CN110421562B - Mechanical arm calibration system and calibration method based on four-eye stereoscopic vision - Google Patents
Mechanical arm calibration system and calibration method based on four-eye stereoscopic vision Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/02—Programme-controlled manipulators characterised by movement of the arms, e.g. cartesian coordinate type
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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
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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
- B25J9/1602—Programme controls characterised by the control system, structure, architecture
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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
- B25J9/1694—Programme controls characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
- B25J9/1697—Vision controlled systems
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Abstract
The invention discloses a four-eye stereoscopic vision-based mechanical arm calibration system, which comprises a mechanical arm, a control box, a computer, two binocular cameras, a calibration plate and a plurality of marking points, wherein the marking points are respectively fixed at the tail end of the mechanical arm and joints of the mechanical arm, the two binocular cameras are distributed in front of and at the sides of the mechanical arm, and the marking points are photographed in real time; the invention also discloses a mechanical arm calibration method based on four-eye stereoscopic vision, which comprises the following steps: solving a conversion matrix of the two coordinate systems; collecting first batch of data for calculation, and constructing an objective function; carrying out iterative optimization on the geometric parameters and the non-geometric parameters of the mechanical arm by adopting a least square algorithm; correcting the zero point of the mechanical arm and the conversion matrix, and completing the calibration of the geometric parameters of the mechanical arm by using the corrected D-H kinematic parameters; and verifying the calibration result. The invention has the beneficial effects of being capable of rapidly completing the geometric parameter calibration and zero correction of the mechanical arm.
Description
Technical Field
The invention relates to the field of mechanical arm control. More particularly, the invention relates to a four-eye stereoscopic vision-based mechanical arm calibration system and a calibration method.
Background
With the intelligent development of the mechanical arm technology, mechanical arm enterprises at home and abroad begin to pay attention to applications outside the industrial field, and the desktop mechanical arm industry has developed. The miniaturized desktop mechanical arm has the advantages of light weight, small volume, good operability, easy development and the like, avoids the heaviness and danger of a large-scale industrial mechanical arm, is successfully applied to the fields of medical treatment, education, food processing and the like at present, but the mechanical arm is mostly developed by foreign production, has very high price and is difficult to popularize and popularize. Although the domestic production consumer-grade desktop mechanical arm is low in price, the problems of low positioning precision, low calibration precision before delivery, no joint angle sensor, zero limiting function and the like exist frequently, the development and application range of the domestic production consumer-grade desktop mechanical arm are limited, and the domestic production consumer-grade desktop mechanical arm can be popularized and applied in all directions only by solving the key problem, so that the domestic production consumer-grade desktop mechanical arm can serve consumers better.
The measurement index of the mechanical arm positioning performance is generally divided into two main types of repeated positioning precision and absolute positioning precision, and researches find that the influence of the kinematic parameter error on the absolute positioning precision accounts for more than 90% of the total error. The mechanical arm kinematics parameter calibration is an effective way for improving the absolute positioning accuracy of the robot, and generally comprises 4 steps of modeling, data measurement, parameter identification and error compensation, wherein real pose data of the tail end of the mechanical arm are usually acquired by means of external advanced measuring equipment when the data measurement is carried out. Commonly used measuring equipment such as a three-coordinate measuring machine, a laser tracker, a motion capture system and the like is generally high in price and complex to operate.
The existing calibration method based on vision measurement, such as the robot kinematics calibration method based on vision measurement and distance error model provided by Chinese invention application CN 105773609A, establishes a complete error model, and performs simultaneous calibration on the hand-eye relation and the kinematics parameters, but has the biggest problem that the camera is fixed at the tail end of the mechanical arm for measurement, and more calculation cost is spent, so that the data acquisition process is more time-consuming.
The implementation method of the mechanical arm calibration and tracking system based on visual motion capture is as provided in the Chinese invention patent CN 102848389B: and setting a marking point on the mechanical arm, acquiring the space coordinates of the marking point by adopting a visual motion capturing system, and combining a driving command of the mechanical arm joint with position data of the mechanical arm joint captured in real time to finish the calibration of each joint. The method is an effective calibrating and tracking method, but because the method needs to calibrate each joint in turn, the calibrating process consumes more time, and the measuring equipment is expensive, the method is not beneficial to popularization and application in the calibration of the mechanical arm.
