmetic processing device has RAM (Random Access Memory), ROM (Read Only Memory), etc. connected to the CPU via a bus. The robot 1 is driven based on operation commands from the control device 2.

[0017] The control device main body 40 includes a storage unit 42 that stores any information related to the robot system 3. The storage unit 42 can be configured with a non-transitory storage medium capable of storing information. For example, the storage unit 42 can be configured with a storage medium such as a volatile memory, a non-volatile memory, a magnetic storage medium, or an optical storage medium. The processor is configured to be able to read the information stored in the storage unit 42.

[0018] An operation program 61 created in advance for operating the robot 1 is input to the control device 2. Alternatively, an operator can set teaching points for the robot 1 by operating the teaching pendant 26 to drive the robot 1. The control device 2 can then generate the operation program 61 based on the teaching points. The operation program 61 is stored in the storage unit 42.

[0019] The operation control unit 43 sends operation commands to the robot driving unit 44 for driving the robot 1 based on the operation program 61. The robot driving unit 44 includes an electrical circuit for driving the drive motor, and supplies electricity to the robot driving device 21 based on the operation commands. The operation control unit 43 also sends operation commands for driving the hand driving device 22 to the hand driving unit 45. The hand driving unit 45 includes an electrical circuit for driving an air pump or the like, and supplies electricity to the air pump or the like based on the operation commands.

[0020] The operation control unit 43 corresponds to a processor that operates in accordance with the operation program 61. The processor reads the operation program 61 and performs the control defined in the operation program 61, thereby functioning as the operation control unit 43.

[0021] The robot 1 includes a state detector for detecting the position and posture of the robot 1. In this embodiment, the state detector includes a position detector 23 attached to the drive motor of each drive shaft of the robot drive device 21. The position detector 23 can be configured, for example, by an encoder that detects the rotational position of the output shaft of the drive motor. The position and posture of the robot 1 are detected based on the output of each position detector 23.

[0022] In the robot system 3, a reference coordinate system 71 is set that remains stationary even when the position and posture of the robot 1 change. In the example shown in Fig. 1, the origin of the reference coordinate system 71 is located on the base 14 of the robot 1. The reference coordinate system 71 is also called a world coordinate system. In the reference coordinate system 71, the position of the origin is fixed, and further, the orientation of the coordinate axes is fixed.

[0023] A tool coordinate system 72 is set in the robot system 3, with its origin set at an arbitrary position on the work tool. The position and orientation of the tool coordinate system 72 change along with the work tool. In this embodiment, the origin of the tool coordinate system 72 is set at the tool tip point of the hand 5. The position of the robot 1 corresponds to the position of the tool tip point in the reference coordinate system 71 (the position of the origin of the tool coordinate system 72). The orientation of the robot 1 corresponds to the orientation of the tool coordinate system 72 with respect to the reference coordinate system 71.

[0024] The teaching pendant 26 is connected to the control device main body 40 via a communication device. The teaching pendant 26 includes an input unit 27 for inputting information about the robot 1 and the hand 5. The input unit 27 is composed of input members such as a keyboard and a dial. The teaching pendant 26 includes a display unit 28 for displaying information about the robot 1 and the hand 5. The display unit 28 can be composed of a display panel capable of displaying information, such as a liquid crystal display panel or an organic EL (Electro Luminescence) display panel. When the teaching pendant is equipped with a touch panel type display panel, the display panel functions as both the input unit and the display unit.

[0025] The robot system 3 in this embodiment is equipped with an imaging device that detects the position of a workpiece. The imaging device includes a camera 6 that captures an image of the workpiece as an object. The camera 6 in this embodiment is a two-dimensional camera that captures two-dimensional images. The camera 6 in this embodiment is supported by the robot 1. The camera 6 is fixed to a flange 16 via a support member. The position and orientation of the camera 6 change together with the hand 5. The camera 6 can capture images in a field of view 6a. Note that the camera is not limited to a two-dimensional camera, and may be a three-dimensional camera such as a stereo camera that can detect the three-dimensional position of the object being imaged.

[0026] In the robot system 3, a camera coordinate system 73 is set relative to the camera 6. The position and orientation of the camera coordinate system 73 change along with the camera 6. The origin of the camera coordinate system 73 is set at a predetermined position on the camera 6, such as the lens center or optical center of the camera 6. The camera coordinate system 73 has an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. In the present embodiment, the camera coordinate system 73 is set so that the Z-axis extends in a direction parallel to the optical axis of the lens of the camera 6. In this embodiment, the camera 6 is fixed to the flange 16, so the relative position and orientation of the camera coordinate system 73 with respect to the tool coordinate system 72 are constant. Note that, although the position and orientation of the camera in this embodiment change along with the robot, this is not a limitation. The camera may be supported on a mount or the like so that its position and orientation do not change. In this case, the camera coordinate system becomes a coordinate system whose position and orientation do not change.

[0027] The control device main body 40 includes an image processing unit 51 that processes images captured by the camera 6. The image processing unit 51 includes an imaging control unit 56 that sends a command to the camera 6 to capture an image. The image processing unit 51 includes a feature detection unit 54 that detects predetermined feature portions of the object in the captured image. Furthermore, the feature detection unit 54 can calculate the three-dimensional position of the feature portions of the object using camera parameters. The image processing unit 51 includes an operation command generation unit 55 that generates operation commands for the robot 1 and the hand 5 based on the results of image processing.

