Non-contact calibration device and method for robotic arm workpiece coordinate system

Abstract

The present invention relates to a non-contact calibration device and method for the workpiece coordinate system of a robotic arm. The calibration method includes the following steps: Install three laser pointers on the robotic arm and make the emitted laser beams intersect at a point to form a laser intersection point; Adjust the attitude of the laser pointers so that the laser intersection point is located below the tool; Install a camera on the robotic arm and set the camera towards the end of the tool and the laser intersection point; Use the laser intersection point to calibrate the calibration coordinate system on the workpiece surface. During the calibration process, use the camera to capture video data of the end of the tool and the laser intersection point and display it; According to the distance between the laser intersection point and the end of the tool, convert the calibration coordinate system into the workpiece coordinate system, thereby completing the non-contact calibration of the workpiece coordinate system. The present invention uses the laser intersection point to replace the end tool of the robotic arm, solving the problem that the tool cannot directly contact the ground or the workpiece. The calibration method is simple to operate and the calibration result has high accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial robot calibration, and particularly refers to a non-contact calibration device and method for the workpiece coordinate system of a robotic arm. Background Art

[0002] Since the invention of robots, after years of development, many significant achievements have been made in their technology. The calibration of robot accuracy is an essential part of it. At present, although many robots have high repeat positioning accuracy, their absolute positioning accuracy is relatively low, which has become one of the bottlenecks restricting the development of the robot industry. In order to improve the absolute positioning accuracy of robots, robot calibration technology has emerged.

[0003] Scholars at home and abroad have conducted extensive and in-depth research on robot calibration technology from aspects such as modeling and measurement methods. Among them, the calibration of the workpiece coordinate system of the robotic arm has a very practical effect on the actual application of robots. There are many methods for calibrating the workpiece coordinate system of industrial robots, such as the common three-point calibration method, that is, using the center point of the tool at the end of the robotic arm to sequentially touch three points on the ground and record them respectively. However, in some applications, the end tool cannot directly touch the ground to avoid damaging the end tool. Therefore, the workpiece coordinate system of the robot cannot be directly calibrated, which has led to many methods for calibrating the workpiece coordinate system of the robotic arm using different measurement means and tools, such as calibrating using a calibration object, calibrating using the handshake operation of multiple robots, etc. The above methods all require installing corresponding end-effectors or using multiple robots, and the operation is relatively complex; calibrating using a calibration object has high requirements for the object itself, and its accuracy remains to be investigated. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a non-contact calibration device and method for the workpiece coordinate system of a robotic arm, so as to solve the problems that the existing three-point calibration method cannot be applied to the situation where the end tool of the robotic arm cannot directly touch the ground, the operation of multi-robot calibration is complex, and the accuracy of calibration using a calibration object remains to be investigated.

[0005] The technical solution to achieve the above purpose is as follows:

[0006] The present invention provides a non-contact calibration method for the workpiece coordinate system of a robotic arm. A tool is installed at the end of the robotic arm. The calibration method includes the following steps:

[0007] Provide three laser pointers, install the three laser pointers on the robotic arm and make the laser beams emitted by the three laser pointers intersect at a point to form a laser intersection point;

[0008] Adjust the posture of the laser pointer so that the laser intersection point is located below the tool;

[0009] Provide a camera, install the camera on the robotic arm, and arrange the camera to face the end of the tool and the laser intersection point;

[0010] Use the laser intersection point to calibrate a calibration coordinate system on the workpiece surface. During the calibration process, use the camera to capture video data of the end of the tool and the laser intersection point and display it; and

[0011] According to the distance between the laser intersection point and the end of the tool, convert the calibration coordinate system into a workpiece coordinate system, thereby completing the non-contact calibration of the workpiece coordinate system.

[0012] The calibration method of the present invention takes advantage of the high precision and non-contact calibration of the laser beam. It uses the laser intersection point of the laser beam to replace the tool at the end of the robotic arm to solve the problem that the tool at the end of the robotic arm cannot directly contact the ground or the workpiece. Furthermore, the calibration coordinate system is calibrated by the three-point method using the laser intersection point. Since the laser intersection point is located below the tool, the calibration coordinate system can be converted according to the distance between the laser intersection point and the tool to obtain the workpiece coordinate system. During the entire calibration process, the camera records the end of the tool and the laser intersection point throughout the process, enabling remote observation of the calibration process. The calibration method of the present invention is simple to operate, has low requirements for robot operation, does not involve the readings of internal encoders and joint angle values of the robot, avoids the influence of calibration accuracy caused by human operation errors and robot itself errors, and at the same time takes advantage of the high measurement accuracy of the laser, resulting in high calibration accuracy.

[0013] A further improvement of the non-contact calibration method of the workpiece coordinate system of the robotic arm of the present invention is that when calibrating using the laser intersection point, the position of the laser intersection point is adjusted through the following steps so that the laser intersection point is located on the workpiece surface:

[0014] Control the robotic arm to move upward, and judge whether the distance between the three laser points on the workpiece surface becomes larger according to the video data captured by the camera;

[0015] If so, control the robotic arm to move downward until the laser intersection point is located on the workpiece surface;

[0016] If not, control the robotic arm to continue moving upward until the laser intersection point is located on the workpiece surface.

