CN115115931A - Rapid workpiece positioning method for robot machining system - Google Patents

Rapid workpiece positioning method for robot machining system Download PDF

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CN115115931A
CN115115931A CN202210009499.7A CN202210009499A CN115115931A CN 115115931 A CN115115931 A CN 115115931A CN 202210009499 A CN202210009499 A CN 202210009499A CN 115115931 A CN115115931 A CN 115115931A
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workpiece
robot
coordinate system
positioning
vision
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张刚
郝大贤
乔永立
杨龙
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HUST Wuxi Research Institute
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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
    • B25J9/1669—Programme controls characterised by programming, planning systems for manipulators characterised by special application, e.g. multi-arm co-operation, assembly, grasping
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/0002—Inspection of images, e.g. flaw detection
    • G06T7/0004—Industrial image inspection
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/60—Analysis of geometric attributes
    • G06T7/62—Analysis of geometric attributes of area, perimeter, diameter or volume
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/70—Determining position or orientation of objects or cameras
    • G06T7/73—Determining position or orientation of objects or cameras using feature-based methods
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10004—Still image; Photographic image
    • G06T2207/10012—Stereo images
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30108—Industrial image inspection
    • G06T2207/30164—Workpiece; Machine component

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  • Physics & Mathematics (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Robotics (AREA)
  • Mechanical Engineering (AREA)
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Abstract

The invention relates to a method for quickly positioning a workpiece of a robot machining system, wherein the whole calibration process comprises two steps of (1)3D vision system rough positioning and (2) contact measurement fine positioning. The invention combines the usability of vision measurement positioning and the accuracy of contact measurement positioning, utilizes a low-cost 3D vision product to carry out rough positioning on the coordinates of a workpiece, utilizes a robot to grasp a contact measuring head to carry out fine positioning on the workpiece after roughly determining the coordinate system of the workpiece, and can quickly position the coordinate system of the workpiece on a worktable when measuring a large component. The method has important practical application value for processing large-scale components of various types and small batches.

Description

Rapid workpiece positioning method for robot machining system
Technical Field
The invention relates to the field of robot machining, in particular to a method for quickly positioning a workpiece of a robot machining system.
Background
The robot processing technology of the large-scale complex component has wide application prospect in the manufacturing field of the large-scale complex component in the fields of aviation, aerospace, energy, delivery and the like, is directly related to national economy and national defense safety, and reflects the important strategic demands of the country. Compared with the traditional manufacturing industry, the large complex component has the characteristics of large size, high precision, small batch, multiple varieties, complex structure, severe working conditions and the like, and the processing and the manufacturing thereof represent the core competitiveness of the national manufacturing industry.
The off-line programming task of the robot is mostly defined under the workpiece coordinate system, and therefore, it is very important to obtain the coordinates of the feature to be processed under the workpiece coordinate system during the robot processing. At present, a method for positioning a workpiece by a robot mainly obtains coordinate values of a feature to be processed under a workpiece coordinate system in a manual teaching mode, but the manual teaching method is time-consuming and labor-consuming, low in efficiency and low in accuracy of teaching points, so that a method for quickly positioning the position of the feature of the workpiece under the workpiece coordinate system is needed to be found. Especially, in the process of milling an aviation component by using a robot, a large number of feature points are often required to be acquired, and it is not practical to teach the feature points manually, because in the process of milling the aviation component, the phenomena that the types of the processed workpieces are various and the processing positions are randomly placed are often encountered, so that it is very important to find out a method for quickly positioning the features of the workpieces.
In patent CN 109848989 a, a robot based on ruby probe is disclosed to perform an automatic calibration and detection method of the end. The surface profile of the workpiece is subjected to touch searching calibration by using a fixed ruby probe, the surface profile of the workpiece before and after processing is calculated, and the calculation result is transmitted to a robot controller, so that the surface profile of the workpiece at the tail end of the robot is calculated and displayed. The automatic calibration of the execution tail end of the robot can be realized, and the surface profile detection before and after the workpiece processing can be automatically completed.
In patent CN202010823167.3, a method for quickly positioning a workpiece of a robot milling system based on a laser tracker and a binocular camera is disclosed. A robot milling system workpiece rapid positioning method based on a laser tracker and a binocular camera is disclosed. The method can quickly convert point cloud obtained by scanning of the binocular camera into a workpiece coordinate system, extract feature points under the workpiece coordinate system through point cloud processing, and guide the robot to move to the position of the feature points based on the feature points. The method has high efficiency, avoids errors of manual teaching, and improves the workpiece positioning accuracy of the robot milling system.
