Industrial robot calibration device based on three-axis magnetic sensor and calibration method thereof

Abstract

The invention discloses an industrial robot calibration device based on a three-axis magnetic sensor and a calibration method thereof. The device comprises a calibration clamp, a calibration magnet, a calibration platform, a three-axis magnetic sensor module and an upper computer. The calibration magnet is used for providing a stable magnetic field for the three-axis magnetic sensor module; the three-axis magnetic sensor module is used for sensing the magnetic field intensity of the calibration magnet and transmitting the magnetic field intensity value to the upper computer; and the upper computer is used for displaying the magnetic field intensity value in real time, receiving multiple groups of six-axis rotation angle data from the industrial robot body, and substituting the multiple groups of six-axis rotation angle data into a kinematic model of the industrial robot body to carry out DH parameter solving so as to complete DH parameter calibration. According to the scheme, the accuracy and consistency of calibration are guaranteed, non-contact calibration is adopted, and abrasion caused by inherent rigid contact of a contact calibration method is avoided.

Description

Technical Field

[0001] The invention belongs to the field of industrial robots, and in particular relates to an industrial robot calibration device based on a three-axis magnetic sensor and a calibration method thereof. Background Art

[0002] With the widespread application of industrial robots in manufacturing, logistics, medical and other fields, the requirements for their accuracy are also increasing. High-precision positioning and operation capabilities are the key to ensuring that robots can complete tasks efficiently. However, various factors such as mechanical manufacturing errors, assembly errors and environment will cause certain positioning deviations in industrial robots during actual operation. These errors not only affect the working efficiency of the robot, but may also lead to reduced product quality and safety hazards. Therefore, in order to ensure that industrial robots can meet the expected performance standards before being put into use, it is particularly important to perform accuracy calibration before leaving the factory.

[0003] The current precision calibration methods are mainly divided into two types: non-contact and contact. Although non-contact calibration methods, such as laser tracker calibration, can effectively improve the calibration accuracy, their equipment costs are relatively high, making them impractical in some application scenarios with limited budgets.

[0004] In terms of contact calibration, Chinese invention patent applications with publication numbers CN113146613A and CN118305794A both proposed contact calibration devices and methods based on grating rulers. Although these two methods can provide relatively accurate calibration results, their calibration tooling design is relatively complex, which is not only difficult to process, but also has a high overall cost. In addition, contact measurement also has the risk of test tool wear, which may cause mechanical parts to be damaged during long-term use, thereby affecting the calibration accuracy. In addition, the Luoshi robot uses a method of allowing the end of the robotic arm to touch a fixed tip in different postures for parameter calibration. However, this method relies on the operator to use the naked eye to judge whether the end of the robot is in the same fixed position. This judgment method is highly subjective and it is difficult to ensure the accuracy and consistency of the calibration. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide an industrial robot calibration device and a calibration method based on a three-axis magnetic sensor, which ensures the accuracy and consistency of the calibration, and adopts non-contact calibration to avoid the wear caused by the rigid contact inherent in the contact calibration method.

[0006] Technical solution: The present invention is an industrial robot calibration device based on a three-axis magnetic sensor, comprising a calibration fixture installed at the end of the industrial robot body, a calibration magnet clamped by the calibration fixture, a calibration platform placed below the calibration magnet, a three-axis magnetic sensor fixedly arranged on the upper surface of the calibration platform for sensing the magnetic field strength of the calibration magnet, and a host computer connected to the three-axis magnetic sensor; the host computer is also connected to the industrial robot body;

[0007] The calibration magnet is used to provide a stable magnetic field for the three-axis magnetic sensor;

[0008] The three-axis magnetic sensor is used to sense the magnetic field strength of the calibration magnet and transmit the magnetic field strength value to the host computer;

[0009] The host computer is used to display the magnetic field strength value in real time, and receive multiple sets of six-axis rotation angle data from the industrial robot body, bring the multiple sets of six-axis rotation angle data into the kinematic model of the industrial robot body to solve the DH parameters, and complete the DH parameter calibration.

[0010] Furthermore, the three-axis magnetic sensor is connected to a host computer via a sensor data line, and the host computer is connected to the industrial robot body via a body data line.

[0011] Furthermore, the calibration fixture is a mechanical fixed fixture or a pneumatic fixture.

[0012] Furthermore, the calibration magnet is selected from a calibration magnet with a magnetic needle shape, a spindle shape, a slender cylinder or a slender rectangular parallelepiped structure.

