Calibration method of tracking type laser scanning system and tracking type laser scanning system

Abstract

The invention relates to a calibration method of a tracking type laser scanning system and the tracking type laser scanning system. The calibration method comprises the following steps: establishing a coordinate system of a first device as a first coordinate system, and establishing a coordinate system of a second device as a second coordinate system; obtaining coordinates of the calibration object in a first coordinate system of the first device as first coordinates, and obtaining coordinates of the calibration object of the first device in a second coordinate system of the first device as second coordinates; calculating a first conversion relationship based on the first device first coordinate and the first device second coordinate; acquiring, as a first relative relationship, a relationship between a position parameter relating to the position of the first device assist mechanism and the first coordinate system of the first device; and calibrating a relation of the first device position parameter relative to the first device second coordinate system as a second relative relation based on the first device first relative relation and the first device first conversion relation. Therefore, the three-dimensional information of the to-be-measured object can be measured conveniently, and the measurement precision can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of intelligent manufacturing equipment industry, and specifically to a calibration method for a tracking laser scanning system and a tracking laser scanning system. Background Art

[0002] In the field of industrial measurement, laser measuring instruments have become an important tool for scanning and measuring workpieces due to their non-contact, high-precision and fast response characteristics. Tracking laser scanners are instruments that can quickly measure workpieces. By combining optical tracking technology and optical scanning technology, they can accurately capture the three-dimensional information of the workpiece (such as geometric shape and size).

[0003] Generally speaking, a tracking laser scanner includes a tracking device and a scanning device. During the measurement of a workpiece, the scanning device moves on the surface of the workpiece to measure the three-dimensional data of the workpiece, while the tracking device is usually fixed at a certain position and measures the posture of the scanning device to convert the three-dimensional data measured by the scanning device into the tracker coordinate system. In this way, all three-dimensional data can be unified into the tracker coordinate system, which is convenient for calculating the shape and size of the workpiece. Since the measurement range of the tracking laser scanner is relatively limited, when it is applied to a large range of measurement scenarios, the tracking device usually needs to perform a "station transfer" operation, that is, it needs to be moved to a new measurement position.

[0004] However, the coordinate system of the tracking device changes before and after the "station transfer" operation. In order to obtain the complete three-dimensional data of the workpiece, the coordinate system of the tracking device before and after the "station transfer" operation needs to be matched (for example, each "station transfer" operation requires the tracking device to identify the label stickers attached to the workpiece before and after the "station transfer" to achieve coordinate system matching before and after the "station transfer" operation). This not only increases the complexity of the operation, but may also cause interruptions and delays in measurement. In addition, the process of identifying label stickers is easily affected by environmental factors, such as damage, contamination or poor lighting conditions of the label, which may affect the accuracy of the coordinate system matching and thus affect the accuracy of the three-dimensional information of the measured workpiece. Summary of the invention

[0005] The present disclosure is made in view of the above situation, and its purpose is to provide a calibration method and a tracking laser scanning system that can facilitate the measurement of three-dimensional information of an object to be measured and improve the measurement accuracy.

[0006] To this end, a first aspect of the present disclosure provides a calibration method for a tracking laser scanning system, the tracking laser scanning system comprising a first device, a second device cooperating with the first device and used to scan an object to be measured, and an auxiliary mechanism fixedly arranged on the second device and used to reflect a light beam emitted by the first device, the calibration method comprising: establishing a coordinate system of the first device as a first coordinate system, and establishing a coordinate system of the second device as a second coordinate system; obtaining the coordinates of the calibration object in the first coordinate system as first coordinates, and obtaining the coordinates of the calibration object in the second coordinate system as second coordinates; calculating the transformation relationship between the first coordinate system and the second coordinate system based on the first coordinates and the second coordinates as a first transformation relationship; and obtaining the relationship of a position parameter related to the position of the auxiliary mechanism relative to the first coordinate system as a first relative relationship, and calibrating the relationship of the position parameter relative to the second coordinate system as a second relative relationship based on the first relative relationship and the first transformation relationship.

[0007] In the calibration method involved in the present disclosure, the first coordinate and the second coordinate can be directly obtained by the first device and the second device respectively, so it is easy to obtain the conversion relationship between the coordinate system for characterizing the first device and the coordinate system of the second device, that is, the first conversion relationship; in addition, the first device can directly obtain the relative relationship of the position parameters for characterizing the auxiliary mechanism relative to the coordinate system of the first device based on the light beam reflected by the auxiliary mechanism, that is, the first relative relationship; based on the first relative relationship and the first conversion relationship, the relative relationship of the position parameters for characterizing the auxiliary mechanism relative to the coordinate system of the second device can be obtained, that is, the second relative relationship. As a result, global correction can be directly completed with the help of the second relative relationship during the measurement of the object to be measured, that is, the coordinates of the object to be measured obtained by scanning the second device are unified into the coordinate system of the first device through simple calculation.

[0008] In addition, in the calibration method of the tracking laser scanning system involved in the first aspect of the present disclosure, optionally, the number of the calibration objects is at least 3, and at least the 3 calibration objects are not collinear. In this case, by measuring the coordinates of at least 3 calibration objects, the accuracy of the first transformation relationship obtained can be improved, and the risk of less than 3 valid data of the calibration objects obtained due to the obstruction of the calibration objects can be reduced; in addition, the transformation relationship between the first coordinate system and the second coordinate system can have only one solution, thereby improving the accuracy of subsequent coordinate transformation.

[0009] In addition, in the calibration method of the tracking laser scanning system involved in the first aspect of the present disclosure, optionally, it also includes verifying whether the accuracy of the second relative relationship meets the preset requirements, and verifying whether the accuracy of the second relative relationship meets the preset requirements includes: moving the second device, obtaining the relationship of the position parameter relative to the first coordinate system as the third relative relationship; calculating the transformation relationship between the first coordinate system and the second coordinate system after the second device moves based on the second relative relationship and the third relative relationship as the second transformation relationship; verifying whether the accuracy of the second relative relationship meets the preset requirements based on the second transformation relationship. In this case, by verifying the accuracy of the second relative relationship, the second relative relationship whose accuracy meets the preset requirements is used as the basis for calculating the coordinate transformation in the subsequent measurement process, the measurement accuracy of the object to be measured can be improved.

