CN110883774A - Robot joint angle zero calibration system, method and storage medium - Google Patents

Robot joint angle zero calibration system, method and storage medium Download PDF

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Publication number
CN110883774A
CN110883774A CN201911142997.3A CN201911142997A CN110883774A CN 110883774 A CN110883774 A CN 110883774A CN 201911142997 A CN201911142997 A CN 201911142997A CN 110883774 A CN110883774 A CN 110883774A
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calibration
robot
joint angle
sensor
robot joint
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CN110883774B (en
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郭东生
余杰先
钟文涛
高小云
张志波
王佳威
周家裕
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Gree Electric Appliances Inc of Zhuhai
Zhuhai Gree Intelligent Equipment Co Ltd
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Gree Electric Appliances Inc of Zhuhai
Zhuhai Gree Intelligent Equipment 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
    • B25J9/16—Programme controls
    • B25J9/1679—Programme controls characterised by the tasks executed
    • B25J9/1692—Calibration of manipulator
    • 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
    • B25J9/1602—Programme controls characterised by the control system, structure, architecture
    • B25J9/161—Hardware, e.g. neural networks, fuzzy logic, interfaces, processor
    • 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
    • B25J9/1628—Programme controls characterised by the control loop
    • B25J9/1633—Programme controls characterised by the control loop compliant, force, torque control, e.g. combined with position control
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
    • Y02P90/02—Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

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  • Engineering & Computer Science (AREA)
  • Robotics (AREA)
  • Mechanical Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Physics & Mathematics (AREA)
  • Artificial Intelligence (AREA)
  • Evolutionary Computation (AREA)
  • Fuzzy Systems (AREA)
  • Mathematical Physics (AREA)
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  • Numerical Control (AREA)

Abstract

The invention provides a zero calibration system, a zero calibration method and a storage medium for a joint angle of a robot, wherein the system comprises: the tail end executing device is arranged on the robot and comprises a plane, a laser fixed on the plane and a visual servo structure of the laser; the calibration device arranged in the working space of the robot comprises a fixing device, a first calibration sensor and a second calibration sensor, wherein the first calibration sensor and the second calibration sensor are arranged on the fixing device; the controller comprises a data acquisition module and a calibration module, the data acquisition module acquires the angular speed of the robot joint acquired by the first calibration sensor and the second calibration sensor, and the calibration module calibrates the zero offset value of the robot joint angle according to the angular speed of the robot joint. The zero calibration system for the joint angle of the robot can quickly, automatically and accurately realize the calibration of the joint angle of the robot.

Description

Robot joint angle zero calibration system, method and storage medium
Technical Field
The invention relates to the technical field of industrial robots, in particular to a robot joint angle zero position calibration system, a robot joint angle zero position calibration method and a storage medium.
Background
With the continuous widening of the application field of the robot, the requirements for high operation precision and high reliability of the robot are increased. The positioning precision of the robot is generally divided into absolute positioning precision and repeated positioning precision, the dragging teaching application of the robot mainly depends on the repeated positioning precision, so that the robot can realize repeated actions, along with the rapid development of modern industry, more and more robots are applied to occasions with higher requirements on the absolute positioning precision, such as processing, installation, welding and the like, however, the absolute positioning precision of the robot is far lower than the repeated positioning precision, the actual application requirements can not be met, and the zero position of the joint angle of the robot must be recalibrated to improve the absolute positioning precision.
In the process of implementing the invention, the inventor finds that the existing robot calibration method at least has the following defects: the method is very easily influenced by environmental factors, the equipment cost is high, and the calibration algorithm is time-consuming and complex.
Therefore, how to provide a method for calibrating the zero position of the joint angle of the robot, which can realize the quick, automatic and accurate calibration, is of great significance.
Disclosure of Invention
The present invention is directed to overcome the above technical problems, and provides a system, a method and a storage medium for calibrating a zero position of a joint angle of a robot.