[0028] The robot system 3 of this embodiment includes a calibration device that calibrates camera parameters for detecting the position of an object from an image captured by the camera 6. In this embodiment, the control device 2 functions as the calibration device. The feature detection unit 54 detects feature portions of the calibration plate 80 in an image captured of the calibration plate 80 placed on the stand 34. The image processing unit 51 includes an identification unit 57 that identifies the type of the calibration plate imaged by the camera 6 from multiple types of calibration plates 80. The image processing unit 51 includes a parameter setting unit 58 that sets camera parameters based on information about the calibration plate identified by the identification unit 57.

[0029] The image processing unit 51 corresponds to a processor that operates in accordance with the operation program 61. In particular, each of the imaging control unit 56, feature detection unit 54, operation command generation unit 55, identification unit 57, and parameter setting unit 58 corresponds to a processor that operates in accordance with the operation program 61. The processor reads the operation program 61 and performs the control defined in the operation program 61, thereby functioning as each unit.

[0030] 1, when the robot system 3 actually performs a workpiece transport operation, the workpiece is placed on the surface of the base 34 in a predetermined manner. The control device 2 changes the position and posture of the robot 1, and the hand 5 grasps the workpiece placed on the top surface of the base 34. The robot 1 then transports the workpiece to a predetermined position by changing its position and posture.

[0031] In the robot system 3 of this embodiment, the camera 6 captures an image of the workpiece when the workpiece is grasped. At this time, the distance from the surface of the characteristic portion of the workpiece to the camera 6 is determined in advance. If the camera is a three-dimensional camera, the distance from the surface of the characteristic portion of the workpiece to the camera can be detected by the three-dimensional camera, so the distance from the surface of the characteristic portion of the workpiece to the camera does not need to be determined in advance. The feature detection unit 54 of the image processing unit 51 detects the characteristic portion of the workpiece by performing pattern matching. A template image for detecting the characteristic portion of the workpiece is created in advance and stored in the memory unit 42.

[0032] The feature detection unit 54 detects the three-dimensional position of the feature based on the position of the feature in the image using a computational model such as a pinhole camera model. The computational model includes camera parameters 62. The camera parameters 62 are determined in advance and stored in the storage unit 42.

[0033] The camera parameters 62 generally include extrinsic parameters and intrinsic parameters. The extrinsic parameters are information about the physical position and orientation of the camera. The extrinsic parameters include, for example, information about the relative position and orientation of the camera coordinate system 73 with respect to the tool coordinate system 72. The intrinsic parameters are information about the optical system of the camera, such as the focal length of the lens, lens distortion, and dimensions of the light receiving element. For example, the intrinsic parameters include coefficients for correcting three-dimensional position due to lens distortion.

[0034] Based on the internal parameters, the feature detection unit 54 calculates the coordinate values ​​of the feature parts in the camera coordinate system 73 from the positions of the feature parts in the image. Based on the external parameters and the position and posture of the robot, the feature detection unit 54 can convert the coordinate values ​​of the feature parts in the camera coordinate system 73 into coordinate values ​​in the reference coordinate system 71.

[0035] The feature detection unit 54 calculates the position of the workpiece to be grasped by the hand 5 based on the positions of the feature parts of the workpiece in the reference coordinate system 71. The operation command generation unit 55 generates operation commands for the position and posture of the robot 1 so as to correspond to the position of the workpiece. Then, the operation control unit 43 changes the position and posture of the robot 1 to grasp the workpiece with the hand 5.

[0036] When the robot system 3 of this embodiment transports a workpiece, the feature detection unit 54 detects the feature of the workpiece and calculates the three-dimensional position of the workpiece based on the positions of the feature. This allows the robot system 3 to grip the workpiece with high precision. In particular, even if the position of the workpiece on the platform 34 is deviated from the reference position or the workpiece has a dimensional error, the robot system 3 can transport the workpiece with high precision.

[0037] Next, the control device 2 of this embodiment functions as a calibration device that calibrates the camera parameters 62. The calibration of this embodiment includes generating new camera parameters 62 and correcting the camera parameters 62.

[0038] 1, the calibration plate 80 has a plate-like shape. The calibration plate 80 is placed on the surface of the stand 34. The calibration plate 80 of this embodiment has a basic figure formed on its surface, which shows a predetermined interval. The basic figure of this embodiment includes dots as basic points. The basic figure of this embodiment is drawn by aligning a plurality of dots.

[0039] 3 shows a plan view of the first calibration plate 81 of this embodiment. The basic figure of the first calibration plate 81 of this embodiment is a dot pattern including a plurality of dots 81a. The dots 81a function as basic points of the basic figure. In this embodiment, the dots 81a are formed to have a circular planar shape. The plurality of dots 81a are regularly arranged at predetermined intervals. The plurality of dots 81a of this embodiment are arranged so that the vertical and horizontal intervals are constant. In the first calibration plate 81, the dots 81a are formed so that the intervals between them are 5 mm.

[0040] On the calibration plate 81, a coordinate system mark 81e including dots 81b as coordinate system points is formed in the area where the dots 81a are formed. The coordinate system mark 81e defines a coordinate system for detecting the coordinate values ​​of each dot 81a. In this embodiment, the coordinate system mark 81e has a bent shape (L-shape). The centers of the dots 81b, which form the corners of the coordinate system mark 81e, are the origin of the coordinate system. The X-axis and Y-axis are set in the directions from the origin to the alignment of the dots 81b. The positions of the multiple dots 81a are predetermined by the coordinate values ​​of the coordinate system defined by the coordinate system mark 84e. Note that in this embodiment, the coordinate system mark is formed in addition to the basic figure, but this is not a limitation, and the coordinate system mark may not be formed.

[0041] The dots 81a included in the basic figure and the dots 81b included in the coordinate system mark 81e are different in size, which allows the feature detection unit 54 of the image processing unit 51 to detect the coordinate system mark 81e formed in the area of ​​the basic figure.

