CN110370272B - Robot TCP calibration system based on vertical reflection - Google Patents

Robot TCP calibration system based on vertical reflection Download PDF

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CN110370272B
CN110370272B CN201910539099.5A CN201910539099A CN110370272B CN 110370272 B CN110370272 B CN 110370272B CN 201910539099 A CN201910539099 A CN 201910539099A CN 110370272 B CN110370272 B CN 110370272B
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robot
coordinate system
binocular vision
target point
coordinate
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CN110370272A (en
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唐倩
李志航
周浩
李代杨
刘联超
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Chongqing University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
    • B25J19/0095—Means or methods for testing manipulators
    • 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
    • B25J9/1679—Programme controls characterised by the tasks executed
    • B25J9/1692—Calibration of manipulator

Abstract

The invention discloses a robot TCP calibration system based on vertical reflection, which combines a binocular vision system, a robot and a working tool for operation, uses a plane mirror as an auxiliary tool, utilizes the relationship between the kinematics of the robot and the space coordinate transformation to measure a space fixed point for multiple times, establishes the hand-eye relationship, detects a tail end circular target point of the working tool, and completes the calibration of TCP through the characteristics of the coordinate transformation relationship and the imaging symmetry of the plane mirror. The TCP calibration system is different from a contact type calibration system, has no collision risk and is high in safety coefficient.

Description

Robot TCP calibration system based on vertical reflection
Technical Field
The invention relates to the field of intelligent manufacturing, in particular to a robot TCP calibration system based on vertical reflection.
Background
Under the background of industry 4.0, the autonomous operation of the binocular vision system assisted robot has become normal. By taking welding as an example, the binocular vision system can track and identify the welding seam in real time, and is beneficial to improving the welding quality and the welding efficiency. The accuracy of the calibration of the work point (TCP) of a work tool directly affects the actual work quality. The traditional teaching contact type TCP calibration method has the problems of low efficiency, collision and the like, can not meet the current operation requirements, and has important significance for industrial production.
Therefore, the technical personnel in the field are dedicated to develop a robot TCP calibration system based on vertical reflection with high safety factor.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the technical problem to be solved by the present invention is to provide a vertical reflection-based robot TCP system with a high safety factor.
In order to achieve the purpose, the invention provides a robot TCP calibration system based on vertical reflection, which comprises a robot, a plane mirror and a binocular vision system, wherein the binocular vision system comprises two cameras, the two cameras are respectively arranged on two sides of the tail end of the robot, and the plane mirror is arranged in the shooting range of the binocular vision system.
Preferably, the two cameras are fixed on the working tool through a connecting bracket, and the two cameras are respectively fixedly arranged at two ends of the connecting bracket.
Preferably, the binocular vision system further comprises a logic operation module and a data acquisition module, wherein the data acquisition module is arranged between the logic operation module and the binocular vision system, the data acquisition module is used for acquiring a measured value measured by the binocular vision system, and the data acquisition module transmits acquired data to the logic operation module.
Preferably, the logical operation module comprises a human eye relation logical operation module and a TCP calibration logical operation module, and the human eye relation logical operation module determines a transformation matrix of a coordinate system { C } of the binocular vision system relative to a coordinate system { E } of the tail end of the robot through the kinematics and the space coordinate transformation of the robot
Figure GDA0003077444840000021
Figure GDA0003077444840000022
Is a robot eye-hand relationship; the TCP calibration logical operation module obtains the robot eye-eye relationship through calculation
Figure GDA0003077444840000023
To complete the calibration of the work tool end TCP.