In one aspect of the present invention, a zero calibration system for a joint angle of a robot is provided, the system comprising:
the tail end executing device is arranged on the robot main body and comprises a plane, a laser fixed on the plane and a visual servo structure of the laser;
the calibration device arranged in the working space of the robot comprises a fixing device, a first calibration sensor and a second calibration sensor, wherein the first calibration sensor and the second calibration sensor are arranged on the fixing device;
the controller comprises a data acquisition module and a calibration module, the data acquisition module is used for acquiring the angular speed of the robot joint acquired by the first calibration sensor and the second calibration sensor, and the calibration module is used for calibrating the zero offset value of the robot joint angle according to the angular speed of the robot joint.
Optionally, the visual servo structure comprises a binocular visual servo structure composed of cameras arranged on two sides of the laser.
Optionally, the first calibration sensor and the second calibration sensor are located on different planes, and a preset angle is formed between the installation directions of the first calibration sensor and the second calibration sensor.
Optionally, a first calibration position and a second calibration position are arranged on a reflected light path of the second calibration sensor, and a third calibration position and a fourth calibration position are arranged on a light path from the laser to the center position of the first calibration sensor;
the data acquisition module is used for respectively acquiring the angular speeds of the four groups of robot joints acquired by the first calibration sensor and the second calibration sensor when the tail end execution device is at the third calibration position and the fourth calibration position and the emitted laser irradiates the first calibration position and the second calibration position.
Optionally, the calibration module includes:
the first calculation unit is used for calculating the pose states of the 4 groups of end effectors according to the angular velocities of the four groups of robot joints according to a positive kinematics formula of the industrial robot;
the second calculation unit is used for obtaining linear equations of the end effector at corresponding calibration positions according to the pose state of the end effector and calculating 4 intersection points P formed by four groups of linear equations1、P2、P3And P4；
And the searching unit is used for searching a target robot joint angle which enables the mean square error of the mean values of the 4 intersection points and the intersection points to be minimum according to a point constraint principle, and calibrating the zero offset value of the robot joint angle according to the target robot joint angle.
Optionally, the distance between the first calibration position and the second calibration position is the same as the distance between the third calibration position and the fourth calibration position.
Optionally, the angle between the calibration coordinate system of the calibration device and the base coordinate system of the robot is approximately 0 °.
In another aspect of the present invention, there is provided a robot joint angle zero calibration method using the robot joint angle zero calibration system as described above, the method including:
acquiring four groups of robot joint angular velocities acquired by the first calibration sensor and the second calibration sensor when the end effector is at the third calibration position and the fourth calibration position and the emitted laser irradiates the first calibration position and the second calibration position;
and calibrating the zero offset value of the joint angles of the robot according to the angular speeds of the four groups of robot joints.
Optionally, the calibrating the zero offset value of the robot joint angle according to the angular speeds of the four groups of robot joints includes:
the system is used for calculating the pose states of 4 groups of end effectors according to the positive kinematic formula of the industrial robot and the angular velocities of the four groups of robot joints;
obtaining linear equations of the end effector at corresponding calibration positions according to the pose state of the end effector, and calculating 4 intersection points formed by four groups of linear equationsP1、P2、P3And P4；
And searching a target robot joint angle which enables the mean square error of the mean values of the 4 intersection points and the intersection points to be minimum according to a point constraint principle, and calibrating the zero offset value of the robot joint angle according to the target robot joint angle.
Furthermore, the invention also provides a computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method as described above.