[0013] Furthermore, the magnetic sensor used by the three-axis magnetic sensor is a HALL, AMR or TMR magnetic sensor.

[0014] Based on the same inventive concept, an industrial robot calibration method based on a three-axis magnetic sensor of the present invention is applied to the above-mentioned industrial robot calibration device based on a three-axis magnetic sensor, comprising:

[0015] Assemble an industrial robot calibration device based on a three-axis magnetic sensor;

[0016] The axes of the industrial robot body start to move, and the calibration magnet is moved to 2 to 5 mm above the three-axis magnetic sensor. The three-axis magnetic sensor detects the magnetic field strength of the calibration magnet and transmits it to the host computer. The magnetic field strength value displayed by the host computer at this time is recorded as the zero point, and the six-axis rotation angle of the industrial robot body at this time is read and recorded.

[0017] The host computer controls the industrial robot body to change its posture, and fine-tunes the position of the calibration magnet so that the three-axis magnetic field strength of the calibration magnet displayed by the host computer returns to zero, and reads and records the current six-axis rotation angle value of the industrial robot body again;

[0018] Repeat the previous step to obtain multiple sets of six-axis rotation angle values ​​of the industrial robot body;

[0019] The host computer brings the recorded six-axis rotation angle values ​​of multiple sets of industrial robot bodies into the kinematic model of the industrial robot body to solve the DH parameters and complete the DH parameter calibration.

[0020] Furthermore, the axes of the industrial robot body start to move, and the calibration magnet is moved to 2 to 5 mm above the three-axis magnetic sensor. The three-axis magnetic sensor detects the magnetic field strength of the calibration magnet and transmits it to the host computer. The magnetic field strength value displayed by the host computer at this time is recorded as the zero point, and the six-axis rotation angle of the industrial robot body at this time is read and recorded, including:

[0021] The axes of the industrial robot body start to move, so that the calibration magnet moves to 2 to 5 mm above the three-axis magnetic sensor. The three-axis magnetic sensor detects the magnetic field strength of the calibration magnet and transmits it to the host computer. The host computer displays the magnetic field strength value and records the currently displayed magnetic field strength value as the zero point. At this time, the position of the tip of the calibration magnet in the world coordinate system is recorded as point P w (x w ,y w ,z w ), read and record the six-axis rotation angle of the industrial robot body at this time Where i is the rotation axis number of the robot body.

[0022] Furthermore, the host computer controls the industrial robot body to change its posture, and fine-tunes the position of the calibration magnet so that the three-axis magnetic field strength of the calibration magnet displayed by the host computer returns to zero, and reads and records the current six-axis rotation angle value of the industrial robot body again, including:

[0023] The host computer controls the industrial robot to change its posture and fine-tune the position of the calibration magnet. When the three-axis magnetic field strength of the calibration magnet displayed by the host computer returns to zero, it is considered that the tip of the calibration magnet is still at point P. w (x w ,y w ,z w ) position, read and record the current six-axis rotation angle of the industrial robot body again

[0024]

[0025] Furthermore, the host computer brings the recorded six-axis rotation angle values ​​of the multiple sets of industrial robot bodies into the kinematic model of the industrial robot body to solve the DH parameters and complete the DH parameter calibration, including:

[0026] The DH model of the six-axis industrial robot has nine coordinate systems, namely the world coordinate system {w}, the base coordinate system {0}, the tool coordinate system {t} and the six-axis coordinate system {i}; the transformation between different coordinate systems is obtained by rotation and translation, so its homogeneous transformation matrix is:

[0027]

[0028] In the formula, r represents the relative rotation angle; Δ represents the relative displacement;

[0029] The DH parameters of each axis of the industrial robot body are i =(α i ,a i ,d i ,θ i ) into formula (1) to obtain the MDH homogeneous transformation matrix of the industrial robot:

[0030]

[0031] In the formula, α i ,a i ,d i ,θ represents the DH parameters of the robot body;

[0032] Since the base is fixed, the world coordinate system {w} is equivalent to the base coordinate system {0}; and since the calibration magnet is fixed on the calibration fixture, and the calibration fixture is fixed on the end flange of the industrial robot body, the coordinates of the tip of the calibration magnet in the sixth-axis coordinate system are expressed as P6 (x6, y6, z6). The coordinates P6 (x6, y6, z6) of the tip of the calibration magnet (2) in the sixth-axis coordinate system are converted to the representation in the world coordinate system {w}, that is, the representation in the base coordinate system {0} is:

[0033]

[0034] In the formula, there are 6 unknown quantities: x0, y0, z0, x6, y6, z6, a i-1 ,d i There are 12 unknown quantities in total, so at least 18 groups are required. The data can be solved to get the calibrated a i-1 ,d i value; to ensure calibration accuracy, n≥20 is usually taken.