The above two patents measure or calibrate the workpiece from contact measurement and non-contact measurement, respectively. However, the simple contact measurement requires a positioning tool to be designed, and the workpiece can be measured only after being fixed to a determined position, and only can be adapted to a specific workpiece. The processing requirements of multiple varieties and small-batch hardness attack can not be met. Although the laser tracker and the binocular camera used in the non-contact measuring method can meet the requirement of automatically measuring and calibrating workpieces, the overall equipment cost is high, and the low-cost wide application is difficult to realize.
In addition, the precision requirement of the robot machining for large workpieces is usually higher than 0.5mm, the matching and positioning precision of the general large-field 3D vision product for the workpiece is about ± 2mm, and if a vision device or a laser scanning product with higher precision is adopted, the price is usually very high, and the cost of the system is greatly increased. And direct use contact measuring equipment marks, because the locating position of work piece is random, needs the manual work to teach the robot, carries out work piece location and marks, and work load is big, and is higher to operating personnel's technical merit requirement, does not satisfy the automatic measurement operation of robot.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a rapid workpiece positioning method for a robot machining system, which combines the usability of visual measurement positioning and the accuracy of contact measurement positioning, roughly positions the coordinates of a workpiece by using a low-cost 3D visual product, determines the approximate coordinate system of the workpiece and then precisely positions the workpiece by using a robot to hold a contact measuring head.
The technical scheme for realizing the purpose of the invention is as follows: a method for quickly positioning the workpiece in robot machining system includes
The method comprises the following steps: the 3D vision system coarse positioning specifically comprises the following steps:
1.1 establishing a workpiece coordinate system by utilizing a workpiece digital model;
1.2, calibrating the robot eyes, and calibrating the pose relationship between a robot base coordinate system and a vision measurement coordinate system;
1.3, installing and fixing a workpiece to be measured;
1.4, scanning a workpiece by using a 3D camera to obtain workpiece point cloud data; processing the point cloud data of the workpiece to obtain workpiece characteristics;
1.5 matching the characteristics with the digital-analog characteristics, establishing a workpiece coordinate system of the robot according to coordinates obtained by matching,
1.6, converting the coordinates of the workpiece features from a 3D vision camera coordinate system to a workpiece coordinate system to complete initial positioning;
step two: contact measurement fine positioning specifically comprises:
2.1 the processing robot grasps the contact type measuring tool from the tool magazine;
2.2 according to the result of the coarse positioning of the 3D vision system, the robot obtains the initial position coordinates of the workpiece features to be calibrated;
2.3 the robot uses a contact type measuring head to sequentially measure the characteristic points of the corresponding workpiece digifax and measure at least three characteristic points;
2.4, establishing a precise workpiece coordinate system by using a three-point construction method to finish the precise positioning of the workpiece.
The above technical solution 1.3 specifically includes: installing a plurality of flexible tools on a workbench, wherein the bottom of each flexible tool is a magnetic seat which is fixed on the workbench; the top of the flexible tool is provided with a vacuum adsorption sucker, the workpiece is fixed through vacuum adsorption, and then a workpiece coordinate system is calibrated through the rapid calibration process of the workpiece.
The above technical solution 1.4 specifically includes: the 3D vision camera is installed on the guide rail of workstation top, moves on the guide rail through servo motor drive 3D vision camera, can acquire the bigger field of vision.
