Industrial robot track iterative compensation method based on displacement load coupling relation

Abstract

The invention discloses an industrial robot track iterative compensation method based on a displacement load coupling relation. The method comprises the steps that a rigidity model of an industrial robot is established; carrying out displacement compensation on the metal plate under a plurality of poses, measuring an external load borne by a tool head of the industrial robot, and solving a displacement compensation-load equation through a least square method; the rigidity model and the displacement compensation-load equation are combined, and a track iteration compensation model of the industrial robot is constructed; a designed tool track is adopted for forming machining of the metal plate, external loads borne by a tool head in the forming process are collected and substituted into a track iteration compensation model of the industrial robot, and a compensation tool track is obtained through solving; and the metal sheet is formed through the compensation tool track. According to the industrial robot track iterative compensation method based on the displacement load coupling relation, the forming precision of the industrial robot can be efficiently improved with low cost, and the precision forming manufacturing requirement of high-strength metal plate parts is met.

Description

TECHNICAL FIELD

[0001] The present specification relates to the technical field of precision forming manufacturing, and particularly relates to an industrial robot trajectory iterative compensation method based on displacement-load coupling relationship. BACKGROUND

[0002] Industrial robots are widely used in the forming manufacturing of personalized customized plate parts due to their high flexibility and large processing range. However, the processing stiffness of industrial robots is generally much lower than that of traditional numerical control machine tools due to their unique multi-link series structure. When processing high-strength metal materials, the tool trajectory of the industrial robot will deviate significantly due to the large external load, resulting in low dimensional accuracy of the target part, and thus limiting the further application of industrial robots in advanced manufacturing.

[0003] In order to improve the forming accuracy of industrial robots, displacement compensation methods are widely used to correct the tool trajectory of industrial robots offline or online. However, the traditional offline compensation strategy generally only compensates for displacement once according to the measured external load, and the influence of the compensation tool trajectory on the external load is often ignored, so it is difficult to achieve good compensation effect. In contrast, the online compensation strategy can dynamically correct the tool trajectory deviation under the external load, but it often needs to be equipped with advanced hardware devices such as laser trackers and multi-camera to achieve, which is high in cost. In order to improve the forming accuracy of industrial robots and improve their application level in precision forming manufacturing, it is urgent to propose a low-cost and efficient industrial robot tool trajectory compensation method. SUMMARY

[0004] In view of the deficiencies of the prior art, one object of the present specification is to provide an industrial robot trajectory iterative compensation method based on displacement-load coupling relationship, which can improve the forming accuracy of industrial robots at low cost and high efficiency to meet the precision forming manufacturing needs of high-strength metal plate parts.

[0005] To achieve the above object, the embodiment of the present specification provides an industrial robot trajectory iterative compensation method based on displacement-load coupling relationship, comprising the following steps:

[0006] Establishing a stiffness model of the industrial robot;

[0007] Displacement compensation is performed on the metal plate at multiple poses, and the external load received by the tool head of the industrial robot is measured, and a displacement compensation-load equation is solved by least squares method;

[0008] Combining the stiffness model and the displacement compensation-load equation to construct a trajectory iterative compensation model of the industrial robot;

[0009] The forming process of the metal sheet is carried out by using the designed tool trajectory, the external load borne by the tool head in the forming process is collected, the tool trajectory iterative compensation model of the industrial robot is substituted, and the compensation tool trajectory is obtained by solving;

[0010] The metal sheet is formed by using the compensation tool trajectory.

[0011] As a preferred embodiment, the establishment of the stiffness model of the industrial robot comprises the following steps:

[0012] Based on the kinematics theory of the robot, a link coordinate system of the industrial robot is constructed, a kinematics equation of the industrial robot is solved, and a Jacobian matrix of the industrial robot is calculated based on the kinematics equation;

[0013] The stiffness of the industrial robot is detected to obtain a joint stiffness matrix of the industrial robot;

[0014] The Jacobian matrix and the joint stiffness matrix are used to calculate a mathematical relationship between the end position deviation and the external load of the industrial robot.

