CN106426172B - A kind of scaling method and system of industrial robot tool coordinates system - Google Patents
A kind of scaling method and system of industrial robot tool coordinates system Download PDFInfo
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- CN106426172B CN106426172B CN201610958034.0A CN201610958034A CN106426172B CN 106426172 B CN106426172 B CN 106426172B CN 201610958034 A CN201610958034 A CN 201610958034A CN 106426172 B CN106426172 B CN 106426172B
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- 238000000034 method Methods 0.000 title claims abstract description 52
- 239000003550 marker Substances 0.000 claims abstract description 120
- 238000003384 imaging method Methods 0.000 claims abstract description 103
- 230000000007 visual effect Effects 0.000 claims description 18
- 230000008569 process Effects 0.000 claims description 8
- 238000003860 storage Methods 0.000 claims description 5
- 230000006872 improvement Effects 0.000 description 13
- 238000004364 calculation method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 230000036544 posture Effects 0.000 description 7
- 230000008859 change Effects 0.000 description 5
- 239000011159 matrix material Substances 0.000 description 4
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- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
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- 238000003466 welding Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1656—Programme controls characterised by programming, planning systems for manipulators
- B25J9/1664—Programme controls characterised by programming, planning systems for manipulators characterised by motion, path, trajectory planning
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
- G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
- G01B21/04—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness by measuring coordinates of points
- G01B21/042—Calibration or calibration artifacts
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Abstract
A kind of scaling method and system of industrial robot tool coordinates system, wherein method includes: a bit for being imaged on the center of circle of circle marker object in viewing field of camera, records imaging radius R, the center pixel coordinate of marker under original statepAnd the coordinate of mechanical arm tail endP 1；Make the ring flange of mechanical arm tail end aroundUShaft rotary random angle, mobile mechanical arm end are arrivedP 2Place makes the center of circle of marker be imaged on the same point in above-mentioned viewing field of camera, according to coordinate twiceP 1WithP 2Value obtains the horizontal component of tool center point relative mechanical arm end；Make any joint of mechanical arm aroundWShaft rotary random angle, mobile mechanical arm end are arrivedP 3Place makes the center of circle of marker be imaged on the same point in above-mentioned viewing field of camera, and the imaging long axis length of marker is made to be equal to imaging radius R, according to coordinate twiceP 2WithP 3Value and horizontal component obtain the vertical component of the space vector of tool center point relative mechanical arm end.This method speed is fast, precision is high.
Description
Technical Field
The invention relates to a method and a system for calibrating an industrial robot tool coordinate system, and belongs to the field of manipulator control.
Background
In an industrial production line, special parts are usually fixed at the end of a robot arm of an industrial robot as tools, such as a jig, a welding gun, etc., and a coordinate system, a so-called tool coordinate system, is usually established at a fixed position on the tools. The trajectory planning of the robot is usually performed for a certain Point of the Tool after adding the Tool as described above, and this Point is usually called a Tool Center Point (TCP). In general, the origin of the tool coordinate system is TCP, and after the tool is mounted on the end of the mechanical arm of the robot, the relation of the tool coordinate system with respect to the robot end coordinate system is fixed and unchanged unless the mounting position of the tool is changed artificially. The correct calibration of the tool coordinate system has an important influence on the trajectory planning of the robot, and the tool coordinate system of the robot may need to be changed frequently according to different application scenarios, so a fast and accurate calibration method of the robot tool coordinate system is urgently needed.
The document "calibration research of industrial robot tool and workpiece coordinate system" discloses a vision-based tool system coordinate automatic calibration principle and scheme, which utilizes two industrial cameras to collect images, and utilizes an image correlation algorithm to identify a ring mark and mark the coordinate of a ring center point. When the robot makes the coordinate values of the center of the marker ring in the two images consistent in different postures, the robot can be considered to make the center point or the feature point of the end tool be in the same position in space in a plurality of postures. And further solving through positive kinematics to obtain the coordinates of the center of the mark point under the robot base coordinate system. However, if the number of devices required for tool coordinate system calibration is reduced and the number of times the robot arm needs to change its posture during calibration is reduced, the calibration of the tool coordinate system can be made faster and more accurate.
Disclosure of Invention
The invention aims to simplify the calibration process of a calibration tool coordinate system and improve the calibration speed and precision of the tool coordinate system, and provides a calibration method and a calibration system of an industrial robot tool coordinate system.
In order to achieve the purpose, the invention adopts the following technical scheme:
according to a first aspect of the present invention, there is provided a method for calibration of an industrial robot tool coordinate system, the method comprising the steps of:
s1, fixing the circular marker at the center point of the tool in parallel relative to the flange surface at the tail end of the mechanical arm, imaging the center of the marker at one point in the camera view field, making the flange surface at the tail end of the mechanical arm parallel relative to the camera imaging plane H, and recording the imaging radius R of the marker, the pixel coordinate P of the center of the marker and the space coordinate P of the tail end of the mechanical arm in the image shot by the camera at the moment1；
S2, enabling the flange at the tail end of the mechanical arm to rotate at any angle A around the U shaft1Moving the end of the robot arm to a spatial coordinate P2Imaging the center of the marker at the same point in the camera view field according to the space coordinate P of the mechanical arm end twice1And P2Calculating horizontal components (a, b) of the central point of the tool relative to the space vector of the tail end of the mechanical arm, wherein the U axis is vertical to the plane H;
s3, rotating any joint of the mechanical arm by any angle A around the W axis2Moving the end of the robot arm to a spatial coordinate P3The center of the marker is imaged in the cameraAt the same point in the field, and making the length of the imaging long axis of the marker on the plane H equal to the imaging radius R of the marker according to the space coordinate P of the end of the mechanical arm twice2And P3And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm1The W axis is parallel to plane H.
As a further improvement of the above method of the present invention, in step S1, one point in the camera view field is a midpoint in the camera view field, or a central pixel point of an image captured by the camera.