[0042] 1 , when calibrating the camera parameters 62, the calibration plate 80 is placed on the stand 34 with the surface on which the basic shape is drawn facing up. When the robot 1 is driven, the camera 6 is placed at a predetermined position and orientation relative to the calibration plate 80. For example, the operator changes the position and orientation of the robot 1 by operating the teaching pendant 26. Alternatively, the operation control unit 43 may drive the robot 1 based on the operation program 61 so that the camera 6 is placed at a predetermined position and orientation.

[0043] The camera 6 is positioned so as to capture an image of the figure formed on the calibration plate 80. In this embodiment, the camera 6 is positioned directly above the calibration plate 80, but this is not limiting. The camera can be positioned at any position where it can capture an image of the calibration plate. That is, the camera can be positioned so that the calibration plate is located within the field of view of the camera. Furthermore, the attitude of the camera 6 can be adjusted so that the optical axis of the camera 6 extends in a direction perpendicular to the surface of the calibration plate 80. The camera 6 can be positioned at a predetermined distance from the surface of the calibration plate 80 in the direction of the Z axis of the camera coordinate system 73.

[0044] Next, the camera 6 captures an image of the figure formed on the calibration plate 80. When the first calibration plate 81 is used as the calibration plate, the feature detection unit 54 identifies the coordinate system mark 81e by a method such as pattern matching. The feature detection unit 54 sets a coordinate system on the calibration plate 80 in the image based on the coordinate system mark 81e. The feature detection unit 54 detects multiple dots 81a by a method such as pattern matching. The feature detection unit 54 calculates the coordinate values ​​of each dot 81a in the image. Alternatively, the feature detection unit 54 calculates the spacing between the dots 81a in the image.

[0045] The parameter setting unit 58 can calculate the camera parameters included in the calculation model based on the actual spacing between the dots 81 a and the spacing between the dots 81 a in the image. In this way, the image processing unit 51 can set the parameters included in the calculation model.

[0046] In this embodiment, the dots formed on the calibration plate are formed so that the vertical and horizontal spacings are constant, but this is not limited to this. Multiple dots can be generated at predetermined spacings. Therefore, the spacing between dots may be different in the vertical and horizontal directions. Alternatively, the spacing between dots may be different for each of multiple regions.

[0047] Incidentally, when calibrating camera parameters, it is preferable to change the size and spacing of the dots formed on the calibration plate depending on the camera characteristics or the environment in which the camera is used. For example, when correcting lens distortion using internal parameters, it is preferable that the dots are displayed thinly across the entire field of view of the camera. On the other hand, if the dots are too small, the feature detection unit may not be able to detect them. For this reason, it is preferable to capture the dots large enough so that the feature detection unit can detect them.

[0048] Furthermore, a camera with a lens having a long focal length has a narrow field of view. In this case, it is preferable that the dots are small and the spacing between the dots is small. On the other hand, if the field of view of the camera is wide, it is preferable that the dots are large and the spacing between the dots is large. Alternatively, it is preferable to change the size and spacing of the dots formed on the calibration plate depending on the environment in which the camera is used, such as the distance from the camera to the workpiece and the temperature at which the camera is used.

[0049] It is preferable for the operator to prepare multiple types of calibration plates that differ in at least one of the dot size and dot spacing. Alternatively, if the robot system is equipped with multiple cameras, the calibration plate may be changed depending on the camera. In this case, it is also preferable for the operator to prepare multiple types of calibration plates.

[0050] The worker selects a calibration plate according to the characteristics of the camera to be used in the current task and the environment in which the camera will be used. When actually calibrating the camera parameters, the control device must identify the type of calibration plate. In particular, the control device must obtain information about the spacing between dots on the calibration plate.

[0051] The image processing unit 51 in this embodiment can identify the type of calibration plate to be used for actual calibration based on the image of the calibration plate captured by the camera 6. The identification unit 57 identifies the type of calibration plate based on the feature portion detected by the feature detection unit 54. The feature portion is formed on the surface of the calibration plate on which a basic figure indicating a predetermined interval is formed. In other words, the feature portion is formed on one surface of the calibration plate together with the basic figure. The feature portion in this embodiment includes a specific mark having a shape different from the coordinate system mark. The identification unit 57 in this embodiment identifies the type of calibration plate based on the position of the specific mark.

[0052] Fig. 4 shows a plan view of a second calibration plate in this embodiment. Fig. 5 shows a plan view of a third calibration plate in this embodiment. A plurality of dots 82a, 83a constituting a basic figure are formed on the second calibration plate 82 and the third calibration plate 83 as well. The interval between the dots 82a on the second calibration plate 82 is 10 mm. The interval between the dots 83a on the third calibration plate 83 is 15 mm.

[0053] Coordinate system marks 82e, 83e including a plurality of dots 82b, 83b are formed on the calibration plates 82, 83, respectively. Furthermore, a specific mark 82f having a shape different from the coordinate system mark 82e is formed on the second calibration plate 82. A specific mark 83f having a shape different from the coordinate system mark 83e is formed on the third calibration plate 83. In this embodiment, the specific marks 82f, 83f are composed of dots 82c, 83c as specific points. The dot 82c is formed to be a different size from the dot 82a. The dot 83c is formed to be a different size from the dot 83a.

[0054] Information about the calibration plates, including the spacing between dots and the positions of the specific marks on the calibration plates 81, 82, and 83, is created in advance and stored in the storage unit 42. The information about the calibration plates may include the positions of the dots.

