Automatic calibration equipment and calibration system

Abstract

The present application provides an automatic calibration device and a calibration system, which includes a cabinet, a bracket and a robotic arm. A clarity detection plate and a calibration rod are placed on the upper surface of the cabinet; the bracket is fixedly connected to the cabinet and is arranged at the first end of the upper surface of the cabinet, and is used to place a terminal with a camera; the robotic arm is used to: pick up the clarity detection plate through a pick-and-place element and move it to a first preset position, so that the terminal with a camera can detect whether the image is clear; and, after the clarity detection is completed, move to a second preset position and place the clarity detection plate through a pick-and-place element; the robotic arm is also used to: pick up the calibration rod through a pick-and-place element and perform a preset wave, so that the terminal with a camera can perform camera calibration; and, after the camera calibration is completed, move to a third preset position and place the calibration rod through a pick-and-place element. It can be seen that the present application waves the calibration rod in an automated manner to assist in completing camera calibration, thereby solving the problems existing in traditional technologies.

Description

Technical Field

[0001] The present application relates to the technical field of camera calibration, and in particular to an automatic calibration device and a calibration system. Background Art

[0002] In an optical motion capture system, there is a certain relationship between the three-dimensional position of an object in real space and the two-dimensional position obtained by camera imaging, so a geometric model between the two can be established; and by migrating the relevant parameters in the geometric model to the camera, the three-dimensional position of the object can be associated with the two-dimensional position in the camera. In a multi-camera system, the accuracy of the intrinsic and extrinsic parameters of each camera will directly affect the accuracy of the entire system in capturing objects in real space. Therefore, before the optical motion capture system is operated, it is necessary to determine the status of all cameras themselves and the relative positional relationship between different cameras. This step is camera calibration.

[0003] In traditional technology, camera calibration can be completed with the help of a calibration rod. Specifically, the camera can be fixed first, and then the calibration rod can be manually waved within the effective viewing angle of the camera. During this process, the camera will take multiple images, and the camera calibration is completed based on these images. It can be seen that the quality of camera calibration is affected by multiple images, but this method of manually waving the calibration rod is difficult to ensure the quality of multiple images taken by the camera, which in turn affects the quality of camera calibration. Utility Model Content

[0004] Based on this, the present application provides an automatic calibration device and a calibration system, which swings a calibration rod in an automated manner to assist in completing camera calibration.

[0005] In a first aspect, the present application provides an automatic calibration device, comprising:

[0006] A cabinet, a clarity detection plate and a calibration rod are placed on the upper surface of the cabinet;

[0007] a bracket, fixedly connected to the cabinet and disposed at a first end of an upper surface of the cabinet; the bracket is used to place a terminal with a camera; and

[0008] A mechanical arm, the mechanical arm is mounted on the upper surface of the cabinet and is arranged at a second end opposite to the first end of the upper surface, and an operating end of the mechanical arm is provided with a pick-and-place element; the pick-and-place element is used to pick up and place the clarity detection plate or the calibration rod, and the mechanical arm can move in position and rotate in angle relative to the terminal with a camera;

[0009] The robot arm is used to: pick up the clarity detection plate through the pick-and-place element and move it to a first preset position so that the terminal with a camera can detect whether the image is clear; and after the clarity detection is completed, move to a second preset position and place the clarity detection plate through the pick-and-place element;

[0010] The robotic arm is also used to: pick up the calibration rod through the pick-and-place element and perform a preset wave so that the terminal with a camera can perform camera calibration; and after completing the camera calibration, move to a third preset position and place the calibration rod through the pick-and-place element.

[0011] In the automatic calibration device provided in the present application, the picked-up surface of the clarity detection plate and the picked-up surface of the calibration rod are smooth planes;

[0012] The pick-and-place element comprises a first suction cup, the diameter of which is smaller than the width of the picked-up surface of the clarity detection plate and the width of the picked-up surface of the calibration rod;

[0013] The automatic calibration device also includes a first vacuum generator, which is connected to the first air hole of the first suction cup.