In view of the foregoing, there is still a need for a low-cost and complete calibration apparatus and method for a mechanical arm, so as to solve the problem of low positioning accuracy of a consumer-level desktop mechanical arm.
Disclosure of Invention
It is an object of the present invention to solve at least the above problems and to provide at least the advantages to be described later.
The invention also aims to provide a mechanical arm calibration system based on four-eye stereoscopic vision, and also provides a mechanical arm calibration method based on four-eye stereoscopic vision, which has the beneficial effects of being capable of quickly completing mechanical arm geometric parameter calibration and zero point correction.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a four-eye stereoscopic vision-based robot calibration system including a robot, a control box connected to the computer, the control box controlling movement of the robot, and further including:
the two binocular cameras are respectively distributed in front of and at the sides of the mechanical arm and are connected with the computer;
the calibration plate is used for calibrating the binocular camera and constructing a world coordinate system of the mechanical arm calibration system;
the marking points are respectively fixed at the tail end of the mechanical arm and each joint of the mechanical arm.
Preferably, the computer comprises a camera control module, a data processing module, a mechanical arm calibration module and a mechanical arm control module;
the camera control module is used for controlling synchronous shooting of two binocular cameras, calibrating the binocular cameras and setting a world coordinate system of a mechanical arm calibration system;
the data processing module is used for receiving the image data transmitted by the binocular camera, identifying and measuring the marking points on the mechanical arm through image data processing, and finally calculating the three-dimensional coordinates of the marking points at the tail end of the mechanical arm and the angles of all joints through conversion of a world coordinate system and the mechanical arm coordinate system;
the mechanical arm calibration module is used for calibrating kinematic parameters of the mechanical arm, sending the result to the mechanical arm control module and completing zero point correction;
the mechanical arm control module is used for carrying out path planning and motion control on the mechanical arm.
The mechanical arm calibration method based on four-eye stereoscopic vision comprises the following steps:
step 1, solving a conversion matrix between a world coordinate system of a mechanical arm calibration system and a mechanical arm coordinate system;
step 2, collecting first batch of data for processing and calculating, wherein the first batch of data comprises coordinate theoretical values and measured values of a plurality of points which are uniformly reached in space by the tail end of the mechanical arm in a mechanical arm coordinate system, and corresponding theoretical values and measured values of all joint angles of the mechanical arm;
step 3, constructing an objective function of the optimization problem according to the first batch of data, and performing iterative optimization on the geometrical parameters of the mechanical arm and non-geometrical parameters generated by a world coordinate system and a conversion matrix of the mechanical arm coordinate system by adopting a least square algorithm;
step 4, correcting the D-H kinematic parameters and the conversion matrix, and completing calibration of the mechanical arm geometric parameters and zero point correction by using the corrected D-H kinematic parameters;
and step 5, verifying the calibration result, and carrying out a test experiment by using the corrected D-H kinematic parameters and the conversion matrix to judge whether the distance error meets the requirement.
