Workpiece coordinate system calibration device and method of industrial robot and industrial robot

Abstract

The invention provides a workpiece coordinate system calibration device of an industrial robot. The workpiece coordinate system calibration device comprises a camera module and a coordinate system marking module. The coordinate system marking module comprises two marking points located on a first straight line and two marking points located on a second straight line; the camera module is used for acquiring an image of the coordinate system mark module, identifying the positioning mark points from the image, determining coordinates of the positioning mark points in a camera coordinate system, and determining coordinates of an intersection point of the first straight line and the second straight line in the camera coordinate system; according to the conversion relation between the camera coordinate system and the base coordinate system, the camera module is used for determining the slope kx of the first straight line relative to the x axis of the base coordinate system, the slope ky of the second straight line relative to the x axis of the base coordinate system and the coordinates of the intersection point in the base coordinate system, and the workpiece coordinate system is determined through the coordinates of the intersection point, the slope kx and the slope ky. Automatic operation of workpiece coordinate system calibration can be achieved, compared with manual calibration, the calibration position is more accurate, and calibration time is greatly shortened.

Description

Technical Field

[0001] The present invention relates to the field of robots, and in particular to a workpiece coordinate system calibration device and a calibration method for an industrial robot and an industrial robot. Background Art

[0002] With the rapid development of industrial robot technology, more and more product manufacturing workshops use industrial robots for automated production or automatic palletizing in warehousing. In the process of automatically processing workpieces using the processing tools on the industrial robot's mechanical arm, the workpiece coordinate system is generally used to make the position of the processing action applied by the robot to the workpiece more accurate. During palletizing operations, there are precision requirements for the position of the load-bearing platform, and the workpiece coordinate system is also required to align the palletizing position.

[0003] However, as the robot processing production line works for a long time, the workpiece fixed on the workbench often produces a certain posture deviation due to external forces such as vibration. At this time, there may be a certain error between the workpiece coordinate system and the initial workpiece coordinate system calibrated before processing, which affects the accuracy of the processing position and the stability of the processing quality. Therefore, after the robot processing production line has been working for a long time, the workpiece coordinate system needs to be recalibrated to reflect the accurate position of the workpiece after displacement in real time. The same problem exists in the palletizing operation scenario, and the load-bearing platform may also be displaced.

[0004] At present, the three-point method is commonly used to calibrate the workpiece coordinate system, and the calibration is generally performed through manual operation. The calibration position accuracy is very dependent on the worker's operating experience and proficiency, the accuracy stability is poor, and it is time-consuming and labor-intensive, which seriously affects the work efficiency and processing quality of the robot processing automation production line. Summary of the invention

[0005] One of the purposes of the present invention is to provide a workpiece coordinate system calibration device for an industrial robot, in which four marking points are set on the workpiece in a certain manner to form a two-dimensional coordinate system, and its image is acquired by a camera; according to the conversion relationship between the camera coordinate system and the base coordinate system, the relative positions of the two coordinate axes and their intersection points of the two-dimensional coordinate system in the base coordinate system are obtained in the camera. Since the position of the base coordinate system of the industrial robot is fixed, the position change of the two-dimensional coordinate system newly set on the workpiece in the camera coordinate system can be reflected by the change of the relative position, and the above relative position relationship can be used as the basis for the calibration of the workpiece coordinate system.

[0006] Another object of the present invention is to provide a method for calibrating the workpiece coordinate system of an industrial robot, by determining the two-dimensional coordinate system and its position in the camera coordinate system by four marking points set on the workpiece, converting the above position into a relative position in the base coordinate system according to the conversion relationship between the camera coordinate system and the base coordinate system, and calibrating the workpiece coordinate system according to the relative position.

[0007] The third object of the present invention is to provide an industrial robot based on the above-mentioned calibration device and calibration method.

