CN115816463A - Robot precision improving method and system based on joint full-closed-loop and rigid-flexible coupling model - Google Patents
Robot precision improving method and system based on joint full-closed-loop and rigid-flexible coupling model Download PDFInfo
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Abstract
The invention provides a robot precision improving method and system based on a joint full closed loop and rigid-flexible coupling model, which comprises the following steps: step1: installing a grating ruler and a reading head on each joint of the robot, and accessing a position signal of the reading head into a servo controller of each shaft motor to realize full closed-loop control of each joint shaft; step2: calibrating the positioning precision of each joint of the robot by using a laser interferometer; and step3: establishing a robot enhanced rigid-flexible coupling kinematics model; and 4, step4: calibrating parameters of the robot enhanced rigid-flexible coupling kinematics model by using a laser tracker; step (ii) of 5: and compensating the robot positioning by using the enhanced rigid-flexible coupling kinematic model. According to the invention, through the enhanced rigid-flexible coupling model and the compensation algorithm, the compensation of the gravity deformation and the geometric error of the connecting rod of the industrial robot is realized, and the spatial absolute positioning precision of the robot is greatly improved.
Description
Technical Field
The invention relates to the technical field of robots, in particular to a robot precision improving method and system based on a joint full closed loop and rigid-flexible coupling model.
Background
The industrial robot has better repeated positioning accuracy, but because each joint of the standard industrial robot adopts semi-closed loop control, and the rigidity of the joint and the connecting rod is poorer, the absolute positioning accuracy of the industrial robot is lower. In order to meet the requirement of aviation high-position precision hole making, the absolute positioning precision of the robot needs to be further improved.
Patent document CN107457785a (application number: cn201710881683.x) discloses a position compensation method of a robot based on robot joint feedback, and the method uses a device including an absolute grating ruler, an adapter and a computer. Absolute grating rulers are respectively installed on each joint shaft of the robot, reading signals of reading heads of the grating rulers are converted and connected to a computer through an adapter, the adapter is secondarily developed in an upper computer, feedback signals of a plurality of gratings are read at the same time, a rotation angle value of a joint is generated according to a calibrated model, and a space error is converted into a joint rotation angle error through an established space error estimation model and an error coupling model; in addition, a real-time interaction environment of the upper computer and the robot is established, and the rotation angle value of the robot joint is corrected to a target value through the PD control model, so that the position compensation of the robot is realized. However, the gravity deformation of the connecting rod of the robot is not compensated, the precision is improved to a limited extent, the upper computer and the robot are adopted for interactive control, and the compensation and positioning efficiency can be greatly influenced by communication delay.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a robot precision improving method and system based on a joint full closed loop and rigid-flexible coupling model.
The robot precision improving method based on the joint full closed loop and the rigid-flexible coupling model provided by the invention comprises the following steps:
step1: installing a grating ruler and a reading head on each joint of the robot, and accessing a position signal of the reading head into a servo controller of each shaft motor to realize full closed-loop control of each joint shaft;
step2: calibrating the positioning precision of each joint of the robot by using a laser interferometer;
and 3, step3: establishing a robot enhanced rigid-flexible coupling kinematics model;
and 4, step4: calibrating parameters of the robot enhanced rigid-flexible coupling kinematics model by using a laser tracker;
and 5: and compensating the robot positioning by using the enhanced rigid-flexible coupling kinematic model.
Preferably, the step3 comprises: under the action of an external force F, a moment M and self gravity mg, the deformation of a coordinate system { ei } at the tail end of the connecting rod is as follows:
wherein: x is a radical of a fluorine atom ei 、y ei 、z ei 、α ei 、β ei 、γ ei Is the deformation of the connecting rod under the stress of the coordinate system { ei }.
