CN109311155B - Method and device for calibrating tool coordinate system origin of industrial robot - Google Patents

Method and device for calibrating tool coordinate system origin of industrial robot Download PDF

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CN109311155B
CN109311155B CN201680086636.XA CN201680086636A CN109311155B CN 109311155 B CN109311155 B CN 109311155B CN 201680086636 A CN201680086636 A CN 201680086636A CN 109311155 B CN109311155 B CN 109311155B
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coordinate system
origin
tool
flange
groups
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CN109311155A (en
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叶根
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Shenzhen A&E Intelligent Technology Institute Co Ltd
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Shenzhen A&E Intelligent Technology Institute Co Ltd
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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
    • B25J9/02—Programme-controlled manipulators characterised by movement of the arms, e.g. cartesian coordinate type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/02—Programme-controlled manipulators characterised by movement of the arms, e.g. cartesian coordinate type
    • B25J9/04—Programme-controlled manipulators characterised by movement of the arms, e.g. cartesian coordinate type by rotating at least one arm, excluding the head movement itself, e.g. cylindrical coordinate type or polar coordinate type

Abstract

The embodiment of the invention discloses a method for calibrating an origin of a tool coordinate system of an industrial robot, which comprises the following steps: controlling the robot to drive a tool to be calibrated, which is arranged at the tail end of the robot, to move, so that the origin of a tool coordinate system of the tool to be calibrated reaches a fixed reference point along N different tracks; respectively recording the rotation angle of each axis of the robot when the origin of the tool coordinate system reaches a reference point; and calculating coordinate values of the tool coordinate system origin in the flange coordinate system of the robot according to the recorded N groups of rotation angles. Through the mode, the origin coordinates of the tool coordinate system can be obtained by calibrating only through the self-motion of the industrial robot without the aid of a measuring tool of an external standard.

Description

Method and device for calibrating tool coordinate system origin of industrial robot
[ technical field ] A method for producing a semiconductor device
The embodiment of the invention relates to the field of robots, in particular to a method and a device for calibrating an origin of a tool coordinate system of an industrial robot.
[ background of the invention ]
In the use process of the robot, a tool is generally required to be assembled at the tail end of the robot, and then the corresponding function is realized. To obtain better machining effect, the position and posture of the tool relative to the robot end coordinate system (flange coordinate system) are often calibrated after the tool is equipped. At present, a standard measuring Tool is generally used for measuring coordinates of a Tool coordinate system origin (Tool Center Point, TCP) in a flange coordinate system, and the technical problems of high cost, complex operation and the like exist.
[ summary of the invention ]
The embodiment of the invention provides a method and a device for calibrating an origin of a tool coordinate system of an industrial robot, which are used for solving at least part of problems caused by calibrating the origin of the tool coordinate system by a standard measuring tool in the prior art.
In order to solve the above technical problem, one technical solution adopted by the embodiments of the present invention is: a method for calibrating an origin of a tool coordinate system of an industrial robot is provided, which comprises the following steps: controlling the robot to drive a tool to be calibrated, which is arranged at the tail end of the robot, to move, so that the origin of a tool coordinate system of the tool to be calibrated reaches a fixed reference point along N different tracks, wherein when the origin of the tool coordinate system reaches the reference point along the different tracks, a connecting line between the origin of a flange coordinate system of the robot and the origin of the tool coordinate system is not overlapped, and N is an integer greater than or equal to 3; respectively recording the rotation angle of each axis of the robot when the origin of the tool coordinate system reaches a reference point; and calculating coordinate values of the tool coordinate system origin in the flange coordinate system of the robot according to the recorded N groups of rotation angles.
Wherein, the step of calculating the coordinate value of the tool coordinate system origin in the flange coordinate system of the robot according to the recorded N groups of rotation angles comprises the following steps: randomly selecting three groups from the recorded N groups of rotation angles, and calculating to obtain three groups of homogeneous matrixes of corresponding flange coordinate systems; and calculating the coordinate values of the origin of the tool coordinate system in the flange coordinate system by using the three homogeneous matrixes.