[0010] In addition, in the calibration method of the tracking laser scanning system involved in the first aspect of the present disclosure, optionally, verifying whether the accuracy of the second relative relationship meets the preset requirements based on the second conversion relationship includes: obtaining the coordinates of the calibration object in the second coordinate system as the fourth coordinate; calculating the coordinates of the fourth coordinate in the first coordinate system as the fifth coordinate based on the second conversion relationship; and in response to the difference between the fifth coordinate and the first coordinate being not greater than the preset value, determining that the accuracy of the second relative relationship meets the preset requirements. In this case, the coordinates of the calibration object in the second coordinate system after the "station transfer" operation can be converted to the first coordinate system, and the first coordinate is the coordinate obtained by directly measuring the calibration object by the first device, and the fifth coordinate is the coordinate converted to the first coordinate system by measuring the calibration object by the second device based on the second conversion relationship. Since the absolute position of the calibration object has not changed, the difference between the first coordinate and the fifth coordinate should be zero in theory. Therefore, it is possible to judge whether the second relative relationship meets the preset requirements based on the difference between the first coordinate and the fifth coordinate. If the difference between the first coordinate and the fifth coordinate is not greater than the preset value, it can be determined that the accuracy of the second relative relationship meets the preset requirements.

[0011] In addition, in the calibration method of the tracking laser scanning system involved in the first aspect of the present disclosure, optionally, the auxiliary mechanism is configured to receive the light beam emitted by the first device and reversely track the first device based on the received light beam. In this case, the range of the incident angle of the laser beam that the auxiliary mechanism can receive can be expanded, and the situation where the measurement is interrupted when the target of the auxiliary mechanism is not aligned with the first device can be reduced. At the same time, the position parameters can be directly obtained based on parameters such as the rotation angle and the tilt angle during the reverse tracking of the auxiliary mechanism.

[0012] In addition, in the calibration method of the tracking laser scanning system involved in the first aspect of the present disclosure, optionally, the position parameter related to the position of the auxiliary mechanism is the coordinate system of the auxiliary mechanism, the coordinate system of the auxiliary mechanism is set as a third coordinate system, and obtaining the first relative relationship includes: obtaining the third coordinate system through the first device; and calculating the conversion relationship between the third coordinate system and the first coordinate system as the first relative relationship. In this way, the measurement relationship between the first device and the auxiliary mechanism can be established.

[0013] In addition, in the calibration method of the tracking laser scanning system involved in the first aspect of the present disclosure, optionally, the auxiliary mechanism includes at least three reflection units fixedly arranged on the second device, and at least three of the reflection units are not collinear. In this case, the relative position of the auxiliary mechanism relative to the second device can be kept fixed. In addition, since there is no direct measurement relationship between the first device and the second device, the second device can be made unique in the coordinate system of the first device by means of at least three reflection units fixed to the second device, thereby improving the accuracy of subsequent measurement calculations.

[0014] In addition, in the calibration method of the tracking laser scanning system involved in the first aspect of the present disclosure, optionally, the position parameter related to the position of the auxiliary mechanism is the coordinate of the auxiliary mechanism, and the coordinate of the auxiliary mechanism in the first coordinate system is obtained as the first relative relationship. In this case, since the first relative relationship can be obtained by directly measuring the auxiliary mechanism by the first device, the steps of calibrating the second relative relationship can be simplified, thereby improving the calibration efficiency.

[0015] In addition, in the calibration method of the tracking laser scanning system involved in the first aspect of the present disclosure, optionally, the calibration object includes a base and a marker disposed on the base, and the marker includes at least one of a reference sphere, a standard sphere, or a target sphere. Thus, different types of markers can be used to match each measuring instrument in the tracking laser scanning system to improve the measurement accuracy of the calibration object.

[0016] A second aspect of the present disclosure provides a tracking laser scanning system, which uses the calibration method provided by the first aspect of the present disclosure to calibrate the second relative relationship.

[0017] According to the present disclosure, a calibration method of a tracking laser scanning system and a tracking laser scanning system can be provided, which can facilitate the measurement of three-dimensional information of an object to be measured and improve the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present disclosure will now be explained in further detail, by way of example only, with reference to the accompanying drawings.

[0019] Figure 1 is a diagram showing an application scenario of the tracking laser scanning system involved in the example of the present disclosure.

[0020] Figure 2A It is a scene schematic diagram showing the first embodiment of the assist mechanism involved in the example of the present disclosure. Figure 2B It is a front view schematic diagram showing a first embodiment of the auxiliary mechanism involved in the example of the present disclosure, which is provided in a visual mechanism.

[0021] Figure 3 is a flow chart showing a calibration method involved in an example of the present disclosure.

[0022] Figure 4A Schematic diagram showing the structure of the base involved in the example of the present disclosure. Figure 4B Schematic diagram showing the structure of the marker involved in the example of the present disclosure.

[0023] Figure 5 is a flowchart showing the verification of the second relative relationship involved in the example of the present disclosure.

[0024] Figure 6 3 is a flowchart showing the method of verifying whether the accuracy of the second relative relationship meets the preset requirements based on the second conversion relationship involved in the example of the present disclosure.

[0025] Fig. 7A It is a scene schematic diagram showing the second embodiment of the assist mechanism involved in the example of the present disclosure. Figure 7B It is a front view schematic diagram showing a second embodiment of the auxiliary mechanism involved in the example of the present disclosure, which is provided in the visual mechanism.

[0026] Figure 8 is a flow chart showing a measurement method involved in the examples of the present disclosure. DETAILED DESCRIPTION

[0027] Hereinafter, the preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same symbols are assigned to the same components, and repeated descriptions are omitted. In addition, the accompanying drawings are only schematic diagrams, and the ratio of the dimensions of the components or the shapes of the components may be different from the actual ones.

[0028] In addition, the subheadings and the like involved in the following description of the present disclosure are not intended to limit the content or scope of the present disclosure, but are merely used as a reminder for reading. Such subheadings should neither be understood as being used to divide the content of the article, nor should the content under the subheading be limited to the scope of the subheading.