Preferably, the robot eye-hand relationship is determined
Figure GDA0003077444840000024
The process is as follows:
(S101) establishing the hand-eye relationship of the robot as
Figure GDA0003077444840000025
Wherein R isCAs the robot end coordinate system { E } andthe binocular vision system coordinate system { C } converted rotation matrix is a fixed value; t isCTranslation vectors converted for a robot terminal coordinate system { E } and a binocular vision system coordinate system { C } are constant values;
(S102) setting a first circular target point on a working platform, wherein the first circular target point is a fixed point, the tail end of the robot keeps unchanged in posture, the robot makes linear motion, and the tail end of the robot sequentially moves to a plurality of positions and measures the first circular target point;
(S103) sequentially controlling the robot to perform posture changing movement to a plurality of positions and measuring the first circular target point under a binocular vision system coordinate system { C };
(S104) calculating the measured value of the first circular target point in the steps (S102) and (S103) through the relation of robot kinematics and space coordinate transformation to obtain RCAnd TCTo calibrate the hand-eye relationship of the robot
Figure GDA0003077444840000031
Preferably, the robot kinematics and spatial coordinate transformation logical operation in the human eye relationship logical operation module includes:
(B1) establishing a transformation matrix of a robot terminal coordinate system { E } relative to a robot base coordinate system { B }
Figure GDA0003077444840000032
Wherein, R is a rotation matrix converted from a base coordinate { B } of the robot and a terminal coordinate system { E } of the robot, and the terminal attitude of the robot is kept unchanged, namely R is unchanged and R is a fixed value in the process of linear motion of the robot; t is a translation vector converted by a robot base coordinate { B } and a robot end coordinate system { E };
the coordinate conversion formula can obtain:
Figure GDA0003077444840000033
unfolding to obtain:
Figure GDA0003077444840000034
Pcthe coordinate value can be obtained by measuring with a binocular vision system;
wherein, PcThe coordinate of the first circular target point under a binocular vision system coordinate system { C };
Pbis the coordinate, P, of the first circular target point under the robot base coordinate { B }bIs a constant value;
Figure GDA0003077444840000035
and
Figure GDA0003077444840000036
are respectively PcAnd PbA transposed matrix of the conversion;
(B2) since the pose of the robot end is kept unchanged in the step (S102), the robot end moves to a plurality of positions in sequence, two positions are selected, and the measurement value of the first circular target point is obtained under the coordinate system { C } of the binocular vision system
Figure GDA0003077444840000037
And
Figure GDA0003077444840000038
by substituting the equations (a1) respectively, the following equations can be established:
Figure GDA0003077444840000041
the subtraction of the two equations yields:
Figure GDA0003077444840000042
since R is an orthogonal matrix, the above formula can be changed to:
Figure GDA0003077444840000043
measuring different position parameters of the first circular target point under a binocular vision system coordinate system { C } for four times in sequence to obtain a measured value of the first circular target point
Figure GDA0003077444840000044
And
Figure GDA0003077444840000045
in the formula (a2), we can obtain:
Figure GDA0003077444840000046
namely RcA＝b；
It can be seen that,
Figure GDA0003077444840000047
b＝RT[T1-T2 T2-T3 T3-T4]；
r obtained by solving matrix singular value decompositionC；
Wherein the content of the first and second substances,
Figure GDA0003077444840000048
and
Figure GDA0003077444840000049
respectively representing the coordinates of the first circular target point in a binocular vision system coordinate system { C };
Figure GDA00030774448400000410
and
Figure GDA00030774448400000411
are respectively as
Figure GDA00030774448400000412
And
Figure GDA00030774448400000413
the transposed matrix of (2);
T1、T2、T3and T4Respectively converting translation vectors of a robot base coordinate system { B } and a robot terminal coordinate system { E } at different positions when the robot moves;
(B3) in the step (S103), the coordinate value of the first circular target point in the coordinate system { C } of the binocular vision system changes with the change of the pose-changing motion of the robot, and two moving positions are selected to obtain the measurement value of the first circular target point
Figure GDA00030774448400000414
And
Figure GDA00030774448400000415
the following equations are established:
Figure GDA0003077444840000051
subtracting the two equations to obtain:
Figure GDA0003077444840000052
Figure GDA0003077444840000053
can be measured by a binocular vision system, and the above-mentioned obtained R is usedCIn the formula, T is obtainedCCalibrating hand-eye relationships
Figure GDA0003077444840000054
Wherein R is11And R22Respectively converting rotation matrixes of a robot base coordinate system { B } and a robot terminal coordinate system { E } at different positions when the robot moves in the posture changing manner;
T11and T22Respectively converting translation vectors of a robot base coordinate system { B } and a robot terminal coordinate system { E } at different positions when the robot moves in the posture changing manner;
Figure GDA0003077444840000055
and
Figure GDA0003077444840000056
respectively representing the coordinates of the first circular target point in a binocular vision system coordinate system { C };
Figure GDA0003077444840000057
and
Figure GDA0003077444840000058
are respectively as
Figure GDA0003077444840000059
And
Figure GDA00030774448400000510
the transposed matrix of (2).
Preferably, the process of TCP calibration at the end of the work tool includes:
and placing the plane mirror on a working platform, pasting a second circular target point at the tail end of a working tool at the tail end of the robot, controlling the robot to arrange the second circular target point above the plane mirror, and keeping the tail end of the robot perpendicular to the plane mirror.
Preferably, the logic operation of the TCP calibration logic operation module includes:
the point of the second round target point at the tail end of the working tool in the plane mirror is a projection point, the value of the projection point in a coordinate system { C } of a binocular vision system is measured through the binocular vision system, and the projection point is measured through the coordinate system { C } of the binocular vision system
Figure GDA00030774448400000511
Obtaining the value (x ', y ', z ') of the projection point in the coordinate system { E } of the robot end; suppose thatThe second circular target point has a value of (x, y, z) in the robot end coordinate system { E }; from the vertical relationship, x ═ x ', y ═ y'; selecting symmetrical points on the working platform, and firstly obtaining Z-axis coordinate values Z of the symmetrical points under a robot terminal coordinate system { E }mFrom the symmetry, z '-2 × (z' -z)m) And finally, solving the value of the second circular target point in the robot terminal coordinate system { E }, and finishing the calibration of the TCP.