The robot joint angle zero-position calibration system, method and storage medium provided by the embodiment of the invention solve the problems of complexity, time consumption and low accuracy of the existing industrial robot zero-position calibration algorithm, provide a robot joint angle zero-position calibration system based on visual servo structure assistance, and design a robot joint angle zero-position calibration method based on point constraint, so that the calibration of the industrial robot joint angle can be quickly, automatically and accurately realized.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 is a schematic structural diagram of a zero calibration system for a joint angle of a robot according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an end effector in the zero calibration system for joint angles of a robot according to the embodiment of the present invention;
fig. 3 is a schematic structural diagram of a calibration device in a robot joint angle zero position calibration system according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a controller in the robot joint angle zero position calibration system according to the embodiment of the present invention;
FIG. 5 is a schematic diagram of an implementation of a zero calibration system for a joint angle of a robot according to an embodiment of the present invention;
fig. 6 is a schematic flow chart of a robot joint angle zero position calibration method provided in the embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Fig. 1 schematically shows a structural schematic diagram of a robot joint angle zero calibration system according to an embodiment of the present invention. Referring to fig. 1, the zero calibration system for the joint angle of the robot according to the embodiment of the present invention specifically includes an end effector 10 installed on a robot main body, a calibration device 20 disposed in a robot working space, and a controller (not shown in the figure).
As shown in fig. 2, the end effector 10 includes a plane 101, a laser 102 fixed on the plane 101, and a visual servo structure of the laser, where the visual servo structure includes a binocular visual servo structure composed of cameras 103 and 104 disposed on two sides of the laser 102.
As shown in fig. 3, the calibration device 20 includes a fixing device 201, and a first calibration sensor 202 and a second calibration sensor 203 mounted on the fixing device, and during calibration, laser emitted by the laser 102 irradiates the center of the first calibration sensor 202 and is reflected to the center of the second calibration sensor 203 by the first calibration sensor 202.
In the zero calibration system for the joint angle of the robot provided by the embodiment of the invention, the positions of the first calibration sensor 202 and the second calibration sensor 203 enable the angle between the calibration coordinate system of the calibration device 20 and the base coordinate system of the robot to be approximately 0 degree, and by utilizing the double cameras fixed near the laser pointer on the end execution device 10 of the industrial robot, the laser beam can be irradiated on the center of the first calibration sensor 202 and reflected to the center of the second calibration sensor 202 through the visual servo function, so that the center calibration of the position sensor of the laser beam 102 is realized.
As shown in fig. 4, the controller includes a data acquisition module 301 and a calibration module 302, where the data acquisition module 301 is configured to acquire the angular velocities of the robot joints acquired by the first calibration sensor 202 and the second calibration sensor 203, and the calibration module 302 is configured to calibrate the zero offset value of the robot joint angle according to the angular velocities of the robot joints.
In this embodiment, the first calibration sensor 202 and the second calibration sensor 203 are located on different planes, and a preset angle is formed between the installation directions of the first calibration sensor and the second calibration sensor.
The robot joint angle zero-position calibration system provided by the embodiment of the invention solves the problems of complexity, time consumption and low accuracy of the existing industrial robot zero-position calibration algorithm, provides a robot joint angle zero-position calibration system based on the assistance of a visual servo structure, and can quickly, automatically and accurately realize the calibration of the industrial robot joint angle.
Fig. 5 is an implementation schematic diagram of a zero calibration system for a joint angle of a robot according to an embodiment of the present invention. As shown in fig. 5, in the embodiment of the present invention, a first calibration position a and a second calibration position B are disposed on a reflection optical path of the second calibration sensor 203, and a third calibration position C and a fourth calibration position D are disposed on an optical path from the laser 102 to a center position of the first calibration sensor 202. The distance between the first calibration position A and the second calibration position B is the same as the distance between the third calibration position C and the fourth calibration position D. When the first calibration position a, the second calibration position B, the third calibration position C and the fourth calibration position D are used for calibration, the laser on the end effector 10 is used for acquiring a preset position of calibration data, the laser on the end effector of the industrial robot is controlled to be at the position a, and the direction is adjusted, so that the laser irradiates the center of the a-position sensor and is reflected to the center of the C-position sensor, and 1 group of joint angles (6) of the industrial robot are obtained, and similarly, the positions 2 and 1, and the positions 3 and 4 are respectively on the same line and have the same distance, and therefore, when the laser is moved to the position B, C, D, 3 groups of joint angles can be obtained.
The data acquisition module 301 is configured to acquire the angular velocities of the four groups of robot joints acquired by the first calibration sensor and the second calibration sensor when the end effector is at the third calibration position and the fourth calibration position, and the emitted laser irradiates the first calibration position and the second calibration position.