Wherein, select three groups wantonly in N group's of rotation angles of record, calculate three group homogeneous matrixes of the flange coordinate system that obtain to correspond step includes: and respectively calculating three groups of homogeneous matrixes of the corresponding flange coordinate system by using a positive kinematic algorithm from the selected three groups of rotation angles, wherein the three groups of homogeneous matrixes are respectively expressed as:
Figure GPA0000261335130000041
and
Figure GPA0000261335130000042
in the above expression, R1、R2And R33 x3 matrixes respectively for representing three times of workers corresponding to the three groups of rotation angles respectivelyHaving the direction of the flange coordinate system when the origin of the coordinate system reaches the reference point, O1、O2And O3And the matrixes are 3 multiplied by 1 respectively and are used for representing the coordinates of the origin of the flange coordinate system when the origins of the cubic tool coordinate systems corresponding to the three groups of rotation angles reach the reference point respectively.
Wherein, the step of calculating the coordinate value of the tool coordinate system origin in the flange coordinate system by the three groups of homogeneous matrixes comprises the following steps: calculating the coordinate value of the tool coordinate system origin in the flange coordinate system by using the following formula:
OT＝(R1+R3-2R2)-1(2O2-O1-O3)
in the above expression, OTIs a 3 x1 matrix for representing the coordinate values of the tool coordinate system origin in the flange coordinate system.
Wherein N is an integer greater than or equal to 4, the method further comprising: according to at least one of the three homogeneous matrices, OTAnd calculating the error of the coordinate value of the origin of the tool coordinate system in the flange coordinate system by the remaining at least one group of rotation angles.
Wherein O is selected from at least one of the three homogeneous matricesTAnd the step of calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by the remaining at least one group of rotation angles comprises: and calculating at least one fourth homogeneous matrix of the corresponding flange coordinate system from the rest at least one group of rotation angles by using a positive kinematic algorithm, and expressing as follows:
Figure GPA0000261335130000043
in the above expression, R4Is a 3 x3 matrix for representing the direction of the flange coordinate system when the origin of the tool coordinate system corresponding to the remaining at least one set of rotation angles reaches the reference point, O4The matrix is 3 multiplied by 1 and is used for representing the coordinates of the origin of the flange coordinate system when the origin of the tool coordinate system corresponding to the rest at least one group of rotation angles reaches the reference point; according to the above three groupsAt least one of homogeneous matrices, OTAnd the fourth group of homogeneous matrixes calculates errors of coordinate values of the tool coordinate system origin in the flange coordinate system.
Wherein O is selected from at least one of the three homogeneous matricesTAnd the step of calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by the fourth homogeneous matrix comprises the following steps: calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by using the following formula:
Tn＝RnOT+On
T4＝R4OT+O4
err＝|Tn-T4|
in the above expression, RnAnd OnRespectively R in the three groups of homogeneous matrixes1、R2And R3Any one of (1) and O1、O2And O3Err represents an error value.
In order to solve the above technical problem, one technical solution adopted by the embodiments of the present invention is: there is provided a calibration device for an origin of a tool coordinate system of an industrial robot, comprising: the control unit is used for controlling the robot to drive a tool to be calibrated, which is arranged at the tail end of the robot, to move, so that the origin of a tool coordinate system of the tool to be calibrated reaches a fixed reference point along N different tracks, wherein when the origin of the tool coordinate system reaches the reference point along the different tracks, the connecting line of the origin of a flange coordinate system of the robot and the origin of the tool coordinate system is not overlapped, and N is an integer greater than or equal to 3; the recording unit is used for respectively recording the rotation angle of each axis of the robot when the origin of the tool coordinate system reaches the reference point; and the coordinate calculation unit is used for calculating the coordinate value of the tool coordinate system origin in the flange coordinate system of the robot according to the recorded N groups of rotation angles.
Wherein the coordinate calculation unit includes: the first sub-coordinate calculating unit is used for randomly selecting three groups from the recorded N groups of rotating angles and calculating to obtain three groups of homogeneous matrixes of corresponding flange coordinate systems; and the second sub-coordinate calculating unit is used for calculating and obtaining the coordinate value of the origin of the tool coordinate system in the flange coordinate system according to the three groups of homogeneous matrixes.
Wherein, the first sub-coordinate calculating unit respectively calculates three groups of homogeneous matrixes of the corresponding flange coordinate system by the selected three groups of rotation angles by applying a positive kinematics algorithm, and the three groups of homogeneous matrixes are respectively expressed as:
Figure GPA0000261335130000051
and
Figure GPA0000261335130000052
in the above expression, R1、R2And R33 x3 matrixes respectively for respectively representing the directions of the flange coordinate system when the three tool coordinate system origins corresponding to the three groups of rotation angles reach the reference point, O1、O2And O3And the matrixes are 3 multiplied by 1 respectively and are used for representing the coordinates of the origin of the flange coordinate system when the origins of the cubic tool coordinate systems corresponding to the three groups of rotation angles reach the reference point respectively.