Preferably, the robot, the logic operation module, the data acquisition module, the robot and the binocular vision system are all connected with the control device.
The invention has the beneficial effects that: the TCP calibration system of the robot based on the vertical reflection does not need additional auxiliary calibration equipment, only needs one mirror, and is low in cost and convenient to operate; the system is different from a contact type calibration system, has no collision risk and high safety coefficient; the TCP calibration can be completed only by controlling the robot to move for four times, so that the rapid and accurate calibration of the TCP is realized, and the calibration requirement of the terminal tool parameters of the robot in the actual industrial production can be met.
Drawings
Fig. 1 is a schematic structural diagram of a TCP calibration system of a robot based on vertical reflection according to an embodiment of the present invention.
Fig. 2 is a block diagram of fig. 1.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
as shown in fig. 1, an embodiment of the present invention discloses a robot TCP calibration method based on vertical reflection, including the following steps:
(S1) establishing a binocular vision system coordinate system { C } on the binocular vision system; establishing a robot end coordinate system { E } at the robot end 6, and determining a transformation matrix of a binocular vision system coordinate system { C } relative to the robot end coordinate system { E }
Figure GDA0003077444840000061
Figure GDA0003077444840000062
In robot eye-hand relationship.
In this embodiment, in the step (S1), the specific steps are:
(S101) establishing the relationship between the eyes and hands of the robot
Figure GDA0003077444840000063
Wherein R isCConverting rotation matrixes of a robot terminal coordinate system { E } and a binocular vision system coordinate system { C } and setting the rotation matrixes to be constant values; t isCTranslation vectors converted for a robot terminal coordinate system { E } and a binocular vision system coordinate system { C } are constant values; in other embodiments, the binocular vision system coordinate system { C } is established with one camera 2 in the binocular vision system.
(S102) setting a first circular target point P on a working platform, wherein the first circular target point P is a fixed point, the posture of the tail end 6 of the robot is kept unchanged, the robot 1 makes linear motion, and the tail end 6 of the robot sequentially moves to a plurality of positions and measures the first circular target point P under a coordinate system { C } of a binocular vision system; in this embodiment, the first circular target point P is fixed on the working platform, the robot is controlled to perform posture-changing movement, the coordinate system { C } of the binocular vision system is also changed, the coordinate systems { C } of the binocular vision system at different positions are different, and further, the coordinate values of the first circular target point P are also different.
(S103) sequentially controlling the robot 1 to perform posture-changing movement to a plurality of positions and measuring the first circular target point P under a binocular vision system coordinate system { C }. In the present embodiment, both the posture and the position of the robot 1 are changed.
(S104) calculating the measured value of the first circular target point P in the steps (S102) and (S103) through the relation between the robot kinematics and the space coordinate transformation to obtain RCAnd TCCalibrating hand-eye relationships
Figure GDA0003077444840000071
In this embodiment, in the step (S104), the following steps are specifically included:
(B1) the coordinate conversion formula can obtain:
Figure GDA0003077444840000072
unfolding to obtain:
Figure GDA0003077444840000073
Pcthe coordinate value can be obtained by measuring with a binocular vision system;
wherein, PcIs the coordinate of the first circular target point P under the coordinate system { C } of the binocular vision system;
Pbis the coordinate of the first circular target point P under the robot base coordinate { B }, PbIs a constant value;
Figure GDA0003077444840000081
and
Figure GDA0003077444840000082
are respectively PcAnd PbThe transposed matrix of the conversion.
Establishing a transformation matrix of a robot terminal coordinate system { E } relative to a robot base coordinate system { B }
Figure GDA0003077444840000083
Wherein, R is a rotation matrix converted from a robot base coordinate { B } and a robot terminal coordinate system { E }, and because the robot 1 does linear motion, the posture of the robot terminal 6 is kept unchanged, namely R is unchanged, and R is a fixed value; t is a translation vector converted by the robot base coordinate system { B } and the robot end coordinate system { E }.