As a further improvement of the above method of the present invention, the step S2 includes the following steps:
s21, enabling the flange at the tail end of the mechanical arm to rotate around the U shaft by any angle A step by step1The U axis is vertical to the plane H, the step rotation is divided into two or more steps, and the total angle of the step rotation is A1；
S22, after each step of rotation, moving the tail end of the mechanical arm in parallel relative to the plane H to enable the circle center of the marker to be infinitely close to the same point in the camera view field, and recording the absolute position difference between the pixel coordinate p' of the circle center of the marker in the image shot by the camera after each step of rotation and the pixel coordinate p of the circle center of the marker in the step S1 to be not more than 0.5 pixel, wherein the circle center of the marker is imaged at the same point in the camera view field;
s23, reading the space coordinate P of the tail end of the mechanical arm when the circle center of the marker is imaged at the same point in the visual field of the camera2；
S24, according to the space coordinate P of the tail end of the mechanical arm twice1And P2The horizontal direction components (a, b) of the space vector of the tool center point with respect to the end of the robot arm are calculated.
As a further improvement of the above method of the invention, said angle A1Is 180 deg..
As a further improvement of the above method of the present invention, the step S3 includes the following steps:
s31, rotating any joint of the mechanical arm by any angle A around the W axis step by step2The W axis is parallel to the plane H, the step rotation is divided into two or more step rotations, and the total angle of the step rotations is A2；
S32, after each step of rotation, moving the tail end of the mechanical arm in parallel relative to the plane H to enable the imaging of the circle center of the marker to be infinitely close to the original pixel coordinate p of the circle center, and recording the pixel coordinate p 'of the circle center of the marker in the image obtained by the step of rotation after each step of rotation, wherein when the absolute position difference between the p' and the pixel coordinate p of the circle center of the marker in the step S1 is not more than 0.5 pixel, the circle center of the marker is imaged at the pixel coordinate p;
s33, enabling the tail end of the mechanical arm to vertically move relative to the plane H, stopping moving the mechanical arm when the length of the imaging long axis of the marker in the image shot by the camera is equal to the imaging radius R of the marker, and imaging the circle center of the marker at the same point in the visual field of the camera;
s34, reading the space coordinate P of the tail end of the mechanical arm3；
S35, according to the space coordinate P of the tail end of the mechanical arm twice2And P3And the horizontal direction component (a, b) in step S2 is calculated to obtain a vertical direction component c of the space vector of the tool center point with respect to the end of the robot arm1。
As a further improvement of the above method of the invention, said angle A2Is 60 degrees.
As a further improvement of the above method of the present invention, after the step S3, there is a step S4, which is specifically: returning the tail end of the mechanical arm to the state of completion of the step S2, and rotating any joint of the mechanical arm by any angle A around the V axis3Moving the end of the robot arm to a spatial coordinate P4Arranged to image the centre of a circle of a marker in the field of view of said cameraAt the same point, the length of the imaging long axis of the marker is equal to the imaging radius R of the marker according to the space coordinate P of the tail end of the mechanical arm twice2And P4And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm2Twice the component c of the vertical direction1And c2As the component of the final tool center point with respect to the vertical direction of the space vector of the end of the arm, said V-axis being parallel to the plane H and perpendicular to the W-axis.
As a further improvement of the above method of the present invention, there is a step before the step S3, which specifically includes: any joint of the mechanical arm rotates by any angle A around the V axis3Moving the end of the robot arm to a spatial coordinate P4Imaging the center of the marker at the same point in the visual field of the camera, and making the length of the imaging long axis of the marker equal to the imaging radius R of the marker according to the space coordinate P of the tail end of the mechanical arm twice2And P4And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm2Then, the robot arm tip is returned to the state of completion of step S2, and further, after completion of step S3, the component c of the vertical direction is divided twice1And c2As the component of the final tool center point with respect to the vertical direction of the space vector of the end of the arm, said V-axis being parallel to the plane H and perpendicular to the W-axis.
According to a second aspect of the present invention there is provided a calibration system for an industrial robot tool coordinate system, the system comprising:
the acquisition module is used for acquiring images of the tail end of the mechanical arm;
the storage module is used for storing the images acquired by the acquisition module, the data of the movement of each joint of the mechanical arm, the intermediate data of data processing and the final calibration result;
the display module is used for displaying the image acquired by the acquisition module in real time and displaying the calibration result;
the control module is used for controlling the mechanical arm to move or rotate;
and the processing module is used for processing the image, extracting the mark point from the image and sending a corresponding instruction to the control module according to a processing result.
According to a third aspect of the present invention there is provided a calibration system for an industrial robot tool coordinate system, the system comprising: the industrial robot comprises a base and a mechanical arm, wherein the base is fixed at one application place of the industrial robot, the mechanical arm is provided with two or more joints, a rotatable flange is arranged at the tail end of the mechanical arm, the flange is provided with a protrusion or a groove for fixing a tool, and the joints can rotate to enable the mechanical arm to reach a target object;
one end of the tool is fixedly connected with the flange plate, and the other end of the tool is used for completing different applications;
the marker is adhered to the central point of the tool and is placed in parallel relative to the flange surface of the flange plate, and the central point of the tool is determined according to a point needing to be calibrated;
the camera is fixed below the tail end of the mechanical arm, an imaging plane of the camera is parallel to the flange surface in the initial state of the industrial robot, the initial state of the industrial robot is that the tail end of the mechanical arm is placed along the U axis in a spherical coordinate system O' -UWV where the base is located, and the rotation angle of the flange plate is 0 degree;
the memory is used for storing pictures shot by the camera in the calibration process, data of movement of each joint of the mechanical arm, intermediate data of data processing and a final calibration result;
the display is used for displaying the pictures shot by the camera in real time and displaying the calibration result;
a controller for controlling the mechanical arm to move or rotate;
and the processor is used for processing the image, extracting the mark points from the image and sending corresponding instructions to the controller according to the processing result.
According to a fourth aspect of the present invention there is provided a calibration system for an industrial robot tool coordinate system, the system comprising the following means:
the first device is arranged to fix the circular marker at the center point of the tool in parallel relative to the flange surface at the tail end of the mechanical arm, enable the circle center of the marker to be imaged at one point in the field of view of the camera and enable the flange surface at the tail end of the mechanical arm to be parallel relative to the imaging plane H of the camera, and record the imaging radius R of the marker, the pixel coordinate P of the circle center of the marker and the space coordinate P of the tail end of the mechanical arm in the image shot by the camera at the moment1；
A second device which is arranged to make the flange at the tail end of the mechanical arm rotate at any angle A around the U shaft1Moving the end of the robot arm to a spatial coordinate P2Imaging the center of the marker at the same point in the camera view field according to the space coordinate P of the mechanical arm end twice1And P2Calculating horizontal components (a, b) of the central point of the tool relative to the space vector of the tail end of the mechanical arm, wherein the U axis is vertical to the plane H;
a third device for rotating any joint of the mechanical arm by any angle A around the W axis2Moving the end of the robot arm to a spatial coordinate P3Imaging the center of the marker at the same point in the visual field of the camera, and making the length of the imaging long axis of the marker on the plane H equal to the imaging radius R of the marker according to the space coordinate P of the tail end of the mechanical arm twice2And P3And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm1The W axis is parallel to plane H.