[0008] To achieve the above-mentioned purpose, in a first aspect, the present invention provides a workpiece coordinate system calibration device for an industrial robot, comprising a camera module and a coordinate system mark module; the camera module is used to be detachably fixed on the mechanical arm of the industrial robot and is communicatively connected with the industrial robot; the coordinate system mark module is used to be fixed on the aimed object and is in the field of view of the imaging lens of the camera module; the coordinate system mark module comprises two mark points x1 and x2 located on a first straight line and two mark points y1 and y2 located on a second straight line; the camera module is used to capture an image of the coordinate system mark module, identify and locate the mark points x1, x2, y1, y2 from the image, and determine their coordinates in the camera coordinate system respectively, as well as determine the coordinates of the intersection of the first straight line and the second straight line in the camera coordinate system; according to the conversion relationship between the camera coordinate system and the base coordinate system, the camera module is used to respectively determine the slope k of the first straight line relative to the x-axis of the base coordinate system x , the slope k of the second straight line relative to the x-axis of the base coordinate system y , and the coordinates of the intersection point in the base coordinate system (X0, Y0), through the intersection point coordinates (X0, Y0), the slope k x and slope k y Determine the workpiece coordinate system.

[0009] Furthermore, a first locking structure is fixedly provided on the camera module, and a second locking structure is fixedly provided on the mechanical arm of the industrial robot, and the camera module is fixed by the cooperation between the first locking structure and the second locking structure.

[0010] Furthermore, the first locking structure is a positioning block, and the second locking structure is a positioning hole, and the camera module is fixed by inserting the positioning block into the positioning hole.

[0011] Furthermore, a camera in-position sensor is provided on the first locking structure and / or the second locking structure, and the camera in-position sensor is used to send a workpiece coordinate system calibration trigger signal to the camera module and the industrial robot after the first locking structure and the second locking structure are locked in place with each other, so that the two enter the workpiece coordinate system calibration working mode at the same time; in the workpiece coordinate system calibration working mode, the robotic arm of the industrial robot stops moving, and the camera module collects the image of the coordinate system marking module.

[0012] Furthermore, the coordinate system marking module includes two marking strips for being pasted on the aimed object, the marking points x1 and x2 are located on the first marking strip, and the marking points y1 and y2 are located on the second marking strip.

[0013] Furthermore, the camera module is used to convert the coordinates of the marker points x1, x2, y1, and y2 in the camera coordinate system into coordinates (X, Y, and Y) in the base coordinate system. x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), based on the coordinates (X x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), the slope k is calculated by multi-point averaging method. x and the slope k y .

[0014] Furthermore, at least a portion of the marking points are inherent feature points of the workpiece, including at least one of a hole center, an axis center, a centroid, and an edge and corner vertex.

[0015] In a second aspect, the present invention provides a method for calibrating a workpiece coordinate system of an industrial robot, comprising: determining the coordinates of two marking points x1 and x2 on a first straight line on a targeted workpiece in a camera coordinate system, respectively; determining the coordinates of two marking points y1 and y2 on a second straight line on the workpiece in the camera coordinate system, respectively; and determining the coordinates of an intersection of the first straight line and the second straight line in the camera coordinate system; and determining the slope k of the first straight line relative to the x-axis of the base coordinate system according to a conversion relationship between the camera coordinate system and a base coordinate system. x , the slope k of the second straight line relative to the x-axis of the base coordinate system y, and the coordinates of the intersection point in the base coordinate system (X0, Y0); according to the coordinates of the intersection point (X0, Y0), the slope k x and slope k y Determine the workpiece coordinate system.

[0016] Furthermore, a first marking strip and a second marking strip are respectively pasted on the aimed object, the marking points x1 and x2 are located at different positions of the first marking strip, and the marking points y1 and y2 are located at different positions of the second marking strip.

[0017] Furthermore, the targeted object is a pallet for stacking workpieces, and the sticking positions of the first marking strip and the second marking strip are related to the stacking direction of the workpieces on the pallet.

[0018] Furthermore, the marking point x1 and the marking point y1 overlap to form the intersection point.

[0019] Furthermore, an image x containing the first marking strip is acquired through a camera, and the marking points x1 and x2 are identified and located by processing the image x; an image y containing the second marking strip is acquired through a camera, and the marking points y1 and y2 are identified and located by processing the image y.