(B2) Since the pose of the robot end 6 is kept unchanged in step (S102), the robot end 6 moves to a plurality of positions in sequence, two positions are selected, and the measurement value of the first circular target point (P) is obtained under the coordinate system { C } of the binocular vision system
Figure GDA0003077444840000084
And
Figure GDA0003077444840000085
by substituting the equations (a1) respectively, the following equations can be established:
Figure GDA0003077444840000086
the subtraction of the two equations yields:
Figure GDA0003077444840000087
since R is an orthogonal matrix, the above formula can be changed to:
Figure GDA0003077444840000088
measuring different position parameters of the first circular target point P under a binocular vision system coordinate system { C } for four times in sequence to obtain a measured value of the first circular target point P
Figure GDA0003077444840000089
And
Figure GDA00030774448400000810
in the formula (a2), we can obtain:
Figure GDA00030774448400000811
namely RcA＝b；
It can be seen that,
Figure GDA0003077444840000091
b＝RT[T1-T2 T2-T3 T3-T4]；
r obtained by solving matrix singular value decompositionC；
Wherein the content of the first and second substances,
Figure GDA0003077444840000092
and
Figure GDA0003077444840000093
respectively is the coordinate of the first round target point P under a binocular vision system coordinate system { C };
Figure GDA0003077444840000094
and
Figure GDA0003077444840000095
are respectively as
Figure GDA0003077444840000096
And
Figure GDA0003077444840000097
the transposed matrix of (2);
T1、T2、T3and T4The translation vectors are respectively converted into a robot base coordinate system { B } and a robot terminal coordinate system { E } at different positions when the robot 1 moves. T is1、T2、T3And T4Are respectively measured at
Figure GDA0003077444840000098
Figure GDA0003077444840000099
And
Figure GDA00030774448400000910
and (3) translation vectors converted from a robot base coordinate system { B } and a robot end coordinate system { E } under the motion state of the robot during the coordinate values.
(B3) In the step (S103), the coordinate value of the first circular target point P in the coordinate system { C } of the binocular vision system changes along with the change of the posture-changing motion of the robot, and the first circular target point P is selectedTwo moving positions, obtaining a measurement value of a first circular target point (P)
Figure GDA00030774448400000911
And
Figure GDA00030774448400000912
the following equations are established:
Figure GDA00030774448400000916
subtracting the two equations to obtain:
Figure GDA00030774448400000913
Figure GDA00030774448400000914
can be measured by a binocular vision system, and the above-mentioned obtained R is usedCIn the formula, T is obtainedCAnd calibrating the hand-eye relationship:
Figure GDA00030774448400000915
wherein R is11And R22Respectively converting rotation matrixes of a robot base coordinate system { B } and a robot terminal coordinate system { E } at different positions when the robot moves in the posture changing manner; r11And R22Are respectively measured at
Figure GDA00030774448400000917
And
Figure GDA0003077444840000101
when the coordinate values are in the coordinate values, the rotation matrix converted from the robot base coordinate { B } and the robot end coordinate system { E } in the motion state of the robot;
T11and T22A robot base coordinate { B } and a robot tail end seat under different positions respectively during the robot posture changing movementThe translation vector of the { E } transform of the frame; t is11And T22Are respectively measured at
Figure GDA0003077444840000102
And
Figure GDA0003077444840000103
when the coordinate values are calculated, translation vectors converted from a robot base coordinate system { B } and a robot terminal coordinate system { E } under the motion state of the robot are calculated;
Figure GDA0003077444840000104
and
Figure GDA0003077444840000105
respectively is the coordinate of the first round target point P under a binocular vision system coordinate system { C };
Figure GDA0003077444840000106
and
Figure GDA0003077444840000107
are respectively as
Figure GDA0003077444840000108
And
Figure GDA0003077444840000109
the transposed matrix of (2).
In this embodiment, the coordinate system { C } of the binocular vision system changes as the robot performs posture-changing motion, so the coordinate systems { C } of the binocular vision systems for selecting and measuring the first circular target point P twice are different, and the coordinate values of the first circular target point P under different coordinate systems { C } of the binocular vision system are different because the first circular target point P is fixed.
(S2) placing the plane mirror 3 on the working platform, and placing the second circular target point PaA working tool 5 attached to the robot end 6, and controlling the robot 1 to move the second circular target point PaArranged above the plane mirror 3 and used for keeping the tail end 6 of the robot to hang downA second circular target point P at the end of the working tool 5, which is perpendicular to the plane mirror 3aThe point in the plane mirror 3 is a projected point P'aMeasuring projected point P 'by binocular vision system'aValues in the coordinate system { C } of the binocular visual system by
Figure GDA00030774448400001010
Can obtain the projected point P'aThe values (x ', y ', z ') of the coordinate system { E } at the end of the robot; then, a second circular target point P is calculated according to the mirror symmetry of the plane mirror 3aAnd completing the calibration of the TCP at the value under the coordinate system { E } of the tail end of the robot.
In this embodiment, in step (S2), a second circular target point P is then calculated based on the mirror symmetry of the plane mirror 3aThe specific steps of the values under the robot end coordinate system { E }, include:
assuming a second circular target point PaThe value of the coordinate system { E } at the end of the robot is (x, y, z); from the vertical relationship, x ═ x ', y ═ y'; selecting a symmetrical point P on the working platformmFirst, the symmetric point P is obtainedmZ-axis coordinate value Z in robot end coordinate system { E }mFrom the symmetry, z '-2 × (z' -z)m) Finally, a point P is obtainedaValues under the robot end coordinate system { E }. In some embodiments, the point of symmetry PmArranged at a first circular target point P, a symmetrical point PmI.e. the first circular target point P, and in other embodiments, the symmetrical point PmOr may be a point on the work platform other than the first circular target point P.
In some embodiments, work tool 5 is, for example, a welding gun or other tool, and is not limited thereto.