[0017] A further improvement of the non-contact calibration method of the workpiece coordinate system of the robotic arm of the present invention is that when installing the laser pen, provide a laser pen fixing block and install three laser pens on the laser pen fixing block;

[0018] Mount the laser pointer fixing block on the robotic arm in an inclined manner, and place the laser intersection point on the plane where the tool is located and below the end of the tool.

[0019] Rotate and adjust the position of the laser pointer fixing block along the inclined surface of the laser pointer fixing block so that the laser intersection point is located on the axis of the tool.

[0020] A further improvement of the non-contact calibration method for the robotic arm workpiece coordinate system of the present invention is that it further includes:

[0021] Provide a laser pointer bracket, which is provided with a first arc-shaped adjustment groove and a first connection hole located below the first arc-shaped adjustment groove. Mount the laser pointer bracket on the robotic arm and make the mounting surface of the laser pointer bracket perpendicular to the robotic arm.

[0022] Provide a laser pointer fixing frame, which is provided with a second arc-shaped adjustment groove and a second connection hole located below the second arc-shaped adjustment groove. Connect the laser pointer fixing frame to the laser pointer bracket through a fastener passing through the first arc-shaped adjustment groove and the first connection hole, and make the laser pointer fixing frame perpendicular to the laser pointer bracket.

[0023] Place the laser pointer fixing block on the laser pointer fixing frame and connect it to the laser pointer fixing frame through a connecting piece passing through the second arc-shaped adjustment groove and the second connection hole.

[0024] By adjusting the position of the corresponding fastener along the first arc-shaped adjustment groove, the laser pointer fixing frame is rotated and adjusted around the fastener passing through the first connection hole, and then drives the laser pointer fixing block to rotate and adjust, so as to adjust the laser intersection point to be located on the plane where the tool is located and below the end of the tool.

[0025] By adjusting the position of the corresponding connecting piece along the second arc-shaped adjustment groove, the laser pointer fixing block is rotated and adjusted around the connecting piece passing through the second connection hole, so as to adjust the laser intersection point to be located on the axis of the tool.

[0026] A further improvement of the non-contact calibration method for the robotic arm workpiece coordinate system of the present invention is that when installing the camera, mount the camera on the robotic arm in an inclined and rotatable manner, and then rotate and adjust the camera so that the viewing angle range of the camera covers the end of the tool and the laser intersection point.

[0027] A further improvement of the non-contact calibration method for the robotic arm workpiece coordinate system of the present invention is that it further includes:

[0028] Provide a mounting bracket and mount the mounting bracket on the robotic arm and close to the tool;

[0029] Provide a camera bracket and connect the camera bracket to the mounting bracket in a manner that can be rotationally adjusted in a vertical plane;

[0030] Provide a camera fixing bracket and connect the camera fixing bracket to the camera bracket in a manner that can be rotationally adjusted in a longitudinal plane;

[0031] Mount the camera on the camera fixing bracket, and by rotationally adjusting the camera fixing bracket, the camera can be rotationally adjusted in the longitudinal plane, so as to adjust the viewing angle range of the camera to be at the height of the end of the tool and the laser intersection point. By rotationally adjusting the camera bracket, the camera can be rotationally adjusted in the vertical plane, so as to adjust the viewing angle range of the camera to cover the end of the tool and the laser intersection point.

[0032] The present invention also provides a non-contact calibration device for the workpiece coordinate system of a robotic arm. A tool is installed at the end of the robotic arm. The calibration device includes:

[0033] Three laser pens installed on the robotic arm in a manner that the attitude can be adjusted. The laser beams emitted by the three laser pens intersect at a point to form a laser intersection point. By adjusting the attitude of the laser pens, the laser intersection point can be located below the tool; and

[0034] A camera installed on the robotic arm. The camera is arranged towards the end of the tool and the laser intersection point. By shooting the end of the tool and the laser intersection point through the camera, video data is obtained. Thus, a calibration coordinate system can be calibrated on the workpiece surface by using the video data and the laser intersection point, and then the workpiece coordinate system can be obtained by conversion.

[0035] A further improvement of the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention is that it further includes a laser pen fixing block, and the laser pen fixing block is installed on the robotic arm in an inclined manner;

[0036] Three laser pens are installed on the laser pen fixing block.

[0037] A further improvement of the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention is that it further includes a laser pen bracket and a laser pen fixing frame;

[0038] The laser pen bracket is installed on the robotic arm and the laser pen bracket is perpendicular to the mounting surface of the robotic arm. The laser pen bracket is provided with a first arc-shaped adjustment groove and a first connection hole located below the first arc-shaped adjustment groove;

[0039] The laser pointer fixing bracket is connected to the laser pointer support through a fastener passing through the first arc-shaped adjustment slot and the first connection hole, and the laser pointer fixing bracket is perpendicular to the laser pointer support. The laser pointer fixing bracket is provided with a second arc-shaped adjustment slot and a second connection hole located below the second arc-shaped adjustment slot;

[0040] The laser pointer fixing block is placed on the laser pointer fixing bracket and is connected to the laser pointer fixing bracket through a connecting piece passing through the second arc-shaped adjustment slot and the second connection hole;

[0041] By adjusting the position of the corresponding fastener along the first arc-shaped adjustment slot, the laser pointer fixing bracket can be rotated and adjusted around the fastener passing through the first connection hole, and then the laser pointer fixing block can be rotated and adjusted, so as to adjust the laser intersection point to be located on the plane where the tool is located and below the end of the tool;

[0042] By adjusting the position of the corresponding connecting piece along the second arc-shaped adjustment slot, the laser pointer fixing block can be rotated and adjusted around the connecting piece passing through the second connection hole, so as to adjust the laser intersection point to be located on the axis of the tool.

