CN111267143A - Six-degree-of-freedom industrial series robot joint stiffness identification method and system - Google Patents

Abstract

The invention discloses a six-degree-of-freedom industrial series robot joint stiffness identification method and a six-degree-of-freedom industrial series robot joint stiffness identification system, wherein the method comprises the following steps: establishing a robot kinematics model of the industrial robot to be identified by adopting a DH parameter method so as to obtain a DH parameter of the robot kinematics model; based on DH parameters, deriving a robot jacobian matrix by using a differential transformation method, and establishing a robot static stiffness model by combining the robot jacobian matrix; designing a robot joint stiffness identification experiment based on a robot static stiffness model to obtain a plurality of groups of experimental data, wherein the plurality of groups of experimental data comprise to-be-processed experimental data and additional experimental data; and (4) processing the experimental data to be processed through MATLAB programming to obtain a robot joint stiffness matrix. The method reduces the operability of the identification process, improves the identification accuracy, and lays a foundation for searching the optimal rigidity pose of the robot and carrying out deformation compensation, flutter analysis and other researches on the robot.

Description

Method and system for joint stiffness identification of six-degree-of-freedom industrial tandem robot

technical field

The invention relates to the technical field of robots, in particular to a method and system for identifying the structural stiffness of a six-degree-of-freedom industrial serial robot, which is mainly applied to the field of structural analysis of industrial robots.

Background technique

At present, industrial robots are widely used in the field of industrial automation production and processing. However, for some high-precision applications, the current robots have low absolute positioning accuracy, and technical problems such as deformation of the robot end and flutter during operation. In order to analyze and solve these problems, it is necessary to analyze the structural stiffness of the robot first, and then propose a solution to the problem.

At present, the commonly used method to identify the stiffness of the robot joint is to analyze the stiffness of the internal structure of the robot joint such as the motor and the harmonic reducer and convert it into the stiffness of the robot joint. However, this kind of method has great difficulty in operability and accuracy. lower problem. Based on this, a general identification method of structural stiffness parameters of industrial robots is urgently needed to improve its accuracy and precision.

SUMMARY OF THE INVENTION

The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

Therefore, an object of the present invention is to propose a joint stiffness identification method for a six-degree-of-freedom industrial tandem robot, which reduces the operability of the identification process and improves the identification accuracy.

Another object of the present invention is to propose a joint stiffness identification system for a six-degree-of-freedom industrial serial robot.

In order to achieve the above object, an embodiment of the present invention proposes a method for identifying joint stiffness of a six-degree-of-freedom industrial tandem robot, which includes the following steps: using the DH parameter method to establish a robot kinematics model of an industrial robot to be identified, to obtain the robot kinematics model. DH parameters of the model; based on the DH parameters, use the differential transformation method to derive the robot Jacobi matrix, and combine the robot Jacobi matrix to establish a robot static stiffness model; based on the robot static stiffness model, the robot joint stiffness identification experiment is designed to obtain Multiple sets of experimental data, wherein the multiple sets of experimental data include to-be-processed experimental data and additional experimental data; the to-be-processed experimental data is processed through MATLAB programming to obtain a robot joint stiffness matrix.

The method for identifying the joint stiffness of a six-degree-of-freedom industrial tandem robot according to the embodiment of the present invention completes the acquisition and calculation of experimental data based on high-precision measuring equipment such as a laser tracker and a dynamometer, and can accurately identify the joint stiffness of the robot. It has high precision and lays a foundation for researches such as finding the optimal stiffness pose of the robot, and performing deformation compensation and flutter analysis on the robot.

In addition, the joint stiffness identification method for a six-degree-of-freedom industrial serial robot according to the above-mentioned embodiment of the present invention may also have the following additional technical features:

Further, in an embodiment of the present invention, based on the DH parameters, the robot Jacobian matrix is derived by using a differential transformation method, and a robot static stiffness model is established in combination with the robot Jacobian matrix, including: using a differential transformation method Combined with the calculation of the DH parameters, the positive solution of the robot kinematics of the industrial robot to be identified is obtained; the Jacobian matrix under different postures of the industrial robot to be identified is deduced according to the positive solution of the robot kinematics; combined with the Jacobian The matrix establishes the static stiffness model of the robot.