Compared with the prior art, the invention has the following remarkable advantages and beneficial effects:
in the prior art, two cameras are used for imaging a marker, when coordinate values of feature points of the marker in the two cameras are consistent, the tool center point of the tail end of a mechanical arm of an industrial robot or the feature points of the marker are considered to be located at the same spatial position in different postures, and then the coordinates of the center of the marker point in a robot base coordinate system are obtained through positive kinematics solution. According to the invention, by rotating the flange plate at the tail end of the mechanical arm once and imaging the characteristic points of the markers at the same point of the imaging plane of the camera, the horizontal component of the tool center point at the tail end of the mechanical arm or the characteristic points of the markers relative to the space vector at the tail end of the mechanical arm can be obtained by the moving distance of the tail end of the mechanical arm once. And then, by changing the posture of the primary industrial robot and imaging the characteristic points of the markers on the same point of the camera imaging plane, the vertical component of the space vector of the tool center point of the tail end of the mechanical arm or the characteristic points of the markers relative to the tail end of the mechanical arm can be obtained by the vertical movement distance of the tail end of the mechanical arm relative to the camera imaging plane.
According to the invention, the horizontal component and the vertical component of the space vector of the tool center point at the tail end of the mechanical arm or the characteristic point of the marker relative to the tail end of the mechanical arm are respectively obtained, and the space coordinate of the tail end of the mechanical arm under the base coordinate system of the robot base is known, so that the coordinate of the tool center point at the tail end of the mechanical arm or the characteristic point of the marker under the base coordinate system of the robot can be easily obtained, a complex kinematic equation does not need to be solved, the calibration process of the tool coordinate system is greatly simplified, and the calibration precision is further improved.
The invention can calibrate the tool coordinate by only one camera through a visual method, and the calibrating device is simple and fast.
The invention can automatically complete the tool coordinate calibration only by adjusting the gesture of the manipulator once, can rapidly complete the tool coordinate calibration of different tools when different tools are changed, and has stable and reliable calibration method and strong repeatability.
The present invention calibrates the space vector of the tool center point of the end of the robot arm or the characteristic point of the marker with respect to the end of the robot arm, and thus, can further check whether the tool held by the end of the robot arm deviates from the predetermined angle and position for the work and correct the deviation.
Drawings
Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 is a schematic representation of several exemplary patterns of markers useful in the practice of the present invention;
fig. 2 is an overall flow chart of a calibration method of an industrial robot tool coordinate system according to the invention;
fig. 3 is a schematic diagram of the position of an apparatus for implementing the calibration method of the tool coordinate system of an industrial robot according to the present invention;
FIG. 4 shows an embodiment of the present invention where the flange at the end of the robot arm rotates counterclockwise around the U-axis by an arbitrary angle A1Schematic diagrams of the latter coordinate changes;
fig. 5 is a flowchart of step S2 in an embodiment of the method for calibrating a coordinate system of an industrial robot tool according to the present invention;
FIG. 6 is a schematic diagram illustrating the change of coordinates of the flange at the end of the robot arm after rotating 180 degrees counterclockwise around the U-axis according to an embodiment of the present invention;
fig. 7 is a flowchart of step S3 in an embodiment of the method for calibrating a coordinate system of an industrial robot tool according to the present invention;
FIG. 8 is a schematic diagram illustrating the change of coordinates of any joint at the end of the robot arm after rotating about the W-axis by 60 degrees in one embodiment of the present invention;
fig. 9 is a schematic structural diagram of an embodiment of a calibration system of an industrial robot tool coordinate system according to the present invention;
fig. 10 is a schematic structural diagram of another embodiment of the calibration system of the tool coordinate system of the industrial robot.
Detailed Description
The camera required to implement the present invention may be a CMOS camera or a CCD camera. The robot includes a base and a robot arm having two or more joints, and a flange capable of rotating at any angle is usually provided at the end of the robot arm, and the flange can be integrated with the robot arm and can also be provided by a user. The coordinates of each joint and the tail end of the mechanical arm under the base coordinate system O '-XYZ taking the base of the robot as the reference under any posture of the robot can be read in real time, or can be further converted into the coordinates under the corresponding spherical coordinate system O' -WVU. The marker has characteristic points capable of being accurately positioned, the graph of the marker can be set freely according to the preference of a user, and as shown in fig. 1, the graphs of the marker are used for calibration in a common situation, wherein the size of an example graph does not represent the size of the marker actually. The display, the processor and the memory can be integrated devices such as a PC or can be separated into independent devices, the controller is a device for controlling the movement or posture change of the mechanical arm, and the controller controls the movement of the mechanical arm according to the processing result of the processor and displays the result on the display. In a preferred embodiment, the present invention uses a robot gripping system with three articulated arms, an industrial CCD camera for image acquisition, and a PC for displaying the acquired image, processing the image and storing the image, intermediate data and processing results of the present invention, the controller is embedded in the PC in the form of software, the marker used is preferably a circular marker sticker having a graphic as shown in fig. 1a that can be pasted on a tool, the tool used is a suction cup tool or a clamp fixed on a flange and can rotate at any angle along with the flange, the outward surface of the flange is defined as a flange surface F, and the U axis of a spherical coordinate system is defined to be perpendicular to the flange surface F, and the W axis and the V axis are parallel to the flange surface F.
Fig. 2 is a flow chart of an embodiment of the method for calibrating a coordinate system of an industrial robot tool according to the invention, as shown in the figure, the method comprises the following steps:
s1, pasting the circular label M with the figure as shown in fig. 3 on the tool center point of the tool T in parallel with respect to the flange surface at the end of the robot arm, so that the center of the circular label is imaged at a point in the camera view field and the flange surface F at the end of the robot arm is parallel with respect to the camera imaging plane H as shown in fig. 3. Recording the imaging radius R of the circular label paste M, the pixel coordinate P (u, v) of the center of the circle of the circular label paste M and the space coordinate P of the tail end of the mechanical arm in the image shot by the camera1(X1，Y1，Z1) The tool center point is any point on the tool and can be determined according to the requirements of users. According to the suction cup tool used in this embodiment, the circular mark M is preferably pasted in the center of the suction cup. One point in the camera view field is any point in the camera view field or on an image obtained by shooting of the camera. The imaging radius R of the circular label sticker M and the pixel coordinate P (u, v) of the circle center of the circular label sticker M can be obtained by performing an ellipse fitting algorithm on an image, and the space coordinate P of the tail end of the mechanical arm1(X1，Y1，Z1) Can be read directly.