[0029] The present disclosure relates to a calibration method for a tracking laser scanning system (hereinafter referred to as the calibration method), which is a method for calibrating fixed parameters related to the tracking laser scanning system in the process of measuring an object to be measured. By calibrating the above fixed parameters, on the one hand, it is convenient to measure the three-dimensional information of the object to be measured, and on the other hand, it is possible to improve the measurement accuracy. The calibration method for the tracking laser scanning system involved in the present disclosure can also be called a calibration method for a collaborative measurement system, a joint calibration method for a tracking laser scanning system, or a method for calibrating a collaborative measurement system.

[0030] The present disclosure also relates to a tracking laser scanning system, which can execute the calibration method involved in the present disclosure. In addition, the tracking laser scanning system can realize the measurement of the object to be measured. On the one hand, the tracking laser scanning system is convenient for measuring the three-dimensional information of the object to be measured, and on the other hand, it can also improve the measurement accuracy of the object to be measured. The tracking laser scanning system involved in the present disclosure can also be called a collaborative measurement system, an optical tracking system, or an optical measurement system with tracking and scanning functions. In addition, the present disclosure also relates to a measurement method of a tracking laser scanning system (referred to as a measurement method for short), and the tracking laser scanning system uses the measurement method of the present disclosure to realize the measurement of the object to be measured. Below, the present disclosure is described in detail in conjunction with the accompanying drawings.

[0031] Figure 1 is a diagram showing an application scenario of the tracking laser scanning system 1 involved in the example of the present disclosure.

[0032] For some examples, see Figure 1 The tracking laser scanning system 1 may include a first device 11 and a second device 12. The second device 12 may be used to scan the object to be measured. In some examples, the second device 12 may obtain three-dimensional information of the object to be measured, such as coordinates, size, and shape, by scanning the object to be measured.

[0033] In some examples, the second device 12 may include a visual mechanism 121 and a scanner 122. The scanner 122 may be used to scan the three-dimensional information of the object to be measured, and the visual mechanism 121 may be used to measure the position information and posture information (referred to as posture information) of the scanner 122. In some examples, the visual mechanism 121 may be disposed on the bearing surface through a support frame.

[0034] In some examples, the scanner 122 may be a movable device. In some examples, during the measurement process, the scanner 122 may be moved to scan various areas of the object to be measured. In some examples, the scanner 122 may be a handheld scanner. In some examples, the scanner 122 may be a mechanical mobile scanner.

[0035] In some examples, the scanner 122 may include a laser for emitting multiple laser beams, and a receiver for receiving the laser beam reflected by the object to be measured. In some examples, the scanner 122 may emit multiple laser beams to the surface of the object to be measured, and receive the laser beam reflected by the object to be measured and carrying the surface information of the object to be measured. In this case, the three-dimensional information of the object to be measured can be obtained based on the laser beam reflected by the object to be measured. In addition, by emitting multiple laser beams to the surface of the object to be measured, a large area of ​​the object to be measured can be scanned, thereby improving the measurement efficiency.

[0036] Since the scanner 122 needs to move continuously to scan the object to be measured, the coordinate system before and after the movement of the scanner 122 will be transformed, and the local three-dimensional information obtained by measurement is not maintained in a common and absolute coordinate system. If the global three-dimensional information of the object to be measured is measured only based on the scanner 122, it is necessary to match the coordinate system before and after each movement to unify multiple local three-dimensional information into the same coordinate system. This process is complicated and time-consuming, and in the continuous scanning process, multiple coordinate system matching may introduce errors and ultimately lead to low measurement accuracy.

[0037] In some examples, the scanner 122 may include a cage structure arranged around the laser. In some examples, the cage structure may be a spherical cage structure (circular cage structure), a cubic cage structure, or other irregularly shaped cage structures. In some examples, a plurality of marking points 1221 ( Figure 1 Two marking points 1221 are schematically marked. In some examples, the shape of the marking point 1221 can be roughly circular.

[0038] In some examples, the visual mechanism 121 can obtain the position information of the scanner 122 by tracking the multiple marking points 1221, and the position of the visual mechanism 121 can remain unchanged during the tracking process. In other words, while the scanner 122 is scanning the object to be measured, the visual mechanism 121 can remain in the same position and continue to track the scanner 122. In some examples, the visual mechanism 121 can obtain the position information of the scanner 122 based on the multiple marking points 1221 reflecting the light beam emitted by the visual mechanism 121. In some examples, the multiple marking points 1221 can have a light-emitting unit, and the visual mechanism 121 can obtain the position information of the scanner 122 by capturing the information of the light-emitting unit.

[0039] In some examples, the visual mechanism 121 may have a larger measurement field of view. Thus, the scanner 122 can be continuously tracked when the scanner 122 moves to scan the object to be measured. In some examples, the three-dimensional information scanned by the scanner 122 can be converted from the coordinate system of the scanner 122 to the coordinate system of the visual mechanism 121 based on the posture information of the scanner 122. Thus, multiple local three-dimensional information obtained during the scanning process can be unified into the same coordinate system, thereby simplifying the calculation process and improving the measurement accuracy.

[0040] For some examples, see Figure 1 , the visual mechanism 121 may include two image capture units 1211 located at different positions. In some examples, the two image capture units 1211 may capture images of the scanner 122 from different positions, and analyze the parallax information of the multiple markers 1221 in the above images to obtain the position information of the scanner 122. In some examples, the visual mechanism 121 may also be called a binocular camera or an optical tracker.

[0041] When the size of the object to be measured is large, during the measurement process, the scanner 122 may move outside the measurement field of view of the visual mechanism 121, which will cause the visual mechanism 121 to disconnect the tracking of the scanner 122. At this time, the visual mechanism 121 needs to be moved so that the scanner 122 is re-located within the measurement field of view of the visual mechanism 121. The above process of moving the visual mechanism 121 can be called a "station transfer" operation. Considering that the coordinate system before and after the "station transfer" operation of the visual mechanism 121 will change, it is also necessary to match the coordinate system of the coordinate system before and after the "station transfer" operation of the visual mechanism 121. In this way, multiple local three-dimensional information can be unified into the same and absolute coordinate system.

[0042] The calibration method involved in the present disclosure can calibrate fixed parameters that are relatively fixed to the second device 12. During the measurement process, when the "station transfer" operation is performed, multiple local three-dimensional information can be unified into the same and absolute coordinate system without matching the coordinate system before and after the "station transfer" operation of the visual mechanism 121. For the convenience of subsequent description, unifying multiple local three-dimensional information into the same and absolute coordinate system is referred to as global calibration.