[0043] A further improvement of the non-contact calibration device for the mechanical arm workpiece coordinate system of the present invention is that the camera is installed on the mechanical arm in an inclined and rotatable manner, and the camera is rotated and adjusted so that the viewing angle range of the camera covers the end of the tool and the laser intersection point. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic structural diagram of the non-contact calibration device for the mechanical arm workpiece coordinate system of the present invention installed on the mechanical arm.

[0045] Figure 2 It is an enlarged schematic diagram of the non-contact calibration device for the mechanical arm workpiece coordinate system of the present invention after removing the camera.

[0046] Figure 3 It is an enlarged schematic diagram of the non-contact calibration device for the mechanical arm workpiece coordinate system of the present invention after removing the laser pointer.

[0047] Figure 4 It is a side view of the mounting bracket in the non-contact calibration device for the mechanical arm workpiece coordinate system of the present invention.

[0048] Figure 5 It is a schematic structural diagram of the laser pointer fixing block and the laser beam in the non-contact calibration device for the mechanical arm workpiece coordinate system of the present invention.

[0049] Figure 6Schematic diagram of the structure of the laser pen fixing block in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0050] Figure 7 Axonometric view of the laser pen fixing block in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0051] Figure 8 Front view of the laser pen fixing bracket in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0052] Figure 9 Side view of the laser pen fixing bracket in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0053] Figure 10 Axonometric view of the laser pen fixing bracket in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0054] Figure 11 Front view of the laser pen support in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0055] Figure 12 Top view of the laser pen support in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0056] Figure 13 Axonometric view of the laser pen support in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0057] Figure 14 Axonometric view of the camera support in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0058] Figure 15 Front view of the camera support in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0059] Figure 16 Axonometric view of the camera fixing bracket in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0060] Figure 17 Front view of the camera fixing bracket in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0061] Figure 18 Schematic diagram of three possible situations of the laser beams emitted by the three laser pens in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention on the workpiece surface.

[0062] Figure 19 Schematic diagram of each coordinate system during the calibration process of the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention.

[0063] Figure 20 This is a flowchart of a non-contact calibration method for the workpiece coordinate system of the robotic arm of the present invention. Detailed implementation manners

[0064] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0065] Refer to Figure 1 , the present invention provides a non-contact calibration device and method for the workpiece coordinate system of a robotic arm, which uses a laser pointer and a camera to achieve coordinate calibration. The calibration operation is simple. The laser pointer is installed on the robotic arm and can be adjusted in two degrees of freedom. The camera is also installed on the robotic arm and can be adjusted in two degrees of freedom. The laser intersection point formed by the intersection of the laser beams emitted by the laser pointer is used to replace the center point of the tool at the end of the robotic arm. The coordinate system is calibrated by the three-point method, and then the coordinate transformation from the laser intersection point to the tool center point is performed to obtain the workpiece coordinate system. The above calibration method can effectively avoid the direct contact of the tool with the workpiece or the ground during the calibration process, avoid damaging the tool, and the entire calibration process can be remotely observed through the camera. Using the laser pointer for calibration has the characteristic of high calibration result accuracy. The non-contact calibration device and method for the workpiece coordinate system of the robotic arm of the present invention will be described below in conjunction with the accompanying drawings.

[0066] Refer to Figure 1 , which shows a schematic structural diagram of the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention installed on the robotic arm. Refer to Figure 2 , which shows an enlarged schematic diagram of the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention after removing the camera. Refer to Figure 5 , which shows a schematic structural diagram of the laser pointer fixing block and the laser beam in the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention. The following will be described in conjunction with Figure 1 , Figure 2 and Figure 5 , the non-contact calibration device for the workpiece coordinate system of the robotic arm of the present invention will be described.

[0067] As Figure 1 , Figure 2 and Figure 5As shown in the figure, the non-contact calibration device for the robotic arm workpiece coordinate system of the present invention includes three laser pointers 31 and a camera 32. A tool 20 is installed at the end of the robotic arm 10, and the tool 20 is usually arranged in a vertical state. Among them, the three laser pointers 31 are installed on the robotic arm 10 in a manner that the attitude can be adjusted. The laser beams 311 emitted by the three laser pointers 31 intersect at a point to form a laser intersection point 312. By adjusting the attitude of the laser pointer 31, the laser intersection point 312 can be made to be located below the tool 20. Preferably, the laser intersection point 312 is located below the center point of the tool 20, and there is a certain distance between the laser intersection point 312 and the center point of the tool 20. The camera 32 is installed on the robotic arm 20, and the camera 32 is arranged towards the end of the tool 20 and the laser intersection point 312. Video data is obtained by the camera 32 photographing the end of the tool 20 and the laser intersection point 312. Thus, the calibration coordinate system can be calibrated on the workpiece surface by using the video data and the laser intersection point 312, and then the workpiece coordinate system can be obtained through conversion.

[0068] Preferably, the video data photographed by the camera 32 can be played through a display device. The calibration process can be observed through the played video data. When calibrating the coordinates by using the laser intersection point 312, the three-point method can be used to calibrate the calibration coordinate system on the workpiece surface. The laser intersection point 312 is located below the center point of the tool 20, and there is a certain distance between the laser intersection point 312 and the center point of the tool 20. Furthermore, according to this distance, the calibration coordinate system can be converted into the workpiece coordinate system, thus completing the non-contact calibration of the workpiece coordinate system. Using the laser intersection point 312 to calibrate the workpiece coordinate system can avoid the direct contact between the tool 20 and the workpiece, and can prevent the tool 20 from being damaged.