Preferably, an enhanced rigid-flexible coupling kinematic model of the robot is established, and the expression is as follows:
wherein: -1 T 6 the homogeneous transformation of a flange coordinate system {6} under an equipment basic coordinate system { -1 }; i T ei the homogeneous transformation of a connecting rod terminal coordinate system { ei } under a connecting rod coordinate system { i };
is the MDH kinematic parameters of the robot; k represents the flexibility factor of the connecting rod; q represents the coordinates of each axis of the robot; f () is the enhanced rigid-flexible coupling model forward kinematic expression of the robot.
Preferably, the step4 comprises: establishing a calibration model, wherein the expression is as follows:
wherein: L T -1 the homogeneous transformation of an equipment basic coordinate system { -1} under a laser tracker measurement coordinate system { L }, wherein psi is a corresponding pose parameter; i is 3 Is a 3-order identity matrix; 6 T tool the uniform transformation of a tool coordinate system { T } in a flange coordinate system {6} is carried out, and tau is a corresponding pose parameter; b is j Measuring the coordinates of the target ball in the tool coordinate system for the tracker; h () is a comprehensive calibration model expression; lRepresenting the posture of the ith robot; j denotes the jth target ball.
Preferably, the target ball is fixed on the tail end of the robot, and the target ball coordinates corresponding to a plurality of groups of joint coordinates of the robot are measured by the tracker
Deriving a linear calibration model for identification of a Levenberg-Marquardt algorithm, wherein the expression is as follows:
wherein: Δ Q is a deviation vector; j is a unit of ξ Represents a jacobian matrix; δ ξ represents the model parameter error;
deviation of the measured coordinates from the nominal coordinates; and n is the total number of the poses of the robot for calibration.
The robot precision improving system based on the joint full closed loop and the rigid-flexible coupling model comprises the following modules:
a module M1: the position signals of the reading heads are accessed into the servo controllers of the motors of all the axes through the grating rulers and the reading heads which are arranged on all the joints of the robot, so that the full closed-loop control of all the joint axes is realized;
a module M2: calibrating the positioning precision of each joint of the robot by using a laser interferometer;
a module M3: establishing a robot enhanced rigid-flexible coupling kinematics model;
a module M4: calibrating parameters of the robot enhanced rigid-flexible coupling kinematics model by using a laser tracker;
a module M5: and compensating the robot positioning by using the enhanced rigid-flexible coupling kinematic model.
Preferably, the module M3 comprises: under the action of an external force F, a moment M and self gravity mg, the deformation of a coordinate system { ei } at the tail end of the connecting rod is as follows:
wherein: x is the number of ei 、y ei 、z ei 、α ei 、β ei 、γ ei Is the deformation of the connecting rod under the stress of the coordinate system { ei }.
Preferably, an enhanced rigid-flexible coupling kinematic model of the robot is established, and the expression is as follows:
wherein: -1 T 6 the homogeneous transformation of a flange coordinate system {6} under an equipment basic coordinate system { -1 }; i T ei the homogeneous transformation of a connecting rod terminal coordinate system { ei } under a connecting rod coordinate system { i };
is the MDH kinematic parameters of the robot; k represents the flexibility factor of the connecting rod; q represents the coordinates of each axis of the robot; f () is the forward kinematic expression of the enhanced rigid-flexible coupling model of the robot.
Preferably, the module M4 includes: establishing a calibration model, wherein the expression is as follows:
wherein: L T -1 the homogeneous transformation of an equipment basic coordinate system { -1} under a laser tracker measurement coordinate system { L }, wherein psi is a corresponding pose parameter; I.C. A 3 Is a 3-order identity matrix; 6 T tool the uniform transformation of a tool coordinate system { T } in a flange coordinate system {6} is carried out, and tau is a corresponding pose parameter; b is j Measuring the coordinates of the target ball in the tool coordinate system for the tracker; h () is a comprehensive calibration model expression; l represents the pose of the l robot; j denotes the jth target ball.