S2, enabling the flange at the tail end of the mechanical arm to rotate at any angle A around the U shaft1Moving the end of the robot arm to a spatial coordinate P2(X2，Y2，Z2) Imaging the circle center of the circular label M at the same point in the visual field of the camera according to the space coordinate P of the tail end of the mechanical arm twice1(X1，Y1，Z1) And P2(X2，Y2，Z2) The horizontal components (a, b) of the space vector of the tool center point with respect to the end of the arm are calculated, the U-axis being perpendicular to the plane H. Because the camera imaging plane H is parallel to the flange surface F, the circular label sticker is still parallel to the camera imaging plane H after the flange at the tail end of the mechanical arm rotates around the U shaft, and therefore the movement of the tail end of the mechanical arm is water when the circle center of the circular label sticker M is imaged again at the same point in the camera view fieldAnd (4) performing translational motion. FIG. 4 shows the flange at the end of the robot arm rotating at an arbitrary angle A around the U-axis in a counter-clockwise direction1The schematic diagram of the coordinate change at the center of the circle of the rear circular label M represents the spatial coordinate of a point where the center of the circle of the circular label M is imaged in the field of view of the camera by P (X, Y, Z) under the base coordinate system O' -XYZ, i.e., the point P (X, Y, Z) represents the spatial coordinate of the center of the circle of the circular label M corresponding to the pixel coordinate P (u, v). P' is the space coordinate of the circle center of the circular label M after rotation, and the space coordinate P of the point P (X, Y, Z) before rotation relative to the tail end of the mechanical arm is set1(X1，Y1，Z1) Has a space vector of r1(a1，b1，c1) After rotating and moving the end of the mechanical arm to make the circle center of the circular label M image at the same point P (X, Y, Z) in the visual field of the camera, the point P (X, Y, Z) is relative to the space coordinate P of the end of the mechanical arm2(X2，Y2，Z2) Has a space vector of r2(a2，b2，c2) Then, there are:
r1(a1，b1，c1)＝P(X，Y，Z)-P1(X1，Y1，Z1)
r2(a2，b2，c2)＝P(X，Y，Z)-P2(X2，Y2，Z2)
since the motion is parallel, r is expressed by matrix1And r2The relationship between them is:
and due to the space vector r1And r2Is equal and has a vertical component c1＝c2Then, there are:
r1-r2＝P2-P1
namely, it is
As can be seen from the above, the space coordinate P before and after the rotation of the tail end of the mechanical arm in the mechanical arm system is read1(X1，Y1，Z1)、P2(X2，Y2，Z2) And a rotation angle A1Can be solved to obtain r1Horizontal component (a) of1，b1) The value of (a), i.e. the horizontal component (a)1，b1) Is the horizontal component (a, b) of the space vector of the tool center point relative to the end of the arm. Other types of calculation methods may be used as long as the methods are the same.
S3, rotating any joint of the mechanical arm by any angle A around the W axis2Moving the tail end of the mechanical arm to enable the circle center of the circular mark paste M to be imaged at the same point in the view field of the camera, and moving the tail end of the mechanical arm to a space coordinate P3(X3，Y3，Z3) The length of the long axis of the marker is equal to the imaging radius R of the circular marker sticker M according to the space coordinate P of the tail end of the mechanical arm twice2(X2，Y2，Z2) And P3(X3，Y3，Z3) And calculating the horizontal component to obtain the vertical component c of the space vector of the tool center point relative to the tail end of the mechanical arm1The W axis is parallel to plane H. Any joint of the mechanical arm rotates by any angle A around the W axis2And then, the flange surface F is not parallel to the camera imaging plane H, and the circular mark paste M is elliptical on the camera imaging plane. Since the axis of rotation W is parallel to the camera imaging plane H, the radius of the circular sticker along the axis W remains parallel to the camera imaging plane H, but due to the rotationWhich is further from the camera imaging plane and becomes smaller in length on the image. The radius of the circular label M along the V axis will rotate the angle A2And away from the camera imaging plane so that the size of the image imaged on the image will become smaller than the imaging length along the radius of the W-axis. The imaging length of the radius of the circular marker patch M along the W axis is thus the major axis of the imaging ellipse and the imaging length of the radius along the V axis is the minor axis of the imaging ellipse. And (3) firstly moving the tail end of the mechanical arm in parallel relative to the plane H, and then vertically moving the tail end of the mechanical arm, or vice versa, so that the circle center of the circular mark paste M is imaged at the same point in the visual field of the camera, and the length of the long axis of the imaging ellipse of the circular mark paste M is equal to the imaging radius R of the circular mark paste M. The same point corresponds to the center pixel coordinate P (u, v) of the circular label M at the spatial coordinate point P (X, Y, Z). Reading the space coordinate P of the tail end of the mechanical arm at the moment3(X3，Y3，Z3) Due to P3(X3，Y3，Z3) Is at P2(X2，Y2，Z2) On the basis of rotating around the W axis A2Setting the space coordinate P of the point P (X, Y, Z) relative to the tail end of the mechanical arm3(X3，Y3，Z3) Has a space vector of r3(a3，b3，c3) Then, there are:
r2(a2，b2，c2)＝P(X，Y，Z)-P2(X2，Y2，Z2)
r3(a3，b3，c3)＝P(X，Y，Z)-P3(X3，Y3，Z3)
representing r by a matrix2And r3The relationship between them is:
and due to the space vector r1、r2And r3Is equal in modulus and has a transverse component a1＝a2Then, there are:
r2-r3＝P3-P2
namely, it is
As can be seen from the above, the space coordinate P before and after the rotation of the tail end of the mechanical arm in the mechanical arm system is read2(X2，Y2，Z2)、P3(X3，Y3，Z3) And a rotation angle A2Can be solved to obtain r2Vertical component c of2The value of (c). As described in step S2, r2Vertical component c of2Is equal to r1Vertical component c of1The value of (a), i.e. the component c of the tool center point in the vertical direction with respect to the space vector of the end of the robot arm, can be solved simultaneously by the above formulas1. Other types of calculation methods may be used as long as the methods are the same.