[0015] As a preferred embodiment, the kinematics equation is constructed based on the MD-H method, comprising the following steps:

[0016] MD-H parameters of the industrial robot in a specific pose are obtained based on the link coordinate system, the MD-H parameters comprising a link torsion angle α i-1 , a link length l i-1 , a joint torsion angle θ i , and a joint distance d i (1≤i≤6);

[0017] A homogeneous transformation matrix of adjacent link coordinate systems is solved:

[0018]

[0019] The kinematics equation of the industrial robot is solved according to the homogeneous transformation matrix:

[0020]

[0021] As a preferred embodiment, the stiffness model of the industrial robot is ΔX=CF; wherein CF is a flexibility matrix of the industrial robot; K X is a 6×6 Cartesian stiffness matrix of the industrial robot, and K X =J -T K θ J -1J is the Jacobian matrix, K θ is the joint stiffness matrix; F = [f x ,f y ,f z ,t x ,t y ,t z ] T is the external load on the industrial robot.

[0022] As a preferred embodiment, the solving of the displacement compensation-load equation comprises the following steps:

[0023] An experimental platform for displacement compensation of an industrial robot is built, and the metal sheet is fixed on the experimental platform for each forming pass, and the motion of the industrial robot is adjusted to the corresponding pose;

[0024] The industrial robot is controlled by teaching programming to perform displacement compensation on the metal sheet in the opposite direction of the tool head load direction at a fixed increment, while the force sensor is used to measure the external load on the tool head during displacement compensation;

[0025] The displacement compensation and external load data are fitted by the least squares method to obtain the displacement compensation-load equation of the industrial robot corresponding to each forming pass.

[0026] As a preferred embodiment, the displacement compensation-load equation is monotonically increasing, and the displacement compensation-load equation is any one of a polynomial function, an exponential function, and a power function.

[0027] As a preferred embodiment, the experimental platform for displacement compensation of the industrial robot comprises a clamp and a workbench, and the clamp is used to fix the metal sheet on the workbench.

[0028] As a preferred embodiment, the metal sheet is a high-strength metal material with poor plasticity, and the force sensor is installed at the end of the tool head away from the metal sheet.

[0029] As a preferred embodiment, the solving of the compensation tool trajectory comprises the following steps:

[0030] Step S41: The metal sheet is subjected to roll forming processing using the designed tool trajectory, and the initial external load on the tool head during forming is collected and substituted into the stiffness model of the industrial robot to calculate the displacement compensation initial value where i = 0.

[0031] Step S42: The displacement compensation initial value Substitute into the displacement compensation-load equation, calculate the iterative external load Substitute into the stiffness model of the industrial robot again, calculate the displacement compensation iteration value

[0032] Step S43: Calculate the iteration error according to the displacement compensation values obtained by the two times of calculation If the iteration error ε0 is greater than the predetermined value, then i=i+1 and repeat the above step S42; otherwise, end the loop and obtain the final displacement compensation value and the compensated tool trajectory.

[0033] As a preferred embodiment, the predetermined value is 5%.

[0034] Advantages:

[0035] The industrial robot trajectory iterative compensation method based on displacement-load coupling relationship provided by the embodiment, on the basis of the classical industrial robot stiffness model, by means of solving the industrial robot displacement compensation-load equation, innovatively applies the iteration strategy to the forming trajectory correction of the industrial robot, and compared with the traditional offline compensation method and the online compensation method, the method provided by the embodiment can efficiently improve the forming precision of the industrial robot at a lower cost, so as to meet the precise forming manufacturing demand of high-strength metal plate parts, and has high engineering application value.

[0036] Specific embodiments of the application are disclosed below with reference to the attached drawings, which show by way of example the principles of the application. It should be understood that the embodiments of the application are not limited in scope to the examples described.

[0037] Features described and / or illustrated with respect to one embodiment can be used in the same or similar manner in one or more other embodiments, in combination with or in place of features in other embodiments.