Preferably, the target ball is fixed to the end of the robot byTarget ball coordinates corresponding to a plurality of groups of joint coordinates of robot are measured by tracker
Deriving a linear calibration model for identification of a Levenberg-Marquardt algorithm, wherein the expression is as follows:
wherein: Δ Q is a deviation vector; j is a unit of ξ Represents a jacobian matrix; δ ξ represents the model parameter error;
deviation of the measured coordinates from the nominal coordinates; and n is the total number of the poses of the robot for calibration.
Compared with the prior art, the invention has the following beneficial effects:
(1) By installing a grating ruler system on the robot joint and realizing full closed-loop control, the problem of poor joint positioning precision caused by deformation, reverse clearance and other problems in a standard industrial robot semi-closed-loop control mode is solved, and the effects of improving the joint positioning precision and the overall repeated positioning precision of the robot are achieved;
(2) Through the enhanced rigid-flexible coupling model and the compensation algorithm, the compensation of the gravity deformation and the geometric error of the connecting rod of the industrial robot is realized, and the space absolute positioning precision of the robot is greatly improved.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic view of the joint axes of a robot;
FIG. 2 is a simplified diagram of the links of the robot;
FIG. 3 is a force analysis diagram of each link of the robot;
FIG. 4 is a flow diagram of a two-step Levenberg-Marquardt process;
FIG. 5 is a flow chart of a robot control method;
1.1-A1 shaft support; 1.2-A1 axis reading head; 1.3-A1 axis grating ruler; 2.1-A2 shaft support; 2.2-A2 axis reading head; 2.3-A2-axis grating ruler; 3.1-A3 shaft bracket; 3.2-A3 axis reading head; 3.3-A3-axis grating ruler; 4.1-A4 shaft bracket; 4.2-A4 axis reading head; 4.3-A4 axis grating ruler; 5.1-A5 shaft bracket; 5.2-A5 axis reading head; 5.3-A5-axis grating ruler; 6.1-A6 shaft bracket; 6.2-A6 axis reading head; 6.3-A6 axis grating ruler.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the concept of the invention. All falling within the scope of the present invention.
Example 1:
the invention provides a robot precision improving method based on a joint full closed loop and a rigid-flexible coupling model, which is characterized in that a standard industrial robot is subjected to full closed loop modification of a joint and a grating ruler, and then compensation of the absolute position of the robot is carried out by combining an enhanced rigid-flexible coupling model, so that the absolute positioning precision of the robot is improved.
As shown in fig. 1, a grating ruler is added at the output end of each joint shaft of the robot to form the full closed loop control of the joint. Wherein, the grating rulers 1.3, 2.3, 3.3, 4.3, 5.3 and 6.3 are respectively pasted on the rotating surfaces of all joints of the robot, and the reading heads 1.2, 2.2, 3.2, 4.2, 5.2 and 6.2 are respectively fixed at the fixed ends of the joints of the robot through the brackets 1.1, 2.1, 3.1, 4.1, 5.1 and 6.1. Through the scale coordinates of the grating ruler read by the reading head, the control system can calculate the rotation angle of the current joint, and further measure the joint angle in the mode to be used as the reference of joint positioning. And then, calibrating the positioning precision of each joint axis of the robot by using the laser interferometer, calibrating the parameters of the kinematic model by using the laser tracker, and finally realizing the great improvement of the absolute positioning precision of the robot by using a compensation algorithm integrated into a control system.
The method comprises the following concrete steps:
(1) Mounting a grating ruler and a reading head on each joint of the robot, and accessing a position signal of the reading head into a servo controller of each shaft motor to realize full closed-loop control of each joint shaft;
(2) Calibrating the positioning precision of each joint of the robot by using a laser interferometer;
(3) Establishing a robot enhanced rigid-flexible coupling kinematics model, which specifically comprises the following steps:
firstly, simplifying each connecting rod of the robot into the connecting rod shown in fig. 2, and under the action of an external force F, a moment M and self gravity mg, deforming a coordinate system { ei } at the tail end of the connecting rod into:
wherein: x is the number of ei 、y ei 、z ei 、α ei 、β ei 、γ ei The deformation of the connecting rod under the coordinate system { ei } is shown in fig. 3, which is as follows:
wherein, the first and the second end of the pipe are connected with each other,
and
is the compliance coefficient of the connecting rod.