As shown in fig. 1 and 2, an embodiment of the present invention further discloses a robot TCP calibration system based on vertical reflection, which includes a robot 1, a plane mirror 3 and a binocular vision system, wherein the binocular vision system includes two cameras 2, the two cameras 2 are respectively arranged at two sides of the tail end of the robot 1, and the plane mirror 3 is arranged in the shooting range of the binocular vision system.
In the present embodiment, the two cameras 2 are fixed to the work tool 5 by the connecting bracket 4, and the two cameras 2 are respectively fixed to both ends of the connecting bracket 4. In the present embodiment, the work tool 5 is mounted on the robot tip 6. In the present embodiment, the connecting bracket 4 has a disk shape, and the camera 2 is inserted into a mounting groove of the connecting bracket 4 so that the camera 2 can be fixed to the connecting bracket 4. In some embodiments, the connecting bracket 4 is integrally formed with the work tool 5. In other embodiments, the two cameras 2 are fixed on the robot 1 through the connecting bracket 4, and the two cameras 2 are respectively fixed at two ends of the connecting bracket 4.
In this embodiment, the binocular vision system further comprises a logic operation module and a data acquisition module, wherein the data acquisition module is arranged between the logic operation module and the binocular vision system, the data acquisition module is used for acquiring a measured value measured by the binocular vision system, and the data acquisition module transmits acquired data to the logic operation module. The data acquisition module is used for acquiring measured value signals of the binocular vision system and transmitting the measured value signals to the logic operation module for calculation.
In this embodiment, the logical operation module includes a human eye relationship logical operation module and a TCP calibration logical operation module, and the human eye relationship logical operation module determines a transformation matrix of the coordinate system { C } of the binocular vision system relative to the coordinate system { E } of the robot end through the kinematics and the spatial coordinate transformation of the robot
Figure GDA0003077444840000121
Figure GDA0003077444840000122
Is a robot eye-hand relationship; robot hand-eye relation obtained by TCP calibration logical operation module
Figure GDA0003077444840000123
To complete the calibration of the TCP at the end of the work tool 5.
In this embodiment, the robot system further comprises a control device, and the robot 1, the logic operation module, the data acquisition module, the robot 1 and the binocular vision system are all connected with the control device. The control module is used for driving the movement of the robot in each operation step, starting the data acquisition module, measuring the binocular vision system, calculating the logic operation module and the like.
In the present embodiment, the robot eye relationship is determined
Figure GDA0003077444840000124
The process is as follows:
(S1) establishing a binocular vision system coordinate system { C } on the binocular vision system; establishing a robot end coordinate system { E } at the robot end 6, and determining a transformation matrix of a binocular vision system coordinate system { C } relative to the robot end coordinate system { E }
Figure GDA0003077444840000125
Figure GDA0003077444840000126
In robot eye-hand relationship.
In the step (S1), the method specifically includes the following steps:
(S101) establishing the hand-eye relationship of the robot as
Figure GDA0003077444840000127
Wherein R isCConverting rotation matrixes of a robot terminal coordinate system { E } and a binocular vision system coordinate system { C } and setting the rotation matrixes to be constant values; t isCTranslation vectors converted for a robot terminal coordinate system { E } and a binocular vision system coordinate system { C } are constant values; in other embodiments, the binocular vision system coordinate system { C } is established with one camera 2 in the binocular vision system.
(S102) setting a first circular target point P on a working platform, wherein the first circular target point is a fixed point, the posture of the tail end 6 of the robot is kept unchanged, the robot 1 makes linear motion, and the tail end 6 of the robot sequentially moves to a plurality of positions and measures the first circular target point P; in this embodiment, the first circular target point P is fixed on the working platform, the robot is controlled to perform posture-changing movement, the coordinate system { C } of the binocular vision system is also changed, the coordinate systems { C } of the binocular vision system at different positions are different, and further, the coordinate values of the first circular target point P are also different.
(S103) sequentially controlling the robot 1 to perform posture-changing movement to a plurality of positions and measuring the first circular target point P under a binocular vision system coordinate system { C }; in the present embodiment, both the posture and the position of the robot 1 are changed.