The technical scheme is that firstly, a servo motor absolute encoder is utilized to define one point of a 3D vision camera on a moving guide rail as a 3D vision camera original point M0, and the coordinate transformation relation between the 3D vision camera original point and a robot base coordinate system is marked as
Figure BDA0003458439300000031
The above technical solution 1.5 specifically includes: after the 3D vision camera moves the distance L on the guide rail and reaches the point M1, the numerical value of the moving distance L is recorded through an encoder of the servo motor, the hand-eye calibration is carried out again, and the coordinate transformation relation of the 3D vision camera between the point M1 and the robot base coordinate system is obtained and recorded as
Figure BDA0003458439300000032
This calibration is carried out only once,
the coordinate transformation relationship between the points M1 and M0 is
Figure BDA0003458439300000041
The position of the 3D vision camera relative to the robot base coordinate system is changed, and the posture is not changed; the coordinates of M1-M0 are transformed into translation where a, b, c are the moving distances of the vision camera along the X-axis, Y-axis, and Z-axis of the coordinate axis of the M0 coordinate system, respectively. I.e. the components of the moving distance of the guide rail in the directions of three coordinate axes,
Figure BDA0003458439300000042
then the included angle of the guide rail on the coordinate axis of the coordinate system of the origin M0 can be calculated;
Figure BDA0003458439300000043
the above technical solution 1.6 specifically includes: after the first calibration is completed, a transformation matrix of a coordinate system of any visual measurement relative to an M0 coordinate system can be calculated, firstly, the moving distance L1 of the 3D camera needs to be calculated through an encoder, and the moving position of the guide rail in three directions is calculated through formula (4)
Figure BDA0003458439300000044
Will obtain movement direction data input
Figure BDA0003458439300000045
In the matrix, the position transformation of the 3D camera at the L1 position relative to the camera origin M0 is obtained;
shooting and measuring the workpiece by using a 3D camera to obtain the pose of the workpiece under a camera coordinate system
Figure BDA0003458439300000046
The pose of the workpiece in the camera origin M0 coordinate system
Figure BDA0003458439300000047
Figure BDA0003458439300000048
The coordinates of the workpiece in the robot base coordinate system are recorded
Figure BDA0003458439300000049
Figure BDA00034584393000000410
Then, the pose of the workpiece under the robot base coordinate system is obtained by using the formula (6), and the 3D vision initial positioning is completed.
The above technical solution 2.2 specifically includes: completing touch stop-and-point coordinate data assignment by using a Search L instruction in a Rapid program language to realize automatic calibration; while moving, the robot will monitor a digital input signal or a continuous variable; when the value of the signal continuous variable is changed into a required value, the robot immediately reads the current position, then the robot stops moving, then workpiece calibration is carried out by taking the workpiece characteristic hole as an example, the method for determining the center of the workpiece characteristic hole is used for commanding the robot to respectively do linear motion along three different directions, and the three-point method is used for determining the center of the circle.
According to the technical scheme, the robot grabs and holds the measuring equipment, the ruby contact is placed at the center of the circle of the workpiece feature hole subjected to visual calibration and moves linearly along a set program, the robot stops after the measuring head touches the side wall of the circle hole by using a Search L instruction, the measuring head records coordinate data in a current robot controller, then the robot returns to the center of the circle and performs next measurement along the direction set by the program, after at least three measurements are completed, the position coordinates of three points of the feature hole are obtained, (x1, y1), (x2, y2), (x3, y3), the position of the center of the circle is determined by using a three-point method, the accurate position coordinate of the center of the circle is obtained, and the calibration work of the feature hole is completed,
Figure BDA0003458439300000051
after solving the formula, the coordinates of the circle center (x0, y0) are obtained.
The above technical solution 2.3 specifically includes: at least three workpiece feature points are calibrated, 2 feature holes are sequentially selected on the workpiece for calibration, the circle center coordinates of the feature holes are respectively obtained, a workpiece coordinate system is established by using a three-point construction method, and the fine positioning process of contact measurement is completed.
After the technical scheme is adopted, the invention has the following positive effects:
(1) the invention combines the usability of visual measurement positioning and the accuracy of contact measurement positioning, uses a low-cost 3D visual product to perform rough positioning on the coordinates of a workpiece, determines the approximate coordinate system of the workpiece, and then uses a robot to grip a contact measuring head to perform fine positioning on the workpiece;
(2) when the large component is measured, the workpiece feature points on the workbench can be quickly positioned, and compared with the method for acquiring the feature points by adopting the traditional teaching mode, the method has the advantages of high automation degree, good precision and low equipment cost. The method has important practical application value for processing large-scale components of various types and small batches.
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In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which
FIG. 1 is a flow chart of a system arrangement of the present invention;
FIG. 2 is a diagram of the system layout and coordinate system relationship of the present invention;
FIG. 3 is a schematic diagram of a contact measurement calibration method of the present invention;
FIG. 4 illustrates a three-point construction method of a workpiece coordinate system according to the present invention.