Further, in an embodiment of the present invention, the robot joint stiffness discrimination experiment is designed based on the robot static stiffness model, and multiple sets of experimental data are obtained, including: selecting a dynamometer and a laser tracker; The size of the instrument is used to design the tooling workpiece, and the layout of the field equipment is determined according to the industrial robot to be identified, the laser tracker and the dynamometer; based on the layout of the field equipment, the coordinate system of the dynamometer and the coordinate system of the laser tracker are calibrated The transformation relationship is a first transformation matrix, and the transformation relationship between the coordinate system of the calibration laser tracker and the base coordinate system of the industrial robot to be identified is a second transformation matrix; the end pose of the industrial robot to be identified is adjusted multiple times, and the dynamometer is recorded The six-dimensional force vector is measured and the coordinate value of the target ball is measured by the laser tracker.

Further, in an embodiment of the present invention, the processing of the experimental data to be processed through MATLAB programming to obtain a robot joint stiffness matrix includes, through the first transformation matrix, converting the six-dimensional force vector in the dynamometer coordinate system Convert the force vector data at the end flange of the industrial robot to be identified; convert the coordinate value of the target ball into the deformation data under the base coordinate system of the industrial robot to be identified through the second transformation matrix; convert the force vector data and the The deformation amount data is substituted into MATLAB for processing, and the stiffness matrix of the robot joint is obtained.

Further, in an embodiment of the present invention, the method further includes: checking the robot joint stiffness matrix by using the additional experimental data to determine whether the robot joint stiffness matrix is accurate.

In order to achieve the above object, another embodiment of the present invention proposes a six-degree-of-freedom industrial serial robot joint stiffness identification system, including: an acquisition module for establishing a robot kinematics model of the industrial robot to be identified by using the DH parameter method, so as to obtain all The DH parameters of the robot kinematics model; the differential transformation module is used to calculate and deduce the DH parameters to obtain the Jacobian matrix of the robot under different poses; the stiffness module: used to combine the robot Jacobian matrix to establish a robot A static stiffness model; a design module for designing a robot joint stiffness discrimination experiment based on the Jacobian matrix to obtain multiple sets of experimental data, wherein the multiple sets of experimental data include experimental data to be processed and additional experimental data; a processing module, used The robot joint stiffness matrix is obtained by processing the experimental data to be processed through MATLAB programming.

The six-degree-of-freedom industrial tandem robot joint stiffness identification system according to the embodiment of the present invention completes the acquisition and calculation of experimental data based on high-precision measurement equipment such as laser trackers and dynamometers, and can accurately identify the robot joint stiffness. The theoretical logic is rigorous and the identification is It has high precision and lays a foundation for researches such as finding the optimal stiffness pose of the robot, and performing deformation compensation and flutter analysis on the robot.

In addition, the joint stiffness identification system for a six-degree-of-freedom industrial serial robot according to the above-mentioned embodiment of the present invention may also have the following additional technical features:

Further, in an embodiment of the present invention, the differential transformation module includes: a differential transformation unit, configured to obtain a positive solution of robot kinematics of the industrial robot to be identified by combining the DH parameter calculation by a differential transformation method; deriving The unit is used for deriving Jacobian matrices under different postures of the industrial robot to be identified according to the positive solution of the robot kinematics.

Further, in an embodiment of the present invention, the design module includes: a selection unit for selecting a dynamometer and a laser tracker; a design unit for designing a tooling workpiece according to the size of the dynamometer, according to The industrial robot to be identified, the laser tracker and the dynamometer determine the layout of the field equipment; the calibration unit is used for calibrating the conversion relationship between the coordinate system of the dynamometer and the coordinate system of the laser tracker based on the layout of the field equipment: The first transformation matrix, the transformation relationship between the coordinate system of the calibration laser tracker and the base coordinate system of the industrial robot to be identified is the second transformation matrix; the recording unit is used to adjust the end pose of the industrial robot to be identified multiple times, and record the measured The force meter measures the six-dimensional force vector and the laser tracker measures the target ball coordinate value.