[0043] As described above, the tracking laser scanning system 1 may further include a first device 11. In some examples, the second device 12 may cooperate with the first device 11. In some examples, the cooperation between the second device 12 and the first device 11 may refer to a corresponding conversion relationship between the coordinate system of the second device 12 and the coordinate system of the first device 11. Thus, the three-dimensional information of the object to be measured can be converted from the coordinate system of the second device 12 to the coordinate system of the first device 11.

[0044] In some examples, the coordinate system of the second device 12 may refer to the coordinate system of the vision mechanism 121 .

[0045] Figure 2A 1 is a schematic diagram of a scene showing a first embodiment of the assist mechanism 13 according to the present disclosure example. Figure 2B 1 is a front view schematically showing a first embodiment of the auxiliary mechanism 13 according to the disclosed example, which is provided in the visual mechanism 121 .

[0046] In some examples, the tracking laser scanning system 1 may further include an auxiliary mechanism 13 (see Figure 2A or Figure 2B ). In some examples, the first device 11 may measure the auxiliary mechanism 13. In some examples, measuring the auxiliary mechanism 13 may refer to measuring the position and posture information of the auxiliary mechanism 13. In some examples, the first device 11 may track the auxiliary mechanism 13.

[0047] In some examples, the first device 11 may emit a light beam to the auxiliary mechanism 13. In some examples, the light beam emitted by the first device 11 may be a laser beam. In some examples, the auxiliary mechanism 13 may reflect the light beam emitted by the first device 11. Specifically, the auxiliary mechanism 13 may receive the light beam emitted by the first device 11 and reflect the received light beam to the first device 11. Thus, the first device 11 can measure and / or track the auxiliary mechanism 13. In some examples, the first device 11 may be a laser measuring instrument such as a laser tracker.

[0048] As described above, the first device 11 can measure the auxiliary mechanism 13. In some examples, the auxiliary mechanism 13 can be provided in the second device 12. Specifically, the auxiliary mechanism 13 can be provided in the visual mechanism 121 (see Figure 2A ). In this case, through the measurement relationship between the first device 11 and the auxiliary mechanism 13, and the positional relationship between the visual mechanism 121 and the auxiliary mechanism 13, a conversion relationship between the coordinate system of the first device 11 and the coordinate system of the second device 12 can be established, thereby facilitating subsequent measurements.

[0049] In some examples, the auxiliary mechanism 13 can be fixedly arranged on the visual mechanism 121. In this case, the auxiliary mechanism 13 and the visual mechanism 121 can have a relatively fixed positional relationship. In the process of measuring the object to be measured by the tracking laser scanning system 1, even if the "station transfer" operation is performed, the relative relationship between the auxiliary mechanism 13 and the visual mechanism 121 can still remain relatively fixed. Therefore, based on the above relatively fixed positional relationship, directly continuing the process of measuring the object to be measured can also complete the global correction (described later), thereby facilitating the measurement of the three-dimensional information of the object to be measured. In other words, the efficiency of measuring the three-dimensional information of the object to be measured can be improved.

[0050] As described above, the calibration method of the present disclosure can be used to calibrate fixed parameters related to the tracking laser scanning system 1 in the process of measuring the object to be measured. In some examples, the above-mentioned fixed parameters can be the second relative relationship involved in the present disclosure (described later). In some examples, the calibration method of the present disclosure can be used to calibrate the relative position relationship between the auxiliary mechanism 13 and the second device 12. Specifically, it is to calibrate the relative position relationship between the auxiliary mechanism 13 and the visual mechanism 121. In some examples, the relative position relationship between the calibration auxiliary mechanism 13 and the second device 12 refers to the relative position relationship between the calculation auxiliary mechanism 13 and the second device 12.

[0051] In some examples, after the relative position relationship is calibrated, even if the second device 12 performs a "station transfer" operation, it is not necessary to perform coordinate system matching before and after the "station transfer" operation to achieve complete measurement of the object to be measured. In this case, the measurement efficiency in a wide range of measurement scenarios can be improved. Furthermore, since there is no need to perform coordinate system matching before and after the "station transfer" operation, the operation steps can be simplified, the introduction of errors can be reduced, and the measurement accuracy can be improved.

[0052] Figure 3 is a flow chart showing a calibration method involved in an example of the present disclosure.

[0053] For some examples, see Figure 3 The calibration method may include establishing a coordinate system of the first device 11 as a first coordinate system, establishing a coordinate system of the second device 12 as a second coordinate system (step S200), obtaining coordinates of a calibration object 2 (described later) in the first coordinate system as first coordinates, obtaining coordinates of the calibration object 2 in the second coordinate system as second coordinates (step S300), calculating a first conversion relationship based on the first coordinates and the second coordinates (step S400), and obtaining a first relative relationship, and calibrating the second relative relationship based on the first relative relationship and the first conversion relationship (step S500).

[0054] In the calibration method involved in the present disclosure, the first coordinate and the second coordinate can be directly obtained by the first device 11 and the second device 12 respectively, so it is easy to obtain the conversion relationship between the coordinate system for characterizing the first device 11 and the coordinate system of the second device 12, that is, the first conversion relationship; in addition, the first device 11 can directly obtain the relative relationship of the position parameters for characterizing the auxiliary mechanism 13 relative to the coordinate system of the first device 11 based on the light beam reflected by the auxiliary mechanism 13, that is, the first relative relationship; based on the first relative relationship and the first conversion relationship, the relative relationship of the position parameters for characterizing the auxiliary mechanism 13 relative to the coordinate system of the second device 12 can be obtained, that is, the second relative relationship, thereby, the global correction can be directly completed with the help of the second relative relationship during the measurement of the object to be measured, that is, the coordinates of the object to be measured obtained by scanning the second device 12 are unified into the coordinate system of the first device 11 through simple calculation.

[0055] In some examples, in step S200, the first coordinate system and the second coordinate system may be three-dimensional coordinate systems. In some examples, the first coordinate system may be established with any position of the first device 11 as the coordinate origin. For example, the first coordinate system may be established with the intersection of the rotation axes of the first device 11 as the coordinate origin.