[0014] In the automatic calibration device provided in the present application, the pick-and-place element further comprises a second suction cup nested in the first suction cup, and the diameter of the second suction cup is smaller than the diameter of the first suction cup;

[0015] The first vacuum generator is also connected to the second air hole of the second suction cup; or, the automatic calibration device also includes a second vacuum generator, and the second vacuum generator is connected to the second air hole of the second suction cup.

[0016] In the automatic calibration device provided in the present application, the height of the second suction cup is smaller than the height of the first suction cup.

[0017] In the automatic calibration device provided in the present application, when the automatic calibration device further includes a second vacuum generator,

[0018] The first vacuum generator and the second vacuum generator are used to operate when the first suction cup contacts the picked-up surface of the clarity detection plate or the picked-up surface of the calibration rod, and to stop operating when the first suction cup and the second suction cup both suck the clarity detection plate or the calibration rod.

[0019] In the automatic calibration device provided in the present application, the first suction cup and the second suction cup are integrally formed.

[0020] In the automatic calibration device provided in the present application, the number of the second suction cups is 2; and / or the diameter of the first suction cup is less than or equal to 22 mm and greater than or equal to 20 mm, and the diameter of the second suction cup is less than or equal to 6 mm and greater than or equal to 5 mm.

[0021] In a second aspect, the present application provides a calibration system, comprising an automatic calibration device as described in any one of the first aspects.

[0022] Based on the above technical solution, the robot arm can not only pick up the clarity detection plate through the pick-and-place component and move it to the first preset position so that the terminal with the camera can detect whether the image is clear, and after the clarity detection is completed, move to the second preset position and place the clarity detection plate through the pick-and-place component; it can also pick up the calibration rod through the pick-and-place component and perform a preset wave so that the terminal with the camera can perform camera calibration, and after the camera calibration is completed, move to the third preset position and place the calibration rod through the pick-and-place component. Therefore, the present application swings the calibration rod in an automated manner to assist in completing the camera calibration, thus solving the problems existing in the traditional technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A schematic diagram of the structure of an automatic calibration device provided in an embodiment of the present application;

[0025] Figure 2 It is a schematic diagram of the structure of the pick-and-place component in an embodiment of the present application at a viewing angle;

[0026] Figure 3 A schematic diagram of the structure of the pick-and-place component in another perspective in an embodiment of the present application;

[0027] Figure 4 This is a schematic diagram of the structure in which the first suction cup and the second suction cup share a vacuum generator in an embodiment of the present application;

[0028] Figure 5 This is a schematic diagram of the structure in which the first suction cup and the second suction cup each have their own vacuum generator in the embodiment of the present application. DETAILED DESCRIPTION

[0029] In traditional technology, camera calibration can be completed with the help of a calibration rod. Specifically, the camera can be fixed first, and then the calibration rod can be manually waved within the effective viewing angle of the camera. During this process, the camera will take multiple images, and the camera calibration will be completed based on these images. It can be seen that the quality of camera calibration is affected by multiple images, but this method of manually waving the calibration rod is difficult to ensure the quality of multiple images taken by the camera, which in turn affects the quality of camera calibration. For example, in the process of manual waving, there is a situation where the calibration rod is swung outside the effective viewing angle of the camera, causing the camera to fail to capture the complete calibration rod, and then the quality of camera calibration is affected by such images during the calibration process. For another example, in the process of manual waving, there is a situation where the waving speed is too fast, causing the image taken by the camera to be blurred or have afterimages, etc., and then the quality of camera calibration is affected by such images during the calibration process.

[0030] To this end, an embodiment of the present application provides an automatic calibration device that swings a calibration rod in an automated manner to assist in completing camera calibration. In addition, an embodiment of the present application also provides a calibration system using the automatic calibration device.

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] The present application provides an automatic calibration device 100, see Figures 1 to 5 , may include a cabinet 110 , a bracket 120 and a robotic arm 130 .