[0020] Furthermore, in response to a positioning signal indicating that the camera is in position, the camera and the industrial robot are triggered to simultaneously enter a workpiece coordinate system calibration working mode; in the workpiece coordinate system calibration working mode, the robotic arm of the industrial robot is controlled to stop moving, and the camera is controlled to capture the image x and the image y.

[0021] Furthermore, the coordinates of the marker points x1, x2, y1, y2 in the camera coordinate system are converted into coordinates in the base coordinate system (X x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), based on the coordinates (X x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), the slope k is calculated by multi-point averaging method. x and the slope k y .

[0022] Furthermore, the transformation relationship between the camera coordinate system and the base coordinate system is determined by hand-eye calibration.

[0023] In a third aspect, the present invention provides an industrial robot, comprising a workpiece coordinate system calibration device for an industrial robot as described in any technical solution of the first aspect, or a workpiece coordinate system calibration method for an industrial robot as described in any technical solution of the second aspect.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] Four marking points are set on the workpiece in a certain way to form a two-dimensional coordinate system, and its image is obtained by the camera; according to the conversion relationship between the camera coordinate system and the base coordinate system, the relative positions of the two coordinate axes and their intersections of the two-dimensional coordinate system in the base coordinate system are obtained in the camera. Since the position of the base coordinate system of the industrial robot is fixed, the position change of the two-dimensional coordinate system newly set on the workpiece in the camera coordinate system can be reflected by the change of the relative position, and the above relative position relationship can be used as the basis for the calibration of the workpiece coordinate system. Since the above process is automatically processed by the built-in algorithm of the camera module, the automatic operation of the workpiece coordinate system calibration can be realized. Compared with manual calibration, the calibration position is more accurate and the calibration time is greatly shortened, thereby making the workpiece processing accuracy and processing efficiency higher, and finally making the quality stability of the finished product better, the output per unit time greater, and the economic benefits significantly improved.

[0026] Other advantages of the present invention will be further illustrated in some embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0028] Figure 1 It is a structural schematic diagram of an embodiment of the device of the present invention;

[0029] Figure 2 for Figure 1 The enlarged partial view of the circled part A is the enlarged schematic view of the sign bar;

[0030] Figure 3 for Figure 1 A magnified schematic diagram of the camera module;

[0031] Figure 4 for Figure 3 Variable angle view (looking up);

[0032] Figure 5 for Figure 4 The enlarged partial view of the circled portion in B is an enlarged schematic view of the locking structure;

[0033] Figure 6 The present invention is a flowchart of an embodiment of the method.

[0034] In the accompanying drawings, there are an industrial robot 1 ; a second locking structure 11 ; a coordinate system marking module 2 ; a camera module 3 ; a first locking structure 31 ; a camera screen 32 ; and a lens 33 . DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0036] It should be noted that the directional words such as left, right, inside, outside, up, and down mentioned in this article refer to the directions shown in the diagram or the directions commonly understood by technical personnel in this field, and do not represent the directions on actual objects, nor do they constitute any limitations, and are only for the convenience of explanation.

[0037] like Figure 1-Figure 5 As shown, an embodiment of the workpiece coordinate system calibration device of the industrial robot of the present invention includes a camera module 3 and a coordinate system marking module 2; the camera module 3 is used to be detachably fixed on the mechanical arm of the industrial robot 1 and is in communication connection with the industrial robot 1; the coordinate system marking module 2 is used to be fixed on the aimed object and is in the field of view of the imaging lens 33 of the camera module 3; the coordinate system marking module 2 includes two marking points x1 and x2 located on the first straight line and two marking points y1 and y2 located on the second straight line; the camera module 3 is used to collect the image of the coordinate system marking module 2, identify and locate the marking points x1, x2, y1, y2 from the image, and determine their coordinates in the camera coordinate system respectively, and determine the coordinates of the intersection of the first straight line and the second straight line in the camera coordinate system; according to the conversion relationship between the camera coordinate system and the base coordinate system, the camera module 3 is used to respectively determine the slope k of the first straight line relative to the x-axis of the base coordinate system x , the slope k of the second straight line relative to the x-axis of the base coordinate system y , and the coordinates of the intersection point in the base coordinate system (X0, Y0), through the intersection point coordinates (X0, Y0), the slope k x and slope k y Determine the workpiece coordinate system.