[0035] Furthermore, an industrial robot calibration device based on a three-axis magnetic sensor is assembled, comprising:

[0036] Fasten the calibration fixture to the end of the industrial robot body and clamp the calibration magnet; fasten the three-axis magnetic sensor to the calibration platform, adjust the position and height of the calibration platform so that it is within the calibrable range of the industrial robot body; connect the host computer to the three-axis magnetic sensor, and connect the host computer to the industrial robot body to be calibrated.

[0037] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows:

[0038] The present invention has no strict shape restrictions on the calibration fixture and the calibration magnet, and standard parts can be used. The manufacturing and use costs are much lower than those of existing laser trackers and grating calibration equipment.

[0039] The present invention adopts a sensitive three-axis magnetic sensor to ensure that the ends of the calibration magnets in different robot arm postures are located at the same fixed position, eliminating the interference of subjective factors of the operator. Whether they are in the same position is given by a numerical value, ensuring the accuracy and consistency of the calibration.

[0040] The present invention adopts non-contact calibration, thereby avoiding the wear caused by rigid contact inherent in the contact calibration method. In addition, the absence of rigid contact also improves the operating efficiency of the calibration personnel.

[0041] The present invention completes the calibration of the calibration magnet and the calibration fixture while completing the DH parameter calibration, that is, the calibration result is independent of the installation accuracy of the calibration magnet and the calibration fixture, thus saving the preparation work before calibration.

[0042] The calibration device of the present invention is simple in design. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the structure of an industrial robot calibration device based on a three-axis magnetic sensor disclosed in an embodiment of the present invention;

[0044] Figure 2 The present invention discloses a method for calibrating an industrial robot based on a three-axis magnetic sensor. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is described in detail below in conjunction with specific implementation methods and the accompanying drawings of the specification.

[0046] Example 1

[0047] like Figure 1As shown, an industrial robot calibration device based on a three-axis magnetic sensor of the present invention comprises a calibration fixture 1, a calibration magnet 2, a calibration platform 3, a three-axis magnetic sensor 4, a sensor data line 5, a body data line 6 and a host computer 7. Among them, the calibration fixture 1 is installed at the end of the industrial robot body, the calibration magnet 2 is clamped by the calibration fixture 1, and the calibration platform 3 is placed below the calibration magnet 2. The three-axis magnetic sensor 4 is placed and fixed on the upper surface of the calibration platform 3, and is used to sense the magnetic field strength of the calibration magnet 2. The three-axis magnetic sensor 4 is connected to the host computer 7 through the sensor data line 5, and the host computer 7 is connected to the industrial robot body through the body data line 6. The calibration magnet 2 is used to provide a stable magnetic field for the three-axis magnetic sensor 4. The three-axis magnetic sensor 4 is used to sense the magnetic field strength of the calibration magnet 2, and transmit the magnetic field strength value to the host computer 7 through the sensor data line 5. The body data line 6 is used to transmit multiple groups of six-axis rotation angle data of the industrial robot body to the host computer 7. The host computer 7 is used to display the magnetic field strength value sensed by the three-axis magnetic sensor 4 in real time, and receive multiple sets of six-axis rotation angle data from the industrial robot body, bring the multiple sets of six-axis rotation angle data into the kinematic model of the industrial robot body to solve the DH parameters, and complete the DH parameter calibration.

[0048] The calibration fixture 1 may be a mechanical fixed fixture, a pneumatic fixture or other fixtures that will not generate a changing magnetic field sufficient to affect the measurement result; in this embodiment, a sliding guide three-jaw air gripper is used.

[0049] The cross section of the calibration magnet 2 facing the three-axis magnetic sensor 4 should be as small as possible, and a calibration magnet of a magnetic needle type, a spindle type, a slender cylinder or a slender rectangular parallelepiped structure can be selected. In this embodiment, the calibration magnet 2 is a neodymium iron boron magnet with a bottom diameter of 2 mm and a thickness of 20 mm;

[0050] The magnetic sensor used by the three-axis magnetic sensor 4 may be a HALL, AMR or TMR magnetic sensor. In this embodiment, the three-axis magnetic sensor 4 uses the LIS3MDL three-axis magnetometer of STMicroelectronics, which has a full scale of ±4 gauss and a resolution of 16 bits.