Further, in an embodiment of the present invention, the processing module includes: a first conversion unit, configured to convert the six-dimensional force vector in the dynamometer coordinate system into the end of the industrial robot to be identified through a first conversion matrix The force vector data at the flange; the second conversion unit is used to convert the coordinate value of the target ball into the deformation amount data in the base coordinate system of the industrial robot to be identified through the second conversion matrix; the processing unit is used to convert the force The vector data and the deformation data are substituted into MATLAB for processing to obtain the robot joint stiffness matrix.

Further, in an embodiment of the present invention, it further includes: a verification module, configured to perform verification on the robot joint stiffness matrix by using the additional experimental data, and determine whether the robot joint stiffness matrix is accurate.

Additional aspects and advantages of the present invention will be set forth, in part, from the following description, and in part will be apparent from the following description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

1 is a flowchart of a method for identifying joint stiffness of a six-degree-of-freedom industrial tandem robot according to an embodiment of the present invention;

2 is an experimental flowchart of a method for identifying joint stiffness of a six-degree-of-freedom industrial tandem robot according to a specific example of the present invention;

3 is a schematic diagram of a kinematics model of a robot at zero position according to a specific example of the present invention;

Fig. 4 is a schematic diagram of the layout of the experimental equipment according to a specific example of the present invention, wherein 1-robot body, 2-laser tracker target ball, 3-dynamometer, 4-end effector, 5-laser tracker;

5 is a comparison diagram of the predicted value and the actual value of the deformation of the middle robot end according to a specific example of the present invention;

FIG. 6 is a schematic structural diagram of a joint stiffness identification system for a six-degree-of-freedom industrial serial robot according to an embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention and should not be construed as limiting the present invention.

The method and system for identifying joint stiffness of a 6-DOF industrial tandem robot according to the embodiments of the present invention will be described below with reference to the accompanying drawings.

It should be noted that the method for identifying the joint stiffness of a six-degree-of-freedom industrial tandem robot proposed by the present invention adopts equipment: a robot, a robot end effector, a laser tracker, a workpiece and a dynamometer tooling.

FIG. 1 is a flowchart of a method for identifying joint stiffness of a six-degree-of-freedom industrial tandem robot according to an embodiment of the present invention.

As shown in Figure 1, the joint stiffness identification method of the six-degree-of-freedom industrial serial robot includes the following steps:

In step S1, the DH parameter method is used to establish the robot kinematic model of the industrial robot to be identified, so as to obtain the DH parameters of the robot kinematic model.

Specifically, it is first determined that the industrial robot to be identified needs to be identified, and the DH parameter method is used to establish the robot kinematics model according to the parameters of the industrial robot to be identified to obtain the DH parameters.

In step S2, based on the DH parameters, a differential transformation method is used to derive a robot Jacobian matrix, and a robot static stiffness model is established in combination with the robot Jacobian matrix.

Further, in an embodiment of the present invention, based on the DH parameters, a differential transformation method is used to derive a robot Jacobian matrix, and a robot static stiffness model is established in combination with the robot Jacobian matrix, including:

Through differential transformation method combined with DH parameter calculation, the positive solution of robot kinematics of the industrial robot to be identified is obtained;

According to the positive solution of robot kinematics, the Jacobian matrix under different postures of the industrial robot to be identified is derived.

That is to say, the positive solution of robot kinematics is derived by the differential transformation method, and the change of the joint angle of the industrial robot to be identified is linked with the change of the end pose of the industrial robot to be identified according to the positive solution of the robot kinematics, and the corresponding joint angle of the robot can be obtained. and Jacobian matrix J under the pose, based on the Jacobian matrix J of the robot, and according to Hooke's law F=KX, the static stiffness model of the robot is established.

Specifically, the differential transformation method is used to obtain the Jacobian matrix of the robot under different poses, the kinematics model of the robot is established according to the DH parameter method, the DH parameter table is listed, and the coordinate system is established at each joint of the robot, then each joint The transformation formula relative to the previous joint is:

Write it in another form:

Then the transformation matrix from each joint of the robot to the end of the robot is:

The elements of each column of the Jacobian matrix of the robot in the corresponding pose are:

Further, the Jacobian matrix under the corresponding pose of the robot can be obtained:

Based on the Jacobian matrix J of the robot, according to Hooke's law, the static stiffness model of the robot is established: F=(J ^-T K _θ J ^-1 )X.