[0038] In this embodiment, the lens 33 of the camera module 3 generally needs to face the coordinate system marking module 2 to ensure the image shooting effect. Among the four marking points, x1, x2, y1, and y2 are paired to determine a coordinate axis respectively, that is, the first straight line connecting x1 and x2 forms the first coordinate axis or the x-axis, and the second straight line connecting y1 and y2 forms the second coordinate axis or the y-axis, forming a new two-dimensional coordinate system in the camera coordinate system environment. The angle between the two coordinate axes of the two-dimensional coordinate system can be a right angle, or it can be an oblique angle according to the actual working conditions of the industrial robot 1. Since there is a definite coordinate conversion relationship between the camera coordinate system and the base coordinate system of the industrial robot 1, the first coordinate axis, the second coordinate axis, and the intersection of the two, that is, the coordinate origin of the two-dimensional coordinate system under the camera coordinate system, can all be converted into a spatial position under the base coordinate system. Specifically, for the first coordinate axis, the spatial position is its slope k relative to the x-axis of the base coordinate system. x The second coordinate axis is the slope k relative to the y-axis of the base coordinate system. y , the coordinates of the intersection point, i.e. the origin of the coordinate system, in the base coordinate system are (X0, Y0). With the slope k x , slope k y And the coordinate origin (X0, Y0) can determine the workpiece coordinate system in a base coordinate system environment.

[0039] In this embodiment, the camera module 3 can be divided into at least four organic components according to the functions: an image acquisition unit, an image processing unit, a position conversion calculation unit and a communication unit. The image acquisition unit captures the image of the coordinate system mark module 2 and displays it on the camera screen 32 in real time, so that the image quality can be checked. If it is not clear, it can be retaken; the image processing unit is used to process the image, find out four mark points, form two coordinate axes, and obtain the intersection of the two coordinate axes or their extension lines; the position conversion calculation unit is used to calculate the above-mentioned slope k according to the conversion relationship between the camera coordinate system and the base coordinate system. x , slope k y The communication unit is used for data communication with the industrial robot 1 to realize data sharing and action synchronization between the two. These functions are all realized automatically, which greatly improves the convenience and reliability of the workpiece coordinate system calibration operation, making the calibration more accurate and time-saving.

[0040] In this embodiment, the camera module 3 is detachably mounted on the mechanical arm of the industrial robot 1, and the installation position is unique. Once a calibration operation is required, the camera module 3 is installed and then removed after the calibration operation is completed, thus achieving plug-and-play, and convenient and efficient installation and use.

[0041] In this embodiment, as the name implies, the aimed object is the object that the industrial robot needs to aim at at all times during the working process to ensure the operating accuracy of the industrial robot. The aimed object varies with the application scenarios of the industrial robot. For example, if it is a workpiece processing scenario, the aimed object is the workpiece being processed. If it is a workpiece stacking scenario, the aimed object is a carrier platform for stacking multiple layers of workpieces, such as a pallet.

[0042] like Figure 3-Figure 5 As shown, in one embodiment of the workpiece coordinate system calibration device of the industrial robot of the present invention, a first locking structure 31 is fixedly provided on the camera module 3, and a second locking structure 11 is fixedly provided on the mechanical arm of the industrial robot 1, and the camera module 3 is fixed by the cooperation between the first locking structure 31 and the second locking structure 11. In this embodiment, the camera module 3 and the mechanical arm of the industrial robot 1 are quickly locked or disassembled by the mutual cooperation between the first locking structure 31 and the second locking structure 11, and the locking position of the two is unique, which can ensure the accurate installation position of the camera module 3 and realize the convenience of installation / disassembly.

[0043] like Figure 3-Figure 5 As shown, in one embodiment of the workpiece coordinate system calibration device of the industrial robot of the present invention, the first locking structure 31 is a positioning block, and the second locking structure 11 is a positioning hole, and the positioning block is inserted into the positioning hole to fix the camera module 3. In this embodiment, the specific shape of the positioning block can be a button shape, and the positioning hole is a round hole. The two are locked by interference fit, and the installation method is simple.