[0051] Example 2

[0052] like Figure 2 As shown, an industrial robot calibration method based on a three-axis magnetic sensor according to an embodiment of the present invention is applied to the industrial robot calibration device based on a three-axis magnetic sensor according to Embodiment 1. The calibration method includes:

[0053] S1. Assemble an industrial robot calibration device based on a three-axis magnetic sensor; the details are as follows:

[0054] Fasten the calibration fixture 1 to the end of the industrial robot body and clamp the calibration magnet 2; fasten the three-axis magnetic sensor 4 to the calibration platform 3, adjust the position and height of the calibration platform 3 so that it is within the calibrable range of the industrial robot body; connect the host computer 7 and the three-axis magnetic sensor 4 with the sensor data line 5; connect the host computer 7 and the industrial robot body to be calibrated with the body data line 6.

[0055] S2. The axes of the industrial robot body start to move, and the calibration magnet 2 is moved to 2 to 5 mm above the three-axis magnetic sensor 4. The three-axis magnetic sensor 4 detects the magnetic field strength of the calibration magnet 2 and transmits it to the host computer 7. The magnetic field strength value displayed by the host computer 7 at this time is recorded as the zero point, and the six-axis rotation angle of the industrial robot body at this time is read and recorded.

[0056] In this embodiment, the axes of the industrial robot body start to move, so that the calibration magnet 2 moves to 2 to 5 mm above the three-axis magnetic sensor 4. The three-axis magnetic sensor 4 detects the magnetic field strength of the calibration magnet 2 and transmits it to the host computer 7. The host computer 7 displays the magnetic field strength value and records the currently displayed magnetic field strength value as the zero point. At this time, the position of the tip of the calibration magnet 2 in the world coordinate system is recorded as point P w (x w ,y w ,z w ), and read and record the six-axis rotation angle of the industrial robot body at this time through the body data line 6 Where i is the rotation axis number of the robot body.

[0057] S3, the host computer 7 controls the industrial robot body to change its posture, and fine-tunes the position of the calibration magnet 2 so that the three-axis magnetic field strength of the calibration magnet 2 displayed by the host computer 7 returns to zero, and reads and records the current six-axis rotation angle value of the industrial robot body again.

[0058] In this embodiment, the host computer 7 controls the industrial robot body to change its posture and fine-tune the position of the calibration magnet 2. When the three-axis magnetic field strength of the calibration magnet 2 displayed by the host computer 7 returns to zero, it is considered that the tip of the calibration magnet 2 is still at point P. w (x w ,y w ,z w ) position, read and record the current six-axis rotation angle of the industrial robot body again

[0059] S4. Repeat the previous step to obtain multiple sets of six-axis rotation angle values ​​of the industrial robot body.

[0060] In this embodiment, step S3 is repeated to obtain multiple sets of six-axis rotation angle values ​​of the industrial robot body. Where n is the number of groups of recorded data.

[0061] S5. The host computer 7 brings the recorded multiple groups of six-axis rotation angle values ​​of the industrial robot body into the kinematic model of the industrial robot body to solve the DH parameters and complete the DH parameter calibration.

[0062] The host computer 7 records n groups The data is brought into the kinematic equation of the industrial robot to complete the DH parameter calibration. The specific steps are as follows:

[0063] S5.1. Generally, the DH model of a six-axis industrial robot has nine coordinate systems, namely the world coordinate system {w}, the base coordinate system {0}, the tool coordinate system {t} and the six-axis coordinate system {i}. The transformation between different coordinate systems can be obtained by rotation and translation, so its homogeneous transformation matrix is:

[0064]

[0065] Where r represents the relative rotation angle; Δ represents the relative displacement.

[0066] S5.2. Set the DH parameters of each axis of the industrial robot body to Φ i =(α i ,a i ,d i ,θ i ) into formula (1) to obtain the MDH homogeneous transformation matrix of the industrial robot:

[0067]

[0068] In the formula, α i ,a i ,d i ,θ represents the DH parameters of the robot body.