Preferably, the method for obtaining the transformation matrix in the step 1 is as follows: the tail end of the mechanical arm is driven to reach different positions in space, and a coordinate point set of the tail end of the mechanical arm under a world coordinate system and a mechanical arm coordinate system is collectedA rotation matrix R and a translation vector T are obtained through a matrix SVD method;
due to errors in the transformation matrix, the error of the rotation matrix R is noted Δr=rot (X, β 1 )rot(Y,β 2 )rot(Z,β 3 ) The error of the parallel vector T is noted Δt= [ T ] 1 ,t 2 ,t 3 ] T ，β＝[β 1 ,β 2 ,β 3 ]Beta represents the rotation deflection angle around each coordinate axis
Constructing a conversion matrix according to the rotation matrix R, the translation vector T, the error of the rotation matrix R and the error of the parallel vector TMarked as->
Preferably, the processing and calculating process of the theoretical value and the actual value of the end mark point of the mechanical arm in the step 2 is as follows;
the theoretical value calculating method comprises the following steps: constructing a homogeneous transformation matrix of the mechanical arm D-H kinematic parameters according to the first batch of data, wherein the homogeneous transformation matrix is as follows:
wherein the joint degrees of freedom i=1, 2, …, n, c=cos, s=sin, and the mechanical arm geometrical parameters comprise the joint rotation angle θ i Angle of torsion alpha i Length d of joint i And offset distance a i ；
The homogeneous pose matrix of the tail end of the mechanical arm relative to the coordinate system of the mechanical arm is obtained according to the homogeneous transformation matrix and the kinematic positive solution, and is:
from this, the theoretical three-dimensional coordinate of the arm end in the arm coordinate system is P r ＝[p x ,p y ,p z ] T The theoretical value of the coordinates of the marking point at the tail end of the mechanical arm is as follows: p (P) e ＝P r +Δt, the coordinate error between the actual end of the mechanical arm and the mark point is Δt= [dx,dy,dz] T ；
The actual value calculating method comprises the following steps: converting the coordinates of the marking points from a world coordinate system to a mechanical arm coordinate system to obtain the actual values of the coordinates of the marking points at the tail end of the mechanical arm:
in addition, the mechanical arm control module can calculate and obtain theoretical values of the angles of all joints through inverse solution of the mechanical arm; the actual value of each joint angle is calculated by the data processing module, specifically, the length of a straight line is obtained by two mark point coordinates of each joint which are fixed in a straight line, the included angle of two adjacent straight lines is obtained by calculation through trigonometric functions, sine and cosine theorem and the like, and the initial included angle in the zero point state is subtracted to obtain the actual joint angle.
Preferably, the objective function in step 3 isWhere j=1, 2, …, m represents the serial number of the first data acquisition sequence.
Preferably, the specific operation method of the step 3 is as follows: solving error delta theta of mechanical arm geometric parameters i 、Δα i 、Δa i 、Δd i And (3) carrying out iterative optimization on the non-geometric parameter errors delta T, delta R and delta T generated in the process of solving the conversion matrix from the world coordinate system to the mechanical arm coordinate system by adopting a least square method, and carrying out iterative optimization on the non-geometric parameter errors delta T, delta R and delta T by adopting the least square method.
Preferably, the calibration result in step 5 is verified as follows: calculating by using the homogeneous transformation matrix and the transformation matrix of the corrected D-H kinematic parameters, collecting second batch of data for testing experiments, and differencing the actual three-dimensional coordinates of the corresponding tail end marking points after the mechanical arm moves with theoretical values to obtain error vectorsThe absolute positioning error of the mechanical arm is represented by the Euclidean distance between two points in space>And judging whether the distance error meets the requirement, wherein the second batch of data comprises a theoretical coordinate value and a measured value of a plurality of points which are uniformly reached in the space at the tail end of the mechanical arm in a mechanical arm coordinate system, and a theoretical value and a measured value of the corresponding angles of all joints of the mechanical arm.
The invention at least comprises the following beneficial effects: the mechanical arm calibration system and the calibration method are low in cost, simple and convenient to operate, capable of rapidly completing mechanical arm geometric parameter calibration and zero point correction, and easy to popularize and apply in calibration of the desktop mechanical arm and the serial mechanical arm.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
FIG. 1 is a schematic structural diagram of a mechanical arm calibration system according to one embodiment of the present invention;
FIG. 2 is a schematic diagram of a computer module according to one embodiment of the present invention;
fig. 3 is a schematic flow chart of a calibration method of a mechanical arm according to one embodiment of the present invention.
Detailed Description
The present invention is described in further detail below with reference to the drawings and examples to enable those skilled in the art to practice the invention by referring to the description.