On the basis, an enhanced rigid-flexible coupling kinematics model of the robot is established as follows:
wherein: -1 T 6 is a homogeneous change of a flange coordinate system {6} under an equipment basic coordinate system { -1 {Changing; i T ei the homogeneous transformation of a connecting rod end coordinate system { ei } under a connecting rod coordinate system { i }; k represents the flexibility coefficient of the connecting rod, and q represents the coordinate of each axis of the robot;
i-1 T i ＝Rot x (α i-1 )Trans x (a i-1 )Rot z (θ i )Trans z (d i )
2 T 3 ＝Rot y (β 2 )Rot x (α 2 )Trans x (a 2 )Rot z (θ 3 ) In which α is i-1 ，a i-1 ，θ i ，d i For the kinematic parameters of the MDH of the robot, using
And (4) indicating.
(4) And calibrating parameters of the robot reinforced rigid-flexible coupling model by using the laser tracker.
Firstly, establishing a calibration model as follows:
wherein:
1) L T -1 ＝Trans x (x -1 )Trans y (y -1 )Trans z (z -1 )Rot z (α -1 )Rot y (β -1 )Rot x (γ -1 ) For a homogeneous transformation, x, of the basic coordinate system { -1} of the device in the measurement coordinate system { L } of the laser tracker -1 ,y -1 ,z -1 ,α -1 ,β -1 ,γ -1 Is a pose parameter, expressed by psi;
2) 6 T tool ＝Trans x (x t )Trans y (y t )Trans z (z t )Rot z (α t )Rot y (β t )Rot x (γ t ) For a homogeneous transformation of the tool coordinate system { T } in the flange coordinate system {6}, x t ,y t ,z t ,α t ,β t ,γ t Representing the corresponding pose parameter by tau;
3)
measuring the coordinates of the target ball in a tool coordinate system for the tracker;
4)I 3 is a 3-order identity matrix
From this, a linear calibration model for the Levenberg-Marquardt method identification was derived as follows:
wherein, J ξ Representing a jacobian matrix, δ ξ representing model parameter errors,
deviation of the measured coordinates from the nominal coordinates;
fixing the target ball on the end of the robot, and then measuring the coordinates of the target ball of the robot under a plurality of joint coordinate systems by using a tracker
Parameter identification is accomplished by the two-step Levenberg-Marquardt (LM) method shown in FIG. 4:
step1: firstly, psi and tau are set as parameters xi of rough identification i The initial parameter value of the calibration model adopts a nominal value;
step2: calculating the coordinates of the target ball under the calibration model corresponding to the coordinates of each group of joints
Step3: target ball coordinate measured by laser tracker
And target ball coordinates under the model
Calculating a deviation vector Δ Q and a model parameter ξ i Corresponding mean point error
Step4: when t consecutive MEs occur i After the standard deviation is lower than a set threshold or the iteration times exceeds the set threshold, if the current stage is in a coarse identification stage, turning to Step8, and if the current stage is in a fine identification stage, turning to Step9; otherwise, executing Step5;
step5: using xi i Jacobian matrix J for calculation and identification ξ And the provisional parameter vector χ i The temporary parameter vector is used for restricting the value range of the finally identified parameter, and the following relation exists between the temporary parameter vector and the calibration model parameter:
wherein diag { } represents a diagonal matrix, χ i,k Is composed of Chi shape i The k-th element of (a) is,
corresponding to the compliance parameters in the calibration model parameters.
Step6: computing a temporary Jacobian matrix J χ ＝J ξ diag{1,1,...,χ k ,χ k+1 ,., 1,1, and the correction of the temporary parameter vector: δ χ = (J) χ T J χ +λI) -1 J χ T ΔQ
Wherein, λ is the parameter of LM method, I is the unit matrix.