[0069] S5.3. Since the base is fixed, the world coordinate system {w} is equivalent to the base coordinate system {0}; and since the calibration magnet 2 is fixed on the calibration fixture 1, and the calibration fixture 1 is fixed on the end flange of the industrial robot body, the coordinates of the tip of the calibration magnet 2 in the sixth-axis coordinate system can be expressed as P6 (x6, y6, z6). The coordinates P6 (x6, y6, z6) of the tip of the calibration magnet 2 in the sixth-axis coordinate system are converted to the representation in the world coordinate system {w}, that is, the representation in the base coordinate system {0} is:

[0070]

[0071] In the formula, there are 6 unknown quantities: x0, y0, z0, x6, y6, z6, a i-1 ,d i There are 12 unknown quantities in total, so at least 18 groups are required. The data can be solved to get the calibrated a i-1 ,d i To ensure the calibration accuracy, generally, n≥20. In this embodiment, 20 sets of formula (3) are combined to obtain the calibrated a i ,d i value.

[0072] During calibration, the robot is operated to move the calibration magnet close to the three-axis magnetic sensor, and the three-axis magnetic field strength displayed by the host computer is set to zero, and the six-axis rotation angle data is recorded. The robot posture is changed multiple times, and multiple groups of six-axis rotation angle data are obtained under the condition that the three-axis magnetic field strength displayed by the host computer is zero. The data is brought into the kinematic model of the industrial robot to complete the calibration. The calibration method of the present invention has the advantages of low cost, convenient operation, and accurate calibration.

Claims

1. An industrial robot calibration device based on a three-axis magnetic sensor, characterized in that: The invention comprises a calibration fixture (1) installed at the end of an industrial robot body, a calibration magnet (2) clamped by the calibration fixture (1), a calibration platform (3) placed below the calibration magnet (2), a three-axis magnetic sensor (4) fixedly arranged on the upper surface of the calibration platform (3) for sensing the magnetic field strength of the calibration magnet (2), and a host computer (7) connected to the three-axis magnetic sensor (4); the host computer (7) is also connected to the industrial robot body; The calibration magnet (2) is used to provide a stable magnetic field for the three-axis magnetic sensor (4); The three-axis magnetic sensor (4) is used to sense the magnetic field strength of the calibration magnet (2) and transmit the magnetic field strength value to the host computer (7); The host computer (7) is used to display the magnetic field intensity value in real time, and receive multiple groups of six-axis rotation angle data from the industrial robot body, bring the multiple groups of six-axis rotation angle data into the kinematic model of the industrial robot body to solve the DH parameters, and complete the DH parameter calibration.

2. The industrial robot calibration device based on a three-axis magnetic sensor according to claim 1, characterized in that: The three-axis magnetic sensor (4) is connected to a host computer (7) via a sensor data line (5), and the host computer (7) is connected to an industrial robot body via a body data line (6).

3. The industrial robot calibration device based on a three-axis magnetic sensor according to claim 1, characterized in that: The calibration fixture (1) is a mechanical fixed fixture or a pneumatic fixture.

4. The industrial robot calibration device based on a three-axis magnetic sensor according to claim 1, characterized in that: The calibration magnet (2) is selected from a calibration magnet of a magnetic needle type, a spindle type, a slender cylindrical or slender rectangular parallelepiped structure.

5. The industrial robot calibration device based on a three-axis magnetic sensor according to claim 1, characterized in that: The magnetic sensor used by the three-axis magnetic sensor (4) is a HALL, AMR or TMR magnetic sensor.

6. A calibration method for an industrial robot based on a three-axis magnetic sensor, characterized in that: The calibration method is applied to the industrial robot calibration device based on the three-axis magnetic sensor according to any one of claims 1 to 5, comprising: Assemble an industrial robot calibration device based on a three-axis magnetic sensor; Each axis of the industrial robot body starts to move, and the calibration magnet (2) is moved to a position 2 to 5 mm above the three-axis magnetic sensor (4). The three-axis magnetic sensor (4) detects the magnetic field strength of the calibration magnet (2) and transmits it to the host computer (7). The magnetic field strength value displayed by the host computer (7) at this time is recorded as the zero point, and the six-axis rotation angle of the industrial robot body at this time is read and recorded. The host computer (7) controls the industrial robot body to change its posture, and fine-tunes the position of the calibration magnet (2) so that the three-axis magnetic field strength of the calibration magnet (2) displayed by the host computer (7) returns to zero, and reads and records the current six-axis rotation angle value of the industrial robot body again; Repeat the previous step to obtain multiple sets of six-axis rotation angle values ​​of the industrial robot body; The host computer (7) brings the recorded multiple groups of six-axis rotation angle values ​​of the industrial robot body into the kinematic model of the industrial robot body to solve the DH parameters and complete the DH parameter calibration.