[0056] In some examples, the second coordinate system can be established with any position of the second device 12 as the coordinate origin. As described above, the coordinate system of the second device 12 can be the coordinate system of the visual mechanism 121. In some examples, the second coordinate system can be established with the midpoint of the line connecting the two image capture units 1211 of the visual mechanism 121 as the coordinate origin.

[0057] In some examples, in step S300, the calibration object 2 may be fixedly disposed in the measurement scene. In some examples, the calibration object 2 may be measured by the first device 11 to obtain the first coordinate. Specifically, the first device 11 emits a light beam to the calibration object 2, and the calibration object 2 receives the light beam and reflects the received light beam back to the first device 11. Thus, the first device 11 can measure the coordinates of the calibration object 2 in the first coordinate system based on the light beam reflected by the calibration object 2, that is, the first coordinate.

[0058] In some examples, the calibration object 2 may be measured by the second device 12 to obtain the second coordinates. Specifically, the image of the calibration object 2 may be captured by the visual mechanism 121, and the coordinates of the calibration object 2 in the second coordinate system, that is, the second coordinates, may be obtained through the captured image.

[0059] In some examples, the calibration object 2 may be scanned by the scanner 122 to obtain coordinates of the calibration object 2 in the scanner coordinate system, and the coordinates of the calibration object 2 in the scanner coordinate system may be converted into coordinates in the vision mechanism coordinate system as second coordinates.

[0060] In some examples, the number of calibration objects 2 may be at least 3. For example, the number of calibration objects 2 may be 3, 4, 5, 6, 7, or 8. In this case, by measuring the coordinates of at least 3 calibration objects 2, the accuracy of the first conversion relationship can be improved, and the risk of obtaining less than 3 valid data of the calibration object 2 due to the calibration object 2 being blocked can be reduced.

[0061] In some examples, at least three calibration objects 2 may not be collinear. Thus, the transformation relationship between the first coordinate system and the second coordinate system can have only one solution, thereby improving the accuracy of subsequent coordinate conversion.

[0062] Figure 4A Schematic diagram showing the structure of the base 21 involved in the example of the present disclosure. Figure 4B 2 is a schematic diagram showing the structure of the marker 22 involved in the example of the present disclosure as a reference sphere.

[0063] In some examples, the calibration object 2 may refer to a workpiece dedicated to calibrating the second relative relationship. Figure 4A and Figure 4B The calibration object 2 may include a base 21 and a marker 22. In some examples, the marker 22 may be disposed on the base 21. In some examples, the base 21 may be fixedly disposed at any position within the measurement range of the tracking laser scanning system 1. In some examples, the base 21 may have a groove 211 for accommodating the marker 22.

[0064] In some examples, the marker 22 may have a spherical feature. In some examples, the marker 22 may have a spherical center. In some examples, the coordinates of the spherical center of the marker 22 may be used as the coordinates of the calibration object 2. In some examples, there may be different categories of markers 22. In some examples, different categories of markers 22 may include reference spheres, standard spheres, or target spheres, etc. Among them, the reference sphere may be an incomplete sphere with the center exposed, the standard sphere may be a standard sphere, and the target sphere may be a retroreflector (hollow corner cube prism).

[0065] In some examples, different types of markers 22 can be adapted to different measuring devices. In some examples, the marker can include at least one of a reference ball, a standard ball, or a target ball. Thus, different types of markers 22 can be used to match various measuring instruments in the tracking laser scanning system 1 to improve the measurement accuracy of the calibration object 2.

[0066] In some examples, the marker 22 used in the first device 11 may be a target sphere. In some examples, the marker 22 used in the vision mechanism 121 may be a reference sphere. In some examples, the marker 22 used in the scanner 122 may be a standard sphere.

[0067] In some examples, if a standard sphere is used as the marker 22 , the outline of the standard sphere can be scanned by the scanner 122 , and the center of the standard sphere can be fitted based on the surface contour data of the standard sphere.

[0068] For some examples, see Figure 4B The reference sphere may be affixed with a label S. The center S1 of the label S may coincide with the center of the sphere. Thus, the coordinates of the sphere center can be obtained by identifying the center S1 of the label S in the captured image.

[0069] In some examples, the radii of different types of markers 22 may be the same. In this case, even if the markers 22 used by the first device 11 and the second device 12 are different during the calibration process, the coordinates of the center of the sphere of the marker 22 do not change, in other words, the absolute position of the coordinates of the center of the sphere of the marker 22 does not change, so the first coordinates measured by the first device 11 and the second coordinates measured by the second device 12 can be used as the basis for calculating the first conversion relationship in the subsequent steps.

[0070] In some examples, the same type of marker 22 may be applicable to the measurement scenarios of the first device 11 and the second device 12. In other words, the first device 11 and the second device 12 may measure the same marker 22. In this case, the marker 22 does not need to be replaced during the calibration process, which can simplify the calibration process.

[0071] In some examples, in step S400, a first conversion relationship may be calculated based on the first coordinate and the second coordinate. Since the first coordinate is the coordinate of the calibration object 2 in the first coordinate system, and the second coordinate is the coordinate of the calibration object 2 in the second coordinate system, the first conversion relationship obtained by calculation may represent the conversion relationship between the first coordinate system and the second coordinate system. In other words, the conversion relationship between the first coordinate system and the second coordinate system may be calculated as the first conversion relationship based on the first coordinate and the second coordinate. In the present disclosure, the conversion relationship between the coordinate systems may be a conversion matrix.

[0072] In some examples, the calibration object 2 may be measured multiple times to obtain multiple sets of first coordinates and multiple sets of second coordinates. In some examples, the average value of the multiple sets of first coordinates and the average value of the multiple sets of second coordinates may be calculated to calculate the first conversion relationship. Thus, the accuracy of calculating the first conversion relationship can be improved.

[0073] In some examples, the relationship between the first coordinate, the second coordinate, and the first conversion relationship can be expressed as formula (1):

[0074]

[0075] Among them, C1 represents the first coordinate, C2 represents the second coordinate, Indicates the first conversion relationship.

[0076] As described above, in step S500, the first relative relationship may be acquired. In some examples, the relationship of the position parameter related to the position of the auxiliary mechanism 13 with respect to the first coordinate system may be taken as the first relative relationship.