[0069] In a specific embodiment of the present invention, as Figure 1 、 Figures 5 to 7 shown, the calibration device of the present invention further includes a laser pointer fixing block 343. The laser pointer fixing block 343 is installed on the robotic arm 10 in an inclined manner, and the three laser pointers 31 are installed on the laser pointer fixing block 343.

[0070] More preferably, the laser pointer fixing block 343 is a flat plate.

[0071] Furthermore, the laser pointer fixing block 343 is provided with a mounting groove, and the laser pointer 31 is correspondingly placed in the mounting groove. The laser beams 311 emitted by the three laser pointers 31 exactly converge at one point. The laser pointer fixing block 343 is installed on the robotic arm 10 in an inclined manner. The plane where the laser pointer fixing block 343 is located intersects with the plane where the tool 20 is located. By adjusting the installation position of the laser pointer fixing block 343, the laser intersection point 312 can be exactly located below the center point of the tool 20. Rotate and adjust the position of the laser pointer fixing block 343 along the inclined surface of the laser pointer fixing block 343 so that the laser intersection point 312 is located on the axis of the tool 20.

[0072] In a specific embodiment of the present invention, as Figure 1 and Figure 2 shown, the laser pointer fixing block 343 is adjustably installed on the robotic arm 10 through the laser pointer bracket 341 and the laser pointer fixing frame 342, so that the laser intersection point 312 can be adjusted below the tool 20. Furthermore, as shown in FIG. 10, the laser pointer bracket 341 is installed on the robotic arm 10. The laser pointer bracket 341 is perpendicular to the installation surface of the robotic arm. The laser pointer bracket 341 is provided with a first arc-shaped adjustment groove 3411 and a first connection hole 3412 located below the first arc-shaped adjustment groove 3411. Combining Figure 8 and Figure 2 shown, the laser pointer fixing frame 342 is connected to the laser pointer bracket 341 through a fastener passing through the first arc-shaped adjustment groove 3411 and the first connection hole 3412, and the laser pointer fixing frame 342 is perpendicular to the laser pointer bracket 341. The laser pointer fixing frame 342 intersects but is not perpendicular to the plane where the tool 20 is located. In a preferred embodiment, in the state shown in Figure 1 the end of the tool 20 is vertically arranged and is located in the vertical plane. The installation surface of the robotic arm 10 is parallel to the vertical plane, and the laser pointer bracket 341 is perpendicular to the installation surface of the robotic arm.

[0073] Preferably, as Figures 8 to 10As shown, the laser pointer holder 342 includes a fixing portion 3423 located at the upper part and a connecting portion 3424 located at the lower part. The connecting portion and the fixing portion 3423 are arranged in parallel and in different planes, and there is a connecting section vertically connecting the connecting portion 3424 and the fixing portion 3423. The fixing portion 3423 is used to connect with the laser pointer bracket 341, and the connecting portion 3424 is used to connect with the laser pointer fixing block 343. Through holes are provided on opposite sides of the fixing portion 3423. When connecting the fixing portion 3423 and the laser pointer bracket 341, align the through holes with the first arc-shaped adjustment groove 3411 and the first connection hole 3412 on the laser pointer bracket 341. Insert a fastener through the first arc-shaped adjustment groove 3411 and the corresponding through hole, and insert another fastener through the first connection hole 3412 and the corresponding through hole. Fasten and connect the fixing portion 3423 and the laser pointer bracket 341 with the two fasteners. When fastening and connecting, let the fastener located in the first arc-shaped adjustment groove 3411 adjust its position along the first arc-shaped adjustment groove 3411, so that the laser pointer holder 342 rotates and adjusts around the fastener located in the first connection hole 3412 as the axis. In this way, the adjustment of one degree of freedom is achieved. When the laser pointer fixing block 343 installs the laser pointer on the laser pointer holder 342, the front and back rotation adjustment of the laser pointer 31 is achieved through the first arc-shaped adjustment groove 3411, that is, the laser pointer 31 rotates in the direction of approaching or moving away from the tool 20.

[0074] Furthermore, as Figures 11 to 13 shown, the laser pointer bracket 341 includes two longitudinally arranged plates 3413 arranged opposite to each other and a horizontally arranged horizontal plate 3414 connected to the tops of the two longitudinally arranged plates 3413. The horizontal plate 3414 is used to connect to the robotic arm 10; the first arc-shaped adjustment groove 3411 and the first connection hole 3412 are provided on the longitudinally arranged plates 3413. When connecting the laser pointer holder 342, place the fixing portion 3423 of the laser pointer holder 342 between the two longitudinally arranged plates 3413, and let the fasteners pass through the two longitudinally arranged plates 3413 and the laser pointer holder 342, and then fasten and connect after adjusting the posture.