As shown in fig. 1-2, the invention provides a four-eye stereoscopic vision-based mechanical arm calibration system, which comprises a mechanical arm 1, a control box 2 and a computer 3, wherein the control box 2 is connected with the computer 3, and the control box 2 controls the movement of the mechanical arm 1 and further comprises:
the two binocular cameras 4 are respectively distributed in front of and at the sides of the mechanical arm 1, the binocular cameras 4 are connected with the computer 3, the binocular cameras 4 shoot the mechanical arm 1 in real time and transmit image data to the computer 3, and software in the computer 3 identifies mark points 5 on the shot mechanical arm 1;
the calibration plate is used for calibrating the binocular camera 4 and constructing a world coordinate system of a mechanical arm calibration system, the calibration plate used in the embodiment is a black-white checkerboard, the outline dimension is 297 x 210mm, the lattice dimension is 20 x 20mm, and the array is 12 x 9;
the two-dimensional robot arm comprises a plurality of marking points 5, wherein the marking points 5 are respectively fixed at the tail end of the robot arm 1 and joints of the robot arm, the marking points 5 are silver light-reflecting balls, the diameters of the balls are about 20mm, one marking point 5 is fixed at the tail end of the robot arm 1, the marking points 5 are respectively fixed on the side surfaces of 5 joint connecting rods along the central axis, the binocular camera 4 shoots the two-dimensional robot arm in real time, software in the computer 3 is convenient to identify the marking points 5 at the tail end and joints of the robot arm 1 after the binocular camera 4 shoots the robot arm 1 and uploads the robot arm 1 to the computer 3, and the angles at the joints of the robot arm 1 and the coordinate positions at the tail end of the robot arm 1 are convenient to obtain.
The computer 3 comprises a computer host, a display and control software running on the computer host, wherein the control software in the computer 3 comprises a camera control module, a data processing module, a mechanical arm calibration module and a mechanical arm control module;
the camera control module is used for controlling synchronous shooting of a plurality of binocular cameras 4, calibrating the binocular cameras 4 and setting a world coordinate system of a mechanical arm calibration system;
the data processing module is used for receiving the image data transmitted by the binocular camera 4, identifying and measuring the marking points 5 on the mechanical arm through image data processing, and finally calculating the three-dimensional coordinates of the marking points at the tail end of the mechanical arm 1 and the angles of all joints through conversion of a world coordinate system and the mechanical arm coordinate system;
the mechanical arm calibration module is used for calibrating kinematic parameters of the mechanical arm 1, sending the result to the mechanical arm control module and completing zero point correction;
the mechanical arm control module is used for carrying out path planning and motion control on the mechanical arm 1.
The embodiment of the invention also provides a mechanical arm calibration method based on four-eye stereoscopic vision, which comprises the following steps:
step 1, solving a world coordinate system of a mechanical arm calibration system and a conversion matrix of the mechanical arm coordinate system;
the method for obtaining the conversion matrix comprises the following steps: driving the tail end of the mechanical arm to reach different positions in space, at least more than 10 points, and collecting a coordinate point set of the tail end of the mechanical arm under a world coordinate system and a mechanical arm coordinate systemThe binocular camera 4 shoots the end mark point image in the moving process in real time and uploads the end mark point image to the data processing module of the computer 3 to obtain the three-dimensional coordinate of the tail end of the mechanical arm under the world coordinate system; the three-dimensional coordinates of the tail end marking point of the mechanical arm under the mechanical arm coordinate system are sent to a data processing module by a mechanical arm control module, and then a rotation matrix R and a translation vector T are obtained by a matrix SVD method;
due to errors in the transformation matrix, the error of the rotation matrix R is noted Δr=rot (X, β 1 )rot(Y,β 2 )rot(Z,β 3 ) The error of the parallel vector T is noted Δt= [ T ] 1 ,t 2 ,t 3 ] T ，β＝[β 1 ,β 2 ,β 3 ]Beta represents a rotation deflection angle around each coordinate axis;
constructing a conversion matrix according to the rotation matrix R, the translation vector T, the error of the rotation matrix R and the error of the parallel vector TMarked as->
Step 2, collecting first batch of data for processing calculation, wherein the first batch of data comprises coordinate theoretical values and measured values of a plurality of points which are uniformly reached by the tail end of the mechanical arm in space in a mechanical arm coordinate system, at least more than 70 points which are uniformly reached by the tail end of the mechanical arm in space, and theoretical values and measured values of corresponding joint angles of the mechanical arm;
in the data processing module, the theoretical value and the actual value of the marking point at the tail end of the mechanical arm are processed as follows;
the theoretical value calculating method comprises the following steps: constructing a homogeneous transformation matrix of the mechanical arm D-H kinematic parameters according to the first batch of data, wherein the homogeneous transformation matrix is as follows:
wherein the joint degrees of freedom i=1, 2, …, n, c=cos, s=sin, and the mechanical arm geometrical parameters comprise the joint rotation angle θ i Angle of torsion alpha i Length d of joint i And offset distance a i ；
And obtaining the homogeneous pose matrix of the tail end of the mechanical arm relative to the coordinate system of the mechanical arm through kinematic ortholysis according to the homogeneous transformation matrix, wherein the homogeneous pose matrix is as follows:
from this, the theoretical three-dimensional coordinate of the arm end in the arm coordinate system is P r ＝[p x ,p y ,p z ] T The theoretical value of the coordinates of the marking point at the tail end of the mechanical arm is as follows: p (P) e ＝P r +Δt, the coordinate error between the actual end of the mechanical arm and the mark point is Δt= [ dx, dy, dz] T ；
The actual value calculating method comprises the following steps: converting the coordinates of the marking points from a world coordinate system to a mechanical arm coordinate system to obtain the actual values of the coordinates of the marking points at the tail end of the mechanical arm:
in addition, the mechanical arm control module can calculate and obtain theoretical values of the angles of all joints through inverse solution of the mechanical arm; the actual value of each joint angle is calculated by the data processing module, specifically, the length of a straight line is obtained by two mark point coordinates of each joint which are fixed in a straight line, the included angle of two adjacent straight lines is obtained by calculation through trigonometric functions, sine and cosine theorem and the like, and the initial included angle in the zero point state is subtracted to obtain the actual joint angle.