(S104) calculating the measured value of the first circular target point P in the steps (S102) and (S103) through the relation between the robot kinematics and the space coordinate transformation to obtain RCAnd TCTo calibrate the hand-eye relationship of the robot
Figure GDA0003077444840000131
In this embodiment, the robot kinematics and spatial coordinate transformation logical operations in the human-eye relationship logical operation module include:
(B1) establishing a transformation matrix of a robot terminal coordinate system { E } relative to a robot base coordinate system { B }
Figure GDA0003077444840000132
Wherein, R is a rotation matrix converted from a robot base coordinate { B } and a robot terminal coordinate system { E }, and because the robot 1 does linear motion, the posture of the robot terminal 6 is kept unchanged, namely R is unchanged, and R is a fixed value; t is a translation vector converted by a robot base coordinate { B } and a robot end coordinate system { E };
the coordinate conversion formula can obtain:
Figure GDA0003077444840000133
unfolding to obtain:
Figure GDA0003077444840000134
Pcthe coordinate value can be obtained by measuring with a binocular vision system;
wherein, PcIs a first circular target point P at two eyesCoordinates under the visual system coordinate system { C };
Pbis the coordinate of the first circular target point P under the robot base coordinate { B }, PbIs a constant value;
Figure GDA0003077444840000141
and
Figure GDA0003077444840000142
are respectively PcAnd PbA transposed matrix of the conversion;
(B2) since the pose of the robot end 6 is kept unchanged in step (S102), the robot end 6 moves to a plurality of positions in sequence, two positions are selected, and the measurement value of the first circular target point P is obtained under the coordinate system { C } of the binocular vision system
Figure GDA0003077444840000143
And
Figure GDA0003077444840000144
by substituting the equations (a1) respectively, the following equations can be established:
Figure GDA0003077444840000145
the subtraction of the two equations yields:
Figure GDA0003077444840000146
since R is an orthogonal matrix, the above formula can be changed to:
Figure GDA00030774448400001411
measuring different position parameters of the first round target point P under the coordinate system { C } of the binocular vision system four times in sequence to obtain the measured value of the first round target point P
Figure GDA0003077444840000147
And
Figure GDA0003077444840000148
in the formula (a2), we can obtain:
Figure GDA0003077444840000149
namely RcA＝b；
It can be seen that,
Figure GDA00030774448400001410
b＝RT[T1-T2 T2-T3 T3-T4]；
r obtained by solving matrix singular value decompositionC。
(B3) In the step (S103), the coordinate value of the first circular target point (P) in the coordinate system { C } of the binocular vision system changes along with the change of the posture-changing motion of the robot, and two moving positions are selected to obtain the measured value of the first circular target point P
Figure GDA0003077444840000151
And
Figure GDA0003077444840000152
the following equations are established:
Figure GDA0003077444840000153
subtracting the two equations to obtain:
Figure GDA0003077444840000154
Figure GDA0003077444840000155
can be measured by a binocular vision system, and the above-mentioned obtained R is usedCIn the formula, T is obtainedCCalibrating hand-eye relationships
Figure GDA0003077444840000156
In this embodiment, the process of TCP calibration at the end of the work tool 5 includes:
placing the plane mirror 3 on the working platform, and placing the second circular target point PaA working tool 5 attached to the robot end 6, and controlling the robot 1 to move the second circular target point PaIs arranged above the plane mirror 3 keeping the robot end 6 perpendicular to the plane mirror 3.
In this embodiment, the logical operation of the TCP calibration logical operation module includes:
second circular target point P on the end of the work tool 5aThe point in the plane mirror 3 is a projected point P'aMeasuring projected point P 'by binocular vision system'aValues in the coordinate system { C } of the binocular visual system by
Figure GDA0003077444840000157
Can obtain the projected point P'aThe values (x ', y ', z ') of the coordinate system { E } at the end of the robot; then, a second circular target point P is calculated according to the mirror symmetry of the plane mirror 3aAnd completing the calibration of the TCP at the value under the coordinate system { E } of the tail end of the robot.
In this embodiment, during the logic operation of the TCP calibration logic operation module, the second circular target point P is calculated according to the mirror symmetry of the plane mirror 3aThe specific steps of the values under the robot end coordinate system { E }, include:
assuming a second circular target point PaThe value of the coordinate system { E } at the end of the robot is (x, y, z); from the vertical relationship, x ═ x ', y ═ y'; selecting a symmetrical point P on a working platformmFirst, the symmetric point P is obtainedmZ-axis coordinate value Z in robot end coordinate system { E }mFrom the symmetry, z '-2 × (z' -z)m) Finally, a second circular target point P is obtainedaAnd completing the calibration of the TCP at the value under the coordinate system { E } of the tail end of the robot. In some embodiments, the point of symmetry PmArranged at a first circular target point P, a symmetrical point PmI.e. the first circular target point P, and in other embodiments, the symmetrical point PmOr may be a point on the work platform other than the first circular target point P.
The invention discloses a TCP calibration method and a TCP calibration system of a robot based on vertical reflection, which are based on hand-eye relationship and based on vertical reflection. By finding out the coordinate conversion relation between the coordinate system { E } of the robot end and the coordinate system { C } of the camera
Figure GDA0003077444840000161
And the rapid and accurate calibration of the TCP is realized. As shown in FIG. 1, let the robot base coordinate system be { B }, the robot end coordinate system be { E }, the binocular vision system coordinate system be { C }, the first circular target point P is fixed on the horizontal platform in the camera vision range, and its coordinate under the coordinate system { C } is PcThe coordinate under the base coordinate system { B } is PbAnd P isbIs a constant value.