Detailed Description
The flow chart of the invention is shown in fig. 1 below, and mainly aims to rapidly calibrate and position a randomly placed workpiece coordinate system by using a robot, a 3D vision camera and a contact type measuring device.
The overall system layout and coordinate system relationships are shown in fig. 2. The whole calibration process is divided into two steps: the method comprises the following steps: coarse positioning of the 3D vision system, and step two: and (5) contact measurement fine positioning.
Step 1.1: establishing a workpiece coordinate system by using a workpiece digital model;
step 1.2: and calibrating the vision measurement system, and calibrating after the whole set of equipment is installed. And performing hand-eye calibration on the 3D camera and the robot by using a universal hand-eye calibration method.
Step 1.3: at first, an operator installs a certain number of flexible tools on a workbench, and the bottom of each tool is provided with a magnetic seat which can be fixed on the workbench. The top of the tool is provided with a vacuum adsorption sucker, and the workpiece is fixed through vacuum adsorption. The flexible tool is placed at any position of the workbench, so that the workpiece can be better fixed. And after the flexible tool is installed, placing the workpiece on the flexible tool. The workpiece placing position can be placed at will, and then the workpiece coordinate system is calibrated through the rapid calibration process of the workpiece.
Step 1.4: accomplish the robot hand eye and mark, 3D vision camera installs on the guide rail of workstation top, moves on the guide rail through servo motor drive 3D vision camera, can acquire bigger field of vision, utilizes servo motor absolute encoder at first, and one point of definition 3D vision camera on the removal guide rail is 3D vision camera initial point M0. Coordinate transformation relation between the 3D vision camera origin and the robot base coordinate system, and is recorded as
Figure BDA0003458439300000061
Step 1.5: after moving the 3D vision camera on the guide rail by the distance L, the 3D vision camera reaches the point M1. The value of the distance L of movement is recorded by the encoder of the servomotor. And performing hand-eye calibration again to obtain the coordinate transformation relation between the M1 point and the robot base coordinate system of the 3D vision camera, and recording the relation as
Figure BDA0003458439300000071
This calibration is performed only once.
The coordinate transformation relationship between the points M1 and M0 is
Figure BDA0003458439300000072
The position of the 3D vision camera relative to the robot base coordinate system is changed, and the posture is not changed. The coordinate transformation of M1 to M0 is translated in that a, b, c are relative to the M0 coordinate system, the position of the rail movement in three directions,
Figure BDA0003458439300000073
the angle of the guide rail in the coordinate axis of the M0 coordinate system can be calculated.
Figure BDA0003458439300000074
Step 1.6: after the first calibration is completed, a transformation matrix of a coordinate system of any visual measurement relative to an M0 coordinate system can be calculated, firstly, the moving distance L1 of the 3D camera needs to be calculated through an encoder, and the moving position of the guide rail in three directions is calculated through formula (4)
Figure BDA0003458439300000075
Will obtain movement direction data input
Figure BDA0003458439300000076
In the matrix, the positional transformation of the 3D camera at the L1 position with respect to the camera origin M0 is obtained.
Shooting and measuring the workpiece by using a 3D camera to obtain the pose of the workpiece under a camera coordinate system
Figure BDA0003458439300000077
The pose of the workpiece under the camera origin M0 coordinate system
Figure BDA0003458439300000078
Figure BDA0003458439300000079
The coordinates of the workpiece in the robot base coordinate system are recorded
Figure BDA00034584393000000710
Figure BDA0003458439300000081
And obtaining the pose of the workpiece under the robot base coordinate system by using the formula (6), and finishing the 3D vision primary positioning.
(2) And (5) contact measurement fine positioning.
After the coarse visual positioning, the workpiece coordinate system is basically determined relative to the base coordinate system, but the precision is still to be improved. Thus requiring the use of contact measurements in making the fine positioning.
Taking the hole pattern characteristic of the workpiece as an example, the robot grasps the contact type measuring head, and moves the characteristic position of the workpiece determined according to the visual coarse positioning to the corresponding characteristic hole position. And measuring at least three points in one characteristic hole by the robot, and fitting the characteristic hole through the measuring points to obtain the diameter and the circle center position of the characteristic hole. After measuring the three features, a three-point construction method is used to establish an accurate workpiece coordinate system.
Step 2.1: the processing robot runs a contact measurement program, and starts measurement by holding a contact measurement tool in the tool magazine.