Step7: calculating a corrected temporary parameter vector χ i+1 ＝χ i + δ χ and calibration model parameters;
step8: the setting psi is set such that,
kappa and tau as parameters ξ to be identified i Then, ψ and τ obtained by the rough recognition are set as initial values for the fine recognition, and the process proceeds to Step5 to start the fine recognition.
Step9: the resulting last psi will be identified,
κ and τ are output as the final identified parameters.
(5) And the robot is positioned by utilizing the reinforced rigid-flexible coupling model to realize compensation.
As shown in fig. 5, a compensation algorithm is integrated into the robot control system, so as to realize the final compensation of the positioning accuracy of the robot, and the steps are as follows:
step1: to program pose Pos p Assign to nominal pose Pos n ；
Step2: calculating nominal pose Pos according to the inverse solution of the nominal DH kinematic model n A corresponding joint angle coordinate q;
step3: calculating the positive solution pose Pos corresponding to q by using an enhanced rigid-flexible coupling model t ；
Step4: calculating pose deviation delta Pos = Pos p -Pos t If the deviation is smaller than the set threshold value, turning to Step6, otherwise, executing Step4;
step5: superimposing the deviation to the nominal pose Pos n(i+1) ＝Pos ni + δ Pos, go to Step2;
step6: as the robot parameters in the control system adopt the nominal DH kinematic parameters, the robot positioning is set to q or Pos in the control system n The final actual positioning position of the robot can be close to Pos p 。
Example 2:
the invention also provides a robot precision improving system based on the joint fully closed loop and the rigid-flexible coupling model, which can be realized by executing the process steps of the robot precision improving method based on the joint fully closed loop and the rigid-flexible coupling model, namely, a person skilled in the art can understand the robot precision improving method based on the joint fully closed loop and the rigid-flexible coupling model as the preferred implementation mode of the robot precision improving system based on the joint fully closed loop and the rigid-flexible coupling model.
The robot precision improving system based on the joint full closed loop and the rigid-flexible coupling model comprises the following modules: a module M1: the position signals of the reading heads are accessed into the servo controllers of the motors of all the axes through the grating scales and the reading heads which are arranged on all the joints of the robot, so that the full closed-loop control of all the joint axes is realized; a module M2: calibrating the positioning precision of each joint of the robot by using a laser interferometer; a module M3: establishing a robot enhanced rigid-flexible coupling kinematics model; a module M4: calibrating parameters of the robot enhanced rigid-flexible coupling kinematics model by using a laser tracker; a module M5: and compensating the robot positioning by using the enhanced rigid-flexible coupling kinematic model.
The module M3 comprises: under the action of an external force F, a moment M and self gravity mg, the deformation of a coordinate system { ei } at the tail end of the connecting rod is as follows:
wherein: x is the number of ei 、y ei 、z ei 、α ei 、β ei 、γ ei Is the deformation of the connecting rod under the stress of the coordinate system { ei }.
Establishing an enhanced rigid-flexible coupling kinematics model of the robot, wherein the expression is as follows:
wherein: -1 T 6 the homogeneous transformation of a flange coordinate system {6} under an equipment basic coordinate system { -1 }; i T ei being the end of a connecting rodHomogeneous transformation of the coordinate system { ei } under the connecting rod coordinate system { i };
is the MDH kinematic parameters of the robot; k represents the flexibility factor of the connecting rod; q represents the coordinates of each axis of the robot; f () is the enhanced rigid-flexible coupling model forward kinematic expression of the robot.
The module M4 comprises: establishing a calibration model, wherein the expression is as follows:
wherein: L T -1 the homogeneous transformation of an equipment basic coordinate system { -1} under a laser tracker measurement coordinate system { L }, wherein psi is a corresponding pose parameter; i is 3 Is a 3-order identity matrix; 6 T tool the homogeneous transformation of a tool coordinate system { T } in a flange coordinate system {6} is carried out, and tau is a corresponding pose parameter; b is j Measuring the coordinates of the target ball in the tool coordinate system for the tracker; h () is a comprehensive calibration model expression; l represents the pose of the l robot; j denotes the jth target ball.