The second sub-coordinate calculating unit calculates the coordinate value of the tool coordinate system origin in the flange coordinate system by using the following formula:
OT＝(R1+R3-2R2)-1(2O2-O1-O3) (2)
in the above expression, OTIs a 3 x1 matrix for representing the coordinate values of the tool coordinate system origin in the flange coordinate system.
Wherein N is an integer greater than or equal to 4, and an error calculation unit for calculating O according to at least one of the three homogeneous matrixesTAnd calculating the error of the coordinate value of the origin of the tool coordinate system in the flange coordinate system by the remaining at least one group of rotation angles.
Wherein the error calculation unit includes: a first sub-error calculating unit, configured to calculate, from the remaining at least one set of rotation angles, at least one fourth-set homogeneous matrix of a corresponding flange coordinate system by using a positive kinematic algorithm, and express as:
Figure GPA0000261335130000061
in the above expression, R4Is a 3 x3 matrix for representing the direction of the flange coordinate system when the origin of the tool coordinate system corresponding to the remaining at least one set of rotation angles reaches the reference point, O4The matrix is 3 multiplied by 1 and is used for representing the coordinates of the origin of the flange coordinate system when the origin of the tool coordinate system corresponding to the rest at least one group of rotation angles reaches the reference point; a second sub-error calculating unit for calculating O according to at least one of the three homogeneous matrixesTAnd the fourth group of homogeneous matrixes calculates errors of coordinate values of the tool coordinate system origin in the flange coordinate system.
The second sub-error calculation unit calculates the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by using the following formula:
Tn＝RnOT+On
T4＝R4OT+O4
err＝|Tn-T4|
in the above expression, RnAnd OnRespectively R in the three groups of homogeneous matrixes1、R2And R3Any one of (1) and O1、O2And O3Err represents an error value.
In order to solve the above technical problem, one technical solution adopted by the embodiments of the present invention is: the calibration device comprises a processor and a memory connected with the processor, wherein the processor executes the steps by running a program stored in the memory.
The embodiment of the invention has the beneficial effects that: in the method and the device for calibrating the tool coordinate system origin of the industrial robot provided by the embodiment of the invention, the tool coordinate system origin coordinate can be calibrated only through the self-motion of the industrial robot without an external standard measuring tool, and a calibration error can be further given.
[ description of the drawings ]
Fig. 1 is a schematic structural view of an industrial robot according to a first embodiment of the invention;
fig. 2 is a schematic flow chart of a method for calibrating the origin of the tool coordinate system of an industrial robot according to a second embodiment of the present invention;
fig. 3 is a schematic block diagram of a calibration arrangement of the tool coordinate system origin of an industrial robot according to a third embodiment of the invention;
fig. 4 is a schematic block diagram of a calibration arrangement of the tool coordinate system origin of an industrial robot according to a fourth embodiment of the invention.
[ detailed description ] embodiments
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, fig. 1 is a schematic structural view of an industrial robot according to a first embodiment of the present invention. The industrial robot of the present embodiment mainly includes a base 11, robot arms 12, 13, and a tool 14 equipped at the tip of the robot arm 13. Wherein, the mechanical arm 12 and the base 11 and the mechanical arms 12 and 13 are respectively connected through rotating shafts 15 and 16, and the tool 14 is driven to different positions by controlling the rotation of the rotating shafts 15 and 16.
For convenience in describing the motion or pose change of the robot, the robot is generally specified to exist in the following coordinate system: (1) a world coordinate system, which a user specifies a coordinate system that is fixed to the earth and that does not change during operation, such as the coordinate system defined by origin o1 and coordinate axes x1 and y1 in FIG. 1; (2) the base coordinate system, based on the coordinate system of the robot base, does not generally change during operation, such as the coordinate system defined by origin o2 and coordinate axes x2 and y2 in fig. 1. Generally, when multiple robots cooperate, each robot has its own base coordinate system, and the world coordinate system is a common reference coordinate system of the base coordinate system; (3) flange coordinate system, the coordinate system of the section of the robot arm at the end of the robot to which the tool is attached, e.g. the coordinate system defined by the origin o3 and the coordinate axes x3 and y3 in fig. 1. Generally, when the robot posture changes, the flange coordinate system changes along with the change. (4) A tool coordinate system, a coordinate system located on the tool, such as the coordinate system defined by origin o4 and coordinate axes x4 and y4 in fig. 1.