The six-dimensional force vector of the robot end flange is F=[F ₁ F ₂ F ₃ F ₄ F ₅ F ₆ ] ^T , and the corresponding deformation at the center point of the robot end flange is X=[U ₁ U ₂ U ₃ UR ₁ UR ₂ UR ₃ ] ^T , K _x is the end operation stiffness matrix of the robot, then there is F=K _x X. The corresponding small deformation at the joint is Δθ=[δθ ₁ δθ ₂ δθ ₃ δθ ₄ δθ ₅ δθ ₆ ], and the force at the joint corresponding to the generalized force at the end of the robot is Γ=K _θ Δθ, where K _θ is The robot joint stiffness matrix, and the generalized force at the end and the joint force have a relationship Γ = J ^T F, the relationship between the joint deformation Δθ and the robot end deformation is X = JΔθ, and the robot static stiffness model F = (J ^-T K _θ J ^-1 ) X, further derivation can be

And the inverse matrix of K _θ is:

Rewrite the robot Jacobian as:

则由

可以写成：which order

then by

can be written as:

or

为关节柔度的

的变形形式。in,

for joint flexibility

deformed form.

Next, based on the above formula, in order to solve the robot joint stiffness K _θ , the six-dimensional force vector F on the end of the industrial robot to be identified and its end deformation X are measured experimentally, and a large amount of data is used to establish the equation system through the above formula, according to The least squares principle solves the equation system, converts the deformation data of the end of the industrial robot to be identified to the data in the base coordinate system of the industrial robot to be identified, and converts the six-dimensional force vector data measured by the dynamometer to the end flange of the industrial robot to be identified. At the center point, the robot joint flexibility value (ie the robot joint flexibility matrix) is obtained by MATLAB programming, and the robot joint stiffness value (ie the robot joint stiffness matrix) is obtained by further processing the robot joint flexibility value.

In step S3, a robot joint stiffness discrimination experiment is designed based on the Jacobian matrix, and multiple sets of experimental data are obtained, wherein the multiple sets of experimental data include experimental data to be processed and additional experimental data.

Further, in an embodiment of the present invention, a robot joint stiffness discrimination experiment is designed based on the Jacobian matrix, and multiple sets of experimental data are obtained, including:

Select dynamometer and laser tracker;

Design the tooling workpiece according to the size of the dynamometer, and determine the layout of the field equipment according to the industrial robot, laser tracker and dynamometer to be identified;

Based on the layout of the field equipment, the transformation relationship between the calibration dynamometer coordinate system and the laser tracker coordinate system is the first transformation matrix, and the transformation relationship between the calibration laser tracker coordinate system and the base coordinate system of the industrial robot to be identified is the second transformation matrix;

Adjust the end pose of the industrial robot to be identified many times, record the six-dimensional force vector measured by the dynamometer and the coordinate value of the target ball measured by the laser tracker.

Specifically, select the appropriate dynamometer model and laser tracker model, design the tooling workpiece according to the size parameters of the dynamometer, and determine the field equipment layout according to the industrial robot, end effector, laser tracker, dynamometer and other equipment to be identified. ;The workpiece is designed and processed strictly according to the size of the dynamometer and according to the preset level of accuracy. The laser tracker target ball positioning and installation holes are designed on the upper surface of the workpiece, and the installation is strictly coordinated with the dynamometer; the conversion between the workpiece coordinate system and the laser tracker coordinate system is completed. For the calibration of the relationship, place the target ball in different mounting holes of the workpiece and calculate the coordinates of the target ball in the dynamometer coordinate system according to the dimensional relationship, and read the coordinates of the target ball in the laser tracker coordinate system, which can be calculated and obtained. The transformation matrix of the dynamometer coordinate system and the laser tracker coordinate system can further obtain the first transformation matrix of the dynamometer coordinate system and the laser tracker coordinate system; Identify the flange at the end of the industrial robot, control the industrial robot to be identified to reach different points in space with different attitudes, and record the pose parameters of the industrial robot to be identified and the coordinates of the target ball read by the laser tracker. According to the point in different coordinate systems Calculate the coordinate value of the laser tracker to obtain the second transformation relationship matrix between the coordinate system of the laser tracker and the base coordinate system of the industrial robot to be identified; after obtaining the first transformation relationship matrix and the second transformation relationship matrix, keep the position of the laser tracker target ball, and control the Identify the industrial robot with different attitudes to make the end effector close to the surface of the workpiece, complete the stiffness identification experiment of the industrial robot to be identified according to the experimental design, and obtain multiple sets of force and deformation experimental data.