[0075] Even further, as Figures 8 to 10As shown, the laser pointer fixing bracket 342 is provided with a second arc-shaped adjustment groove 3421 and a second connection hole 3422 located below the second arc-shaped adjustment groove 3421. The laser pointer fixing block 343 is placed on the laser pointer fixing bracket 342 and is connected to the laser pointer fixing bracket 342 through a connecting piece passing through the second arc-shaped adjustment groove 3421 and the second connection hole 3422. In this way, by adjusting the position of the corresponding fastener along the first arc-shaped adjustment groove 3411, the laser pointer fixing bracket 342 can be rotated and adjusted around the fastener passing through the first connection hole 3412, and then the laser pointer fixing block 343 can be rotated and adjusted, so as to realize the adjustment that the laser intersection point is located on the plane where the tool is located and below the end of the tool; by adjusting the position of the corresponding connecting piece along the second arc-shaped adjustment groove 3421, the laser pointer fixing block 343 can be rotated and adjusted around the connecting piece passing through the second connection hole 3422, so as to realize the adjustment that the laser intersection point is located on the axis of the tool.

[0076] Preferably, the second connection hole 3422 below the second arc-shaped adjustment groove 3421 is arranged on the connection part 3424 of the laser pointer fixing bracket 342, and the connection part 3424 is a flat plate. Figure 6 As shown, the laser pointer fixing block 343 is attached to the connection part 3424, and then is connected through a connecting piece passing through the corresponding second arc-shaped adjustment groove 3421 and the second connection hole 3422. The second arc-shaped adjustment groove 3421 and the second connection hole 3422 provide another degree of freedom adjustment for the laser pointer, and the laser pointer can be adjusted to rotate left and right in the oblique plane where the connection part 3424 is located.

[0077] As Figure 1 and Figure 3 shown, the mounting bracket 33 is L-shaped, including a first mounting part 331 and a second mounting part 332. The first mounting part 331 and the second mounting part 332 are perpendicularly arranged. The first mounting part 331 is horizontally arranged, and the second mounting part 332 is vertically arranged. The second mounting part 332 is attached to the mounting surface of the robotic arm 10 and fixedly connected to the mounting surface. Figure 9 and Figure 10 shown, the first mounting part 331 is used to connect the laser pointer bracket 341. The horizontal plate 3414 of the laser pointer bracket 341 is attached to the first mounting part 331 and tightly connected to the first mounting part 331. The longitudinal plate 3413 of the laser pointer bracket 341 is perpendicular to the first mounting part 331, the second mounting part 332 and the mounting surface of the robotic arm 10.

[0078] In a specific embodiment of the present invention, as Figure 1 and Figure 3As shown, the camera 32 is installed on the robotic arm 10 in an inclined and rotatable manner. By rotating and adjusting the camera 32, the viewing angle range A of the camera 32 covers the end of the tool 20 and the laser intersection point 312. The end of the tool 20 is the bottom of the tool 20.

[0079] Furthermore, the camera 32 is installed on the second mounting portion 332 of the mounting bracket 33, and the lens of the camera 32 is set obliquely downward. The mounting bracket 33 is arranged close to the tool 20, and the tool 20 is installed on the end flange of the robotic arm 10. Combining Figure 4 As shown, a card slot is provided at the top of the mounting bracket 33. The mounting bracket 33 is sleeved on the end of the robotic arm 10 through this card slot, and then is fixedly connected to the robotic arm 10 through the wall plates on both sides of the card slot.

[0080] Combining Figure 14 and Figure 16 As shown, the camera 32 is installed on the second mounting portion 332 of the mounting bracket 33 through the camera bracket 35 and the camera fixing bracket 36. The camera bracket 35 can be rotationally adjusted within the vertical plane of the second mounting portion 332. By rotating and adjusting the camera bracket 35 and the camera fixing bracket 36, the position of the viewing angle range A of the camera 32 can be adjusted so that the viewing angle range A covers the end of the tool 20 and the laser intersection point 312.

[0081] When adjusting the viewing angle range A of the camera 32, first rotate and adjust the camera bracket 35 to align the viewing angle range A of the camera 32 with the end of the tool 20, and then rotate and adjust the camera fixing bracket 36 to move the viewing angle range A of the camera 32 downward until it covers the end of the tool 20 and the laser intersection point 312.

[0082] As Figure 14 and Figure 15 As shown, the camera bracket 35 is L-shaped, including a fitting plate 351 and an assembly plate 352 that are perpendicular to each other. The fitting plate 351 is provided with a mounting hole 3512 and a first arc-shaped long hole 3511. The first arc-shaped long hole 3511 is located below the mounting hole 3512. The fitting plate 351 is fixedly connected to the second mounting portion 331 by bolts passing through the corresponding mounting hole 3512 and the first arc-shaped long hole 3511. The first arc-shaped long hole 3511 provides rotational adjustment for the camera 32 within the vertical plane. Specifically, the position of the bolt is adjusted along the first arc-shaped long hole 3511, so that the fitting plate 351 can rotate around the bolt located in the mounting hole 3512 as the axis, realizing the adjustment of one degree of freedom of the camera 32.

[0083] As Figure 16 and Figure 17As shown, the camera fixing bracket 36 includes a pair of ear plates 361 arranged oppositely and a bottom plate 362 vertically connected to the bottoms of the pair of ear plates 361. The bottom plate 362 is fixedly connected to the camera 32. Second arc-shaped long holes 3611 and assembly holes 3612 are provided on the pair of ear plates 361. The assembly holes 3612 are located above the second arc-shaped long holes 3611. Combining Figure 14 As shown, when installing the camera fixing bracket 36, the pair of ear plates 361 are sleeved on the assembly plate 352, and then the connection between the camera fixing bracket 36 and the camera bracket 35 is realized by passing a connecting bolt through the second arc-shaped long holes 3611, the assembly holes 3612 and the assembly plate 352. The second arc-shaped long holes 3611 provide rotational adjustment of the tilting angle for the camera 32, that is, front-back rotation adjustment, realizing the adjustment of another degree of freedom of the camera 32.