As a further improvement of the above embodiment, in step S1, a point in the camera view field is preferably a midpoint in the camera view field, or a central pixel point of an image captured by the camera, so that a calibration error caused by distortion of a camera lens is greatly reduced.
As a further improvement of the above embodiment, step S2 shown in fig. 5 includes the following steps:
s21, enabling the flange at the tail end of the mechanical arm to rotate around the U shaft by any angle A step by step1The U axis is perpendicular to the plane H, and the step-by-step rotation is divided into two or more stepsStep rotation, the total angle of step rotation is A1。
S22, after each step of rotation, the tail end of the mechanical arm is moved in parallel relative to the plane H to enable the circle center of the circular mark paste M to be infinitely close to the same point in the camera view field, pixel coordinates p ' (u ', v ') of the circle center of the circular mark paste M in an image obtained by shooting through the camera after each step of rotation are recorded, and if the absolute position difference between the pixel coordinates p (u, v) of the circle center of the circular mark paste M in the step S1 is not more than 0.5 pixel, the circle center of the circular mark paste M is considered to be imaged at the same point in the camera view field.
S23, reading the space coordinate P of the tail end of the mechanical arm when the circle center of the circular label M is imaged at the same point in the visual field of the camera2(X2，Y2，Z2)；
S24, according to the space coordinate P of the tail end of the mechanical arm twice1(X1，Y1，Z1) And P2(X2，Y2，Z2) The horizontal direction components (a, b) of the space vector of the tool center point with respect to the end of the robot arm are calculated according to the above calculation process.
As a further improvement of the above embodiment, said angle a1 is preferably 180 °, the process of obtaining the horizontal components (a, b) of the space vector of the tool center point relative to the end of the robot arm is greatly simplified. At this time, a spatial coordinate point P (X, Y, Z) of the center of the circle of the circular label M, a spatial coordinate point P after the rotation thereof, and a spatial coordinate P of the end of the robot arm before and after the movement1(X1，Y1，Z1) And P2(X2，Y2，Z2) The positional relationship of (2) is shown in FIG. 6. At this time, there are:
and represents r by a matrix1And r2The relationship between them is:
namely, it is
The simultaneous expression is as follows:
i.e. the horizontal component (a)1，b1) Is the horizontal component (a, b) of the space vector of the tool center point relative to the end of the arm. Other types of calculation methods may be used as long as the methods are the same.
As a further modification of the above embodiment, the step S3 includes the following steps as shown in fig. 7:
s31, rotating any joint of the mechanical arm by any angle A2 step by step around a W axis, wherein the W axis is parallel to a camera imaging plane H, the step rotation is divided into two or more steps, and the sum of the angles of the step rotation is A2.
And S32, after each step of rotation, moving the tail end of the mechanical arm in parallel relative to the imaging plane H of the camera, recording pixel coordinates p '(u', v ') of the circle center of the circular mark paste M in the image obtained by shooting of the camera after each step of rotation, and if the absolute position difference between the p' (u ', v') and the pixel coordinates p (u, v) of the circle center of the circular mark paste M in the step S1 is not more than 0.5 pixel, considering that the circle center of the circular mark paste M is imaged at the pixel coordinates p (u, v). After the step rotation is completed, the imaging of the circular marker sticker M on the imaging plane changes from a circle to an ellipse.
And S33, enabling the tail end of the mechanical arm to vertically move relative to the camera imaging plane H, stopping moving the mechanical arm when the length of the long axis of the imaging ellipse of the circular label sticker M in the image obtained by the camera is equal to the imaging radius R of the circular label sticker M, and considering that the circle center of the circular label sticker M is imaged at the same point in the camera view field at the moment, wherein the space coordinate of the circle center is the point P (X, Y, Z).
S34, reading the space coordinate P of the tail end of the mechanical arm3(X3，Y3，Z3)；
S35, according to the space coordinate P of the tail end of the mechanical arm twice2(X2，Y2，Z2) And P3(X3，Y3，Z3) And the horizontal direction component (a, b) in step S2 is calculated by the aforementioned calculation method to obtain the vertical direction component c of the space vector of the tool center point with respect to the robot arm tip1。
As a further improvement to the above embodiment, the angle A2Preferably 60 deg., the vertical component c of the space vector of the tool center point with respect to the end of the arm is obtained1The process of (2) will be greatly simplified. As shown in fig. 8, since P3(X3，Y3，Z3) Is at P2(X2，Y2，Z2) On the basis of a 60 DEG rotation about the W axis, whereby P2(X2，Y2，Z2) And P3(X3，Y3，Z3) Space vector r relative to P (X, Y, Z)2And r3Are identical in X-coordinate, i.e. a2＝a3And the length of the central point relative to the end of the mechanical arm is unchanged before and after rotation, then:
representing r by a matrix1And r2The relationship between them is:
and step S2 is executed when the end of the mechanical arm rotates by an angle A around the U-axis1Preferably 180 DEG, having a2＝-a1，b2＝-b1，c2＝c1The simultaneous upper formula is as follows:
thus:
namely:
the horizontal component b derived from the above1The component c of the tool center point relative to the vertical direction of the space vector of the tail end of the mechanical arm can be obtained1。
As a further improvement of the above embodiment, after the step S3, there is a step S4, which is specifically: returning the tail end of the mechanical arm to the state of completion of the step S2, and rotating any joint of the mechanical arm by any angle A around the V axis3The V axis is parallel to the plane H and perpendicular to the W axis, the rotation can be step-by-step rotation, the tail end of the mechanical arm needs to be moved after each step of step-by-step rotation is completed, the mechanical arm can be moved in parallel relative to the plane H and then moved vertically, or the sequence is reversed, the circle center of the circular mark paste M is imaged at the same point in the visual field of the camera, and the space coordinate is set as P4(X4，Y4，Z4) And the length of the long axis of the imaging ellipse of the circular label paste M is equal to the imaging radius R of the circular label paste M. According to the space coordinate P of the tail end of the mechanical arm twice2(X2，Y2，Z2) And P4(X4，Y4，Z4) And the horizontal direction components (a, b) can be calculated according to the calculation method to obtain the vertical direction component c of the space vector of the tool center point relative to the tail end of the mechanical arm2Comprises the following steps:
twice the component c of the vertical direction1And c2The average value c of the distance between the final tool center point and the tail end of the mechanical arm is used as the component of the final tool center point relative to the vertical direction of the space vector of the tail end of the mechanical arm, so that the calibration precision in the vertical direction can be improved.