Fixing the target ball on the tail end of the robot, and measuring the coordinates of the target ball corresponding to the coordinates of a plurality of groups of joints of the robot by using a tracker
Deriving a linear calibration model for identification of a Levenberg-Marquardt algorithm, wherein the expression is as follows:
wherein: Δ Q is a deviation vector; j is a unit of ξ Represents a jacobian matrix; δ ξ represents the model parameter error;
deviation of the measured coordinates from the nominal coordinates; and n is the total number of the poses of the robot for calibration.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the apparatus, and the modules thereof provided by the present invention may be considered as a hardware component, and the modules included in the system, the apparatus, and the modules for implementing various programs may also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. A robot precision improving method based on a joint full closed loop and a rigid-flexible coupling model is characterized by comprising the following steps:
step1: installing a grating ruler and a reading head on each joint of the robot, and accessing a position signal of the reading head into a servo controller of each shaft motor to realize full closed-loop control of each joint shaft;
step2: calibrating the positioning precision of each joint of the robot by using a laser interferometer;
and step3: establishing a robot enhanced rigid-flexible coupling kinematics model;
and 4, step4: calibrating parameters of the robot enhanced rigid-flexible coupling kinematics model by using a laser tracker;
and 5: and compensating the robot positioning by using the enhanced rigid-flexible coupling kinematic model.
2. The robot precision improvement method based on the joint full closed-loop and rigid-flexible coupling model according to claim 1, wherein the step3 comprises: under the action of an external force F, a moment M and self gravity mg, the deformation of a coordinate system { ei } at the tail end of the connecting rod is as follows:
wherein: x is the number of ei 、y ei 、z ei 、α ei 、β ei 、γ ei Is the deformation of the connecting rod under the stress of the coordinate system { ei }.
3. The robot precision improving method based on the joint full closed loop and rigid-flexible coupling model according to claim 2, characterized in that an enhanced rigid-flexible coupling kinematics model of the robot is established, and the expression is as follows:
wherein: -1 T 6 the homogeneous transformation of a flange coordinate system {6} under an equipment basic coordinate system { -1 }; i T ei the homogeneous transformation of a connecting rod terminal coordinate system { ei } under a connecting rod coordinate system { i };
is the MDH kinematic parameters of the robot; k represents the flexibility factor of the connecting rod; q represents the coordinates of each axis of the robot; f () is the enhanced rigid-flexible coupling model forward kinematic expression of the robot.
4. The robot precision improving method based on the joint full closed-loop and rigid-flexible coupling model according to claim 3, wherein the step4 comprises: establishing a calibration model, wherein the expression is as follows:
wherein: L T -1 the homogeneous transformation of an equipment basic coordinate system { -1} under a laser tracker measurement coordinate system { L }, wherein psi is a corresponding pose parameter; i is 3 Is a 3-order identity matrix; 6 T tool the homogeneous transformation of a tool coordinate system { T } in a flange coordinate system {6} is carried out, and tau is a corresponding pose parameter; b is j Measuring the coordinates of the target ball in the tool coordinate system for the tracker; h () is a comprehensive calibration model expression; l represents the pose of the l robot; j denotes the jth target ball.
5. The method for improving the accuracy of the robot based on the fully closed-loop and rigid-flexible joint coupling model of claim 4, wherein the target ball is fixed on the end of the robot, and the target ball coordinates corresponding to a plurality of sets of joint coordinates of the robot are measured by a tracker
Deriving a linear calibration model for identification of a Levenberg-Marquardt algorithm, wherein the expression is as follows:
wherein: Δ Q is a deviation vector; j. the design is a square ξ Represents a jacobian matrix; delta xi generationError of table model parameters;
deviation of the measured coordinates from the nominal coordinates; and n is the total number of the poses of the robot for calibration.