[0084] As Figure 3 shown, an installation shell is sleeved outside the camera 32, and the camera fixing bracket 36 is fixedly connected to the installation shell, thereby realizing the installation of the camera 32.

[0085] When calibrating using the calibration device of the present invention, there are usually three laser points on the surface of the workpiece to be calibrated, rather than the laser intersection point 312. As Figure 18 shown, three laser points are shown on the first plane 41 and the third plane 43, and the laser intersection point 312 is located on the second plane 42. At this time, it is necessary to adjust the robotic arm 10 to move so that the laser intersection point 312 is located on the tool surface. When adjusting, first move the robotic arm 10 upward, and then judge the change in the distance between the laser points on the workpiece surface. If the distance between the laser points becomes larger, it indicates that the laser intersection point 312 is above the workpiece surface, and it is necessary to move the robotic arm 10 downward for adjustment until the laser intersection point 312 is located on the workpiece surface. If the distance between the laser points becomes smaller, it indicates that the laser intersection point 312 is below the workpiece surface, and continue to move the robotic arm 10 upward until the laser intersection point 312 is located on the workpiece surface. After that, the workpiece coordinate system can be calibrated using the laser intersection point.

[0086] As Figure 19 shown, the three-point method for calibrating the coordinate system is realized by setting three teaching points on the surface of the workpiece. The first teaching point 51 is the origin, the second teaching point 52 is in the positive X-axis direction, and the line connecting the third teaching point 53 and the second teaching point 52 is parallel to the Y-axis, and the third teaching point 53 is located in the positive Y-axis region. Move the robotic arm 10 with the laser intersection point to the first teaching point 51, and then move to the second teaching point 52 and the third teaching point 53, thereby obtaining the origin, X-axis and Y-axis of the calibrated coordinate system B, and then the Z-axis is determined by the right-hand rule. Denote the coordinate system of the laser intersection point as T Laser , and denote the coordinate system of the tool 20 as T Tool, the coordinate system of the end flange of the robotic arm is denoted as T Flange , the reference coordinate system of the robotic arm is denoted as T Base , at a distance of h in the Z-axis direction, the coordinate transformation matrix is as follows:

[0087]

[0088] The coordinate system of the tool 20 has been calibrated relative to the coordinate system of the end flange of the robotic arm, so the coordinate system T of the laser intersection point can be obtained Laser relative to the reference coordinate system T of the robotic arm Base The coordinate transformation matrix is as follows:

[0089]

[0090] As described above, the coordinate system T of the laser intersection point Laser relative to the reference coordinate system T of the robotic arm Base Each part of the coordinate transformation matrix is known, so the workpiece coordinate system can be calibrated using the above laser intersection point. Before calibration, select the tool represented by the laser intersection point coordinate system T stored in the robotic arm memory Laser .

[0091] During the calibration process of the workpiece coordinate system, the camera 32 always aims at the tool end and the laser intersection point for shooting, realizing remote observation of the calibration process

[0092] The present invention also provides a non-contact calibration method for the workpiece coordinate system of a robotic arm. The calibration method will be described below

[0093] As Figure 20 shown, the calibration method of the present invention includes the following steps:

[0094] Execute step S101, provide three laser pointers, install the three laser pointers on the robotic arm and make the laser beams emitted by the three laser pointers intersect at a point to form a laser intersection point; then execute step S102;

[0095] Execute step S102, adjust the posture of the laser pointer so that the laser intersection point is located below the tool; then execute step S103;

[0096] Execute step S103, provide a camera, install the camera on the robotic arm, and set the camera towards the end of the tool and the laser intersection point; then execute step S104;

[0097] Execute step S104, use the laser intersection point to calibrate the calibration coordinate system on the workpiece surface. During the calibration process, use the camera to shoot the end of the tool and the laser intersection point to form video data and display it; then execute step S105;

[0098] Execute step S105 to convert the calibration coordinate system into the workpiece coordinate system according to the distance between the laser intersection point and the end of the tool, thereby completing the non-contact calibration of the workpiece coordinate system.

[0099] In a specific embodiment of the present invention, when calibrating using the laser intersection point, the position of the laser intersection point is adjusted through the following steps to make the laser intersection point located on the workpiece surface:

[0100] As Figure 18 shown, control the robotic arm to move upward, and judge whether the distance between the three laser points on the workpiece surface becomes larger according to the video data captured by the camera;

[0101] If so, control the robotic arm to move downward until the laser intersection point 312 is located on the workpiece surface;

[0102] If not, control the robotic arm to continue moving upward until the laser intersection point 312 is located on the workpiece surface.

[0103] In a specific embodiment of the present invention, as Figure 5 and Figure 6 shown, when installing the laser pen 31, provide a laser pen fixing block 343, and install the three laser pens 31 on the laser pen fixing block 343;

[0104] Combined with Figure 1 and Figure 2 shown, install the laser pen fixing block 343 on the robotic arm 10 in an inclined state, and make the laser intersection point 312 located on the vertical plane where the tool 20 is located and below the end of the tool 20;

[0105] Rotate and adjust the position of the laser pen fixing block 343 along the inclined surface of the laser pen fixing block 343 so that the laser intersection point 312 is located on the axis of the tool 20.