Further, the calibration module specifically includes a first calculating unit, a second calculating unit, and a searching unit, wherein:
the first calculation unit is used for calculating the pose states of the 4 groups of end effectors according to the angular velocities of the four groups of robot joints according to a positive kinematics formula of the industrial robot;
the second calculation unit is used for obtaining linear equations of the end effector at corresponding calibration positions according to the pose state of the end effector and calculating 4 intersection points P formed by four groups of linear equations1、P2、P3And P4；
And the searching unit is used for searching a target robot joint angle which enables the mean square error of the mean values of the 4 intersection points and the intersection points to be minimum according to a point constraint principle, and calibrating the zero offset value of the robot joint angle according to the target robot joint angle.
And calculating the positions and postures of the 4 groups of end effectors according to a positive kinematic formula of the industrial robot. Theoretically, the linear equations for the laser at position A, B are the same, and the linear equations for the laser at position C, D are the same. And 4 intersection points P1, P2, P3 and P4 formed by four groups of linear equations including positions A and C, positions A and D, positions B and C, positions B and D and the like are obtained.
Calculating the average number of coordinates of the four intersection points as P, wherein the four intersection points are the same point according to the point constraint principle, and obtaining:
fi＝Pi-Pi＝1，2，3，4
in the formula: f. ofiIs a zero offset value of 4 joint angles, PiIs the coordinate value of 4 intersection points, and P is the coordinate average value of 4 intersection points.
Using the principle of least squares, such thatiThe mean square error of the initial joint angle of the industrial robot is minimum, and a zero offset value △ q of the initial joint angle of the industrial robot is obtained through an Isqnolin search algorithm, so that the calibration work is completed.
Fig. 6 schematically shows a flowchart of a zero calibration method for a joint angle of a robot according to an embodiment of the present invention. The method is suitable for the robot joint angle zero position calibration system, and referring to fig. 6, the robot joint angle zero position calibration method provided by the embodiment of the invention specifically comprises the following steps:
and S11, acquiring the angular speeds of the four groups of robot joints acquired by the first calibration sensor and the second calibration sensor when the end effector is at the third calibration position and the fourth calibration position and the emitted laser irradiates the first calibration position and the second calibration position.
And S12, calibrating the zero offset value of the joint angles of the robot according to the angular speeds of the joints of the four groups of robots.
Further, the calibrating the zero offset value of the robot joint angle according to the angular speeds of the four groups of robot joints specifically includes the following steps that are not shown in the attached drawings:
s121, calculating the pose states of 4 groups of end effectors according to the angular velocities of the joints of the four groups of robots and a positive kinematics formula of the industrial robot;
s122, obtaining linear equations of the end effector at corresponding calibration positions according to the pose state of the end effector, and calculating 4 intersection points P formed by four groups of linear equations1、P2、P3And P4；
And S123, searching a target robot joint angle with the minimum mean square error of the mean values of the 4 intersection points and the intersection points according to a point constraint principle, and calibrating the zero offset value of the robot joint angle according to the target robot joint angle.
The calibration algorithm proposed by the present invention is specifically explained by the following specific embodiments.
Assumed coordinate system o2In the middle, the angular velocity of the joint is
Figure BDA0002281458980000081
The pose velocity of the end effector is
Figure BDA0002281458980000082
It can be found that:
Figure BDA0002281458980000083
in the formula: j. the design is a squarer(q) is a basic coordinate system o2A Jacobian matrix of the joint angle of the medium industrial robot and the pose of the end effector;
Figure BDA0002281458980000084
angular velocity of 6 joint angles;
Figure BDA0002281458980000085
the pose velocity of the end effector.