As a further improvement of the above embodiment, there is a step before the step S3, which specifically includes: any joint of the mechanical arm rotates by any angle A around the V axis3The V axis is parallel to the plane H and perpendicular to the W axis, the rotation can be step-by-step rotation, the tail end of the mechanical arm needs to be moved after each step of step-by-step rotation is completed, the mechanical arm can be moved in parallel relative to the plane H and then moved vertically, or the sequence is reversed, the circle center of the circular mark paste M is imaged at the same point in the visual field of the camera, and the space coordinate is set as P4(X4，Y4，Z4) And the length of the long axis of the imaging ellipse of the circular label paste M is equal to the imaging radius R of the circular label paste M. According to the space coordinate P of the tail end of the mechanical arm twice2(X2，Y2，Z2) And P4(X4，Y4，Z4) And the horizontal direction components (a, b) can be calculated according to the calculation method to obtain the vertical direction component c of the space vector of the tool center point relative to the tail end of the mechanical arm2Then, the robot arm tip is returned to the state of completion of step S2, and further, after completion of step S3, the component c of the vertical direction is divided twice1And c2The average value c of the distance between the final tool center point and the tail end of the mechanical arm is used as the component of the final tool center point relative to the vertical direction of the space vector of the tail end of the mechanical arm, so that the calibration precision in the vertical direction can be improved.
According to another embodiment of the invention, a system for calibrating a tool coordinate system of an industrial robot, as shown in fig. 9, comprises:
the acquisition module is used for acquiring images of the tail end of the mechanical arm;
the storage module is used for storing the images acquired by the acquisition module, the data of the movement of each joint of the mechanical arm, the intermediate data of data processing and the final calibration result;
the display module is used for displaying the image acquired by the acquisition module in real time and displaying the calibration result;
the control module is used for controlling the mechanical arm to move or rotate;
and the processing module is used for processing the image, extracting the mark point from the image and sending a corresponding instruction to the control module according to a processing result.
According to another embodiment of the invention, a calibration system for an industrial robot tool coordinate system, as shown in fig. 10, comprises:
the industrial robot comprises a base and a mechanical arm, wherein the base is fixed at one application place of the industrial robot, the mechanical arm is provided with two or more joints, a rotatable flange is arranged at the tail end of the mechanical arm, the flange is provided with a protrusion or a groove for fixing a tool, and the joints can rotate to enable the mechanical arm to reach a target object;
one end of the tool is fixedly connected with the flange plate, and the other end of the tool is used for completing different applications;
the marker is adhered to the central point of the tool and is placed in parallel relative to the flange surface of the flange plate, and the central point of the tool is determined according to a point needing to be calibrated;
the camera is fixed below the tail end of the mechanical arm, an imaging plane of the camera is parallel to the flange surface in the initial state of the industrial robot, the initial state of the industrial robot is that the tail end of the mechanical arm is placed along the U axis in a spherical coordinate system O' -UWV where the base is located, and the rotation angle of the flange plate is 0 degree;
the memory is used for storing pictures shot by the camera in the calibration process, data of movement of each joint of the mechanical arm, intermediate data of data processing and a final calibration result;
the display is used for displaying the pictures shot by the camera in real time and displaying the calibration result;
a controller for controlling the mechanical arm to move or rotate;
and the processor is used for processing the image, extracting the mark points from the image and sending corresponding instructions to the controller according to the processing result.
According to another embodiment of the invention, a calibration system for an industrial robot tool coordinate system comprises the following means:
the first device is arranged to fix the circular marker at the center point of the tool in parallel relative to the flange surface at the tail end of the mechanical arm, enable the circle center of the marker to be imaged at one point in the field of view of the camera and enable the flange surface at the tail end of the mechanical arm to be parallel relative to the imaging plane H of the camera, and record the imaging radius R of the marker, the pixel coordinate P of the circle center of the marker and the space coordinate P of the tail end of the mechanical arm in the image shot by the camera at the moment1；
A second device which is arranged to make the flange at the tail end of the mechanical arm rotate at any angle A around the U shaft1Moving the end of the robot arm to a spatial coordinate P2Imaging the center of the marker at the same point in the camera view field according to the space coordinate P of the mechanical arm end twice1And P2ComputingObtaining horizontal components (a, b) of a space vector of a tool central point relative to the tail end of the mechanical arm, wherein the U axis is vertical to the plane H;
a third device for rotating any joint of the mechanical arm by any angle A around the W axis2Moving the end of the robot arm to a spatial coordinate P3Imaging the center of the marker at the same point in the visual field of the camera, and making the length of the imaging long axis of the marker on the plane H equal to the imaging radius R of the marker according to the space coordinate P of the tail end of the mechanical arm twice2And P3And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm1The W axis is parallel to plane H.
The invention relates to a method and a system for calibrating a tool coordinate system of an industrial robot, which are used for calibrating a space vector of a central point of a tool relative to the tail end of a mechanical arm, so that the method and the system can be further used for calibrating whether a tool clamped by the mechanical arm deviates from a preset angle and position, and the precision in industrial operation is improved.