[0106] Make the laser intersection point 312 located on the axis of the tool 20, and use the laser intersection point 312 to replace the end of the tool 20 to achieve non-contact calibration.

[0107] In a specific embodiment of the present invention, it further includes:

[0108] As Figures 11 to 13 shown, provide a laser pen bracket 341, the laser pen bracket 341 is provided with a first arc-shaped adjustment groove 3411 and a first connection hole 3412 located below the first arc-shaped adjustment groove 3411, install the laser pen bracket 341 on the robotic arm 10 and the laser pen bracket 341 is perpendicular to the vertical plane where the tool 20 is located;

[0109] As Figures 8 to 10As shown, a laser pointer holder 342 is provided. The laser pointer holder 342 is provided with a second arc-shaped adjustment groove 3421 and a second connection hole 3422 located below the second arc-shaped adjustment groove 3421. The laser pointer holder 342 is connected to the laser pointer bracket 341 through a fastener passing through the first arc-shaped adjustment groove 3421 and the first connection hole 3422, and the laser pointer holder 342 is perpendicular to the laser pointer bracket 341;

[0110] Place the laser pointer fixing block 343 on the laser pointer holder 342 and connect it to the laser pointer holder 342 through a connecting member passing through the second arc-shaped adjustment groove 3421 and the second connection hole 3422;

[0111] By adjusting the position of the corresponding fastener along the first arc-shaped adjustment groove 3411, the laser pointer holder 342 is rotated and adjusted around the fastener passing through the first connection hole 3412, and then the laser pointer fixing block 343 is rotated and adjusted, so as to adjust the laser intersection point to be located on the vertical plane where the tool is located and below the end of the tool;

[0112] By adjusting the position of the corresponding connecting member along the second arc-shaped adjustment groove 3421, the laser pointer fixing block 343 is rotated and adjusted around the connecting member passing through the second connection hole 3422, so as to adjust the laser intersection point to be located on the axis of the tool.

[0113] In a specific embodiment of the present invention, as Figure 1 and Figure 3 shown, when installing the camera 32, the camera 32 is installed on the robotic arm 10 in an inclined and rotatable manner, and then the camera 32 is rotated and adjusted so that the viewing angle range A of the camera 32 covers the end of the tool 20 and the laser intersection point 312.

[0114] In a specific embodiment of the present invention, it further includes:

[0115] As Figure 1 and Figure 4 shown, an installation bracket 33 is provided, and the installation bracket 33 is installed on the robotic arm 10 and is arranged close to the tool 20;

[0116] Combined with Figure 14 and Figure 15 shown, a camera bracket 35 is provided, and the camera bracket 35 is connected to the installation bracket 33 in a manner that can be rotated and adjusted in the vertical plane;

[0117] Combined with Figure 16 and Figure 17 shown, a camera fixing frame 36 is provided, and the camera fixing frame 36 is connected to the camera bracket 35 in a manner that can be rotated and adjusted in the longitudinal plane;

[0118] Mount the camera 32 on the camera fixing bracket 36. By rotating the camera fixing bracket 36, the camera 32 can be rotationally adjusted in the longitudinal plane, so as to adjust the viewing angle range A of the camera 32 to be at the height of the end of the tool and the laser intersection point. By rotating the camera support 35, the camera 32 can be rotationally adjusted in the vertical plane, so as to adjust the viewing angle range of the camera to cover the end of the tool and the laser intersection point. Specifically, let the viewing angle range A of the camera 32 cover the end of the tool 20 and the laser intersection point 312, and take pictures of the whole process of laser calibration.

[0119] The present invention has been described in detail above in combination with the embodiments with reference to the drawings. Those of ordinary skill in the art can make various variations of the present invention according to the above description. Therefore, some details in the embodiments should not constitute a limitation to the present invention, and the protection scope of the present invention will be defined by the scope defined in the appended claims.

Claims

1. A non-contact calibration method for the workpiece coordinate system of a robotic arm, wherein a tool is installed at the end of the robotic arm, characterized in that, The calibration method includes the following steps: Provide three laser pointers, install the three laser pointers on the robotic arm and make the laser beams emitted by the three laser pointers intersect at a point to form a laser intersection point; Adjust the postures of the laser pointers so that the laser intersection point is located below the tool; Provide a camera, install the camera on the robotic arm, and set the camera towards the end of the tool and the laser intersection point; Calibrate a calibration coordinate system on the workpiece surface by using the laser intersection point. During the calibration process, use the camera to capture video data of the end of the tool and the laser intersection point and display it; and Convert the calibration coordinate system into a workpiece coordinate system according to the distance between the laser intersection point and the end of the tool, so as to complete the non-contact calibration of the workpiece coordinate system; When installing the laser pointers, provide a laser pointer fixing block and install the three laser pointers on the laser pointer fixing block; Install the laser pointer fixing block on the robotic arm in an inclined manner, and make the laser intersection point located on the plane where the tool is located and below the end of the tool; Rotate and adjust the position of the laser pointer fixing block along the inclined surface of the laser pointer fixing block so that the laser intersection point is located on the axis of the tool; It further includes: Provide a laser pointer bracket. The laser pointer bracket is provided with a first arc-shaped adjustment groove and a first connection hole located below the first arc-shaped adjustment groove. Install the laser pointer bracket on the robotic arm and make the installation surface of the laser pointer bracket perpendicular to the robotic arm; Provide a laser pointer fixing frame. The laser pointer fixing frame is provided with a second arc-shaped adjustment groove and a second connection hole located below the second arc-shaped adjustment groove. Connect the laser pointer fixing frame to the laser pointer bracket through a fastener passing through the first arc-shaped adjustment groove and the first connection hole, and make the laser pointer fixing frame perpendicular to the laser pointer bracket; Place the laser pointer fixing block on the laser pointer fixing frame and connect it to the laser pointer fixing frame through a connecting piece passing through the second arc-shaped adjustment groove and the second connection hole; By adjusting the position of the corresponding fastener along the first arc-shaped adjustment groove, make the laser pointer fixing frame rotate and adjust around the fastener passing through the first connection hole, and then drive the laser pointer fixing block to rotate and adjust, so as to realize adjusting the laser intersection point to be located on the plane where the tool is located and below the end of the tool; By adjusting the position of the corresponding connecting piece along the second arc-shaped adjustment groove, make the laser pointer fixing block rotate and adjust around the connecting piece passing through the second connection hole, so as to realize adjusting the laser intersection point to be located on the axis of the tool.