[0055] 1 and 3, the feature detection unit 54 detects the basic figure dots 81a and the coordinate system mark 81e in the case of the first calibration plate 81. Because no specific marks other than the coordinate system mark 81e are detected, the identification unit 57 identifies this calibration plate as a calibration plate 81 with a dot spacing of 5 mm, based on the information about the calibration plate 81.

[0056] 1 and 4, in the case of the second calibration plate 82, the feature detection unit 54 detects the dots 82a of the basic figure and the coordinate system mark 82e. The feature detection unit 54 detects a specific mark 82f including a plurality of dots 82c by pattern matching. The feature detection unit 54 detects the position of the specific mark 82f in the image using coordinate values ​​of the coordinate system defined by the coordinate system mark 82e. The position of the specific mark 82f can be a predetermined position relative to the two dots 82c. For example, the center of gravity of the two dots 82c (the midpoint between the centers of the dots) can be calculated. Based on the position of the specific mark 82f and information related to the calibration plate 82, the identification unit 57 can determine that the calibration plate 82 has a 10 mm spacing between the dots 82a.

[0057] 1 and 5, in the case of the third calibration plate 83, the image processing unit 51 determines the type of the calibration plate by the same control as that for the second calibration plate 82. The feature detection unit 54 detects the reference figure dot 83a, the coordinate system mark 83e including the dot 83b, and the specific mark 83f including the dot 83c. The feature detection unit 54 calculates the position of the specific mark 83f.

[0058] 4 and the third calibration plate 83 shown in Fig. 5, it can be seen that the position and orientation of the specific mark 82f on the second calibration plate 82 are different from the position and orientation of the specific mark 83f on the third calibration plate 83. Based on the position of the specific mark 83f and the information on the calibration plate 83, the identification unit 57 can determine that the calibration plate 83 has dots 83a spaced 15 mm apart.

[0059] In this way, the identification unit 57 can identify the type of calibration plate based on the position of the identification mark. In particular, the identification unit 57 can identify the calibration plate based on the relative position of the identification mark with respect to the coordinate system mark. Here, the position of the coordinate system mark is not limited to the origin of the coordinates, and the position of any part of the coordinate system mark can be selected. The position of the identification mark can be the position of any part of the identification mark.

[0060] The position of the specific mark may be detected regardless of the position of the coordinate system mark. For example, the type of calibration plate may be identified based on the area in which the specific mark is formed in the basic figure. For example, when the specific mark is formed in a predetermined area below the left side of the basic figure, the identification unit may determine that the calibration plate is a predetermined type. Furthermore, with reference to FIG. 3 , when the specific marks 82f and 83f are not detected, the identification unit may determine that the calibration plate is a calibration plate 81 with a predetermined dot spacing. Alternatively, the identification unit may identify the type of calibration plate based on the distance from a predetermined position of the coordinate system mark to a predetermined position of the specific mark. Alternatively, the identification unit may identify the type of calibration plate based on the relative orientation of the specific mark with respect to the coordinate system mark.

[0061] Furthermore, the specific mark as a characteristic portion may have a different shape from the basic figure and the coordinate system mark. For example, the specific mark 82f shown in FIG. 4 and the specific mark 83f shown in FIG. 5 have different shapes because the spacing between the two dots is different. The specific mark 83f consisting of two dots 83c has a more elongated shape than the specific mark 82f consisting of two dots 82c. After the feature detection unit detects the shape of the specific mark, the identification unit may identify the type of calibration plate based on the shape of the specific mark.

[0062] In this embodiment, the type of calibration plate can be identified by capturing an image of the surface on which the basic figure of the calibration plate is formed. For this reason, the control device can automatically set information about the calibration plate, including the spacing in the basic figure. This eliminates the need for an operator to input information about the calibration plate into a teaching operation panel or the like, improving work efficiency. Alternatively, if the spacing between dots is determined visually, the type of calibration plate may be identified incorrectly. In this embodiment, the type of calibration plate can be identified by image processing, so the type of calibration plate, including the spacing between dots, can be set correctly. As a result, it is possible to prevent erroneous calculation of camera parameters.

[0063] The specific mark in this embodiment has a shape of a line of multiple dots, but is not limited to this. Any specific mark can be used as long as it is distinguishable from the basic figure and the coordinate system mark. For example, the specific mark may have a shape of three or more dots arranged in a straight line. Alternatively, the specific mark may include dots that are different from the dots of the basic figure and the dots of the coordinate system mark. For example, the specific mark may include dots that are different in at least one of size and shape. Alternatively, multiple specific marks may be formed for one reference figure.

[0064] Although the dots in this embodiment are circular, they are not limited to this shape. The dots of the basic figure, the dots of the coordinate system marks, and the dots of the specific marks can be formed in any shape. For example, rectangular dots or triangular dots can be used. In particular, the dots of the specific marks may have a shape different from the dots of the basic figure and the dots of the coordinate system marks. The type of calibration plate may be identified based on the shape of the dots of the specific marks. For example, rectangular dots may be used as the specific marks of the calibration plate in FIG. 4, and triangular dots may be used as the specific marks of the calibration plate in FIG. 5, and the type of each calibration plate may be identified.

[0065] In this embodiment, the robot control device functions as the calibration device, but this is not limiting. The calibration device may be configured as a processing unit separate from the robot control device.

[0066] Second Embodiment A calibration device and a robot system including the calibration device according to a second embodiment will be described with reference to Figures 6 to 13. The overall configuration of the robot system according to this embodiment is the same as that of the first embodiment (see Figures 1 and 2). In this embodiment, the type of calibration plate is identified based on the basic points of the basic graphic of the calibration plate and the comparison points of the comparison mark.