Step 3, constructing an objective function of the optimization problem according to the first batch of data, and performing iterative optimization on the geometrical parameters of the mechanical arm and non-geometrical parameters generated by a world coordinate system and a conversion matrix of the mechanical arm coordinate system by adopting a least square algorithm;
inputting the first batch of data into a mechanical arm calibration module for parameter optimization calculation, wherein an objective function constructed according to the first batch of data is as followsWherein j=1, 2, …, m represents the serial number of the first batch of data acquisition sequence;
solving error delta theta of mechanical arm geometric parameters i 、Δα i 、Δa i 、Δd i Performing iterative optimization on the non-geometric parameter errors delta T, delta R and delta T generated in the process of solving the conversion matrix from the world coordinate system to the mechanical arm coordinate system by adopting a least square method, and performing iterative optimization on the non-geometric parameter errors delta T, delta R and delta T by adopting the least square method;
step 4, correcting the D-H kinematic parameters and the conversion matrix, calibrating the geometrical parameters of the mechanical arm by using the corrected D-H kinematic parameters, performing zero point correction, and using the mechanical arm control module to control the mechanical arm according to the optimized delta theta i (i=1, 2, …, 6) correcting the zero point of each joint of the mechanical arm, setting a new initial zero point position, calculating the theoretical pose of the tail end LED by using the optimized delta T, and correcting the coordinate system conversion matrix, wherein R '=R.delta R, T' =R.delta T+T;
step 5, verifying the calibration result, carrying out a test experiment by using the corrected D-H kinematic parameters and the conversion matrix, judging whether the error meets the requirement, if so, ending the calibration, otherwise, returning to the step 2, collecting new experimental data points, and carrying out calibration verification again;
the calibration result is verified as follows: calculating by using the homogeneous transformation matrix and the transformation matrix of the corrected D-H kinematic parameters, and collecting second batch of data for testingThe second batch of data is a theoretical coordinate value and a measured value of a plurality of points which are uniformly reached by the tail end of the mechanical arm in space in a mechanical arm coordinate system and a theoretical value and a measured value of each joint angle of the mechanical arm, at least selecting any 30 points which are reached by the tail end of the mechanical arm in space, and differentiating the actual three-dimensional coordinates of the corresponding tail end marking points after the mechanical arm moves from the theoretical values to obtain an error vectorThe absolute positioning error of the mechanical arm is represented by the Euclidean distance between two points in space>And judging whether the error meets the requirement.
Although embodiments of the present invention have been disclosed above, it is not limited to the details and embodiments shown and described, it is well within the ability of one skilled in the art to adapt the present invention to various modifications and other changes may be readily made therein without departing from the general concept defined by the appended claims and their equivalents.