As further shown in fig. 2, fig. 2 is a flow chart of a method for calibrating the origin of the tool coordinate system of an industrial robot according to a second embodiment of the present invention. In the embodiment, under the condition of a measuring tool without the aid of an external standard, the origin coordinates of the tool coordinate system can be calibrated only through the self-motion of the industrial robot, and the calibration error can be further given. Specifically, the calibration method of the embodiment includes the following steps:
step 21, controlling the robot to drive the tool 14 to be calibrated, which is mounted at the tail end of the robot, to move, so that the tool coordinate system origin o4 of the tool 14 to be calibrated reaches a fixed reference point o5 along N different tracks (for example, the tracks shown by the dotted lines in fig. 1);
in this step, N is an integer greater than or equal to 3, and further preferably, when the tool coordinate system origin o4 reaches the reference point o5 along a different track, a connecting line between the flange coordinate system origin o3 of the robot and the tool coordinate system origin o4 is not coincident, for example, when the tool coordinate system origin o4 reaches the reference point o5 along a different track, an included angle between the connecting lines is greater than 5 degrees;
step 22, respectively recording the rotation angles of the axes (e.g. the rotating axes 15 and 16) of the robot each time the tool coordinate system origin o4 reaches the reference point o 5;
step 23, calculating the coordinate value of the tool coordinate system origin o4 in the flange coordinate system (the coordinate system defined by o3, x3 and y3 in fig. 1) of the robot according to the recorded N sets of rotation angles.
In this step, preferably, three sets of rotation angles are selected from the N sets of recorded rotation angles, three sets of homogeneous matrices of the corresponding flange coordinate system are obtained through calculation, and further, coordinate values of the tool coordinate system origin o4 in the flange coordinate system are obtained through calculation of the three sets of homogeneous matrices.
Specifically, three homogeneous matrixes of the corresponding flange coordinate system are respectively calculated by the three selected rotation angles by using a positive kinematic algorithm and are respectively expressed as:
Figure GPA0000261335130000081
and
Figure GPA0000261335130000082
wherein R is1、R2And R33 x3 matrixes respectively for respectively representing the directions of the flange coordinate system when the three tool coordinate system origins O4 corresponding to the three groups of rotation angles reach the reference point O5, O1、O2And O33 × 1 for representing the coordinates of the flange coordinate system origin o3 when the three tool coordinate systems origin o4 corresponding to the three sets of rotation angles reach the reference point o5, respectively. In the above expression, the direction of the flange coordinate system and the coordinates of the origin o3 can be calculated with the world coordinate system or the base coordinate system as a reference coordinate system. Further, it is common knowledge in the art to calculate the homogeneous matrix according to the rotation angle of each axis of the robot by using a positive kinematic algorithm, and details thereof are not repeated herein.
Subsequently, further define:
Figure GPA0000261335130000091
wherein, OTIs a 3X 1 matrix, XT、YT、ZTFor indicating the coordinate values of the tool coordinate system origin o4 in the flange coordinate system. Furthermore, the tool coordinate system origin o4 corresponding to the three sets of rotation angle data reaches the same reference point o5 in the movement process, namelyAt this time, the coordinates of the tool coordinate system origin o4 corresponding to the three sets of rotation angle data are the same, so the following equation can be listed:
Figure GPA0000261335130000092
Figure GPA0000261335130000093
after unfolding, obtaining:
R1OT+O1＝R2OT+O2
R3OT+O3＝R2OT+O2
adding the above two equations left and right can obtain:
(R1+R3)OT+O1+O3＝2R2OT+2O2
(R1+R3-2R2)OT＝2O2-O1-O3
finally, the following can be obtained:
OT＝(R1+R3-2R2)-1(2O2-O1-O3)
further, the coordinate value of the tool coordinate system origin in the flange coordinate system can be calculated by the above formula.
It can be seen that the coordinates of the tool coordinate system origin o4 in the flange coordinate system can be calibrated by the above method without the aid of an external standard measuring tool, and only by the self-movement of the industrial robot.
Further, as shown in fig. 2, the method of the present embodiment further preferably, but not necessarily, includes:
and 24, calculating the error of the coordinate value of the tool coordinate system origin o4 in the flange coordinate system.