[0067] 6 shows a plan view of a first calibration plate according to this embodiment. Dots 84a are formed on the surface of a first calibration plate 84 as a plurality of basic points constituting a basic figure. A coordinate system mark 84e including dots 84b as coordinate system points is also formed. The dots 84a and 84b are formed so that they are spaced apart at a constant interval of 10 mm.

[0068] A comparison mark having a shape different from that of the basic figure is formed on the surface of the first calibration plate 84 on which the reference figure is formed. A characteristic portion of the calibration plate of this embodiment includes a comparison point of the comparison mark and a basic point of the basic figure. In this embodiment, a coordinate system mark 84e functions as the comparison mark. The coordinate system mark 84e includes a dot 84b as a comparison point. The comparison mark of this embodiment is formed by a plurality of dots 84b.

[0069] The identification unit 57 of this embodiment identifies the type of calibration plate based on the ratio between the size of the dots 84a as base points and the size of the dots 84b as comparison points. Alternatively, the identification unit 57 of this embodiment identifies the type of calibration plate based on the ratio between the size of the dots 84b and the spacing between the dots 84a. For example, the identification unit 57 identifies the calibration plate 84 as one in which the spacing between the dots 84a is 10 mm.

[0070] FIG. 7 shows a plan view illustrating the size of dots and the spacing between dots. Referring to FIGS. 6 and 7, dot 84a, which serves as the basic point of the basic figure, and dot 84b, which serves as the comparison point of the comparison mark, are circular. The diameters of dots 84a and 84b can be used as the sizes of the basic point and the comparison point. For example, the size of dot 84a is diameter D2. Similarly, the size of dot 84b is diameter D1. Furthermore, the spacing between dots corresponds to spacing D3, which is the distance between the centers of dots 84a and 84b.

[0071] 2 and 6, the feature detection unit 54 identifies the dots 84a and 84b and detects their respective diameters D1 and D2. At this time, predetermined values ​​can be used as the camera parameters. Since the camera parameters are provisional values, the detected values ​​may contain errors. The feature detection unit 54 calculates the ratio A (A=D1 / D2) between the diameter D2 of the dot 84a and the diameter D1 of the dot 84b. If the ratio A of the dot diameters is within a predetermined determination range, the identification unit 57 determines that the calibration plate 84 has a 10 mm interval between the dots 84a and 84b.

[0072] Here, multiple dots 84a and multiple dots 84b are formed, and the diameter of the dots 84a and 84b used for the judgment can be the average value of the multiple dots. Alternatively, it may be judged whether the ratio of all combinations of dots 84a and 84b is within the judgment range.

[0073] Alternatively, the identification unit 57 can determine the type of calibration plate based on the ratio B (B=D3 / D1) of the diameter D1 of the dot 84b serving as the comparison point to the spacing D3 between the dots. The feature detection unit 54 identifies the dots 84a and 85a and detects the diameter of each dot and the spacing between the dots. At this time, predetermined values ​​are used as the camera parameters. The feature detection unit 54 then calculates the ratio B. If the ratio B is within a predetermined determination range, the identification unit 57 can determine that the calibration plate 84 has a spacing of 10 mm between the dots 84a and 84b.

[0074] Here, the spacing between dots can be the average value of multiple spacings between dots, or it may be determined whether all combinations of the spacing between dots 84a and 84b and the diameter of dot 84b are within the determination range.

[0075] 8 shows a plan view of the second calibration plate in this embodiment. Dots 85a and 85b are formed on the second calibration plate 85 so that the dot spacing is 15 mm. The second calibration plate 85 has dots 85a as basic points of the basic figure and coordinate system marks 85e as comparison marks. The coordinate system marks 85e include dots 85b as comparison points.

[0076] 9 shows a plan view of a third calibration plate 86 according to this embodiment. On the third calibration plate 86, dots 86a and 86b are formed so that the dot spacing is 30 mm. On the third calibration plate 86, dots 86a are formed as basic points of the basic figure, and coordinate system marks 86e are formed as comparison marks. The coordinate system marks 86e include dots 86b as comparison points.

[0077] 6 to 9, the type of calibration plate can also be determined for the second calibration plate 85 and the third calibration plate 86 by the same control as for the first calibration plate 84. The ratio A between the diameter of the basic point and the diameter of the comparison point, and the ratio B between the diameter of the comparison point and the spacing between the basic points for each of the calibration plates 84, 85, and 86 are shown in Table 1 below. Table 1 shows the actual values ​​for the diameter of the dots and the spacing between the dots for each of the calibration plates 84, 85, and 86.

[0078]

[0079] The determination ranges for the dot ratios A and B shown in Table 1 can be stored in advance in the storage unit 42 as information relating to the respective calibration plates 84, 85, and 86. The determination ranges for the ratios of each calibration plate can be set to have a predetermined width for the ratios A and B shown in Table 1. Furthermore, the determination ranges for the ratios can be set so that they do not overlap among multiple calibration plates. The relationship between the determination ranges for the ratios and the types of calibration plates is created in advance and stored in the storage unit 42.

[0080] The calibration device of this embodiment detects the sizes of the base points and the comparison points, and can determine the type of calibration plate based on the ratios A and B associated with these dots. By making the determination based on the ratios of dimensions associated with the dots, it is possible to identify the type of calibration plate with high accuracy even if the detected dimensions, such as the diameter, contain errors.

[0081] FIG. 10 shows an example of an image of the calibration plate identified by the identification unit. The display unit 28 of the teaching pendant 26 can display an image 97. The image 97 includes an image 98 of a plan view of the identified calibration plate and an image 99 showing the spacing between dots on the calibration plate. In this example, a calibration plate with a dot spacing of 30 mm is detected. The operator can confirm the detection result and calibrate the camera parameters. Alternatively, the operator can confirm the detection result and replace the calibration plate.