2. The non-contact calibration method of the robotic arm workpiece coordinate system according to claim 1, characterized in that When calibrating by using the laser intersection point, adjust the position of the laser intersection point through the following steps so that the laser intersection point is located on the workpiece surface: Control the robotic arm to move upward, and judge whether the distance between the three laser points on the workpiece surface becomes larger according to the video data captured by the camera; If so, control the robotic arm to move downward until the laser intersection point is located on the surface of the workpiece; If not, control the robotic arm to continue moving upward until the laser intersection point is located on the surface of the workpiece.

3. The non-contact calibration method for the robotic arm workpiece coordinate system according to claim 1, characterized in that, When installing the camera, install the camera on the robotic arm in an inclined and rotatable adjustable manner, and then rotate and adjust the camera so that the viewing angle range of the camera covers the end of the tool and the laser intersection point.

4. The non-contact calibration method for the robotic arm workpiece coordinate system according to claim 3, characterized in that, It further includes: Provide a mounting bracket and install the mounting bracket on the robotic arm and close to the tool; Provide a camera bracket and connect the camera bracket to the mounting bracket in a manner that can be rotationally adjusted in the vertical plane; Provide a camera fixing bracket and connect the camera fixing bracket to the camera bracket in a manner that can be rotationally adjusted in the longitudinal plane; Install the camera on the camera fixing bracket, and by rotating and adjusting the camera fixing bracket, the camera is rotationally adjusted in the longitudinal plane, so as to adjust the viewing angle range of the camera to be at the height of the end of the tool and the laser intersection point. By rotating and adjusting the camera bracket, the camera is rotationally adjusted in the vertical plane, so as to adjust the viewing angle range of the camera to cover the end of the tool and the laser intersection point.

5. A non-contact calibration device for the workpiece coordinate system of a robotic arm, wherein a tool is installed at the end of the robotic arm, characterized in that, The calibration device includes: Three laser pens installed on the robotic arm in a manner that the attitude can be adjusted. The laser beams emitted by the three laser pens intersect at a point to form a laser intersection point. By adjusting the attitude of the laser pens, the laser intersection point can be located below the tool; and A camera installed on the robotic arm, the camera is arranged towards the end of the tool and the laser intersection point. By shooting the end of the tool and the laser intersection point by the camera, video data is obtained. Thus, a calibration coordinate system can be calibrated on the surface of the workpiece by using the video data and the laser intersection point, and then a workpiece coordinate system is obtained by conversion; It further includes a laser pen fixing block, and the laser pen fixing block is installed on the robotic arm in an inclined manner; Three laser pens are installed on the laser pen fixing block; It further includes a laser pen bracket and a laser pen fixing bracket; The laser pen bracket is installed on the robotic arm and the laser pen bracket is perpendicular to the installation surface of the robotic arm. The laser pen bracket is provided with a first arc-shaped adjustment groove and a first connection hole located below the first arc-shaped adjustment groove; The laser pen fixing bracket is connected to the laser pen bracket through a fastener passing through the first arc-shaped adjustment groove and the first connection hole, and the laser pen fixing bracket is perpendicular to the laser pen bracket. The laser pen fixing bracket is provided with a second arc-shaped adjustment groove and a second connection hole located below the second arc-shaped adjustment groove; The laser pen fixing block is placed on the laser pen fixing bracket and is connected to the laser pen fixing bracket through a connecting piece passing through the second arc-shaped adjustment groove and the second connection hole; By adjusting the position of the corresponding fastener along the first arc-shaped adjustment groove, the laser pointer holder can be rotationally adjusted around the fastener passing through the first connection hole, and then drive the laser pointer fixing block to perform rotational adjustment, so as to adjust the laser intersection point to be located on the plane where the tool is located and below the end of the tool; By adjusting the position of the corresponding connecting piece along the second arc-shaped adjustment groove, the laser pointer fixing block is rotationally adjusted around the connecting piece passing through the second connection hole, so as to adjust the laser intersection point to be located on the axis of the tool; The camera is installed on the robotic arm in an inclined and rotationally adjustable manner, and the camera is rotationally adjusted so that the viewing range of the camera covers the end of the tool and the laser intersection point.

Images