[0044] like Figure 1 As shown, in one embodiment of the workpiece coordinate system calibration device of the industrial robot of the present invention, a camera position sensor is provided on the first locking structure 31 and / or the second locking structure 11, and the camera position sensor is used to send a workpiece coordinate system calibration trigger signal to the camera module 3 and the industrial robot 1 after the first locking structure 31 and the second locking structure 11 are mutually locked in place, so that both enter the workpiece coordinate system calibration working mode at the same time; in the workpiece coordinate system calibration working mode, the mechanical arm of the industrial robot 1 stops moving, and the camera module 3 collects the image of the coordinate system mark module 2. In this embodiment, the camera position sensor can be any sensor that can sense the position, such as a photoelectric sensor or a proximity switch. Once locked in place, the photoelectric sensor is shielded or the proximity switch is pressed, and a trigger signal is generated to start the workpiece coordinate system calibration working mode, which can realize plug-and-play fool-style calibration and is very convenient to use.

[0045] like Figure 1 and Figure 2As shown, in one embodiment of the workpiece coordinate system calibration device of the industrial robot of the present invention, the coordinate system marking module 2 includes two marking strips for pasting on the aimed workpiece, the marking points x1 and x2 are located on the first marking strip, and the marking points y1 and y2 are located on the second marking strip. In this embodiment, two marking strips are pasted on the surface of the workpiece, and the position of the marking strips is fixed relative to the workpiece. If the position of the workpiece changes, the position of the marking strips will change synchronously. In this way, the position change of the workpiece can be reflected by the position change of the marking strips. Then, a two-dimensional coordinate system is established based on the marking strips, which can cleverly realize the simplification of complex position change problems and make the calibration operation fast and efficient. In this embodiment, at least a part of the marking points can be inherent feature points of the workpiece, including at least one of the hole center, axis center, centroid and corner vertex, etc. The positions of these feature points are fixed and can play the same role as the marking points on the marking strips. In this way, the marking strips can be partially or completely omitted, and the step of pasting the marking strips can be omitted, saving time and cost.

[0046] In one embodiment of the workpiece coordinate system calibration device of the industrial robot of the present invention, the camera module 3 is used to convert the coordinates of the marker points x1, x2, y1, y2 in the camera coordinate system into the coordinates (X1, X2, Y1, Y2) in the base coordinate system. x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), based on the coordinates (X x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), the slope k is calculated by multi-point averaging method. x and the slope k y In this embodiment, for example, the two slopes can be calculated using the two-point average method, that is, the slopes are calculated for the two marking points on each coordinate axis respectively, and then the average is calculated. The specific calculation formula is as follows:

[0047] k x =[(Y x1 -Y0 / X x1 -X0)+(Y x2 -Y0 / X x2 -X0)] / 2;

[0048] k y =[(Yx1 -Y0 / X x1 -X0)+(Y x2 -Y0 / X x2 -X0)] / 2.

[0049] Of course, you can also select the third point and other more points for calculation. Since there will be a certain error in camera recognition, the multi-point average method can be used to calculate the slope value more accurately.

[0050] like Figure 6 As shown, an embodiment of the workpiece coordinate system calibration method of the industrial robot of the present invention includes: determining the coordinates of two marking points x1 and x2 on the aimed object located on a first straight line in the camera coordinate system, determining the coordinates of two marking points y1 and y2 on the workpiece located on a second straight line in the camera coordinate system, and determining the coordinates of the intersection of the first straight line and the second straight line in the camera coordinate system; according to the conversion relationship between the camera coordinate system and the base coordinate system, determining the slope k of the first straight line relative to the x-axis of the base coordinate system x , the slope k of the second straight line relative to the x-axis of the base coordinate system y , and the coordinates of the intersection point in the base coordinate system (X0, Y0); according to the coordinates of the intersection point (X0, Y0), the slope k x and slope k y Determine the workpiece coordinate system.