Step 2.2: and (4) finishing touch stop-and-stop and point coordinate data assignment by using a Search L instruction in a Rapid program language so as to realize automatic calibration. While moving, the robot monitors a digital input signal or a continuous variable. When the value of the signal duration variable becomes a desired value, the robot immediately reads the current position. The robot movement then stops. And then, taking the characteristic hole of the workpiece as an example, calibrating the workpiece. The method for determining the center of the workpiece feature hole is to instruct the robot to perform linear motion along three different directions respectively, and determine the center of the circle by using a three-point method, as shown in fig. 3.
According to the result of vision calibration, the robot grabs and holds the measuring equipment, places the ruby contact at the centre of a circle of the workpiece feature hole of vision calibration, makes linear motion along a set program, uses a Search L instruction, stops after the measuring head touches the side wall of the round hole, and records the coordinate data in the current robot controller. And then the robot returns to the circle center, next measurement is carried out along the direction set by the program, after at least three times of measurement is finished, the position coordinates of the three points of the characteristic hole are obtained, (x1, y1), (x2, y2), (x3, y3), and the circle center position is determined by utilizing a three-point method. And obtaining the precise position coordinates of the circle center. And completing the calibration work of the characteristic hole.
Figure BDA0003458439300000082
After solving the formula, the coordinates of the circle center (x0, y0) are obtained.
Step 2.3: at least three workpiece feature points are calibrated if precise positioning of the calibration workpiece coordinate system is required. Then sequentially selecting 2 characteristic holes on the workpiece for calibration. And respectively obtaining the coordinates of the centers of the characteristic holes. The three-point construction method is used to establish the object coordinate system as shown in fig. 4. And finishing the fine positioning process of the contact measurement. Therefore, the characteristic points of the workpiece are quickly positioned, and the robot can be guided to process.
The invention combines the usability of visual measurement positioning and the accuracy of contact measurement positioning, uses a low-cost 3D visual product to perform rough positioning on the coordinates of a workpiece, determines the approximate coordinate system of the workpiece, and then uses a robot to grasp a contact measuring head to perform fine positioning on the workpiece.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. A method for quickly positioning a workpiece in a robot machining system is characterized by comprising
The method comprises the following steps: the 3D vision system rough positioning specifically comprises the following steps:
1.1 establishing a workpiece coordinate system by utilizing a workpiece digital model;
1.2, calibrating the robot eyes, and calibrating the pose relationship between a robot base coordinate system and a vision measurement coordinate system;
1.3, installing and fixing a workpiece to be measured;
1.4, scanning a workpiece by using a 3D camera to obtain workpiece point cloud data; processing the point cloud data of the workpiece to obtain workpiece characteristics;
1.5 matching the characteristics with the digital-analog characteristics, establishing a workpiece coordinate system of the robot according to coordinates obtained by matching,
1.6, converting the coordinates of the workpiece features from a 3D vision camera coordinate system to a workpiece coordinate system to complete initial positioning;
step two: contact measurement fine positioning specifically comprises:
2.1 the processing robot grasps the contact type measuring tool from the tool magazine;
2.2 according to the result of the coarse positioning of the 3D vision system, the robot obtains the initial position coordinates of the workpiece features to be calibrated;
2.3 the robot uses a contact type measuring head to sequentially measure the characteristic points of the corresponding workpiece digifax and measure at least three characteristic points;
2.4, establishing a precise workpiece coordinate system by using a three-point construction method to finish the precise positioning of the workpiece.
2. The method of claim 1, wherein the step of rapidly positioning the workpiece comprises: the 1.3 specifically comprises the following steps: installing a plurality of flexible tools on a workbench, wherein the bottom of each flexible tool is a magnetic seat which is fixed on the workbench; the top of the flexible tool is provided with a vacuum adsorption sucker, the workpiece is fixed through vacuum adsorption, and then a workpiece coordinate system is calibrated through the rapid calibration process of the workpiece.
3. The method of claim 1, wherein the step of rapidly positioning the workpiece comprises: the 1.4 specifically comprises: the 3D vision camera is installed on the guide rail above the workbench, and the servo motor drives the 3D vision camera to move on the guide rail, so that a larger visual field can be acquired.