In step S4, the experimental data to be processed is processed by MATLAB programming, and the stiffness matrix of the robot joint is obtained.

Further, in an embodiment of the present invention, the experimental data to be processed is processed by MATLAB programming to obtain a robot joint stiffness matrix, including:

Through the first transformation matrix, the six-dimensional force vector of the dynamometer is converted into the force vector data at the end flange of the industrial robot to be identified;

Through the second transformation matrix, the coordinate value of the target ball is transformed into the deformation amount data in the base coordinate system of the industrial robot to be identified;

The force vector data and deformation data are substituted into MATLAB for processing, and the stiffness matrix of the robot joint is obtained.

That is to say, the six-dimensional force vector (that is, the experimental data to be processed) on the end effector of the industrial robot to be identified is measured by a dynamometer, and the deformation of the end of the industrial robot to be identified is obtained according to the coordinate change of the target ball measured by the laser tracker. (that is, the experimental data to be processed), and finally the data is unified into the base coordinate system of the industrial robot to be identified for processing, and the robot joint stiffness matrix is obtained by identification.

Further, in an embodiment of the present invention, the method further includes: using additional experimental data to check the robot joint stiffness matrix to determine whether the robot joint stiffness matrix is accurate.

As shown in FIG. 2 , the joint stiffness identification method for a six-degree-of-freedom industrial serial robot of the present invention will be further described below with reference to specific examples.

As shown in Figure 3, step 1: Select the industrial robot KUKA KR500L340 to be identified, use the DH parameter method to establish the kinematics model of the robot, and list the DH parameters of the robot;

Step 2: Differentiate the DH parameters, derive the Jacobian calculation formula J of the robot under different poses, and establish the robot stiffness model based on the robot Jacobian matrix.

As shown in Figure 4, step 3: Design the robot joint stiffness identification experiment, and select the layout of KUKA KR500 robot, end effector, API laser tracker, Kistler 9255C dynamometer and other tooling equipment. The specific operation steps of the robot joint stiffness identification experiment are as follows:

Step 301: Calibrate the transformation matrix between the coordinate system of the dynamometer and the coordinate system of the laser tracker. Design the mounting holes of the target ball of the laser tracker on the workpiece, calculate the coordinates of the target ball of the laser tracker in the dynamometer coordinate system according to the size relationship, and use the laser tracker to measure the coordinates of the target ball at different points of the workpiece. The coordinate values of a point in different coordinate systems are calculated to obtain the transformation matrix from the coordinate system of the dynamometer to the coordinate system of the laser tracker. In this embodiment, the conversion matrix obtained by solving is:

Step 302: Calibrate the transformation matrix between the laser tracker coordinate system and the robot base coordinate system. The calibration principle is to obtain the coordinates of the target ball in the robot base coordinate system and the coordinates in the laser tracker coordinate system at the same time. The transformation relationship between the robot base coordinate system and the laser tracker coordinate system is the relationship of rotation and translation, and the rotation matrix is recorded. is R, the translation matrix is T, the coordinate processing postscript of the target ball in the robot base coordinate system is ^B P=( ^B P _x ^B P _y ^B P _z 1), and the corresponding coordinate processing post-script ^M in the laser tracker coordinate system P=( ^M P _x ^M P _y ^M P _z 1), then there is ^B P=R ^M P+T, and the formula is written out in detail to get the following formula:

The coordinates of the n groups of target ball points in the laser tracker coordinate system and the coordinate data in the robot base coordinate system are measured experimentally, and the following formula is obtained by further processing with the above formula:

进一步处理即可得到激光跟踪仪坐标系向机器人基坐标系的转换矩阵

本实施例本步骤标定得到的激光跟踪仪坐标系向机器人基坐标系的转换矩阵为：Solve the above formula to get the deformed form of the transformation matrix of the two coordinate systems

After further processing, the transformation matrix from the laser tracker coordinate system to the robot base coordinate system can be obtained

The transformation matrix of the laser tracker coordinate system to the robot base coordinate system obtained by the calibration in this step of this embodiment is:

Step 303: Adjust the posture of the end of the robot, control the end effector to be close to the surface of the workpiece, adjust the presser foot mechanism of the end effector to make it stick to the surface of the workpiece, control the stroke of the presser foot to press the workpiece with different pressing forces, and record at this time The dynamometer measures the pressing force on the workpiece and the coordinates of the target ball measured by the laser tracker. Note that the Z force measured by the dynamometer increases from 0 to 1600N, and the laser tracker records the coordinates of the target ball during this process. , this is a set of data, adjust the robot end pose and repeat the above steps to obtain a total of 8 sets of data, and record the data. Among them, an additional set of experimental data is selected from the 8 sets of data for later verification.

Step 4: Data processing, convert the coordinate value of the target ball measured by the laser tracker into the value under the robot base coordinate through the calibrated laser tracker and the robot base coordinate system transformation matrix, and measure the six-dimensional force vector by the dynamometer Through the transformation matrix of the calibrated dynamometer coordinate system and the robot base coordinate system, the force vector data at the end flange of the robot is converted into the force vector data at the end of the robot. Finally, the seven groups of data are substituted into the stiffness calculation formula, and the KUKA KR500L340 robot in this embodiment is obtained through calculation. The joint stiffness matrix of is:

K _θ =diag(7.649×10 ⁹ 5.760×10 ⁹ 2.429×10 ¹⁰ 8.488×10 ⁹ 3.432×10 ⁹ 3.879×10 ⁹ ) is in N·mm/rad.

Step 5: Check the identified joint stiffness values. An additional set of experimental data is selected, and the Jacobian matrix under the pose is obtained by calculating the joint angle and pose parameters. Combined with the identified stiffness values of the robot joints, the operation stiffness matrix of the robot end under the pose is calculated. Through the experiment The six-dimensional force vector data of the dynamometer in the dynamometer is substituted into the calculation to obtain the deformation values of the robot end along the three directions of the base coordinate system, and the Z-direction force of the dynamometer is compared with the actual measured deformation values of the robot end in this set of experimental data. is the abscissa, the absolute value of the robot end deformation is the ordinate, and the fitting curve of its deformation relationship is established. Accuracy of stiffness values.

According to the joint stiffness identification method for a six-degree-of-freedom industrial tandem robot proposed in the embodiment of the present invention, the acquisition and calculation of experimental data are completed based on high-precision measurement equipment such as a laser tracker and a dynamometer, and the joint stiffness of the robot can be accurately identified, which is the most important method for analyzing the robot's joint stiffness. Provide basic data support for optimal stiffness pose and deformation compensation for robot joint angles.

Next, a joint stiffness identification system for a six-degree-of-freedom industrial serial robot proposed according to an embodiment of the present invention will be described with reference to the accompanying drawings.

6 is a schematic structural diagram of a joint stiffness identification system for a six-degree-of-freedom industrial serial robot according to an embodiment of the present invention.

As shown in FIG. 6 , the system 10 includes: an acquisition module 100 , a differential transformation module 200 , a stiffness module 300 , a design module 400 , a processing module 500 and a checking module 600 .

Wherein, the obtaining module 100 is used for establishing the robot kinematics model of the industrial robot to be identified by using the DH parameter method, so as to obtain the DH parameters of the robot kinematics model. The differential transformation module 200 is used for calculating and deriving the DH parameters to obtain the Jacobian matrix of the robot under different poses. The stiffness module 300 is used to establish a static stiffness model of the robot in combination with the robot Jacobian matrix. The design module 400 is used to design a robot joint stiffness discrimination experiment based on the Jacobian matrix, and obtain multiple sets of experimental data, wherein the multiple sets of experimental data include experimental data to be processed and additional experimental data. The processing module 500 is used to process the experimental data to be processed through MATLAB programming to obtain the robot joint stiffness matrix. The verification module 600 is configured to perform verification on the robot joint stiffness matrix using additional experimental data to determine whether the robot joint stiffness matrix is accurate.