6. The utility model provides a robot precision lift system based on joint is closed loop entirely and just gentle coupling model which characterized in that includes following module:
a module M1: the position signals of the reading heads are accessed into the servo controllers of the motors of all the axes through the grating scales and the reading heads which are arranged on all the joints of the robot, so that the full closed-loop control of all the joint axes is realized;
a module M2: calibrating the positioning precision of each joint of the robot by using a laser interferometer;
a module M3: establishing a robot enhanced rigid-flexible coupling kinematics model;
a module M4: calibrating parameters of the robot enhanced rigid-flexible coupling kinematics model by using a laser tracker;
a module M5: and compensating the robot positioning by using the enhanced rigid-flexible coupling kinematic model.
7. The robot precision lifting system based on joint full closed-loop and rigid-flexible coupling model according to claim 6, characterized in that the module M3 comprises: under the action of an external force F, a moment M and self gravity mg, the deformation of a coordinate system { ei } at the tail end of the connecting rod is as follows:
wherein: x is the number of ei 、y ei 、z ei 、α ei 、β ei 、γ ei Is the deformation of the connecting rod under the stress of the coordinate system { ei }.
8. The robot precision improving system based on the joint fully-closed loop and rigid-flexible coupling model as claimed in claim 7, wherein an enhanced rigid-flexible coupling kinematics model of the robot is established according to the expression:
wherein: -1 T 6 the homogeneous transformation of a flange coordinate system {6} under an equipment basic coordinate system { -1 }; i T ei the homogeneous transformation of a connecting rod terminal coordinate system { ei } under a connecting rod coordinate system { i };
is the MDH kinematic parameters of the robot; k represents the flexibility factor of the connecting rod; q represents the coordinates of each axis of the robot; f () is the enhanced rigid-flexible coupling model forward kinematic expression of the robot.
9. The robot precision lifting system based on joint full closed-loop and rigid-flexible coupling model according to claim 8, characterized in that the module M4 comprises: establishing a calibration model, wherein the expression is as follows:
wherein: L T -1 the homogeneous transformation of an equipment basic coordinate system { -1} under a laser tracker measurement coordinate system { L }, wherein psi is a corresponding pose parameter; i is 3 Is a 3-order identity matrix; 6 T tool the homogeneous transformation of a tool coordinate system { T } in a flange coordinate system {6} is carried out, and tau is a corresponding pose parameter; b is j Measuring the coordinates of the target ball in the tool coordinate system for the tracker; h () is a comprehensive calibration model expression; l represents the pose of the l robot; j denotes the jth target ball.
10. The robot precision lifting system based on joint full closed-loop and rigid-flexible coupling model of claim 9, characterized in that target ball is fixed toOn the tail end of the robot, a tracker is utilized to measure the coordinates of target balls corresponding to the coordinates of a plurality of groups of joints of the robot
Deriving a linear calibration model for identification of a Levenberg-Marquardt algorithm, wherein the expression is as follows:
wherein: Δ Q is a deviation vector; j. the design is a square ξ Represents a jacobian matrix; δ ξ represents the model parameter error;
deviation of the measured coordinates from the nominal coordinates; and n is the total number of the poses of the robot for calibration.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116901081A (en) * | 2023-08-22 | 2023-10-20 | 长广溪智能制造(无锡)有限公司 | Robot DH parameter calibration method and device, electronic equipment and storage medium |
| CN117301082A (en) * | 2023-11-28 | 2023-12-29 | 佛山华数机器人有限公司 | Joint flexibility compensation method for heavy-load robot |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116901081A (en) * | 2023-08-22 | 2023-10-20 | 长广溪智能制造(无锡)有限公司 | Robot DH parameter calibration method and device, electronic equipment and storage medium |
| CN117301082A (en) * | 2023-11-28 | 2023-12-29 | 佛山华数机器人有限公司 | Joint flexibility compensation method for heavy-load robot |
| CN117301082B (en) * | 2023-11-28 | 2024-01-23 | 佛山华数机器人有限公司 | Joint flexibility compensation method for heavy-load robot |
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