[0038] It should be emphasized that the term "comprises / comprising" when used in this specification is taken to mean the presence of stated features, integers, steps or components but not the exclusion of one or more other features, integers, steps, components or groups thereof. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description only illustrate some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0040] Figure 1A step flow chart of an industrial robot trajectory iterative compensation method based on displacement-load coupling relationship provided in the embodiment;

[0041] Figure 2 A kinematic model diagram of an industrial robot in an industrial robot trajectory iterative compensation method based on displacement-load coupling relationship provided in the embodiment;

[0042] Figure 3 A structure diagram of an industrial robot displacement compensation experimental platform provided in the embodiment;

[0043] Figure 4 For Figure 1 A specific step flow chart of step S40 in the embodiment;

[0044] Figure 5 A size precision comparison diagram of a target part made by applying an industrial robot trajectory iterative compensation method based on displacement-load coupling relationship provided in the embodiment.

[0045] BRIEF DESCRIPTION OF DRAWINGS

[0046] 31, worktable; 32, sheet metal; 33, clamp; 34, tool head; 35, force sensor. DETAILED DESCRIPTION

[0047] In order to make the personnel in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should belong to the scope of protection of the present application.

[0048] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can be a middle element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be a middle element. The terms "vertical", "horizontal", "left", "right", and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0050] Referring to Figure 1 The embodiments of the present application provide an industrial robot trajectory iterative compensation method based on displacement-load coupling relationship, comprising:

[0051] Step S10: establishing a stiffness model of the industrial robot;

[0052] Step S20: performing displacement compensation on the metal sheet 32 at multiple poses, while measuring the external load borne by the tool head 34 of the industrial robot, and solving a displacement compensation-load equation by least square method;

[0053] Step S30: combining the stiffness model and the displacement compensation-load equation to construct a trajectory iterative compensation model of the industrial robot;

[0054] Step S40: performing forming processing on the metal sheet 32 by using a designed tool trajectory, collecting the external load borne by the tool head 34 in the forming process, substituting into the trajectory iterative compensation model of the industrial robot, and solving to obtain a compensation tool trajectory;

[0055] Step S50: forming the metal sheet 32 by using the compensation tool trajectory.

[0056] The industrial robot trajectory iterative compensation method based on displacement-load coupling relationship provided by the embodiments of the present application, on the basis of the classical industrial robot stiffness model, innovatively applies the iterative strategy to the forming trajectory correction of the industrial robot by means of solving the industrial robot displacement compensation-load equation, and compared with the traditional offline compensation method and the online compensation method, the method provided by the embodiments of the present application can efficiently improve the forming precision of the industrial robot at a lower cost, so as to meet the precise forming manufacturing demand of high-strength metal sheet parts, and has high engineering application value.

[0057] In the embodiments, the step of establishing the stiffness model of the industrial robot (i.e. step S10) comprises the following steps:

[0058] Step S11: based on the robot kinematics theory, constructing a link coordinate system of the industrial robot, solving to obtain a kinematics equation of the industrial robot, and based on the kinematics equation, calculating to obtain a Jacobian matrix of the industrial robot at a specific pose by vector product method;

[0059] Step S12: stiffness detection is performed on the industrial robot to obtain a joint stiffness matrix of the industrial robot;

[0060] Step S13: a mathematical relationship between the end position deviation and the external load of the industrial robot at a specific pose is calculated using the Jacobian matrix and the joint stiffness matrix, i.e., ΔX = CF.

[0061] In step S11, the kinematic equation is constructed based on the MD-H method. The kinematic modeling of the industrial robot is performed using the MD-H method to establish the link coordinate system of the industrial robot as shown in FIG. 1, wherein the coordinate system corresponding to O0 is the world coordinate system of the industrial robot, and the remaining coordinate systems correspond to the links of the industrial robot. Figure 2

[0062] Specifically, step S11 can include the following steps:

[0063] Step S111: MD-H parameters of the industrial robot at a specific pose are obtained based on the link coordinate system, wherein the MD-H parameters include link twist angles a i-1 , link lengths l i-1 , joint twist angles θ i , joint distances d i (1≤i≤6);

[0064] Step S112: a homogeneous transformation matrix of adjacent link coordinate systems is solved:

[0065]

[0066] Step S113: a coordinate transformation matrix of the industrial robot, i.e., the kinematic equation of the industrial robot, is solved according to the homogeneous transformation matrix:

[0067]

[0068] In step S13, it is assumed that the external load received by the industrial robot is F = [f x , f y , f z , t x , t y , t z ] T , and the end position deviation generated by the industrial robot is ΔX = [d x , d y , d z , δ x , δ y , δ z ] T ​. From Hooke's law, there is an equation F = K X ΔX, where K X is a 6x6 Cartesian stiffness matrix of the industrial robot, which can be calculated by K X = J -T K θ J -1 , J is a Jacobian matrix, and K θ is a joint stiffness matrix. Subsequent matrix transformation can obtain a stiffness model of the industrial robot ΔX = CF, where is a compliance matrix of the industrial robot.