[0051] In this embodiment, the four marking points x1, x2, y1, and y2 are paired to determine a coordinate axis, that is, the first straight line connecting x1 and x2 forms the first coordinate axis or the x-axis, and the second straight line connecting y1 and y2 forms the second coordinate axis or the y-axis, forming a new two-dimensional coordinate system in the camera coordinate system environment. The angle between the two coordinate axes of the two-dimensional coordinate system can be a right angle, or it can be an oblique angle according to the actual working conditions of the industrial robot 1. Taking the palletizing operation as an example, the aimed part is a pallet carrying workpieces. Palletizing is to stack the workpieces one by one on the pallet in the x-axis and y-axis directions, and then stack the next layer after the next layer. If the workpieces arranged along the x-axis are required to be perpendicular to the workpieces arranged along the y-axis, the angle between the two coordinate axes must be a right angle. If perpendicularity is not required, the angle between the two coordinate axes is an oblique angle, which is completely determined according to the actual working conditions.

[0052] In this embodiment, since there is a certain coordinate conversion relationship between the camera coordinate system and the base coordinate system of the industrial robot 1, the first coordinate axis, the second coordinate axis, and the intersection of the two coordinate systems under the camera coordinate system, that is, the coordinate origin of the two-dimensional coordinate system, can all be converted into spatial positions under the base coordinate system. Specifically, for the first coordinate axis, the spatial position is its slope k relative to the x-axis of the base coordinate system. xThe second coordinate axis is the slope k relative to the y-axis of the base coordinate system. y , the coordinates of the intersection point, i.e. the origin of the coordinate system, in the base coordinate system are (X0, Y0). With the slope k x , slope k y And the coordinate origin (X0, Y0), you can determine the workpiece coordinate system in a base coordinate system environment. Since these functions are automatically implemented, the convenience and reliability of the workpiece coordinate system calibration operation are greatly improved, making the calibration more accurate and the calibration time shorter.

[0053] In one embodiment of the workpiece coordinate system calibration method of the industrial robot of the present invention, the first marking strip and the second marking strip are respectively pasted on the aimed workpiece, the marking points x1 and x2 are located at different positions of the first marking strip, and the marking points y1 and y2 are located at different positions of the second marking strip. In this embodiment, two marking strips are pasted on the surface of the workpiece, and the position of the marking strip is fixed relative to the workpiece. If the position of the workpiece changes, the position of the marking strip changes synchronously. In this way, the position change of the workpiece can be reflected by the position change of the marking strip, and then a two-dimensional coordinate system is established based on the marking strip, which can cleverly realize the simplification of complex position change problems and make the calibration operation fast and efficient. In this embodiment, at least a part of the marking points can be the inherent feature points of the workpiece, including at least one of the hole center, axis center, centroid and corner vertex, etc. The positions of these feature points are fixed and can play the same role as the marking points on the marking strip. In this way, the marking strip can be partially or completely omitted, and the step of pasting the marking strip can be omitted, saving time and cost.

[0054] In one embodiment of the workpiece coordinate system calibration method of an industrial robot of the present invention, the aimed part is a pallet for stacking workpieces, and the pasting positions of the first marking strip and the second marking strip are related to the stacking direction of the workpieces on the pallet. In this embodiment, the application scenario is palletizing, that is, stacking a number of workpieces in multiple layers on a pallet, with M rows and N columns on each layer, and two marking strips are pasted on the pallet. If the row direction and column direction of each layer of workpieces are required to be perpendicular to each other, the first marking strip and the second marking strip must also be perpendicular to each other when pasted; if the angle between the row direction and the column direction of each layer of workpieces is required to be an acute angle a, the angle between the pasted first marking strip and the second marking strip is also a. In this way, the pasting position of the marking strip can be flexibly adjusted according to the actual usage situation, with strong adaptability and a wide range of usage scenarios.

[0055] In one embodiment of the method for calibrating the workpiece coordinate system of an industrial robot of the present invention, the marking point x1 coincides with the marking point y1 to form the intersection point. In this embodiment, the two marking bars intersect directly, and the intersection point is shared by the two coordinate axes, that is, only three marking points are actually needed to realize the creation of a two-dimensional coordinate system, making subsequent processing more simple and efficient.