[0077] In some examples, the auxiliary mechanism 13 may be a reverse tracking device with a reverse tracking function. In some examples, the auxiliary mechanism 13 may be configured to receive a light beam (e.g., a laser beam) emitted by the first device 11 and reversely track the first device 11 based on the received light beam. In this case, the range of incident angles of the laser beam that the auxiliary mechanism 13 can receive can be expanded, and the situation where the measurement is interrupted when the target of the auxiliary mechanism 13 is not aligned with the first device 11 can be reduced. At the same time, the position parameters can be directly obtained according to parameters such as the rotation angle and the tilt angle during reverse tracking of the auxiliary mechanism 13.

[0078] In some examples, the first device 11 may have a rotatable emitting unit for emitting a light beam. In some examples, the emitted laser beam may be directed toward the auxiliary mechanism 13 by rotating the emitting unit.

[0079] In some examples, the auxiliary mechanism 13 may have a rotatable target, which may reflect the light beam to the first device 11. In some examples, the reflected laser beam may be directed to the first device 11 by rotating the target.

[0080] In some examples, the position parameter related to the position of the auxiliary mechanism 13 may be a coordinate system of the auxiliary mechanism 13. Let the coordinate system of the auxiliary mechanism 13 be the third coordinate system. In some examples, the first relative relationship may be a conversion relationship between the third coordinate system and the first coordinate system.

[0081] In some examples, acquiring the first relative relationship may include acquiring a third coordinate system through the first device 11 and calculating a conversion relationship between the third coordinate system and the first coordinate system as the first relative relationship. Thus, a measurement relationship between the first device 11 and the auxiliary mechanism 13 can be established.

[0082] In some examples, the position of the auxiliary mechanism 13 relative to the first device 11 can be obtained. In some examples, the laser beam emitted by the emission unit can be aimed at the target, and the position of the auxiliary mechanism 13 relative to the first device 11 can be obtained based on the laser beam reflected by the target.

[0083] In some examples, the distance of the first device 11 can be obtained based on the distance information carried by the laser beam reflected by the target, and the orientation of the auxiliary mechanism 13 can be obtained based on the change angle of the laser beam emitted by the emission unit. In this case, the coordinate system of the auxiliary mechanism 13 can be established based on the distance and orientation of the auxiliary mechanism 13 relative to the first device 11, that is, the third coordinate system.

[0084] In some examples, after obtaining the position of the target relative to the first device 11, the direction vector of the laser beam in the coordinate system of the first device 11 (i.e., the first coordinate system) can be obtained, and after the target is aligned with the laser emitting unit, the direction vector of the laser beam in the auxiliary mechanism coordinate system (i.e., the third coordinate system) can be obtained according to the rotation angle of the target. In some examples, the first relative relationship can be calculated based on the above two direction vectors.

[0085] As described above, in step S500, the second relative relationship can be calibrated based on the first relative relationship and the first conversion relationship. In some examples, the second relative relationship can be a relationship between a position parameter related to the position of the auxiliary mechanism 13 and the second coordinate system. For example, the second relative relationship can be a conversion relationship between the third coordinate system and the second coordinate system.

[0086] In some examples, the relationship between the first relative relationship, the first conversion relationship, and the second relative relationship can be expressed as formula (2):

[0087]

[0088] in, represents the first conversion relationship, Indicates the first relative relationship, In some examples, according to formula (2), when the first conversion relationship and the first relative relationship are known, the second relative relationship can be calculated. As described above, the auxiliary mechanism 13 is fixed to the first device 11, and the second relative relationship can be the relationship between the position parameter related to the position of the auxiliary mechanism 13 and the first coordinate system. Thus, the second relative relationship can be a constant.

[0089] Figure 5 is a flowchart showing the verification of the second relative relationship involved in the example of the present disclosure.

[0090] In some examples, the calibration method involved in the present disclosure may include verifying the second relative relationship. In some examples, verifying the second relative relationship may be verifying whether the accuracy of the second relative relationship meets the preset requirements. If the accuracy of the second relative relationship meets the preset requirements, the process of measuring the object to be measured may be performed based on the second relative relationship that meets the preset requirements; if the accuracy of the second relative relationship does not meet the preset requirements, the above steps S300 to S500 may be repeatedly performed until the accuracy of the second relative relationship meets the preset requirements.

[0091] For some examples, see Figure 5 , verifying whether the accuracy of the second relative relationship meets the preset requirements may include moving the second device 12, obtaining the relationship of the position parameter relative to the first coordinate system as the third relative relationship (step S520), calculating the second conversion relationship based on the second relative relationship and the third relative relationship (step S540), and verifying whether the accuracy of the second relative relationship meets the preset requirements based on the second conversion relationship (step S560). In this case, by verifying the accuracy of the second relative relationship, the second relative relationship whose accuracy meets the preset requirements is used as a reference for calculating coordinate conversion in the subsequent measurement process, which can improve the measurement accuracy of the object to be measured.

[0092] In some examples, in step S520, the third relative relationship may be the relationship between the above position parameters and the first coordinate system after the second device 12 moves. For example, the third relative relationship may be the conversion relationship between the third coordinate system and the first coordinate system after the first device 11 moves. In other words, the third relative relationship is the conversion relationship between the third coordinate system and the first coordinate system after the "station switching" operation is performed. In some examples, the third relative relationship may be directly acquired by the first device 11.

[0093] In some examples, in step S540, the second conversion relationship may be the conversion relationship between the first coordinate system and the second coordinate system after the second device 12 moves. In other words, the second conversion relationship may be the conversion relationship between the first coordinate system and the second coordinate system after the "station transfer" operation is performed.

[0094] In some examples, after the second device 12 moves, the relationship between the second relative relationship, the third relative relationship and the second conversion relationship can be expressed as formula (3):

[0095]

[0096] in, Represents the second conversion relationship, Indicates the third relative relationship, Indicates the second relative relationship. As described above, the second relative relationship is a fixed value, and therefore, the second conversion relationship can be calculated based on the third relative relationship and the second relative relationship obtained in step S520. In this case, since the second conversion relationship is the conversion relationship between the first coordinate system and the second coordinate system after the "station switching" operation, the coordinates measured by the second device 12 at the current station after the "station switching" operation can be converted into the coordinate system of the first device 11 based on the second conversion relationship.