[0069] Specifically, step S20 can take the industrial robot roll forming process as an example. Step S20 can include the following steps:

[0070] Step S21: Build an industrial robot displacement compensation experiment platform. For each forming pass, the metal sheet 32 is fixed on the experiment platform, and the industrial robot is adjusted to the corresponding pose.

[0071] Step S22: Control the industrial robot by teaching programming to perform displacement compensation on the metal sheet 32 in the direction opposite to the direction of the tool head 34 load (i.e. the direction indicated by the dashed line in FIG. 8) at a fixed increment, while using the force sensor 35 to measure the external load F on the tool head 34 during displacement compensation. Figure 3

[0072] Step S23: Fit the displacement compensation and external load data by least squares method to obtain the mathematical relationship between the displacement compensation ΔX and the external load F of the industrial robot corresponding to each forming pass, i.e. the displacement compensation-load equation F = f(ΔX).

[0073] Preferably, the mathematical relationship in step S23 can be a monotonically increasing function type such as a polynomial function, an exponential function, a power function, etc. In addition, the mathematical relationship needs to ensure good fitting accuracy. That is, the displacement compensation-load equation is monotonically increasing, and the displacement compensation-load equation is any one of a polynomial function, an exponential function, and a power function.

[0074] In step S21, the industrial robot displacement compensation experiment platform needs to be built according to the relevant characteristics of the target forming process. For example, as shown in FIG. 8, taking the industrial robot roll forming process as an example, the industrial robot displacement compensation experiment platform includes a clamp 33 and a workbench 31, and the clamp 33 is used to fix the metal sheet 32 on the workbench 31. The workbench 31 should have good stiffness to ensure that the displacement error caused by loading during the experiment is as small as possible. Figure 3

[0075] ​​The metal sheet 32 ​​can be a high-strength metal material with poor plasticity, and its shape corresponds to the design shape under a specific forming pass in the forming process. The tool head 34 is used to process the metal sheet 32 ​​in the forming process, realizing multi-pass roll forming of the metal sheet 32. The force sensor 35 is installed at the end of the tool head 34 away from the metal sheet 32 ​​(i.e., the end point). The force sensor 35 has a large working range and is suitable for real-time detection of force and torque under the forming of high-strength metal materials. Figure 3 The direction indicated by the dashed line is the displacement compensation direction of the tool head 34 in the displacement compensation experiment. It is perpendicular to the contact surface between the metal sheet 32 ​​and the tool head 34, and corresponds to the opposite direction of the main load direction of the industrial robot under a specific forming pass.

[0076] Furthermore, the metal sheet 32 ​​can be a high-strength metal material with poor plasticity. Preferably, the material of the metal sheet 32 ​​can be a high-strength metal material such as high-strength steel, titanium alloy, or magnesium alloy.

[0077] In step S30, specifically, the method employs an iterative compensation strategy to process the influence of a single compensation tool trajectory on external loads in the traditional offline compensation strategy. The industrial robot stiffness model ΔX=CF is combined with the displacement compensation-load equation F=f(ΔX) to iteratively calculate the displacement compensation value for each pass in the industrial robot roll forming process. This allows for the acquisition of a compensation tool trajectory that is closer to the designed tool trajectory within a limited number of iterations.

[0078] In this embodiment, such as Figure 4 As shown, the step of solving for the compensation tool trajectory (i.e., step S40) includes the following steps:

[0079] Step S41: Perform roll forming of the metal sheet 32 ​​using the designed tool path, and collect the initial external load on the tool head 34 during the forming process. The initial values ​​for displacement compensation are then calculated by substituting them into the stiffness model of the industrial robot. Where i = 0;

[0080] Step S42: Set the initial displacement compensation value Substituting into the displacement compensation-load equation, the iterative external load is calculated. Substituting the values ​​back into the stiffness model of the industrial robot, the displacement compensation iteration values ​​are calculated.