[0082] If the ratio A or ratio B for the dots falls outside the determination range, control can be implemented to notify the operator. For example, the identification unit 57 can display an alarm on the display unit 28. It can display a message that the calibration plate imaged in the current calibration work is not the calibration plate stored in the memory unit 42. The display unit 28 can also display a screen for selecting whether or not to proceed with the calibration of the camera parameters. If the operator selects the button to proceed with the calibration of the camera parameters, the calibration of the camera parameters can be carried out. If the operator selects the button to cancel the calibration of the camera parameters, the calibration of the camera parameters can be canceled.

[0083] Fig. 11 shows a plan view of a fourth calibration plate in this embodiment. Fig. 12 shows a plan view of a fifth calibration plate in this embodiment. Fig. 13 shows a plan view of a sixth calibration plate in this embodiment. With reference to Figs. 11 to 13, the dot intervals on the fourth calibration plate 87, the fifth calibration plate 88, and the sixth calibration plate 89 are each 10 mm.

[0084] However, the dots 87a, 88a, and 89a included in the basic figure and the dots 87b, 88b, and 89b included in the coordinate system marks 87e, 88e, and 89e are of different sizes. In this example, the dot 88a on the fifth calibration plate 88 is smaller than the dot 87a on the fourth calibration plate 87. The dot 89b on the sixth calibration plate 89 is larger than the dot 87b on the fourth calibration plate 87.

[0085] In this way, multiple calibration plates with the same dot spacing but different dot sizes may be prepared. Even in this case, the identification unit can determine which calibration plate is which based on the ratio between the dot sizes included in the basic figure and the coordinate system mark. Alternatively, multiple types of calibration plates may have the same dot size but different dot spacing.

[0086] In this embodiment, a coordinate system mark is used as the comparison mark, but this is not limiting. Any mark having a shape different from the basic figure can be used as the comparison mark. Also, any mark including a dot having a size different from the dots included in the basic figure can be used. For example, the specific mark in the first embodiment may be used as the comparison mark.

[0087] Although the base points and comparison points in this embodiment have a circular shape, the shape is not limited to this. The base points and comparison points can have any shape. In this case, the size of the base points and the size of the comparison points can be determined by the dimensions of predetermined portions. For example, if the base points are rectangular, the length of the diagonal can be detected as the size of the base points. Furthermore, the distance between predetermined points on the base points can be used as the spacing between the base points. For example, if the base points are rectangular, the distance between the positions of the centers of gravity can be used as the spacing between the base points.

[0088] The other configurations, operations, and effects are the same as those of the first embodiment, and therefore will not be described repeatedly here.

[0089] 14 to 17, a calibration device and a robot system including the calibration device according to a third embodiment will be described. The configuration of the robot system according to this embodiment is similar to that of the robot system according to the first embodiment (see FIGS. 1 and 2). The basic shape of the calibration plate according to this embodiment includes a lattice-like shape.

[0090] 14 shows a plan view of the first calibration plate 91 of this embodiment. The basic figure of the first calibration plate 91 of this embodiment is configured in a checkerboard pattern. The basic figure includes a plurality of rectangular figures 91a and 91b. Figure 91a is a figure consisting of lines only. Figure 91b is a solid figure. Each of figures 91a and 91b has the same shape and the same size.

[0091] A characteristic portion of the calibration plate of this embodiment includes rectangular figures 91a and 91b. Each of the figures 91a and 91b has a horizontal length W and a vertical length H. The horizontal length W and vertical length H of the figure 91a of the first calibration plate 91 are the same. That is, the ratio C (C = H / W) of the horizontal length W to the vertical length H of the figures 91a and 91b is 1. For example, the horizontal length W and vertical length H are each 10 mm.

[0092] A coordinate system mark 91e including a plurality of dots 91c is formed on the surface on which the basic figure is formed. The feature detection unit 54 detects the respective figures 91a and 91b by a pattern matching method based on template images of the quadrangular figures 91a and 91b.

[0093] In the basic figure, the corners of each of the figures 91a and 91b are positions at which the intervals for calibrating the camera parameters are detected. That is, the corners of the figures 91a and 91b correspond to the positions of the dots of the basic figure in the first embodiment. The parameter setting unit 58 can set the camera parameters based on the intervals between the corners of each of the figures 91a and 91b.

[0094] 15 shows a plan view of the second calibration plate in this embodiment. The basic figure of the second calibration plate 92 includes rectangular figures 92a and 92b. A coordinate system mark 92e including a dot 92c is formed on the second calibration plate 92. Each of the rectangular figures 92a and 92b is formed so that its horizontal length W is longer than its vertical length H. In this example, the ratio C (C = H / W) of the horizontal length W to the vertical length H is (1 / 1.5). In this example, the horizontal length W is 15 mm, and the vertical length H is 10 mm.

[0095] 16 shows a plan view of a third calibration plate according to this embodiment. The third calibration plate 93 includes basic rectangular figures 93a and 93b and a coordinate system mark 93e having a dot 93c. In the third calibration plate 93, the rectangular figures 93a and 93b are formed so that their horizontal lengths W are shorter than their vertical lengths H. That is, the ratio C (C = H / W) of the horizontal length W to the vertical length H is 1.5 / 1. In this example, the horizontal length W is 10 mm and the vertical length H is 15 mm.