[0033] The cabinet 110 can be understood as a box, in which several components required for the automatic calibration device 100 can be placed, such as a device power supply, a communication module, a driver for driving the mechanical arm 130 to rotate and move, a controller, etc. In addition, in the embodiment of the present application, a clarity detection board 111 and a calibration rod 112 are also placed on the upper surface of the cabinet 110. The clarity detection board 111 is a board that assists in detecting whether the camera imaging is clear. For example, a preset pattern feature is provided on the clarity detection board 111. The calibration system determines whether the camera imaging is clear based on whether the camera can recognize the preset pattern feature. For example, the clarity detection board 111 can be provided with a pattern of the English letters "clear". If "clear" can be recognized in the camera imaging, it can be determined that the camera imaging is clear. The calibration rod 112 is used to assist the camera calibration as described in the background technology. It should be noted that the calibration rod 112 is not limited in the embodiment of the present application. In some embodiments, the upper surface of the cabinet 110 can be recessed inward to form a placement portion to place the clarity detection board 111 and the calibration rod 112. Exemplarily, the upper surface of the cabinet 110 can be recessed inward to form two placement portions, wherein the shape and size of one placement portion is adapted to the clarity detection board 111 for placing the clarity detection board 111; and the shape and size of the other placement portion is adapted to the calibration rod 112 for placing the calibration rod 112.

[0034] The bracket 120 is fixedly connected to the cabinet 110 and is disposed at a first end of the upper surface of the cabinet 110. For example, the bracket 120 is fixedly connected to the upper surface of the cabinet 110 by means of screws or the like. In the embodiment of the present application, the bracket 120 is used to place a terminal with a camera. It can be understood that the camera on the terminal is the camera that needs to be calibrated. Of course, the number of cameras on the terminal can be one or more. It should be noted that the embodiment of the present application does not limit the bracket 120, as long as it can support the terminal with a camera to perform camera calibration.

[0035] The mechanical arm 130 is mounted on the upper surface of the cabinet 110 and is arranged at the second end opposite to the first end of the upper surface of the cabinet 110, that is, it is arranged opposite to the bracket 120, so it can be understood that it is arranged opposite to the terminal with a camera, and further it can be understood that the mechanical arm 130 is arranged within the effective viewing angle of the camera. The operating end of the mechanical arm 130 is provided with a pick-up and place element 140, and the pick-up and place element 140 is used to pick up and place the clarity detection plate 111 or the calibration rod 112, that is, the pick-up and place element 140 can pick up the clarity detection plate 111 or the calibration rod 112, and can also place the clarity detection plate 111 or the calibration rod 112. Among them, the mechanical arm 130 can move the position and rotate the angle relative to the terminal with a camera, so when the clarity detection plate 111 or the calibration rod 112 is picked up, it can move the position and rotate the angle relative to the camera under the operation of the mechanical arm 130. It should be noted that the robotic arm 130 is already a prior art, and the embodiment of the present application does not limit its specific structure. For example, the robotic arm 130 may include multiple joints hinged at the head and tail, and each joint is movable.

[0036] Based on this, the robot 130 is used to: pick up the clarity detection plate 111 through the pick-and-place element 140 and move it to the first preset position so that the terminal with the camera can detect whether the image is clear; and, after the clarity detection is completed, move to the second preset position and place the clarity detection plate 111 through the pick-and-place element 140. The robot 130 is also used to: pick up the calibration rod 112 through the pick-and-place element 140 and perform a preset wave so that the terminal with the camera can perform camera calibration; and, after the camera calibration is completed, move to the third preset position and place the calibration rod 112 through the pick-and-place element 140.