[0081] Step S43: Calculate the iteration error based on the displacement compensation values ​​obtained from the two calculations. If the iteration error ε0 is greater than a predetermined value, then i = i + 1 and the above step S42 is repeated; otherwise, the loop is ended and the final displacement compensation value and the compensated tool trajectory are obtained.

[0082] Preferably, the predetermined value is 5%. The predetermined value can be increased according to actual needs to improve the calculation efficiency, or decreased to improve the compensation accuracy.

[0083] In step S50, the metal sheet 32 is roll formed using the compensated tool trajectory to form the target part, which can improve the dimensional accuracy of the target part.

[0084] Specifically, taking the industrial robot roll forming process as an example, the stiffness model and the displacement compensation-load equation under each forming pass are obtained based on the tool trajectory iteration compensation method, and the compensated tool trajectory is further solved and applied to the roll forming of MS1300 ultra-high strength steel. Figure 5 The cross-sectional profiles of the L-shaped bending parts after the roll forming of the metal sheet 32 under different forming conditions are shown, where θ is the springback angle of the L-shaped bending part, and R / t is the ratio of the corner radius of the L-shaped bending part to the sheet thickness (1 mm in this case). It can be seen that by applying the trajectory iteration compensation method in the industrial robot roll forming process, the tool trajectory deviation of the industrial robot during the forming process can be significantly reduced, and the corner radius of the target part obtained is more consistent with the die radius of 1 mm. Preferably, the trajectory iteration compensation method is combined with the laser-assisted forming technology, which can simultaneously reduce the springback and corner radius of the target part, and further improve the dimensional accuracy of the target part.

[0085] Any numerical values recited herein include all values from the lower value and the upper value in increments of one unit, provided that there is a separation of at least two units between any lower value and any higher value. As an example, if a numerical value is recited as from 1 to 90, preferably from 20 to 80, and more preferably from 30 to 70, it is intended that values such as 15 to 85, 22 to 68, 43 to 51, and 30 to 32, etc. are expressly enumerated in this specification. For values which are less than one, one unit is considered to be 0.0001, 0.001, 0.01, 0.1, as appropriate. These are only examples of what is specifically enumerated herein, and are not intended to limit the application in any way. Any numerical value, however, can be expressed as approximately or approximately.

[0086] Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints. "Approximately" or "about" applied to a range of values should be construed as applying to both the end points and all values within the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", including at least the specified endpoints.

[0087] All articles and references, including patent applications and publications, disclosed herein are incorporated by reference for all purposes. The term "consisting essentially of to describe a combination shall include the elements, ingredients, components or steps identified, and such other elements ingredients, components or steps that do not materially affect the basic and novel characteristics of the combination. The use of the term "comprising" or "including" to describe combinations of elements, ingredients, components or steps herein also is taken to mean that other elements, ingredients, components or steps are optional in an embodiment of the present teachings to the extent that "comprising" or "including" is used in the description or claims. The term "consisting essentially of to describe a combination shall include the elements, ingredients, components or steps identified, and such other elements ingredients, components or steps that do not materially affect the basic and novel characteristics of the combination. The use of the term "comprising" or "including" to describe combinations of elements, ingredients, components or steps herein also is taken to mean that other elements, ingredients, components or steps are optional in an embodiment of the present teachings to the extent that "comprising" or "including" is used in the description or claims. The term "may" is intended to mean one or more possible events exist related to an event or circumstance. Language that "comprises," "has," "includes," or "consists of" does not (or should not be interpreted to) exclude the presence of elements other than those identified, it "can," "might," or "may," "comprises," "has," "includes" or "consists of" such other elements in addition to those identified.

[0088] Several elements, ingredients, components or steps can be provided by a single integrated element, ingredient, component or step. Alternatively, a single integrated element, ingredient, component or step might be divided into several separate elements, ingredients, components or steps. To the extent any of the elements, ingredients, components or steps as described herein is presented in a specific format or order, the inventors contemplate any and all formats or orders unless otherwise stated.

[0089] It is understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. The omission of any aspect of the subject matter disclosed herein does not preclude coverage of that aspect of the subject matter in the claims.