At the position sensor o1In a coordinate system, the pose speed of an end effector of the industrial robot is
Figure BDA0002281458980000086
Laser beam is centered between two position sensorsHas a position coordinate of
Figure BDA0002281458980000087
The following can be obtained:
Figure BDA0002281458980000088
in the formula: y ispAs a coordinate system o1A middle end effector position coordinate; j. the design is a squarep(Yp) The position matrix is a Jacobian matrix of the positions of an end effector and a laser point of the industrial robot in a position sensor coordinate system;
Figure BDA0002281458980000089
the pose velocity of the industrial robot end effector;
Figure BDA00022814589800000810
the actual position coordinates of the laser beam at the center of the two position sensors.
Let the industrial robot have a basic coordinate system o2And a position sensor coordinate system o1Is T, then:
Figure BDA00022814589800000811
the following can be obtained:
Figure BDA00022814589800000812
Yp＝f(Yb，T) (5)
in the formula: a (T) coordinate system o2Relative to a coordinate system o1A homogeneous transformation matrix of; r is a rotation transformation matrix; s is a translation vector; y isbAs a coordinate system o2The middle end effector position coordinates.
The complete system model can be obtained from the equations (1) to (5).
Figure BDA0002281458980000091
The first step of the calibration system of an industrial robot based on point constraint must be laser calibrated, given the ideal position of the laser point on 2 PSDs (PSD center point) as follows:
Figure BDA0002281458980000092
in the formula:
Figure BDA0002281458980000093
a transposed matrix of ideal coordinate values of the laser spot at the centers of the two position sensors,
Figure BDA0002281458980000094
and
Figure BDA0002281458980000095
respectively, the horizontal and vertical coordinate values of the centers of the two position sensors.
It can be deduced that:
Figure BDA0002281458980000096
in the formula: k is a gain coefficient, and k is a gain coefficient,
Figure BDA0002281458980000097
actual transformation matrix, u, of ideal coordinate values of the laser spot at the centers of the two position sensorspIs a prediction matrix of ideal coordinate values, Jp[f(Yb，T)]]As a coordinate system o2Jacobian matrix of mid-end-effector position coordinates, { Jp[f(Yb，T)](T)Jr(q)}-1]Is the inverse matrix of the joint angular velocity.
Since the transformation matrix T is unknown, the prediction transformation matrix is assumed to be
Figure BDA0002281458980000098
For any one vector e, if the vector is
Figure BDA0002281458980000099
Element sign and vector of (1) { J }p[f(Yb，T)]A(T)Jr(q)]-1e element symbols in the matrix are kept consistent, and the matrix is estimated
Figure BDA00022814589800000910
Can make upTo achieve
Figure BDA00022814589800000911
This allows the laser beam to be rapidly directed at the 1 st PSD center and reflected to the other 1 PSD center, thereby obtaining 4 positions q1，q2，q3，q4(joint angles of 4 position industrial robots are indicated, respectively).
Let the zero offset value of the joint angle of the industrial robot be delta qjWhen j is 1,2,3,4, then Δ qiThe actual joint angle is qi+ΔqjAccording to the D-H parameters (D-H parameter method) of the industrial robot, the pose state of the industrial robot end effector under 4 groups of joint angles can be calculated, and corresponding linear equations are obtained according to the pose state, so that corresponding intersection points are obtained.
The positions A, B and C, D combine two by two to form 4 intersections P1、P2、P3And P4. And (3) calculating the coordinate mean P of the 4 intersection points, wherein the 4 intersection points are the same point according to the point constraint principle, so that the equation is obtained:
fj＝Pj-P (9)
in the formula: f. ofiIs a zero offset value of 4 joint angles, PiIs the coordinate value of 4 intersections, and P is the coordinate mean of 4 intersections.
And (3) the least square principle is applied to minimize the mean square error of the function f, and the Isqnolin method is applied to search so as to obtain delta q, and finally the joint angle zero offset value of the industrial robot is obtained to finish the calibration work.
The invention provides and designs an industrial robot joint angle calibration algorithm and device system based on point constraint, which can realize quick and accurate calibration of the zero offset value of the industrial robot joint angle.
Furthermore, an embodiment of the present invention also provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor implements the steps of the method as described above.