[0037] Exemplarily, when a terminal with a camera is installed on the bracket 120, the calibration system can perform camera calibration. The control of the automatic calibration device 100 can be implemented by a controller with higher control authority in the calibration system. This example takes the cloud server as an example, but is not limited to this. First, the cloud server can send a clarity detection instruction to the automatic calibration device 100, instructing the automatic calibration device 100 to control the robot 130, so that the robot 130 picks up the clarity detection plate 111 through the pick-and-place element 140 and moves to the first preset position, and then the terminal with a camera can detect whether the camera imaging is clear. After completing the clarity detection, the cloud server can send instructions to the automatic calibration device 100 again, instructing the automatic calibration device 100 to control the robot 130 again, so that the robot 300 moves to the second preset position (that is, the position where the clarity detection plate 111 was originally placed) and places the clarity detection plate 111 through the pick-and-place element 140. It is understandable that if the image is not clear, there is no need to perform camera calibration; but if the image is clear, camera calibration is still required. Therefore, the embodiment of the present application can avoid unnecessary camera calibration operations and improve reliability. When the image is clear, the cloud server can send a camera calibration instruction to the automatic calibration device 100, instructing the automatic calibration device 100 to control the mechanical arm 130, so that the mechanical arm 130 picks up the calibration rod 112 through the pick-and-place element 140 and performs a preset swing. During the swinging process, the camera can take pictures multiple times, and calibrate after obtaining multiple images. It is understandable that since the bracket 120 and the mechanical arm 130 are at opposite ends of the upper surface of the cabinet 110, that is, the mechanical arm 130 is within the effective viewing angle of the camera, the calibration rod 112 is under the control of the mechanical arm 130. When the preset swing is performed, the problems in the traditional technology can be avoided. Therefore, the embodiment of the present application swings the calibration rod 112 in an automated manner to assist in completing the camera calibration, which is more reliable than the traditional technology. Finally, after completing the camera calibration, the cloud server can send instructions to the automatic calibration device 100 again, instructing the automatic calibration device 100 to control the robotic arm 130 again, so that the robotic arm 130 moves to the third preset position (that is, the position where the calibration rod 112 was originally placed) and places the calibration rod 112 through the pick-and-place element 140.

[0038] In some embodiments, the picked-up surface of the clarity detection plate 111 and the picked-up surface of the calibration rod 112 are smooth planes. The smooth plane mentioned here should be understood in a broad sense. As long as a plane can meet the condition of being sucked by the suction cup, it is a smooth plane. Figures 2 to 5 The pick-and-place element 140 may include a first suction cup 141 , and a diameter of the first suction cup 141 is smaller than a width of a picked-up surface of the clarity detection plate 111 and a width of a picked-up surface of the calibration rod 112 to ensure that the first suction cup 141 can suck the clarity detection plate 111 or the calibration rod 112 .

[0039] Based on this, the automatic calibration device 100 may also include a first vacuum generator 150, and the first vacuum generator 150 is connected to the first air hole 1411 of the first suction cup 141. Exemplarily, the first vacuum generator 150 may be disposed in the cabinet 110. Exemplarily, the air pipe between the two may be disposed inside the robot arm body, or may be disposed in other ways, which is not limited in the embodiments of the present application. Specifically, the first vacuum generator 150 acts on the first suction cup 141 to form a vacuum in the disk or destroy the vacuum in the disk. It should be noted that the vacuum generator is already a prior art, and the embodiments of the present application do not limit this. Therefore, the embodiments of the present application can complete the picking and placement of the clarity detection plate 111 or the calibration rod 112 through the first suction cup 141. Exemplarily, when the first suction cup 141 contacts the picked-up surface of the clarity detection plate 111 or the picked-up surface of the calibration rod 112, the first vacuum generator 150 can be operated to extract the air in the first suction cup 141 to form a vacuum condition, so that the first suction cup 141 sucks the clarity detection plate 111 or the calibration rod 112 to complete the picking; on the contrary, when the robotic arm 130 moves the clarity detection plate 111 to the second preset position or moves the calibration rod 112 to the third preset position, the first vacuum generator 150 can stop operating to destroy the vacuum in the first suction cup 141, so that the first suction cup 141 no longer sucks the clarity detection plate 111 or the calibration rod 112 to complete the placement.