Claims

1. An industrial robot trajectory iterative compensation method based on displacement load coupling relationship, characterized in that, The method comprises the following steps: establishing a stiffness model of an industrial robot; compensating for displacement of a metal sheet at multiple poses while measuring external load on a tool head of the industrial robot, and solving a displacement compensation-load equation by least square method; combining the stiffness model and the displacement compensation-load equation to build a trajectory iterative compensation model of the industrial robot; adopting a designed tool trajectory to perform forming of the metal sheet, collecting external load on the tool head during forming, and substituting the external load into the trajectory iterative compensation model of the industrial robot to solve and obtain a compensated tool trajectory; performing forming of the metal sheet by using the compensated tool trajectory.

2. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 1, characterized in that, The method of establishing the stiffness model of the industrial robot comprises the following steps: based on robot kinematics theory, building a link coordinate system of the industrial robot, solving a kinematics equation of the industrial robot, and calculating a Jacobian matrix of the industrial robot based on the kinematics equation; conducting stiffness detection on the industrial robot to obtain a joint stiffness matrix of the industrial robot; calculating a mathematical relationship between end position deviation and external load of the industrial robot by using the Jacobian matrix and the joint stiffness matrix.

3. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 2, characterized in that, The kinematics equation is built based on MD-H method and comprises the following steps: obtaining MD-H parameters of the industrial robot in the specific pose based on the link coordinate system, the MD-H parameters comprising link twist angles a i-1 , link lengths l i-1 , joint twist angles θ i , joint distances d i (1≤i≤6); solving a homogeneous transformation matrix of adjacent link coordinate systems; solving the kinematics equation of the industrial robot according to the homogeneous transformation matrix:

4. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 2, characterized in that, The stiffness model of the industrial robot is ΔX = CF; wherein is the flexibility matrix of the industrial robot; K X is the 6x6 Cartesian stiffness matrix of the industrial robot, by K X = J -T K θ J -1 is calculated, J is the Jacobian matrix, K θ is the joint stiffness matrix; F = [f x ,f y ,f z ,t x ,t y ,t z ] T is the external load to which the industrial robot is subjected.

5. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 1, characterized in that, The method of solving the displacement compensation-load equation comprises the following steps: building an industrial robot displacement compensation experiment platform, fixing the metal sheet on the experiment platform corresponding to each forming pass, and adjusting the industrial robot to move to a corresponding pose; controlling the industrial robot by teaching programming to compensate for displacement of the metal sheet in the opposite direction of the tool head load direction at a fixed increment, and measuring external load on the tool head during displacement compensation by using a force sensor; fitting displacement compensation and external load data by least square method to obtain a displacement compensation-load equation of the industrial robot corresponding to each forming pass.

6. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 5, characterized in that, The displacement compensation-load equation is monotonically increasing, and the displacement compensation-load equation is any one of a polynomial function, an exponential function, and a power function.

7. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 5, characterized in that, The industrial robot displacement compensation experiment platform comprises a clamp and a workbench, and the clamp is used to fix the metal sheet on the workbench.

8. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 5, characterized in that, The metal sheet is a high-strength metal material with poor plasticity, and the force sensor is installed at an end of the tool head away from the metal sheet.

9. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 1, characterized in that, The method of solving and obtaining the compensated tool trajectory comprises the following steps: Step S41: using the designed tool trajectory to perform the roll forming process of the metal sheet, collecting the initial external load received by the tool head during the forming process and substituting into the stiffness model of the industrial robot to obtain the initial displacement compensation value where i = 0; Step S42: Substitute the displacement compensation initial value Substitute into the displacement compensation-load equation to obtain the iteration external load Substitute into the stiffness model of the industrial robot again to obtain the displacement compensation iteration value Step S43: Calculate the iteration error according to the displacement compensation values obtained from the two times of calculation If the iteration error ε0 is greater than a predetermined value, then make i = i + 1 and repeat the above step S42; otherwise, end the loop and obtain the final displacement compensation value and the compensated tool trajectory.

10. The industrial robot trajectory iterative compensation method based on displacement load coupling relationship according to claim 9, characterized in that, The predetermined value is 5%.

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