Claims (1)
1. The mechanical arm calibration method based on the four-eye stereoscopic vision is applied to a mechanical arm calibration system based on the four-eye stereoscopic vision, and the system comprises the following steps: arm (1), control box (2), computer (3), control box (2) with computer (3) are connected, control box (2) control the motion of arm (1), still include:
the two binocular cameras (4) are respectively distributed in front of and at the side of the mechanical arm (1), and the binocular cameras (4) are connected with the computer (3);
the calibration plate is used for calibrating the binocular camera (4) and constructing a world coordinate system of the mechanical arm calibration system;
a plurality of marking points (5), wherein the marking points (5) are respectively fixed at the tail end of the mechanical arm (1) and each joint of the mechanical arm;
the computer (3) comprises a camera control module, a data processing module, a mechanical arm calibration module and a mechanical arm control module;
the camera control module is used for controlling synchronous shooting of two binocular cameras, calibrating the binocular cameras and setting a world coordinate system of a mechanical arm calibration system;
the data processing module is used for receiving the image data transmitted by the binocular camera, identifying and measuring the marking points on the mechanical arm through image data processing, and finally calculating the three-dimensional coordinates of the marking points at the tail end of the mechanical arm and the angles of all joints through conversion of a world coordinate system and the mechanical arm coordinate system;
the mechanical arm calibration module is used for calibrating kinematic parameters of the mechanical arm, sending the result to the mechanical arm control module and completing zero point correction;
the mechanical arm control module is used for carrying out path planning and motion control on the mechanical arm, and is characterized by comprising the following steps:
step 1, solving a conversion matrix between a world coordinate system of a mechanical arm calibration system and a mechanical arm coordinate system;
the method for obtaining the conversion matrix in the step 1 comprises the following steps: the tail end of the mechanical arm is driven to reach different positions in space, and a coordinate point set of the tail end of the mechanical arm under a world coordinate system and a mechanical arm coordinate system is collectedA rotation matrix R and a translation vector T are obtained through a matrix SVD method;
due to errors in the transformation matrix, the error of the rotation matrix R is noted Δr=rot (X, β 1 )rot(Y,β 2 )rot(Z,β 3 ) The error of the parallel vector T is noted Δt= [ T ] 1 ,t 2 ,t 3 ] T ，β＝[β 1 ,β 2 ,β 3 ]Beta represents a rotation deflection angle around each coordinate axis;
constructing a conversion moment according to the rotation matrix R, the translation vector T, the error of the rotation matrix R and the error of the parallel vector TArrayMarked as->
Step 2, collecting first batch of data for processing and calculating, wherein the first batch of data comprises coordinate theoretical values and measured values of a plurality of points which are uniformly reached in space by the tail end of the mechanical arm in a mechanical arm coordinate system, and corresponding theoretical values and measured values of all joint angles of the mechanical arm;
in the step 2, the processing and calculating process of the theoretical value and the actual value of the tail end marking point of the mechanical arm is as follows;
the theoretical value calculating method comprises the following steps: constructing a homogeneous transformation matrix of the mechanical arm D-H kinematic parameters according to the first batch of data, wherein the homogeneous transformation matrix is as follows:
wherein the joint degrees of freedom i=1, 2, l, n, c=cos, s=sin, and the mechanical arm geometrical parameters comprise the joint rotation angle θ i Angle of torsion alpha i Length d of joint i And offset distance a i ；
The homogeneous pose matrix of the tail end of the mechanical arm relative to the coordinate system of the mechanical arm is obtained according to the homogeneous transformation matrix and the kinematic positive solution, and is:
from this, the theoretical three-dimensional coordinate of the arm end in the arm coordinate system is P r ＝[p x ,p y ,p z ] T The theoretical value of the coordinates of the marking point at the tail end of the mechanical arm is as follows: p (P) e ＝P r +Δt, the coordinate error between the actual end of the mechanical arm and the mark point is Δt= [ dx, dy, dz]T；
The actual value calculating method comprises the following steps: converting the coordinates of the marking points from a world coordinate system to a mechanical arm coordinate system to obtain the actual values of the coordinates of the marking points at the tail end of the mechanical arm:
in addition, the mechanical arm control module can calculate and obtain theoretical values of the angles of all joints through inverse solution of the mechanical arm; calculating the actual value of each joint angle by a data processing module, specifically, obtaining the length of a straight line by two mark point coordinates of each joint which are fixed in a straight line, calculating the included angle of two adjacent straight lines by a trigonometric function, and subtracting the initial included angle of a zero point state to obtain the actual joint angle;
step 3, constructing an objective function of the optimization problem according to the first batch of data, and performing iterative optimization on the geometrical parameters of the mechanical arm and non-geometrical parameters generated by a world coordinate system and a conversion matrix of the mechanical arm coordinate system by adopting a least square algorithm;
the objective function in step 3 isWherein j=1, 2, l, m represent the serial numbers of the first batch of data acquisition sequences;
the specific operation method of the step 3 is as follows: solving error delta theta of mechanical arm geometric parameters i 、Δα i 、Δa i 、Δd i Carrying out iterative optimization on the non-geometric parameter errors delta T, delta R and delta T generated in the process of solving a conversion matrix from a world system coordinate system to a mechanical arm coordinate system by adopting a least square method, and carrying out iterative optimization on the non-geometric parameter errors delta T, delta R and delta T by adopting the least square method; step 4, correcting the D-H kinematic parameters and the conversion matrix, and completing calibration of the mechanical arm geometric parameters and zero point correction by using the corrected D-H kinematic parameters;
step 5, verifying the calibration result, and performing a test experiment by using the corrected D-H kinematic parameters and the conversion matrix to judge whether the distance error meets the requirement;
the calibration result verification method in the step 5 is as follows: using corrected D-H motionCalculating homogeneous transformation matrix and transformation matrix of the chemical parameters, collecting second batch of data for test experiment, and differentiating actual three-dimensional coordinates of the corresponding end mark point after the mechanical arm moves with theoretical values to obtain error vectorThe absolute positioning error of the mechanical arm is represented by the Euclidean distance between two points in space>And judging whether the distance error meets the requirement, wherein the second batch of data comprises a theoretical coordinate value and a measured value of a plurality of points which are uniformly reached in the space at the tail end of the mechanical arm in a mechanical arm coordinate system, and a theoretical value and a measured value of the corresponding angles of all joints of the mechanical arm.
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Families Citing this family (24)
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| CN115946123B (en) * | 2023-01-16 | 2023-10-31 | 佛山智能装备技术研究院 | Multi-tool center point and zero point calibration method for industrial robot |
| CN116061196B (en) * | 2023-04-06 | 2023-07-18 | 广东工业大学 | Method and system for calibrating kinematic parameters of multi-axis motion platform |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103991078A (en) * | 2013-02-14 | 2014-08-20 | 佳能株式会社 | Robot system and method for controlling the same |
| CN104942809A (en) * | 2015-06-23 | 2015-09-30 | 广东工业大学 | Mechanical arm dynamic fuzzy approximator based on visual servo system |
| CN206326604U (en) * | 2016-12-26 | 2017-07-14 | 东莞理工学院 | Robot motion's update the system based on computer vision |
| CN109227538A (en) * | 2018-07-13 | 2019-01-18 | 哈尔滨工业大学（深圳） | A kind of position control method and system of the flexible mechanical arm of view-based access control model |
| WO2019138111A1 (en) * | 2018-01-15 | 2019-07-18 | Technische Universität München | Vision-based sensor system and control method for robot arms |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9616573B2 (en) * | 2012-05-25 | 2017-04-11 | The Ritsumeikan Trust | Robot control apparatus, robot control method, program, recording medium and robot system |
-
2019
- 2019-07-24 CN CN201910672050.7A patent/CN110421562B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103991078A (en) * | 2013-02-14 | 2014-08-20 | 佳能株式会社 | Robot system and method for controlling the same |
| CN104942809A (en) * | 2015-06-23 | 2015-09-30 | 广东工业大学 | Mechanical arm dynamic fuzzy approximator based on visual servo system |
| CN206326604U (en) * | 2016-12-26 | 2017-07-14 | 东莞理工学院 | Robot motion's update the system based on computer vision |
| WO2019138111A1 (en) * | 2018-01-15 | 2019-07-18 | Technische Universität München | Vision-based sensor system and control method for robot arms |
| CN109227538A (en) * | 2018-07-13 | 2019-01-18 | 哈尔滨工业大学（深圳） | A kind of position control method and system of the flexible mechanical arm of view-based access control model |
Non-Patent Citations (1)
| Title |
|---|
| 许志杰.六自由度涂胶工业机器人的运动学仿真与标定算法研究.《中国优秀硕士学位论文全文数据库信息科技辑》.2015,第2-3章. * |
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