[0040] In some embodiments, Figure 2 As shown, the pick-and-place element 140 may further include a second suction cup 142 nested in the first suction cup 141, and the diameter of the second suction cup 142 is smaller than the diameter of the first suction cup 141, that is, the second suction cup 142 is a small suction cup arranged in the first suction cup 141. Exemplarily, the height of the second suction cup 142 is smaller than the height of the first suction cup 141, for example, the height of the second suction cup 142 is slightly lower than the first suction cup 141; of course, the height of the second suction cup 142 and the height of the first suction cup 141 may be set at the same height, or the height of the second suction cup 142 may be greater than the height of the first suction cup 141, for example, the height of the second suction cup 142 is slightly higher than the first suction cup 141.

[0041] In one embodiment, if Figure 4 As shown, the first vacuum generator 150 is also connected to the second air hole 1421 of the second suction cup 141, that is, the first suction cup 141 and the second suction cup 142 share the same vacuum generator. Figure 5 As shown, the automatic calibration device 100 may further include a second vacuum generator 160 , which is connected to the second air hole 1421 of the second suction cup 141 , that is, the first suction cup 141 and the second suction cup 142 each have their own vacuum generator.

[0042] In the embodiment of the present application, after the pick-and-place component 140 picks up the calibration rod 112, the mechanical arm 130 will drive the calibration rod 112 to swing in a preset manner. Therefore, in order to enhance the picking strength of the pick-and-place component 140 and prevent the calibration rod 112 from falling off due to air leakage in the first suction cup 141 caused by the swinging, the embodiment of the present application nests the second suction cup 142 in the first suction cup 141. Therefore, the pick-and-place component 140 picks up the clarity detection plate 111 and the calibration rod 112 by sucking the first suction cup 141 and the second suction cup 142 together to the picked-up surfaces of the two. In this way, the use of this nested suction cup method can not only enhance the adsorption strength, but also, during the swinging process of the calibration rod 112, if the first suction cup 141 leaks, the second suction cup 142 can suck the calibration rod 112 to prevent the calibration rod 112 from falling off. Therefore, the embodiment of the present application can enhance the picking strength of the pick-and-place component 140 and improve reliability.

[0043] Exemplarily, in the case where the first suction cup 141 and the second suction cup 142 share the same vacuum generator, when the first suction cup 141 and / or the second suction cup 142 contacts the picked-up surface of the clarity detection plate 111 or the picked-up surface of the calibration rod 112, the first vacuum generator 150 can be operated to extract the air in the two suction cups to form a vacuum condition, so that the first suction cup 141 and the second suction cup 142 suck the clarity detection plate 111 or the calibration rod 112 to complete the picking; on the contrary, when the robotic arm 130 moves the clarity detection plate 111 to the second preset position or moves the calibration rod 112 to the third preset position, the first vacuum generator 150 can stop operating to destroy the vacuum in the two suction cups, so that the first suction cup 141 and the second suction cup 142 no longer suck the clarity detection plate 111 or the calibration rod 112, and the placement is completed.

[0044] In some embodiments, when the disc height of the second suction cup 142 is less than the disc height of the first suction cup 141 and the automatic calibration device 100 also includes a second vacuum generator 160, the first vacuum generator 150 and the second vacuum generator 160 are used to operate when the first suction cup 142 contacts the picked-up surface of the clarity detection plate 111 or the picked-up surface of the calibration rod 112, and stop operating when the first suction cup 141 and the second suction cup 142 both suck the clarity detection plate 111 or the calibration rod 112.

[0045] Specifically, since the height of the second suction cup 142 is smaller than the height of the first suction cup 141, the first suction cup 141 will first contact the picked-up surface, while the second suction cup 142 is "covered" in the suction cup of the first suction cup 141 and cannot contact the picked-up surface. At this time, the two vacuum generators work together, and both extract the air in the first suction cup 141, which is faster and more efficient. Thereafter, as the extraction proceeds, the second suction cup 142 will also contact the picked-up surface. At this time, the first vacuum generator 150 continues to extract the air in the first suction cup 141, and the second vacuum generator 160 starts to extract the air in the second suction cup 142. Since the second suction cup 142 is a small suction cup relative to the first suction cup 141, the two can stop extracting at almost the same time. It can be understood that after stopping the extraction, the first suction cup 141 and the second suction cup 142 both firmly suck the clarity detection plate 111 or the calibration rod 112.