Those skilled in the art will clearly understand that the techniques in the embodiments of the present application may be implemented by means of software plus a necessary general-purpose hardware platform, and optionally also by means of dedicated hardware circuits, such as a large-scale integrated circuit, a CPLD, etc. Based on such understanding, the technical solutions in the embodiments of the present application may be essentially implemented or partially contributed to by the prior art, and/or may be implemented in a form of a software product and/or a hardware product, where the computer software product may be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, and/or the like, and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute the methods described in the embodiments or some parts of the embodiments of the present application.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiment, and the present invention shall fall within the protection scope of the present invention as long as the technical effects of the present invention are achieved by the same means. The invention is capable of other modifications and variations in its technical solution and/or its implementation, within the scope of protection of the invention. Even if individual features are cited in different claims, the invention may also comprise embodiments sharing these features.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (11)
1. A method for calibrating a tool coordinate system of an industrial robot, the industrial robot comprising a base and a robot arm, the tool being fixed to the end of the robot arm, the robot arm having more than two joints, the method comprising the steps of:
s1, fixing the circular marker at the center point of the tool in parallel relative to the flange surface at the tail end of the mechanical arm, imaging the center of the marker at one point in the camera view field, making the flange surface at the tail end of the mechanical arm parallel relative to the camera imaging plane H, and recording the composition of the marker in the image shot by the camera at the momentImage radius R, pixel coordinate P of center of marker circle and space coordinate P of mechanical arm tail end1；
S2, enabling the flange at the tail end of the mechanical arm to rotate at any angle A around the U shaft1Moving the end of the robot arm to a spatial coordinate P2Imaging the center of the marker at the same point in the camera view field according to the space coordinate P of the mechanical arm end twice1And P2Calculating horizontal components (a, b) of the central point of the tool relative to the space vector of the tail end of the mechanical arm, wherein the U axis is vertical to the plane H;
s3, rotating any joint of the mechanical arm by any angle A around the W axis2Moving the end of the robot arm to a spatial coordinate P3Imaging the center of the marker at the same point in the visual field of the camera, and making the length of the imaging long axis of the marker on the plane H equal to the imaging radius R of the marker according to the space coordinate P of the tail end of the mechanical arm twice2And P3And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm1The W axis is parallel to plane H.
2. A method for calibrating a coordinate system of an industrial robot tool according to claim 1, wherein a point in the camera view field in step S1 is a midpoint in the camera view field or a central pixel point of an image captured by the camera.
3. A method of calibration of an industrial robot tool coordinate system according to claim 1, characterized in that: the step S2 includes the following steps:
s21, enabling the flange at the tail end of the mechanical arm to rotate around the U shaft by any angle A step by step1The U shaft is vertical to the plane H, the step rotation is divided into more than two step rotations, and the total angle of the step rotations is A1；
S22, after each step of rotation, moving the tail end of the mechanical arm in parallel relative to the plane H to enable the circle center of the marker to be infinitely close to the same point in the camera view field, and recording the absolute position difference between the pixel coordinate p' of the circle center of the marker in the image shot by the camera after each step of rotation and the pixel coordinate p of the circle center of the marker in the step S1 to be not more than 0.5 pixel, wherein the circle center of the marker is imaged at the same point in the camera view field;
s23, reading the space coordinate P of the tail end of the mechanical arm when the circle center of the marker is imaged at the same point in the visual field of the camera2；
S24, according to the space coordinate P of the tail end of the mechanical arm twice1And P2The horizontal direction components (a, b) of the space vector of the tool center point with respect to the end of the robot arm are calculated.
4. A method for calibration of an industrial robot tool coordinate system according to claim 3, characterized in that said angle a1Is 180 deg..
5. A method for calibration of an industrial robot tool coordinate system according to claim 1, characterized in that said step S3 comprises the steps of:
s31, rotating any joint of the mechanical arm by any angle A around the W axis step by step2The W axis is parallel to the plane H, the step rotation is divided into more than two step rotations, and the total angle of the step rotations is A2；
S32, after each step of rotation, moving the tail end of the mechanical arm in parallel relative to the plane H to enable the imaging of the circle center of the marker to be infinitely close to the original pixel coordinate p of the circle center, and recording the pixel coordinate p 'of the circle center of the marker in the image obtained by the step of rotation after each step of rotation, wherein when the absolute position difference between the p' and the pixel coordinate p of the circle center of the marker in the step S1 is not more than 0.5 pixel, the circle center of the marker is imaged at the pixel coordinate p;
s33, enabling the tail end of the mechanical arm to vertically move relative to the plane H, stopping moving the mechanical arm when the length of the imaging long axis of the marker in the image shot by the camera is equal to the imaging radius R of the marker, and imaging the circle center of the marker at the same point in the visual field of the camera;
s34, reading the space coordinate P of the tail end of the mechanical arm3；
S35, according to the space coordinate P of the tail end of the mechanical arm twice2And P3And the horizontal direction component (a, b) in step S2 is calculated to obtain a vertical direction component c of the space vector of the tool center point with respect to the end of the robot arm1。
6. A method for calibration of an industrial robot tool coordinate system according to claim 5, characterized in that said angle A is2Is 60 degrees.
7. A method for calibration of an industrial robot tool coordinate system according to claim 1 or 5, characterized in that after said step S3, it comprises a step S4, which is embodied by: returning the tail end of the mechanical arm to the state of completion of the step S2, and rotating any joint of the mechanical arm by any angle A around the V axis3Moving the end of the robot arm to a spatial coordinate P4Imaging the center of the marker at the same point in the visual field of the camera, and making the length of the imaging long axis of the marker equal to the imaging radius R of the marker according to the space coordinate P of the tail end of the mechanical arm twice2And P4And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm2Twice the component c of the vertical direction1And c2As the component of the final tool center point with respect to the vertical direction of the space vector of the end of the arm, said V-axis being parallel to the plane H and perpendicular to the W-axis.
8. A method for calibration of an industrial robot tool coordinate system according to claim 1 or 5, characterized in that before said step S3 there is a further step of: any joint of the mechanical arm rotates by any angle A around the V axis3Moving the end of the robot arm to a spatial coordinate P4Imaging the center of the marker at the same point in the camera view field, and making the length of the imaging long axis of the marker equalImaging radius R of the marker according to the space coordinate P of the end of the mechanical arm twice2And P4And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm2Then, the robot arm tip is returned to the state of completion of step S2, and further, after completion of step S3, the component c of the vertical direction is divided twice1And c2As the component of the final tool center point with respect to the vertical direction of the space vector of the end of the arm, said V-axis being parallel to the plane H and perpendicular to the W-axis.