7. The industrial robot calibration method based on a three-axis magnetic sensor according to claim 6, characterized in that: The motion of each axis of the industrial robot body is controlled, and the calibration magnet (2) is moved to a position 2 to 5 mm above the three-axis magnetic sensor (4). The three-axis magnetic sensor (4) detects the magnetic field strength of the calibration magnet (2) and transmits it to the host computer (7). The magnetic field strength value displayed by the host computer (7) at this time is recorded as the zero point. At the same time, the six-axis rotation angle of the industrial robot body at this time is read and recorded, including: The axes of the industrial robot body start to move, so that the calibration magnet (2) moves to 2 to 5 mm above the three-axis magnetic sensor (4). The three-axis magnetic sensor (4) detects the magnetic field strength of the calibration magnet (2) and transmits it to the host computer (7). The host computer (7) displays the magnetic field strength value and records the currently displayed magnetic field strength value as the zero point. At this time, the position of the tip of the calibration magnet (2) in the world coordinate system is recorded as point P. w (x w ,y w ,z w ), read and record the six-axis rotation angle of the industrial robot body at this time Where i is the rotation axis number of the robot body.

8. The industrial robot calibration method based on a three-axis magnetic sensor according to claim 6, characterized in that: The host computer (7) controls the industrial robot body to change its posture, and fine-tunes the position of the calibration magnet (2) so that the three-axis magnetic field strength of the calibration magnet (2) displayed by the host computer (7) returns to zero, and reads and records the current six-axis rotation angle value of the industrial robot body again, including: The upper computer (7) controls the industrial robot body to change its posture and fine-tune the position of the calibration magnet (2). When the three-axis magnetic field strength of the calibration magnet (2) displayed by the upper computer (7) returns to zero, it is considered that the tip of the calibration magnet (2) is still at point P. w (x w ,y w ,z w ) position, read and record the current six-axis rotation angle of the industrial robot body again 9. The industrial robot calibration method based on a three-axis magnetic sensor according to claim 6, characterized in that: The host computer (7) brings the recorded six-axis rotation angle values ​​of the multiple sets of industrial robot bodies into the kinematic model of the industrial robot body to solve the DH parameters and complete the DH parameter calibration, including: The DH model of the six-axis industrial robot has nine coordinate systems, namely the world coordinate system {w}, the base coordinate system {0}, the tool coordinate system {t} and the six-axis coordinate system {i}; the transformation between different coordinate systems is obtained by rotation and translation, so its homogeneous transformation matrix is: In the formula, r represents the relative rotation angle; Δ represents the relative displacement; The DH parameters of each axis of the industrial robot body are i =(α i ,a i ,d i ,θ i ) into formula (1) to obtain the MDH homogeneous transformation matrix of the industrial robot: In the formula, α i ,a i ,d i ,θ represents the DH parameters of the robot body; Since the base is fixed, the world coordinate system {w} is equivalent to the base coordinate system {0}; and since the calibration magnet (2) is fixed on the calibration fixture (1), and the calibration fixture (1) is fixed on the end flange of the industrial robot body, the coordinates of the tip of the calibration magnet (2) in the sixth-axis coordinate system are expressed as P6 (x6, y6, z6). The coordinates P6 (x6, y6, z6) of the tip of the calibration magnet (2) in the sixth-axis coordinate system are converted to the representation in the world coordinate system {w}, that is, the representation in the base coordinate system {0} is: In the formula, there are 6 unknown quantities: x0, y0, z0, x6, y6, z6, a i-1 d i There are 12 unknown quantities in total, so at least 18 groups are required. The data can be solved to get the calibrated a i-1 d i value; to ensure calibration accuracy, n≥20 is usually taken.

10. The industrial robot calibration method based on a three-axis magnetic sensor according to claim 6, characterized in that: Assemble an industrial robot calibration device based on a three-axis magnetic sensor, including: The calibration fixture (1) is fastened to the end of the industrial robot body and the calibration magnet (2) is clamped; the three-axis magnetic sensor (4) is fastened to the calibration platform (3), and the position and height of the calibration platform (3) are adjusted so that the calibration platform (3) is within the calibrable range of the industrial robot body; the host computer (7) is connected to the three-axis magnetic sensor (4), and the host computer (7) is connected to the industrial robot body to be calibrated.

Images