[0096] In this way, the ratio C of the horizontal length W to the vertical length H differs between the first calibration plate 91, the second calibration plate 92, and the third calibration plate 93. The horizontal length W and the vertical length H of each of the calibration plates 91, 92, and 93 are measured in advance and stored in the memory unit 42.

[0097] The feature detection unit 54 identifies the rectangular shapes 91a to 93a and 91b to 93b by pattern matching based on the images of the calibration plates 91, 92, and 93. The feature detection unit 54 detects the ratio C of the width W to the height H. The determination range of the ratio C for each of the calibration plates 91, 92, and 93 is determined in advance and stored in the storage unit 42.

[0098] As in the second embodiment, the identification unit 57 can identify the type of calibration plate based on whether the calculated ratio C is within the determination range. The parameter setting unit 58 can acquire the vertical length and horizontal length of the rectangular shape from the storage unit and calibrate the camera parameters.

[0099] In the first calibration plate 91 to the third calibration plate 93, the ratio C is greater than or less than 1, but is not limited to this. The identification unit can identify the type of calibration plate based on an arbitrary ratio C. For example, a calibration plate with a ratio C of (1 / 1), a calibration plate with a ratio C of (2 / 1), and a calibration plate with a ratio C of (3 / 1) are prepared. Then, the identification unit may identify the type of calibration plate based on the ratio C detected by the feature detection unit.

[0100] In this embodiment, the type of calibration plate is determined based on the ratio of the vertical length to the horizontal length of the rectangular shape and the determination range of the ratio stored in the memory unit, so the actual vertical length and horizontal length of the rectangular shape can be any length.

[0101] 17 shows a plan view of a fourth calibration plate according to the present embodiment. In the first to third calibration plates 91 to 93, the basic figures are configured as checkerboard patterns in which a part of a rectangular figure is filled in, but the present invention is not limited to this form.

[0102] A fourth calibration plate 94 of this embodiment has a basic figure including a quadrilateral figure 94a and a coordinate system mark 94e including dots 94c formed thereon. In the fourth calibration plate 94, the basic figure is composed entirely of quadrilateral figures 94a consisting of lines. Even with such a grid pattern basic figure, the type of calibration plate can be identified based on the ratio C of the horizontal length W to the vertical length H of the quadrilateral figure 94a.

[0103] The other configurations, operations, and effects are similar to those of the first and second embodiments, and therefore will not be described repeatedly here.

[0104] (Fourth embodiment) A calibration device and a robot system including the calibration device according to the fourth embodiment will be described with reference to FIG. 18 . In this embodiment, a colored feature portion is formed on the surface of a calibration plate. An image processing unit 51 identifies the type of calibration plate based on the color of the colored portion. The camera of the robot system according to this embodiment is a color camera that captures color images. The feature detection unit is configured to be able to distinguish the color of an object in the image. The rest of the configuration of the robot system is the same as that of the robot system according to the first embodiment (see FIGS. 1 and 2 ).

[0105] 18 shows a plan view of a calibration plate according to this embodiment. Basic figure dots 95a and coordinate system mark dots 95b are formed on a calibration plate 95 according to this embodiment. The calibration plate 95 according to this embodiment has a colored feature portion on at least a portion of the surface on which the basic figures are formed. In this example, the entire surface on which the basic figures are formed is colored.

[0106] In this embodiment, colors are determined according to the multiple types of calibration plates. For example, in a calibration plate in which the distance between the dots 95a and 95b is 10 mm, the surface is colored red. In a calibration plate in which the distance between the dots 95a and 95b is 15 mm, the surface is colored yellow. In a calibration plate in which the distance between the dots 95a and 95b is 30 mm, the distance between the dots is colored red. In this way, colors are determined according to the distance between each dot. The relationship between the color of the characteristic portion and the distance between the dots is determined in advance. The relationship between the color of the characteristic portion and the distance between the dots is stored in the memory unit 42 as information related to the calibration plate.

[0107] The feature detection unit 54 detects colored portions in an image of the calibration plate by pattern matching. The feature detection unit 54 detects the color of the characteristic portion. The identification unit 57 identifies the type of the calibration plate based on the color of the characteristic portion. The parameter setting unit 58 can set camera parameters based on information about the calibration plate identified by the identification unit 57.

[0108] In this embodiment, the type of calibration plate can be identified by the simple configuration in which at least a portion of the calibration plate is colored.

[0109] In this embodiment, the entire surface of the calibration plate is colored, but this is not limiting. A colored feature can be formed on at least a portion of the surface imaged by the camera. The colored feature can have any shape. For example, a rectangular colored feature can be formed outside the basic shape.

[0110] The other configurations, operations, and effects are the same as those of the first to third embodiments, and therefore will not be described repeatedly here.

[0111] The calibration device according to at least one embodiment described above can identify the type of calibration plate based on an image captured by a camera.

[0112] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0113] The following supplementary notes are disclosed regarding the above-described embodiment and modifications.

[0114] (Supplementary Note 1) A calibration device that calibrates camera parameters for detecting the position of an object from an image captured by a camera, the calibration device comprising: a feature detection unit that detects characteristic parts of a calibration plate in an image captured of the calibration plate; an identification unit that identifies the type of calibration plate captured by the camera from multiple types of calibration plates; and a parameter setting unit that sets camera parameters based on information about the calibration plate identified by the identification unit, wherein the characteristic parts are formed on the surface of the calibration plate together with a basic figure that indicates a predetermined interval, and the identification unit identifies the type of calibration plate based on the characteristic parts detected by the feature detection unit.

[0115] (Supplementary Note 2) A calibration device as described in Supplementary Note 1, wherein the characteristic portion includes a specific mark having a shape different from the coordinate system marks indicating the basic figure and the coordinate axes, the characteristic detection unit detects the position of the specific mark, and the identification unit identifies the type of calibration plate based on the position of the specific mark.