[0056] In one embodiment of the workpiece coordinate system calibration method of the industrial robot of the present invention, the image x of the first marker strip is obtained by a camera, and the marker points x1 and x2 are identified and located by processing the image x; the image y of the second marker strip is obtained by a camera, and the marker points y1 and y2 are identified and located by processing the image y. In this embodiment, the camera includes an image acquisition unit and an image processing unit, wherein the image acquisition unit captures an image of the coordinate system marker module 2, and the image processing unit is used to process the image, find four marker points therefrom, and form two coordinate axes to obtain the intersection of the two coordinate axes or their extension lines. In this way, the position of the newly created two-dimensional coordinate system in the camera coordinate system can be quickly and accurately obtained through the image processing algorithm, providing accurate data for subsequent processing.

[0057] In one embodiment of the workpiece coordinate system calibration method of an industrial robot of the present invention, in response to a positioning signal indicating that the camera is in position, the camera and the industrial robot are triggered to simultaneously enter the workpiece coordinate system calibration working mode; in the workpiece coordinate system calibration working mode, the mechanical arm of the industrial robot is controlled to stop moving, and the camera is controlled to collect the image x and the image y. In this embodiment, the camera positioning sensor can be any sensor that can sense the position, such as a photoelectric sensor or a proximity switch. Once locked in position, the photoelectric sensor is shielded or the proximity switch is pressed, and a trigger signal is generated to start the workpiece coordinate system calibration working mode, which can realize plug-and-play fool-style calibration, and is very convenient to use.

[0058] In one embodiment of the workpiece coordinate system calibration method of the industrial robot of the present invention, the coordinates of the marker points x1, x2, y1, y2 in the camera coordinate system are converted into coordinates (X1, X2, Y1, Y2) in the base coordinate system. x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), based on the coordinates (X x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), the slope k is calculated by multi-point averaging method. x and the slope k y In this embodiment, for example, the two slopes can be calculated using the two-point average method, that is, the slopes are calculated for the two marking points on each coordinate axis respectively, and then the average is calculated. The specific calculation formula is as follows:

[0059] k x =[(Y x1 -Y0 / X x1 -X0)+(Y x2 -Y0 / X x2 -X0)] / 2;

[0060] k y =[(Y x1 -Y0 / X x1 -X0)+(Y x2 -Y0 / X x2 -X0)] / 2.

[0061] Of course, you can also select the third point and other more points for calculation. Since there will be a certain error in camera recognition, the multi-point average method can be used to calculate the slope value more accurately.

[0062] Based on the slope k obtained in this embodiment x and slope k y , the angle αx between the first coordinate axis and the X-axis of the base coordinate system and the angle αy between the second coordinate axis and the X-axis of the base coordinate system can be calculated respectively by the formula k=tanα.

[0063] In one embodiment of the method for calibrating the workpiece coordinate system of an industrial robot of the present invention, the conversion relationship between the camera coordinate system and the base coordinate system is determined by hand-eye calibration. In this embodiment,

[0064] An embodiment of an industrial robot of the present invention comprises a workpiece coordinate system calibration device for an industrial robot as described in any of the above-mentioned embodiments of the workpiece coordinate system calibration device for an industrial robot, or adopts a workpiece coordinate system calibration method for an industrial robot as described in any of the above-mentioned embodiments of the workpiece coordinate system calibration method for an industrial robot. In this embodiment, the application scenario of the industrial robot can be direct processing of the workpiece, in which case the marking point is set on the workpiece. The application scenario of the industrial robot can also be palletizing, in which case the marking point is set on a workpiece carrier, such as a pallet. Any embodiment of the industrial robot of the present invention must have the advantages of any of the above-mentioned embodiments of the workpiece coordinate system calibration device for an industrial robot and / or the embodiments of the workpiece coordinate system calibration method for an industrial robot, which will not be repeated here.

[0065] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A workpiece coordinate system calibration device for an industrial robot, characterized in that: It includes a camera module and a coordinate system mark module; the camera module is used to be detachably fixed on the mechanical arm of the industrial robot and is in communication connection with the industrial robot; the coordinate system mark module is used to be fixed on the aimed object and is in the field of view of the imaging lens of the camera module; The coordinate system marking module includes two marking points x1 and x2 located on a first straight line and two marking points y1 and y2 located on a second straight line.