Further, in an embodiment of the present invention, the differential transformation module 200 includes: a differential transformation unit 201 for obtaining the positive robot kinematics solution of the industrial robot to be identified by combining the differential transformation method with DH parameter calculation; the derivation unit 202 for The positive solution of robot kinematics deduces the Jacobian matrix under different poses of the industrial robot to be identified.

Further, in an embodiment of the present invention, the design module 400 includes: a selection unit 401 for selecting a dynamometer and a laser tracker; a design unit 402 for designing a tooling workpiece according to the size of the dynamometer, according to the industry to be identified The robot, the laser tracker and the dynamometer determine the layout of the field equipment; the calibration unit 403 is used for calibrating the conversion relationship between the coordinate system of the dynamometer and the coordinate system of the laser tracker as a first transformation matrix based on the layout of the field equipment, and calibrating the coordinate system of the laser tracker The transformation relationship with the base coordinate system of the industrial robot to be identified is the second transformation matrix; the recording unit 404 is used to adjust the terminal posture of the industrial robot to be identified multiple times, and to record the six-dimensional force vector measured by the dynamometer and the target measured by the laser tracker. spherical coordinate value.

Further, in an embodiment of the present invention, the processing module 500 includes: a first conversion unit 501 configured to convert the six-dimensional force vector of the dynamometer into the force at the end flange of the industrial robot to be identified through a first conversion matrix vector data; the second conversion unit 502 is used to convert the coordinate value of the target ball into the deformation data under the base coordinate system of the industrial robot to be identified through the second conversion matrix; the processing unit 503 is used to substitute the force vector data and deformation data into MATLAB is used for processing to obtain the robot joint stiffness matrix.

According to the six-degree-of-freedom industrial tandem robot joint stiffness identification system proposed in the embodiment of the present invention, the experimental data acquisition and calculation are completed based on high-precision measurement equipment such as laser trackers and dynamometers, and the robot joint stiffness can be accurately identified. Provide basic data support for optimal stiffness pose and deformation compensation for robot joint angles.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

Although the embodiments of the present invention have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Claims (10)