Figure GDA0003077444840000162
Is the conversion relation between the robot terminal coordinate system { E } and the base coordinate system { B };
Figure GDA0003077444840000163
is the conversion relation between the coordinate system of the binocular vision system { C } and the coordinate system of the robot end { E }, namely the hand-eye relation. The robot is controlled to carry a camera to measure the point P for a plurality of times of change, and the point P can be determined by utilizing the constraint of a fixed point
Figure GDA0003077444840000164
Placing a plane mirror on a platform, pasting a circular target point on the tail end of a working tool 5, controlling the robot to linearly move above the mirror surface (keeping the tail end 6 of the robot perpendicular to the mirror surface), and measuring a projection point P by a binocular vision systema' values in the coordinate System of the binocular Vision System { C }, from
Figure GDA0003077444840000165
Can find out the point Pa' values (x ', y ', z ') of coordinate system { E } at the end of the robot '. P can be calculated according to the symmetry relationaAnd completing TCP calibration on the value under the coordinate system { E } of the tail end of the robot.
The TCP calibration method and system of the robot based on the vertical reflection do not need additional auxiliary calibration equipment, only need one mirror, and are low in cost and convenient to operate; TCP calibration can be completed only by controlling the robot to move for four times, so that rapid and accurate calibration is realized, and the calibration requirement of the parameters of the tool at the tail end of the robot in actual industrial production can be met; the method is different from a contact type calibration method, has no collision risk and is high in safety coefficient.
The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims (6)

1. A robot TCP calibration system based on vertical reflection is characterized in that: including robot (1), level crossing (3) and binocular vision system, binocular vision system includes two camera (2), two camera (2) set up respectively robot end (6) both sides, level crossing (3) set up in binocular vision system's the scope of making a video recording, still include logical operation module and data acquisition module, data acquisition module sets up between logical operation module and the binocular vision system, data acquisition module is used for gathering the measured value of binocular vision system measurement, data acquisition module transmits the data of gathering to logical operation module, logical operation module includes people's eye relation logical operation module and TCP calibration logical operation module, people's eye relation logical operation module confirms through robot kinematics and space coordinate transformDetermining a transformation matrix of a coordinate system { C } of the binocular vision system relative to a coordinate system { E } of the robot end
Figure FDA0003077444830000011
Is a robot eye-hand relationship; the TCP calibration logical operation module obtains the robot eye-eye relationship through calculation
Figure FDA0003077444830000012
To complete the calibration of the TCP at the tail end of the working tool (5); determining the robot eye-hand relationship
Figure FDA0003077444830000013
The process is as follows:
(S101) establishing the hand-eye relationship of the robot as
Figure FDA0003077444830000014
Wherein R isCConverting rotation matrixes of a robot terminal coordinate system { E } and a binocular vision system coordinate system { C } and setting the rotation matrixes to be constant values; t isCTranslation vectors converted for a robot terminal coordinate system { E } and a binocular vision system coordinate system { C } are constant values;
(S102) setting a first circular target point (P) on a working platform, wherein the first circular target point is a fixed point, the posture of the tail end (6) of the robot is kept unchanged, the robot (1) moves linearly, and the tail end (6) of the robot moves to a plurality of positions in sequence and measures the first circular target point (P);
(S103) sequentially controlling the robot (1) to perform posture-changing movement to a plurality of positions and measuring the first circular target point P under a binocular vision system coordinate system { C };
(S104) calculating the measured value of the first circular target point (P) in the steps (S102) and (S103) through the relation of robot kinematics and space coordinate transformation to obtain RCAnd TCTo calibrate the hand-eye relationship of the robot
Figure FDA0003077444830000021
2. The TCP calibration system for a robot based on vertical reflection according to claim 1, wherein: the two cameras (2) are fixed on the operation tool (5) through a connecting support (4), and the two cameras (2) are respectively and fixedly arranged at two ends of the connecting support (4).