[0046] Exemplarily, the first suction cup 141 and the second suction cup 142 are integrally formed, and the integral forming method can improve the structural strength and extend the service life. Exemplarily, the number of the second suction cups 142 is 2; and / or, the diameter of the first suction cup 141 is less than or equal to 22 mm and greater than or equal to 20 mm, and the diameter of the second suction cup 142 is less than or equal to 6 mm and greater than or equal to 5 mm. This size design can meet the needs of most calibration rods on the market.

[0047] In addition, an embodiment of the present application further provides a calibration system, including the automatic calibration device 100 as described in any of the above embodiments. The specific implementation details are discussed above and will not be repeated here.

[0048] It should be understood that the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification of the present application and the appended claims, unless the context clearly indicates otherwise, the singular forms of "one", "an" and "the" are intended to include plural forms. In addition, the terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims or the above-mentioned drawings of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0049] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0050] It should be further understood that the flowcharts (if any) shown in the drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0051] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An automatic calibration device, characterized in that: include: A cabinet, a clarity detection plate and a calibration rod are placed on the upper surface of the cabinet; A bracket, fixedly connected to the cabinet and disposed at a first end of an upper surface of the cabinet; the bracket is used to place a terminal with a camera; as well as A mechanical arm, the mechanical arm is mounted on the upper surface of the cabinet and is arranged at a second end opposite to the first end of the upper surface, and an operating end of the mechanical arm is provided with a pick-and-place element; the pick-and-place element is used to pick up and place the clarity detection plate or the calibration rod, and the mechanical arm can move in position and rotate in angle relative to the terminal with a camera; The robot arm is used to: pick up the clarity detection plate through the pick-and-place element and move it to a first preset position so that the terminal with a camera can detect whether the image is clear; and after the clarity detection is completed, move to a second preset position and place the clarity detection plate through the pick-and-place element; The robotic arm is also used to: pick up the calibration rod through the pick-and-place element and perform a preset wave so that the terminal with a camera can perform camera calibration; and after completing the camera calibration, move to a third preset position and place the calibration rod through the pick-and-place element.

2. The automatic calibration device according to claim 1, characterized in that: The picked-up surface of the clarity detection plate and the picked-up surface of the calibration rod are smooth planes; The pick-and-place element comprises a first suction cup, the diameter of which is smaller than the width of the picked-up surface of the clarity detection plate and the width of the picked-up surface of the calibration rod; The automatic calibration device also includes a first vacuum generator, which is connected to the first air hole of the first suction cup.

3. The automatic calibration device according to claim 2, characterized in that: The pick-and-place component further includes a second suction cup nested in the first suction cup, wherein the diameter of the second suction cup is smaller than the diameter of the first suction cup; The first vacuum generator is also connected to the second air hole of the second suction cup; or, the automatic calibration device also includes a second vacuum generator, and the second vacuum generator is connected to the second air hole of the second suction cup.

4. The automatic calibration device according to claim 3, characterized in that: A cup height of the second suction cup is smaller than a cup height of the first suction cup.

5. The automatic calibration device according to claim 4, characterized in that: In the case where the automatic calibration device further comprises a second vacuum generator, The first vacuum generator and the second vacuum generator are used to operate when the first suction cup contacts the picked-up surface of the clarity detection plate or the picked-up surface of the calibration rod, and to stop operating when the first suction cup and the second suction cup both suck the clarity detection plate or the calibration rod.

6. The automatic calibration device according to claim 3 or 4, characterized in that: The first suction cup and the second suction cup are integrally formed.

7. The automatic calibration device according to claim 3 or 4, characterized in that: The number of the second suction cups is 2; and / or the diameter of the first suction cup is less than or equal to 22 mm and greater than or equal to 20 mm, and the diameter of the second suction cup is less than or equal to 6 mm and greater than or equal to 5 mm.

8. A calibration system, characterized in that: Comprising an automatic calibration device as described in any one of claims 1-7.

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