2. The workpiece coordinate system calibration device for an industrial robot according to claim 1, characterized in that: The camera module is fixedly provided with a first locking structure, and the mechanical arm of the industrial robot is fixedly provided with a second locking structure, and the camera module is fixed by the cooperation between the first locking structure and the second locking structure.

3. The workpiece coordinate system calibration device for an industrial robot according to claim 2, characterized in that: A camera in-place sensor is provided on the first locking structure and / or the second locking structure. The camera in-place sensor is used to send a workpiece coordinate system calibration trigger signal to the camera module and the industrial robot after the first locking structure and the second locking structure are locked in place with each other, so that the two enter the workpiece coordinate system calibration working mode at the same time; in the workpiece coordinate system calibration working mode, the robotic arm of the industrial robot stops moving, and the camera module collects the image of the coordinate system marking module.

4. The workpiece coordinate system calibration device for an industrial robot according to claim 1, characterized in that: The coordinate system marking module includes two marking strips for being pasted on the aimed object, the marking points x1 and x2 are located on the first marking strip, and the marking points y1 and y2 are located on the second marking strip.

5. A method for calibrating a workpiece coordinate system of an industrial robot, characterized in that: include: Determine the coordinates of two marking points x1 and x2 on the aimed object located on a first straight line in the camera coordinate system, determine the coordinates of two marking points y1 and y2 on the workpiece located on a second straight line in the camera coordinate system, and determine the coordinates of the intersection of the first straight line and the second straight line in the camera coordinate system; According to the conversion relationship between the camera coordinate system and the base coordinate system, the slope k of the first straight line relative to the x-axis of the base coordinate system is determined respectively. x , the slope k of the second straight line relative to the x-axis of the base coordinate system y , and the coordinates (X0, Y0) of the intersection point in the base coordinate system; According to the intersection coordinates (X0, Y0), the slope k x and slope k y Determine the workpiece coordinate system.

6. The method for calibrating the workpiece coordinate system of an industrial robot according to claim 5, characterized in that: A first marking strip and a second marking strip are respectively attached to the targeted object, the marking points x1 and x2 are located at different positions of the first marking strip, and the marking points y1 and y2 are located at different positions of the second marking strip.

7. The method for calibrating the workpiece coordinate system of an industrial robot according to claim 6, characterized in that: The targeted object is a pallet for stacking workpieces, and the pasting positions of the first marking strip and the second marking strip are related to the stacking direction of the workpieces on the pallet.

8. The method for calibrating the workpiece coordinate system of an industrial robot according to claim 6, characterized in that: The marking point x1 coincides with the marking point y1 to form the intersection point.

9. The method for calibrating the workpiece coordinate system of an industrial robot according to claim 6, characterized in that: An image x containing the first marking strip is acquired through a camera, and the marking points x1 and x2 are identified and located by processing the image x; an image y containing the second marking strip is acquired through a camera, and the marking points y1 and y2 are identified and located by processing the image y.

10. The method for calibrating the workpiece coordinate system of an industrial robot according to claim 6, characterized in that: In response to a positioning signal indicating that the camera is in position, the camera and the industrial robot are triggered to enter a workpiece coordinate system calibration working mode; in the workpiece coordinate system calibration working mode, the mechanical arm of the industrial robot is controlled to stop moving, and the camera is controlled to capture the image x and the image y.

11. The method for calibrating the workpiece coordinate system of an industrial robot according to claim 5, characterized in that: The coordinates of the marker points x1, x2, y1, y2 in the camera coordinate system are converted into coordinates in the base coordinate system (X x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), based on the coordinates (X x1 , Y x1 )、(X x2 , Y x2 )、(X y1 , Y y1 )、(X y2 , Y y2 ), the slope k is calculated by multi-point averaging method. x and the slope k y .

12. The method for calibrating the workpiece coordinate system of an industrial robot according to claim 5, characterized in that: The conversion relationship between the camera coordinate system and the base coordinate system is determined by hand-eye calibration.

13. An industrial robot, characterized in that: It comprises the workpiece coordinate system calibration device of the industrial robot as described in any one of claims 1 to 4, or adopts the workpiece coordinate system calibration method of the industrial robot as described in any one of claims 5 to 12.

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