At this time, it is necessary to control in steps 21 and 22The origin O4 of the tool coordinate system reaches the reference point O5 along at least 4 different tracks, at least 4 groups of rotation angles are recorded, namely N is an integer greater than or equal to 4, and at least one of the three groups of homogeneous matrixes, O, obtained by calculation according to the stepsTAnd calculating the error of the coordinate value of the origin of the tool coordinate system in the flange coordinate system by the remaining at least one group of rotation angles.
Specifically, at least one fourth homogeneous matrix of the corresponding flange coordinate system is obtained by calculating at least one group of the remaining rotation angles by using a positive kinematic algorithm, and is expressed as:
Figure GPA0000261335130000101
wherein R is4Is a 3 x3 matrix for representing the direction of the flange coordinate system when the origin of the tool coordinate system corresponding to the remaining at least one set of rotation angles reaches the reference point, O4Is a 3 x1 matrix for representing the coordinates of the origin of the flange coordinate system when the origin of the tool coordinate system corresponding to at least one group of the remaining rotation angles reaches the reference point, and further according to at least one of the three groups of homogeneous matrices, OTAnd calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by using a fourth homogeneous matrix, specifically calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by using the following formula:
Tn＝RnOT+On
T4＝R4OT+O4
err＝|Tn-T4|
in the above expression, RnAnd OnRespectively R in the three groups of homogeneous matrixes1、R2And R3Any one of (1) and O1、O2And O3Err represents an error value.
In the above step, the error of the coordinate value of the tool coordinate system origin in the flange coordinate system may be calculated respectively according to the remaining two or more sets of rotation angles, and finally, the final error may be obtained by averaging two or more errors obtained by the calculation.
As shown in fig. 3, fig. 3 is a schematic block diagram of a calibration arrangement for the origin of the tool coordinate system of an industrial robot according to a third embodiment of the present invention. The calibration apparatus of the present embodiment includes a control unit 31, a recording unit 32, and a coordinate calculation unit 33. The control unit 31 is configured to control the robot to drive the tool 14 to be calibrated, which is mounted at the end of the robot, to move, so that an origin o4 of a tool coordinate system of the tool 14 to be calibrated reaches a fixed reference point o5 along N different trajectories, where N is an integer greater than or equal to 3. When the tool coordinate system origin o4 reaches the reference point o5 along a different trajectory, the connecting line of the flange coordinate system origin o3 of the robot and the tool coordinate system origin o4 is not coincident.
The recording unit 32 is used to record the rotation angle of each axis of the robot each time the tool coordinate system origin o4 reaches the reference point o5, respectively. The coordinate calculation unit 33 is configured to calculate coordinate values of the tool coordinate system origin o4 in the flange coordinate system of the robot according to the recorded N sets of rotation angles.
Further, the calculation unit 33 includes a first sub-coordinate calculation unit 331 and a second sub-coordinate calculation unit 332. The first sub-coordinate calculating unit 331 is configured to randomly select three sets from the N sets of recorded rotation angles, and calculate to obtain three sets of homogeneous matrices of the corresponding flange coordinate system, and the second sub-coordinate calculating unit 332 is configured to calculate to obtain coordinate values of the tool coordinate system origin in the flange coordinate system according to the three sets of homogeneous matrices.
Specifically, the first sub-coordinate calculating unit 331 calculates three homogeneous matrices of the corresponding flange coordinate system from the selected three rotation angles by using a positive kinematic algorithm, and the three homogeneous matrices are respectively expressed as:
Figure GPA0000261335130000111
and
Figure GPA0000261335130000112
in the above expression, R1、R2And R33 x3 matrixes respectively for respectively representing the directions of the flange coordinate system when the three tool coordinate system origins O4 corresponding to the three groups of rotation angles reach the reference point O5, O1、O2And O33 × 1 for representing the coordinates of the flange coordinate system origin o3 when the three tool coordinate systems origin o4 corresponding to the three sets of rotation angles reach the reference point o5, respectively.
The second sub-coordinate calculation unit 332 calculates the coordinate value of the tool coordinate system origin o4 in the flange coordinate system using the following formula:
OT＝(R1+R3-2R2)-1(2O2-O1-O3) (2)
in the above expression, OTIs a 3 × 1 matrix for representing the coordinate values of the tool coordinate system origin o4 in the flange coordinate system.