[0097] Figure 6 3 is a flowchart showing the method of verifying whether the accuracy of the second relative relationship meets the preset requirements based on the second conversion relationship involved in the example of the present disclosure.

[0098] As described above, in step S560, it is possible to verify whether the accuracy of the second relative relationship meets the preset requirements based on the second conversion relationship. Figure 6 , step S560 may include: obtaining the coordinate of the calibration object 2 in the second coordinate system as the fourth coordinate (step S562), calculating the coordinate of the fourth coordinate in the first coordinate system as the fifth coordinate based on the second conversion relationship (step S564), and in response to the difference between the fifth coordinate and the first coordinate being not greater than the preset value, determining that the accuracy of the second relative relationship meets the preset requirements (step S566). In this case, the coordinate of the calibration object 2 in the second coordinate system after the "station transfer" operation can be converted to the first coordinate system, and the first coordinate is the coordinate obtained by the first device 11 directly measuring the calibration object 2, and the fifth coordinate is the coordinate converted to the first coordinate system by the fourth coordinate obtained by the second device 12 measuring the calibration object 2 based on the second conversion relationship. Since the absolute position of the calibration object 2 has not changed, theoretically, the difference between the first coordinate and the fifth coordinate should be zero. Therefore, it is possible to judge whether the second relative relationship meets the preset requirements based on the difference between the first coordinate and the fifth coordinate. If the difference between the first coordinate and the fifth coordinate is not greater than the preset value, it can be determined that the accuracy of the second relative relationship meets the preset requirements.

[0099] In some examples, the preset value can be set based on the actual measurement situation. If high-precision measurement is required, the preset value can be set to a smaller value. If rough measurement is required, the preset value can be set to a larger value within a controllable range.

[0100] In some examples, the fourth coordinate may be the coordinate of the calibration object 2 measured again by the second device 12 after the second device 12 moves. In other words, the fourth coordinate is the coordinate of the calibration object 2 measured again after the second device 12 “turns over”.

[0101] In some examples, in step S564, the fifth coordinate may be calculated based on the second conversion relationship and the fourth coordinate. In some examples, the relationship between the second conversion relationship, the fourth coordinate and the fifth coordinate may be expressed as formula (4):

[0102]

[0103] Among them, C1 i represents the fifth coordinate, Represents the second conversion relationship, C2 i The fourth coordinate is represented by . Thus, the fifth coordinate can be calculated based on formula (4).

[0104] In some examples, in response to a difference between the fifth coordinate and the first coordinate being greater than a preset value, the calibration method of the present disclosure may be repeatedly executed until the difference is no greater than the preset value.

[0105] Fig. 7A It is a scene schematic diagram showing a second embodiment of the assist mechanism 13 according to the present disclosure example. Figure 7B 1 is a front view schematically showing a second embodiment of the auxiliary mechanism 13 according to the disclosed example, which is provided in the visual mechanism 121 .

[0106] In some examples, the auxiliary mechanism 13 may include a reflection unit 131 for reflecting the light beam emitted by the first device 11 (see Fig. 7A and Figure 7B ). In some examples, the reflection unit 131 may be a target ball. Thus, the first device 11 can measure the auxiliary mechanism 13. In some examples, the first device 11 can directly measure the coordinates and / or posture of the auxiliary mechanism 13 based on the emitted light beam.

[0107] In some examples, the auxiliary mechanism 13 may include at least three reflective units 131 fixedly disposed on the second device 12. For example, the number of reflective units 131 may be 3, 4, 5, 6, 7 or 8. In some examples, at least three reflective units 131 may not be collinear. In this case, the relative position of the auxiliary mechanism 13 relative to the second device 12 can remain fixed. In addition, since there is no direct measurement relationship between the first device 11 and the second device 12, the second device 12 can be unique in the coordinate system of the first device 11 by means of at least three reflective units 131 fixed to the second device 12, thereby improving the accuracy of subsequent measurement calculations. In some examples, the reflective unit 131 may be fixed to the visual mechanism 121 by a bracket. In some examples, the auxiliary mechanism 13 may be fixedly disposed on the second device 12 by a bracket.

[0108] In some examples, the position parameter related to the position of the auxiliary mechanism 13 may be the coordinates of the auxiliary mechanism 13. In some examples, the coordinates of the auxiliary mechanism 13 in the first coordinate system may be obtained as the first relative relationship. In this case, since the first relative relationship can be obtained by directly measuring the auxiliary mechanism 13 by the first device 11, the steps of calibrating the second relative relationship can be simplified, thereby improving the calibration efficiency.

[0109] In some examples, when the position parameter is the coordinate of the auxiliary mechanism 13, the second relative relationship in step S500 may be the coordinate of the auxiliary mechanism 13 in the second coordinate system. In some examples, when the position parameter is the coordinate of the auxiliary mechanism 13, the relationship between the first relative relationship, the first conversion relationship and the second relative relationship may be expressed as formula (21):

[0110]

[0111] Among them, C3 represents the first relative relationship, represents the first conversion relationship, and C4 represents the second relative relationship. As described above, the auxiliary mechanism 13 is fixed to the first device 11. Thus, the second relative relationship can be a constant value.

[0112] In some examples, when the position parameter is the coordinate of the auxiliary mechanism 13, the third relative relationship in step S520 may refer to the coordinate of the auxiliary mechanism 13 in the first coordinate system after the second device 12 moves. In some examples, the first device 11 may directly measure the coordinate of the auxiliary mechanism 13 in the first coordinate system. In this case, the conversion relationship between the first coordinate system and the second coordinate system after the second device 12 moves can be calculated based on the third relative relationship and the second relative relationship, that is, the second conversion relationship. Specifically, the relationship between the second relative relationship, the third relative relationship, and the second conversion relationship can be expressed as formula (31):

[0113]

[0114] Among them, C3 i Indicates the third relative relationship, represents the second conversion relationship, and C4 represents the second relative relationship. Thus, the second conversion relationship can be calculated according to the second relative relationship calculated in step S500 and the third relative relationship measured in step S520.

[0115] Figure 8 is a flow chart showing a measurement method involved in the examples of the present disclosure.