[0116] (Supplementary Note 3) The calibration device according to Supplementary Note 2, wherein the feature detection unit detects the position of the coordinate system mark, and the identification unit identifies the type of the calibration plate based on the relative position of the identification mark with respect to the coordinate system mark.

[0117] (Supplementary Note 4) A calibration device as described in Supplementary Note 1, wherein the characteristic portion includes a specific mark having a shape different from the coordinate system marks indicating the basic figure and the coordinate axes, the characteristic detection unit detects the shape of the specific mark, and the identification unit identifies the type of calibration plate based on the shape of the specific mark.

[0118] (Appendix 5) A calibration device as described in Appendix 1, wherein the characteristic portion includes a comparison mark having a shape different from the basic figure, the basic figure includes a plurality of basic points, the comparison mark includes a comparison point, and the identification unit identifies the type of calibration plate based on the ratio between the size of the basic point and the size of the comparison point, or the ratio between the size of the comparison point and the spacing between the basic points.

[0119] (Supplementary Note 6) The calibration device according to Supplementary Note 5, wherein the comparison mark is a coordinate system mark indicating an origin and coordinate axes in a basic figure.

[0120] (Supplementary Note 7) A calibration device according to Supplementary Note 5 or 6, wherein the base points and comparison points have a circular shape, and the identification unit identifies the type of calibration plate based on the ratio between the diameter of the base points and the diameter of the comparison points, or the ratio between the diameter of the comparison points and the spacing between the base points.

[0121] (Supplementary Note 8) The calibration device according to Supplementary Note 1, wherein the basic figure includes a grid-like figure, and the characteristic portion includes a quadrilateral figure included in the grid-like figure.

[0122] (Supplementary Note 9) The calibration device according to Supplementary Note 8, wherein the identification unit identifies the type of the calibration plate based on the ratio of the horizontal length to the vertical length of the rectangular shape.

[0123] (Supplementary Note 10) The calibration device according to Supplementary Note 1, wherein the characteristic portion includes a colored portion on at least a part of the surface on which the basic figure is formed, and the identification unit identifies the type of calibration plate based on the color of the characteristic portion.

[0124] 2 Control device 6 Camera 28 Display unit 40 Control device main body 42 Memory unit 51 Image processing unit 54 Feature detection unit 57 Identification unit 58 Parameter setting unit 62 Camera parameters 80 to 89, 91 to 95 Calibration plate 81a, 82a, 83a Dots 81b, 82b, 83b Dots 82c, 83c Dots 81e, 82e, 83e Coordinate system marks 82f, 83f Identification marks 84a, 85a, 86a, 87a, 88a, 89a Dots 84b, 85b, 86b, 87b, 88b, 89b Dots 84e, 85e, 86e, 87e, 88e, 89e Coordinate system marks 91a, 92a, 93a, 94a Figures 91b, 92b, 93b Figures

Claims

1. A calibration device for calibrating camera parameters for detecting the position of an object from an image captured by a camera, comprising: a feature detection unit that detects a feature portion of a calibration plate in an image of the calibration plate; a specifying unit that specifies the type of the calibration plate captured by the camera from a plurality of types of calibration plates; and a parameter setting unit that sets camera parameters based on information regarding the calibration plate specified by the specifying unit, wherein the feature portion is formed on the surface of the calibration plate together with a basic figure indicating a predetermined interval, and the specifying unit specifies the type of the calibration plate based on the feature portion detected by the feature detection unit.

2. The calibration device according to claim 1, wherein the feature portion includes a specific mark having a shape different from that of the basic figure and a coordinate system mark indicating a coordinate axis, the feature detection unit detects the position of the specific mark, and the specifying unit specifies the type of the calibration plate based on the position of the specific mark.

3. The calibration device according to claim 2, wherein the feature detection unit detects the position of the coordinate system mark, and the specifying unit specifies the type of the calibration plate based on the relative position of the specific mark with respect to the coordinate system mark.

4. The calibration device according to claim 1, wherein the feature portion includes a specific mark having a shape different from that of the basic figure and a coordinate system mark indicating a coordinate axis, the feature detection unit detects the shape of the specific mark, and the specifying unit specifies the type of the calibration plate based on the shape of the specific mark.

5. The calibration device according to claim 1, wherein the feature portion includes a comparison mark having a shape different from that of the basic figure, the basic figure includes a plurality of basic points, the comparison mark includes a comparison point, and the specifying unit specifies the type of the calibration plate based on a ratio between the size of the basic point and the size of the comparison point, or a ratio between the size of the comparison point and the interval between the basic points.

6. The calibration device according to claim 5, wherein the comparison mark is a coordinate system mark indicating an origin and a coordinate axis in the basic figure.

7. The calibration device according to claim 5 or 6, wherein the basic point and the comparison point have a circular shape, and the specifying unit specifies the type of the calibration plate based on a ratio between the diameter of the basic point and the diameter of the comparison point, or a ratio between the diameter of the comparison point and the interval between the basic points.

8. The calibration device according to claim 1, wherein the basic figure includes a grid-shaped figure, and the characteristic part includes a quadrangular figure included in the grid-shaped figure.

9. The calibration device according to claim 8, wherein the specific part specifies the type of calibration plate based on the ratio of the horizontal length to the vertical length of the quadrangular figure.

10. The calibration device according to claim 1, wherein the characteristic part includes a part colored on at least a part of the surface on which the basic figure is formed, and the specific part specifies the type of calibration plate based on the color of the characteristic part.

Images