9. A calibration system for an industrial robot tool coordinate system, comprising:
the acquisition module is used for acquiring images of the tail end of the mechanical arm;
the storage module is used for storing the images acquired by the acquisition module, the data of the movement of each joint of the mechanical arm, the intermediate data of data processing and the final calibration result;
the display module is used for displaying the image acquired by the acquisition module in real time and displaying the calibration result;
the control module is used for controlling the mechanical arm to move or rotate;
the processing module is used for processing the image, extracting the mark points from the image and sending corresponding instructions to the control module according to the processing result;
wherein,
the industrial robot comprises a base and a mechanical arm, wherein the tool is fixed at the tail end of the mechanical arm, and the mechanical arm is provided with more than two joints;
the method comprises the steps that a circular marker is fixed at a tool center point in parallel relative to a flange face at the tail end of a mechanical arm, a control module controls the mechanical arm to enable the circle center of the marker to be imaged at one point in a view field of an acquisition module and enable the flange face at the tail end of the mechanical arm to be parallel relative to an imaging plane H of the acquisition module, and a storage module stores the imaging radius R of the marker, the pixel coordinate P of the circle center of the marker and the space coordinate P of the tail end of the mechanical arm in an image shot by the1；
Control moduleThe mechanical arm is controlled by the block to enable the flange at the tail end of the mechanical arm to rotate by any angle A around the U shaft1And controlling the end of the mobile mechanical arm to reach the space coordinate P2The center of the marker is imaged at the same point in the view field of the acquisition module, and the processing module is used for imaging the center of the marker at the same point in the view field of the acquisition module according to the space coordinate P of the tail end of the mechanical arm twice1And P2Calculating horizontal components (a, b) of the central point of the tool relative to the space vector of the tail end of the mechanical arm, wherein the U axis is vertical to the plane H;
the control module controls the mechanical arm to enable any joint of the mechanical arm to rotate by any angle A around the W axis2And controlling the end of the mobile mechanical arm to reach the space coordinate P3Imaging the center of the marker at the same point in the view field of the acquisition module, making the length of the imaging long axis of the marker on the plane H equal to the imaging radius R of the marker, and processing the marker by the processing module according to the space coordinate P of the tail end of the mechanical arm twice2And P3And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm1The W axis is parallel to plane H.
10. A calibration system for an industrial robot tool coordinate system, comprising:
an industrial robot, the industrial robot comprises a base and a mechanical arm, the base is fixed at one application place of the industrial robot, the mechanical arm is provided with more than two joints and a rotatable flange plate at the tail end, the flange plate is provided with a protrusion or a groove for fixing a tool, and the joints can rotate to enable the mechanical arm to reach a target object;
one end of the tool is fixedly connected with the flange plate, and the other end of the tool is used for completing different applications;
the marker is adhered to the central point of the tool and is placed in parallel relative to the flange surface of the flange plate, and the central point of the tool is determined according to a point needing to be calibrated;
the camera is fixed below the tail end of the mechanical arm, an imaging plane of the camera is parallel to the flange surface in the initial state of the industrial robot, the initial state of the industrial robot is that the tail end of the mechanical arm is placed along the U axis in a spherical coordinate system O' -UWV where the base is located, and the rotation angle of the flange plate is 0 degree;
the memory is used for storing pictures shot by the camera in the calibration process, data of movement of each joint of the mechanical arm, intermediate data of data processing and a final calibration result;
the display is used for displaying the pictures shot by the camera in real time and displaying the calibration result;
a controller for controlling the mechanical arm to move or rotate;
the processor is used for processing the image, extracting the mark points from the image and sending corresponding instructions to the controller according to the processing result;
wherein,
the circular marker is fixed at the center point of a tool in parallel relative to the flange surface at the tail end of the mechanical arm, the controller controls the mechanical arm to enable the circle center of the marker to be imaged at one point in the field of view of the camera and enable the flange surface at the tail end of the mechanical arm to be parallel relative to the imaging plane H of the camera, and the memory stores the imaging radius R of the marker, the pixel coordinate P of the circle center of the marker and the space coordinate P of the tail end of the mechanical arm in an image shot by the camera at the moment1；
The controller controls the mechanical arm to enable the flange at the tail end of the mechanical arm to rotate by any angle A around the U shaft1And controlling the end of the mobile mechanical arm to reach the space coordinate P2Imaging the center of the marker at the same point in the camera view field, and processing the image by the processor according to the space coordinate P of the mechanical arm end twice1And P2Calculating horizontal components (a, b) of the central point of the tool relative to the space vector of the tail end of the mechanical arm, wherein the U axis is vertical to the plane H;
the controller controls the mechanical arm to enable any joint of the mechanical arm to rotate by any angle A around the W shaft2And controlling the end of the mobile mechanical arm to reach the space coordinate P3Imaging the center of the marker at the same point in the visual field of the camera, and making the length of the imaging long axis of the marker on the plane H equal to the imaging radius R of the marker, wherein the processor is used for processing the image twiceSpatial coordinate P of the end of the arm2And P3And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm1The W axis is parallel to plane H.
11. A system for calibrating a coordinate system of a tool of an industrial robot, said industrial robot comprising a base and a robot arm, said tool being fixed to the end of the robot arm, said robot arm having more than two joints, characterized in that the system comprises the following means:
the first device is arranged to fix the circular marker at the center point of the tool in parallel relative to the flange surface at the tail end of the mechanical arm, enable the circle center of the marker to be imaged at one point in the field of view of the camera and enable the flange surface at the tail end of the mechanical arm to be parallel relative to the imaging plane H of the camera, and record the imaging radius R of the marker, the pixel coordinate P of the circle center of the marker and the space coordinate P of the tail end of the mechanical arm in the image shot by the camera at the moment1；
A second device which is arranged to make the flange at the tail end of the mechanical arm rotate at any angle A around the U shaft1Moving the end of the robot arm to a spatial coordinate P2Imaging the center of the marker at the same point in the camera view field according to the space coordinate P of the mechanical arm end twice1And P2Calculating horizontal components (a, b) of the central point of the tool relative to the space vector of the tail end of the mechanical arm, wherein the U axis is vertical to the plane H;
a third device for rotating any joint of the mechanical arm by any angle A around the W axis2Moving the end of the robot arm to a spatial coordinate P3Imaging the center of the marker at the same point in the visual field of the camera, and making the length of the imaging long axis of the marker on the plane H equal to the imaging radius R of the marker according to the space coordinate P of the tail end of the mechanical arm twice2And P3And the horizontal direction components (a, b) are calculated to obtain the vertical direction component c of the space vector of the central point of the tool relative to the tail end of the mechanical arm1The W axis is parallel to plane H.
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| CN107363823A (en) * | 2017-06-21 | 2017-11-21 | 深圳市恒科通机器人有限公司 | The coordinate scaling method of mechanical arm |
| CN109916352B (en) * | 2017-12-13 | 2020-09-25 | 北京柏惠维康科技有限公司 | Method and device for acquiring TCP (Transmission control protocol) coordinates of robot |
| CN107953333B (en) * | 2017-12-20 | 2021-04-20 | 深圳大学 | Control method and system for calibrating tool at tail end of manipulator |
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