In this embodiment, the module/unit integrated with the zero calibration system for joint angles of the robot may be stored in a computer readable storage medium if it is implemented in the form of a software functional unit and sold or used as an independent product. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.
The robot joint angle zero-position calibration system, method and storage medium provided by the embodiment of the invention solve the problems of complexity, time consumption and low accuracy of the existing industrial robot zero-position calibration algorithm, provide a robot joint angle zero-position calibration system based on visual servo structure assistance, and design a robot joint angle zero-position calibration method based on point constraint, so that the calibration of the industrial robot joint angle can be quickly, automatically and accurately realized.
Those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than others, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A robot joint angle zero calibration system, characterized in that, the system includes:
the tail end executing device is arranged on the robot main body and comprises a plane, a laser fixed on the plane and a visual servo structure of the laser;
the calibration device arranged in the working space of the robot comprises a fixing device, a first calibration sensor and a second calibration sensor, wherein the first calibration sensor and the second calibration sensor are arranged on the fixing device;
the controller comprises a data acquisition module and a calibration module, the data acquisition module is used for acquiring the angular speed of the robot joint acquired by the first calibration sensor and the second calibration sensor, and the calibration module is used for calibrating the zero offset value of the robot joint angle according to the angular speed of the robot joint.
2. The system of claim 1, wherein the visual servomechanism comprises a binocular visual servomechanism consisting of cameras disposed on either side of the laser.
3. The system of claim 1, wherein the first calibration sensor and the second calibration sensor are located in different planes and have a predetermined angle between their installation directions.
4. The system of claim 1, wherein a first calibration position and a second calibration position are provided on a reflected light path of the second calibration sensor, and a third calibration position and a fourth calibration position are provided on a light path from the laser to a center position of the first calibration sensor;
the data acquisition module is used for respectively acquiring the angular speeds of the four groups of robot joints acquired by the first calibration sensor and the second calibration sensor when the tail end execution device is at the third calibration position and the fourth calibration position and the emitted laser irradiates the first calibration position and the second calibration position.
5. The system of claim 4, wherein the calibration module comprises:
the first calculation unit is used for calculating the pose states of the 4 groups of end effectors according to the angular velocities of the four groups of robot joints according to a positive kinematics formula of the industrial robot;
the second calculation unit is used for obtaining linear equations of the end effector at corresponding calibration positions according to the pose state of the end effector and calculating 4 intersection points P formed by four groups of linear equations1、P2、P3And P4；
And the searching unit is used for searching a target robot joint angle which enables the mean square error of the mean values of the 4 intersection points and the intersection points to be minimum according to a point constraint principle, and calibrating the zero offset value of the robot joint angle according to the target robot joint angle.
6. A system as set forth in claim 4 wherein the spacing between the first and second nominal positions is the same as the spacing between the third and fourth nominal positions.
7. A system according to claim 1, characterized in that the angle of the calibration coordinate system of the calibration device and the base coordinate system of the robot is approximately 0 °.
8. A robot joint angle zero calibration method using the robot joint angle zero calibration system according to any one of claims 1 to 7, the method comprising:
acquiring four groups of robot joint angular velocities acquired by the first calibration sensor and the second calibration sensor when the end effector is at the third calibration position and the fourth calibration position and the emitted laser irradiates the first calibration position and the second calibration position;
and calibrating the zero offset value of the joint angles of the robot according to the angular speeds of the four groups of robot joints.
9. The method of claim 8, wherein calibrating the zero offset value of the robot joint angle according to the angular velocities of the four sets of robot joints comprises:
the system is used for calculating the pose states of 4 groups of end effectors according to the positive kinematic formula of the industrial robot and the angular velocities of the four groups of robot joints;
obtaining linear equations of the end effector at corresponding calibration positions according to the pose state of the end effector, and calculating 4 intersection points P formed by four groups of linear equations1、P2、P3And P4；
And searching a target robot joint angle which enables the mean square error of the mean values of the 4 intersection points and the intersection points to be minimum according to a point constraint principle, and calibrating the zero offset value of the robot joint angle according to the target robot joint angle.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 8 to 9.
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