1. a six-degree-of-freedom industrial serial robot joint stiffness identification method, is characterized in that, comprises the following steps: The DH parameter method is used to establish the robot kinematics model of the industrial robot to be identified, so as to obtain the DH parameters of the robot kinematics model; Based on the DH parameters, a differential transformation method is used to derive the robot Jacobian matrix, and a robot static stiffness model is established in combination with the robot Jacobian matrix; Designing a robot joint stiffness identification experiment based on the robot static stiffness model to obtain multiple sets of experimental data, wherein the multiple sets of experimental data include experimental data to be processed and additional experimental data; and The experimental data to be processed is processed by MATLAB programming, and the stiffness matrix of the robot joint is obtained. 2. The method for identifying joint stiffness of a six-degree-of-freedom industrial tandem robot according to claim 1, characterized in that, based on the DH parameter, the robot Jacobian matrix is deduced by using a differential transformation method, and combined with the robot Jacobian matrix Build the static stiffness model of the robot, including: The positive solution of the robot kinematics of the industrial robot to be identified is obtained through the differential transformation method combined with the calculation of the DH parameters; Deriving the Jacobian matrix under different postures of the industrial robot to be identified according to the positive solution of the robot kinematics; The robot static stiffness model is established in combination with the Jacobian matrix. 3. The method for identifying joint stiffness of a six-degree-of-freedom industrial tandem robot according to claim 1, wherein the robot joint stiffness identification experiment is designed based on the robot static stiffness model, and multiple groups of experimental data are obtained, comprising: Select dynamometer and laser tracker; Design the tooling workpiece according to the size of the dynamometer, and determine the layout of the field equipment according to the industrial robot to be identified, the laser tracker and the dynamometer; Based on the layout of the field equipment, the transformation relationship between the calibration dynamometer coordinate system and the laser tracker coordinate system is a first transformation matrix, and the transformation relationship between the calibration laser tracker coordinate system and the base coordinate system of the industrial robot to be identified is a second transformation matrix; Adjust the end pose of the industrial robot to be identified for many times, and record the six-dimensional force vector measured by the dynamometer and the coordinate value of the target ball measured by the laser tracker. 4. The method for identifying joint stiffness of a six-degree-of-freedom industrial tandem robot according to claim 1, wherein the described experimental data to be processed is processed by MATLAB programming to obtain a robot joint stiffness matrix, comprising: Through the first conversion matrix, the six-dimensional force vector in the dynamometer coordinate system is converted into the force vector data at the end flange of the industrial robot to be identified; Through the second transformation matrix, the coordinate value of the target ball is transformed into the deformation amount data in the base coordinate system of the industrial robot to be identified; Substitute the force vector data and the deformation amount data into MATLAB for processing to obtain the robot joint stiffness matrix. 5. The six-degree-of-freedom industrial tandem robot joint stiffness identification method according to claim 1, characterized in that, further comprising: The robot joint stiffness matrix is checked by using the additional experimental data to determine whether the robot joint stiffness matrix is accurate. 6. A six-degree-of-freedom industrial serial robot joint stiffness identification system, characterized in that, comprising: an acquisition module for establishing a robot kinematics model of the industrial robot to be identified by using the DH parameter method to obtain the DH parameters of the robot kinematics model; The differential transformation module is used to calculate and deduce the DH parameters to obtain the Jacobian matrix of the robot under different poses; a stiffness module, which is used to establish a static stiffness model of the robot in combination with the robot Jacobian matrix; a design module for designing a robot joint stiffness discrimination experiment based on the Jacobian matrix to obtain multiple sets of experimental data, wherein the multiple sets of experimental data include experimental data to be processed and additional experimental data; The processing module is used for processing the experimental data to be processed through MATLAB programming to obtain the robot joint stiffness matrix. 7. The six-degree-of-freedom industrial serial robot joint stiffness identification system according to claim 6, wherein the differential transformation module comprises: a differential transformation unit, used for calculating the DH parameter by the differential transformation method to obtain the positive solution of the robot kinematics of the industrial robot to be identified; A deriving unit, configured to deduce Jacobian matrices of the industrial robot to be identified under different postures according to the positive solution of the robot kinematics. 8. The joint stiffness identification system of a six-degree-of-freedom industrial serial robot according to claim 6, wherein the design module comprises: The selection unit is used to select the dynamometer and the laser tracker; a design unit, configured to design a tooling workpiece according to the size of the dynamometer, and determine the layout of field equipment according to the industrial robot to be identified, the laser tracker and the dynamometer; The calibration unit is used for calibrating the transformation relationship between the coordinate system of the dynamometer and the coordinate system of the laser tracker as a first transformation matrix based on the layout of the field equipment, and the transformation relationship between the coordinate system of the laser tracker and the base coordinate system of the industrial robot to be identified as the first transformation matrix. Two transformation matrices; The recording unit is used to adjust the terminal posture of the industrial robot to be identified for many times, and record the six-dimensional force vector measured by the dynamometer and the coordinate value of the target ball measured by the laser tracker. 9. The joint stiffness identification system of a six-degree-of-freedom industrial serial robot according to claim 6, wherein the processing module comprises: The first conversion unit is used to convert the six-dimensional force vector in the dynamometer coordinate system into the force vector data at the end flange of the industrial robot to be identified through the first conversion matrix; The second conversion unit is used to convert the coordinate value of the target ball into the deformation amount data in the base coordinate system of the industrial robot to be identified through the second conversion matrix; The processing unit is used for substituting the force vector data and the deformation amount data into MATLAB for processing to obtain the robot joint stiffness matrix. 10. The six-degree-of-freedom industrial serial robot joint stiffness identification system according to claim 6, characterized in that, further comprising: The verification module is configured to perform verification on the robot joint stiffness matrix by using the additional experimental data, and determine whether the robot joint stiffness matrix is accurate.

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