In a further preferred embodiment, N is an integer greater than or equal to 4, and the calibration apparatus further includes an error calculation unit 34 configured to calculate O according to at least one of the three homogeneous matricesTAnd the remaining at least one set of rotation angles calculate the error in the coordinate values of the tool coordinate system origin o4 in the flange coordinate system.
Specifically, the error calculation unit 34 includes a first sub-error calculation unit 341 and a second sub-error calculation unit 342. The first sub-error calculation unit 34 is configured to calculate, from the remaining at least one set of rotation angles, at least one fourth homogeneous matrix of the corresponding flange coordinate system using a positive kinematic algorithm, and is expressed as:
Figure GPA0000261335130000121
in the above expression, R4Is a 3 x3 matrix for representing the direction of the flange coordinate system when the tool coordinate system origin O4 corresponding to the remaining at least one set of rotation angles reaches the reference point O5, O4Is a 3 × 1 matrix for representing the remaining at least one set of rotation angle correspondencesTo the tool coordinate system origin o4 to the reference point o 5.
The second sub-error calculation unit 342 is used for calculating at least one of the three homogeneous matrixes, OTAnd a fourth homogeneous matrix calculates the error of the coordinate value of the tool coordinate system origin o4 in the flange coordinate system. Specifically, the second sub-error calculation unit 342 calculates the error of the coordinate value of the tool coordinate system origin o4 in the flange coordinate system using the following formula:
Tn＝RnOT+On
T4＝R4OT+O4
err＝|Tn-T4|
in the above expression, RnAnd OnRespectively R in the three groups of homogeneous matrixes1、R2And R3Any one of (1) and O1、O2And O3Err represents an error value.
As shown in fig. 4, fig. 4 is a schematic block diagram of a calibration apparatus for a tool coordinate system origin of an industrial robot according to a fourth embodiment of the present invention. The calibration apparatus of the present embodiment includes a processor 41 and a memory 42. The processor 41 is connected to the memory 42, and executes the steps of the calibration method according to the second embodiment of the present invention described with reference to fig. 2 by executing the program stored in the memory 42.
In summary, it is easily understood by those skilled in the art that, in the method and apparatus for calibrating the tool coordinate system origin of the industrial robot provided by the embodiment of the present invention, the tool coordinate system origin coordinate can be calibrated only by the self-motion of the industrial robot without using an external standard measuring tool, and the calibration error can be further given.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (8)

1. A method for calibrating an origin of a tool coordinate system of an industrial robot, comprising:
controlling a robot to drive a tool to be calibrated, which is arranged at the tail end of the robot, to move, so that the origin of a tool coordinate system of the tool to be calibrated reaches a fixed reference point along N different tracks, wherein when the origin of the tool coordinate system reaches the reference point along different tracks, the connecting line of the origin of a flange coordinate system of the robot and the origin of the tool coordinate system is not overlapped, and N is an integer greater than or equal to 3;
respectively recording the rotation angle of each axis of the robot when the origin of the tool coordinate system reaches the reference point;
calculating coordinate values of the origin of the tool coordinate system in a flange coordinate system of the robot according to the recorded N groups of rotation angles,
the step of calculating the coordinate values of the tool coordinate system origin in the flange coordinate system of the robot according to the recorded N groups of rotation angles comprises:
and randomly selecting three groups from the recorded N groups of rotation angles, and respectively calculating three groups of homogeneous matrixes of the corresponding flange coordinate system by using a positive kinematic algorithm from the selected three groups of rotation angles, wherein the three groups of homogeneous matrixes are respectively expressed as:
Figure FDA0003421430450000011
and
Figure FDA0003421430450000012
wherein R is1、R2And R33 x3 matrixes respectively for respectively representing the directions of the flange coordinate system when the three tool coordinate system origins corresponding to the three groups of rotation angles reach the reference point, O1、O2And O33 × 1 matrixes respectively for respectively representing the three times of the tools corresponding to the three groups of rotation anglesCoordinates of the origin of the flange coordinate system when the origin of the coordinate system reaches the reference point;
and calculating the coordinate value of the origin of the tool coordinate system in the flange coordinate system by the three homogeneous matrixes, and calculating the coordinate value of the origin of the tool coordinate system in the flange coordinate system by using the following formula: o isT＝(R1+R3-2R2)-1(2O2-O1-O3) Wherein O isTA 3 x1 matrix for representing coordinate values of the tool coordinate system origin in the flange coordinate system;
according to at least one of the three homogeneous matrices, OTAnd calculating the error of the coordinate value of the origin of the tool coordinate system in the flange coordinate system by using the rest at least one group of rotation angles, wherein N is an integer greater than or equal to 4.