4. The method of claim 3, wherein the step of rapidly positioning the workpiece comprises: firstly, defining one point of a 3D vision camera on a moving guide rail as a 3D vision camera original point M0 by using a servo motor absolute encoder, and recording the coordinate transformation relation between the 3D vision camera original point and a robot base coordinate system as
Figure FDA0003458439290000021
5. According to claim4 the robot processing system workpiece rapid positioning method is characterized in that: the 1.5 specifically comprises the following steps: after the 3D vision camera moves the distance L on the guide rail and reaches the point M1, the numerical value of the moving distance L is recorded through an encoder of the servo motor, the hand-eye calibration is carried out again, and the coordinate transformation relation of the 3D vision camera between the point M1 and the robot base coordinate system is obtained and recorded as
Figure FDA0003458439290000022
This calibration is carried out only once,
the coordinate transformation relationship between the points M1 and M0 is
Figure FDA0003458439290000023
The position of the 3D vision camera relative to the robot base coordinate system is changed, and the posture is not changed; the coordinates of M1 through M0 are transformed into translations where a, b, and c are the moving distances of the vision camera along the X, Y, and Z axes of the coordinate axes of the M0 coordinate system, respectively. I.e. the components of the rail movement distance in the directions of the three coordinate axes,
Figure FDA0003458439290000024
then the included angle of the guide rail on the coordinate axis of the coordinate system of the origin M0 can be calculated;
Figure FDA0003458439290000025
6. the method of claim 5, wherein the step of rapidly positioning the workpiece comprises: the 1.6 specifically comprises the following steps: after the first calibration is completed, a transformation matrix of a coordinate system of any visual measurement relative to an M0 coordinate system can be calculated, firstly, the moving distance L1 of the 3D camera needs to be calculated through an encoder, and the moving position of the guide rail in three directions is calculated through formula (4)
Figure FDA0003458439290000026
Will obtain movement direction data input
Figure FDA0003458439290000031
In the matrix, the position transformation of the 3D camera at the L1 position relative to the camera origin M0 is obtained;
shooting and measuring the workpiece by using a 3D camera to obtain the pose of the workpiece under a camera coordinate system
Figure FDA0003458439290000032
The pose of the workpiece in the camera origin M0 coordinate system
Figure FDA0003458439290000033
Figure FDA0003458439290000034
The coordinates of the workpiece in the robot base coordinate system are recorded
Figure FDA0003458439290000035
Figure FDA0003458439290000036
And obtaining the pose of the workpiece under the robot base coordinate system by using the formula (6), and finishing the 3D vision primary positioning.
7. The method of claim 1, wherein the step of rapidly positioning the workpiece comprises: the 2.2 specifically comprises the following steps: completing touch stop-and-point coordinate data assignment by using a Search L instruction in a Rapid program language to realize automatic calibration; while moving, the robot will monitor a digital input signal or a continuous variable; when the value of the signal continuous variable is changed into a required value, the robot immediately reads the current position, then the robot stops moving, then workpiece calibration is carried out by taking the workpiece characteristic hole as an example, the method for determining the center of the workpiece characteristic hole is used for commanding the robot to respectively do linear motion along three different directions, and the three-point method is used for determining the center of the circle.
8. The method of claim 7, wherein the step of rapidly positioning the workpiece comprises: according to the result of vision calibration, the robot grasps the measuring device, places the ruby contact at the center of the workpiece feature hole which is calibrated by vision, makes linear motion along the set program, stops after the measuring head touches the side wall of the hole by using a Search L instruction, records the coordinate data in the current robot controller, then the robot returns to the center of the circle, carries out the next measurement along the direction set by the program, acquires the position coordinates of three points of the feature hole after at least three measurements are completed, (x1, y1), (x2, y2), (x3, y3), determines the center of the circle by using a three-point method, acquires the accurate position coordinates of the center of the circle, and completes the calibration work of the feature hole,
Figure FDA0003458439290000037
after solving the formula, the coordinates of the circle center (x0, y0) are obtained.
9. The method of claim 7, wherein the step of rapidly positioning the workpiece comprises: the 2.3 specifically comprises the following steps: at least three workpiece feature points are calibrated, 2 feature holes are sequentially selected on the workpiece for calibration, the circle center coordinates of the feature holes are respectively obtained, a workpiece coordinate system is established by using a three-point construction method, and the fine positioning process of contact measurement is completed.
CN202210009499.7A 2022-01-06 2022-01-06 Rapid workpiece positioning method for robot machining system Pending CN115115931A (en)

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