3. The TCP calibration system for a robot based on vertical reflection according to claim 1, wherein: the robot kinematics and spatial coordinate transformation logical operation in the human eye relation logical operation module comprises the following steps:
(B1) establishing a transformation matrix of a robot terminal coordinate system { E } relative to a robot base coordinate system { B }
Figure FDA0003077444830000022
Wherein R is a rotation matrix converted from a robot base coordinate { B } and a robot terminal coordinate system { E }, and the attitude of the robot terminal (6) is kept unchanged, namely R is unchanged, and R is a constant value in the process of linear motion of the robot (1); t is a translation vector converted by a robot base coordinate { B } and a robot end coordinate system { E };
the coordinate conversion formula can obtain:
Figure FDA0003077444830000023
unfolding to obtain:
Figure FDA0003077444830000024
Pcthe coordinate value can be obtained by measuring with a binocular vision system;
wherein, PcThe coordinate of the first circular target point P under a binocular vision system coordinate system { C };
Pbis the coordinate, P, of the first circular target point P under the robot base coordinate { B }bIs a constant value;
Figure FDA0003077444830000031
and
Figure FDA0003077444830000032
are respectively PcAnd PbA transposed matrix of the conversion;
(B2) since the posture of the robot tail end (6) is kept unchanged in the step (S102), the robot tail end (6) moves to a plurality of positions in sequence, two positions are selected, and the measured value of the first circular target point (P) is obtained under the coordinate system { C } of the binocular vision system
Figure FDA0003077444830000033
And
Figure FDA0003077444830000034
by substituting the equations (a1) respectively, the following equations can be established:
Figure FDA0003077444830000035
the subtraction of the two equations yields:
Figure FDA0003077444830000036
since R is an orthogonal matrix, the above formula can be changed to:
Figure FDA0003077444830000037
measuring different position parameters of the first circular target point (P) under a binocular vision system coordinate system { C } four times in sequence to obtain a measured value of the first circular target point (P)
Figure FDA0003077444830000038
And
Figure FDA0003077444830000039
in the formula (a2), we can obtain:
Figure FDA00030774448300000310
namely RcA＝b；
It can be seen that,
Figure FDA00030774448300000311
b＝RT[T1-T2 T2-T3 T3-T4]；
r obtained by solving matrix singular value decompositionC；
Wherein the content of the first and second substances,
Figure FDA00030774448300000312
and
Figure FDA00030774448300000313
respectively as the coordinates of the first circular target point (P) in a binocular vision system coordinate system { C };
Figure FDA00030774448300000314
and
Figure FDA00030774448300000315
are respectively as
Figure FDA00030774448300000316
And
Figure FDA00030774448300000317
the transposed matrix of (2);
T1、T2、T3and T4Respectively being said machineTranslation vectors converted from a robot base coordinate system { B } and a robot terminal coordinate system { E } at different positions when the person (1) moves;
(B3) in the step (S103), the coordinate value of the first circular target point (P) in the coordinate system { C } of the binocular vision system changes with the robot performing posture-changing motion, and two moving positions are selected to obtain the measurement value of the first circular target point (P)
Figure FDA0003077444830000041
And
Figure FDA0003077444830000042
the following equations are established:
Figure FDA0003077444830000043
subtracting the two equations to obtain:
Figure FDA0003077444830000044
Figure FDA0003077444830000045
can be measured by a binocular vision system, and the above-mentioned obtained R is usedCIn the formula, T is obtainedCCalibrating hand-eye relationships
Figure FDA0003077444830000046
Wherein R is11And R22Respectively converting rotation matrixes of a robot base coordinate system { B } and a robot terminal coordinate system { E } at different positions when the robot moves in the posture changing manner;
T11and T22Respectively converting translation vectors of a robot base coordinate system { B } and a robot terminal coordinate system { E } at different positions when the robot moves in the posture changing manner;
Figure FDA0003077444830000047
and
Figure FDA0003077444830000048
respectively as the coordinates of the first circular target point (P) in a binocular vision system coordinate system { C };
Figure FDA0003077444830000049
and
Figure FDA00030774448300000410
are respectively as
Figure FDA00030774448300000411
And
Figure FDA00030774448300000412
the transposed matrix of (2).
4. The TCP calibration system for a robot based on vertical reflection according to claim 1, wherein: the process of TCP calibration at the tail end of the working tool (5) comprises the following steps:
placing the plane mirror (3) on the working platform, and placing the second circular target point (P)a) A working tool (5) attached to the robot end (6) and configured to control the robot (1) to move the second circular target point (P)a) And the robot tail end (6) is arranged above the plane mirror (3) and is kept to be vertical to the plane mirror (3).
5. The TCP calibration system for a robot based on vertical reflection according to claim 4, wherein:
the logical operation of the TCP calibration logical operation module comprises the following steps:
a second circular target point (P) on the end of the working tool (5)a) The point in the plane mirror (3) is a projection point (P'a) Projection point (P 'is measured by binocular vision system'a) In pairValues in the coordinate system { C } of the eye vision system by
Figure FDA0003077444830000051
Can obtain a projected point (P'a) The values (x ', y ', z ') of the coordinate system { E } at the end of the robot; assuming a second circular target point (P)a) The value of the coordinate system { E } at the end of the robot is (x, y, z); from the vertical relationship, x ═ x ', y ═ y'; selecting a point of symmetry (P) on said work platformm) First, the symmetric point (P) is obtainedm) Z-axis coordinate value Z in robot end coordinate system { E }mFrom the symmetry, z '-2 × (z' -z)m) Finally, a second circular target point (P) is obtaineda) And completing the calibration of the TCP at the value under the coordinate system { E } of the tail end of the robot.
6. The TCP calibration system for robot based on vertical reflection according to any of claims 1 to 5, wherein: the robot comprises a robot body (1), a logic operation module, a data acquisition module and a binocular vision system, and is characterized by further comprising a control device, wherein the robot body (1), the logic operation module, the data acquisition module and the binocular vision system are all connected with the control device.
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