2. The method of claim 1, wherein O is the number of homogeneous matrices according to at least one of the three sets of homogeneous matricesTAnd the step of calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by the remaining at least one group of rotation angles comprises:
and calculating at least one fourth homogeneous matrix of the corresponding flange coordinate system from the rest at least one group of rotation angles by using a positive kinematic algorithm, and expressing as follows:
Figure FDA0003421430450000021
wherein R is4The matrix is 3 x3 and is used for representing the direction of the flange coordinate system when the origin of the tool coordinate system corresponding to the rest at least one group of rotation angles reaches the reference point; o is4The matrix is 3 x1 and is used for representing the coordinates of the origin of the flange coordinate system when the origin of the tool coordinate system corresponding to the rest at least one group of rotation angles reaches the reference point;
according to at least one of the three homogeneous matrices, OTAnd the fourth group of homogeneous matrixes calculate the error of the coordinate values of the origin of the tool coordinate system in the flange coordinate system.
3. The method of claim 2, wherein O is the number of homogeneous matrices according to at least one of the three sets of homogeneous matricesTAnd the step of calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by the fourth homogeneous matrix comprises the following steps:
calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by using the following formula:
Tn＝RnOT+On
T4＝R4OT+O4
err＝|Tn-T4|
wherein R isnAnd OnRespectively R in the three groups of homogeneous matrixes1、R2And R3Any one of (1) and O1、O2And O3Err represents an error value.
4. An apparatus for calibrating an origin of a tool coordinate system of an industrial robot, the apparatus comprising:
the control unit is used for controlling the robot to drive a tool to be calibrated, which is arranged at the tail end of the robot, to move, so that the origin of a tool coordinate system of the tool to be calibrated reaches a fixed reference point along N different tracks, wherein when the origin of the tool coordinate system reaches the reference point along the different tracks, the connecting line between the origin of a flange coordinate system of the robot and the origin of the tool coordinate system is not overlapped, and N is an integer greater than or equal to 3;
the recording unit is used for respectively recording the rotation angle of each axis of the robot when the origin of the tool coordinate system reaches the reference point;
a coordinate calculation unit for calculating coordinate values of the tool coordinate system origin in the flange coordinate system of the robot according to the recorded N sets of rotation angles, the coordinate calculation unit comprising: the first sub-coordinate calculating unit is used for randomly selecting three groups from the recorded N groups of rotating angles, and respectively calculating three groups of homogeneous matrixes of the corresponding flange coordinate system by using a positive kinematic algorithm from the selected three groups of rotating angles, wherein the three groups of homogeneous matrixes are respectively expressed as:
Figure FDA0003421430450000031
and
Figure FDA0003421430450000032
wherein R is1、R2And R33 x3 matrixes respectively for respectively representing the directions of the flange coordinate system when the three tool coordinate system origins corresponding to the three groups of rotation angles reach the reference point, O1、O2And O3The three homogeneous matrixes are 3 multiplied by 1 respectively and are used for respectively representing three homogeneous matrixes of the flange coordinate system obtained by coordinate calculation of the flange coordinate system when the three tool coordinate system origins corresponding to the three groups of rotation angles reach the reference point;
the second sub-coordinate calculating unit is used for calculating coordinate values of the tool coordinate system origin in the flange coordinate system according to the three groups of homogeneous matrixes, and the second sub-coordinate calculating unit calculates the coordinate values of the tool coordinate system origin in the flange coordinate system by using the following formula: o isT＝(R1+R3-2R2)-1(2O2-O1-O3) Wherein O isTA 3 x1 matrix for representing coordinate values of the tool coordinate system origin in the flange coordinate system;
an error calculation unit for calculating O according to at least one of the three homogeneous matrixesTAnd calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system through the rest at least one group of rotation angles, wherein N is an integer greater than or equal to 4.
5. The calibration device according to claim 4, wherein the error calculation unit comprises:
a first sub-error calculating unit, configured to calculate, from the remaining at least one set of rotation angles, at least one fourth-set homogeneous matrix of the corresponding flange coordinate system by using a positive kinematic algorithm, and express as:
Figure FDA0003421430450000041
wherein R is4The matrix is 3 x3 and is used for representing the direction of the flange coordinate system when the origin of the tool coordinate system corresponding to the rest at least one group of rotation angles reaches the reference point; o is4The matrix is 3 x1 and is used for representing the coordinates of the origin of the flange coordinate system when the origin of the tool coordinate system corresponding to the rest at least one group of rotation angles reaches the reference point;
a second sub-error calculation unit for calculating O according to at least one of the three homogeneous matrixesTAnd the fourth group of homogeneous matrixes calculate the error of the coordinate values of the origin of the tool coordinate system in the flange coordinate system.