[0116] The present disclosure also relates to a measurement method, which can measure the object to be measured based on the calibrated second relative relationship and complete global calibration without the need to match the coordinate system before and after the "station transfer" operation. For ease of description, the above names are still used.

[0117] In some examples, the coordinates of the object to be measured in the first coordinate system can be calculated based on the second relative relationship, the first relative relationship, and the coordinates of the object to be measured in the second coordinate system in the calibration method involved in the present disclosure. Specifically, in some examples, see Figure 8 The measuring method may include obtaining the relationship between the position parameters of the auxiliary mechanism 13 and the first coordinate system as a third relative relationship (step S820), calculating a second transformation relationship based on the second relative relationship and the third relative relationship (step S840), obtaining the coordinates of the object to be measured in the second coordinate system (step S860), and transforming the coordinates of the object to be measured in the second coordinate system into the first coordinate system based on the second transformation relationship (step S880).

[0118] In the measurement method involved in the present disclosure, since the auxiliary mechanism 13 is fixedly arranged on the second device 12, the second relative relationship obtained by calibration can remain relatively fixed. In other words, regardless of whether the second device 12 moves or not, the second relative relationship remains a constant value. During the measurement process, when the second device 12 is "relocated", the first device 11 can still directly obtain the relative relationship (i.e., the third relative relationship) of the position parameters used to characterize the auxiliary mechanism 13 after the "relocation" operation of the second device 12 relative to the coordinate system of the first device 11 through the light beam reflected by the auxiliary mechanism 13. Since the pre-calibrated second relative relationship is a constant value, The conversion relationship between the first coordinate system and the second coordinate system after the "station switching" operation (i.e., the second conversion relationship) can be directly calculated based on the second relative relationship and the third relative relationship. Based on the second conversion relationship, the three-dimensional information of the object to be measured obtained by the second device 12 can be directly converted into the coordinate system of the first device 11 (i.e., the three-dimensional information is converted from the second coordinate system to the first coordinate system). Therefore, there is no need to match the coordinate system of the second device 12 before and after the "station switching" operation, and the complete three-dimensional information of the object to be measured can be unified into the same coordinate system (i.e., unified into the first coordinate system to complete global correction), thereby improving the measurement efficiency and measurement accuracy.

[0119] Although the present disclosure is specifically described above in conjunction with the accompanying drawings and embodiments, it is to be understood that the above description does not limit the present disclosure in any form. Those skilled in the art may modify and change the present disclosure as needed without departing from the essential spirit and scope of the present disclosure, and these modifications and changes all fall within the scope of the present disclosure.

Claims

1. A calibration method for a tracking laser scanning system, characterized in that: The tracking laser scanning system includes a first device, a second device that cooperates with the first device and is used to scan the object to be measured, and an auxiliary mechanism fixedly arranged on the second device and used to reflect the light beam emitted by the first device. The calibration method includes: establishing a coordinate system of the first device as a first coordinate system, and establishing a coordinate system of the second device as a second coordinate system; obtaining the coordinates of the calibration object in the first coordinate system as the first coordinates, and obtaining the coordinates of the calibration object in the second coordinate system as the second coordinates; calculating the transformation relationship between the first coordinate system and the second coordinate system based on the first coordinates and the second coordinates as the first transformation relationship; and obtaining the relationship of the position parameter related to the position of the auxiliary mechanism relative to the first coordinate system as a first relative relationship, and calibrating the relationship of the position parameter relative to the second coordinate system as a second relative relationship based on the first relative relationship and the first transformation relationship.

2. The calibration method of the tracking laser scanning system according to claim 1, characterized in that: The number of the calibration objects is at least 3, and at least the 3 calibration objects are not collinear.

3. The calibration method of the tracking laser scanning system according to claim 1, characterized in that: It also includes verifying whether the accuracy of the second relative relationship meets the preset requirements. Verifying whether the accuracy of the second relative relationship meets the preset requirements includes: moving the second device to obtain the relationship between the position parameter and the first coordinate system as a third relative relationship; calculating the transformation relationship between the first coordinate system and the second coordinate system after the second device is moved based on the second relative relationship and the third relative relationship as a second transformation relationship; and verifying whether the accuracy of the second relative relationship meets the preset requirements based on the second transformation relationship.

4. The calibration method of the tracking laser scanning system according to claim 3, characterized in that: Verifying whether the accuracy of the second relative relationship meets the preset requirements based on the second transformation relationship includes: obtaining the coordinates of the calibration object in the second coordinate system as the fourth coordinate; calculating the coordinates of the fourth coordinate in the first coordinate system as the fifth coordinate based on the second transformation relationship; and in response to the difference between the fifth coordinate and the first coordinate being no greater than a preset value, determining that the accuracy of the second relative relationship meets the preset requirements.

5. The calibration method of a tracking laser scanning system according to any one of claims 1 to 4, characterized in that: The auxiliary mechanism is configured to receive the light beam emitted by the first device and reversely track the first device based on the received light beam.

6. The calibration method of the tracking laser scanning system according to claim 5, characterized in that: The position parameter related to the position of the auxiliary mechanism is the coordinate system of the auxiliary mechanism. Let the coordinate system of the auxiliary mechanism be the third coordinate system. Acquiring the first relative relationship includes: acquiring the third coordinate system through the first device; and calculating the conversion relationship between the third coordinate system and the first coordinate system as the first relative relationship.

7. The calibration method of a tracking laser scanning system according to any one of claims 1 to 4, characterized in that: The auxiliary mechanism includes at least three reflecting units fixedly arranged on the second device, and at least three of the reflecting units are not collinear.

8. The calibration method of the tracking laser scanning system according to claim 7, characterized in that: The position parameters related to the position of the auxiliary mechanism are the coordinates of the auxiliary mechanism, and the coordinates of the auxiliary mechanism in the first coordinate system are acquired as the first relative relationship.

9. The calibration method of the tracking laser scanning system according to claim 1, characterized in that: The calibration object includes a base and a marker disposed on the base, and the marker includes at least one of a reference sphere, a standard sphere or a target sphere.

10. A tracking laser scanning system, characterized in that: The tracking laser scanning system calibrates the second relative relationship using the calibration method according to any one of claims 1 to 9.

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