6. The calibration device according to claim 5, wherein the second sub-error calculation unit calculates the error of the coordinate values of the tool coordinate system origin in the flange coordinate system by using the following formula:
Tn＝RnOT+On
T4＝R4OT+O4
err＝|Tn-T4|
wherein R isnAnd OnRespectively R in the three groups of homogeneous matrixes1、R2And R3Any one of (1) and O1、O2And O3Err represents an error value.
7. Calibration arrangement for an origin of a tool coordinate system of an industrial robot, characterized in that the calibration arrangement comprises a processor and a memory connected to the processor, wherein the processor performs the following steps by running a program stored in the memory:
controlling a robot to drive a tool to be calibrated, which is arranged at the tail end of the robot, to move, so that the origin of a tool coordinate system of the tool to be calibrated reaches a fixed reference point along N different tracks, wherein when the origin of the tool coordinate system reaches the reference point along different tracks, the connecting line of the origin of a flange coordinate system of the robot and the origin of the tool coordinate system is not overlapped, and N is an integer greater than or equal to 3;
respectively recording the rotation angle of each axis of the robot when the origin of the tool coordinate system reaches the reference point;
calculating coordinate values of the origin of the tool coordinate system in a flange coordinate system of the robot according to the recorded N groups of rotation angles;
wherein, the step of calculating the coordinate value of the tool coordinate system origin in the flange coordinate system of the robot according to the recorded N groups of rotation angles comprises the following steps:
and randomly selecting three groups from the recorded N groups of rotation angles, and respectively calculating three groups of homogeneous matrixes of the corresponding flange coordinate system by using a positive kinematic algorithm from the selected three groups of rotation angles, wherein the three groups of homogeneous matrixes are respectively expressed as:
Figure FDA0003421430450000051
and
Figure FDA0003421430450000052
wherein R is1、R2And R33 x3 matrixes respectively for respectively representing the directions of the flange coordinate system when the three tool coordinate system origins corresponding to the three groups of rotation angles reach the reference point, O1、O2And O3The matrixes are 3 x1 respectively and are used for respectively representing the coordinates of the origin of the flange coordinate system when the origin of the tool coordinate system reaches the reference point for three times corresponding to the three groups of rotation angles;
and calculating the coordinate value of the origin of the tool coordinate system in the flange coordinate system by the three homogeneous matrixes, and calculating the coordinate value of the origin of the tool coordinate system in the flange coordinate system by using the following formula: o isT＝(R1+R3-2R2)-1(2O2-O1-O3) Wherein, OTA 3 x1 matrix for representing coordinate values of the tool coordinate system origin in the flange coordinate system;
according to at least one of the three homogeneous matrices, OTAnd calculating the error of the coordinate value of the origin of the tool coordinate system in the flange coordinate system by using the rest at least one group of rotation angles, wherein N is an integer greater than or equal to 4.
8. Calibration arrangement according to claim 7, characterized in that said calibration arrangement is based on at least one of said three homogeneous matrices, OTAnd the step of calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by the remaining at least one group of rotation angles comprises:
and calculating at least one fourth homogeneous matrix of the corresponding flange coordinate system from the rest at least one group of rotation angles by using a positive kinematic algorithm, and expressing as follows:
Figure FDA0003421430450000061
wherein R is4The matrix is 3 x3 and is used for representing the direction of the flange coordinate system when the origin of the tool coordinate system corresponding to the rest at least one group of rotation angles reaches the reference point; o is4Is a 3 x1 matrix for representing the flange coordinate system origin when the tool coordinate system origin corresponding to the remaining at least one group of rotation angles reaches the reference pointCoordinates of the points;
calculating the error of the coordinate value of the tool coordinate system origin in the flange coordinate system by using the following formula:
Tn＝RnOT+On
T4＝R4OT+O4
err＝|Tn-T4|
wherein R isnAnd OnRespectively R in the three groups of homogeneous matrixes1、R2And R3Any one of (1) and O1、O2And O3Err represents an error value.
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