Shoe tree glue spraying path automatic generation method based on point cloud data processing

Abstract

The invention provides a shoe tree glue spraying path automatic generation method based on point cloud data processing, and the method comprises the steps: carrying out the point cloud data preprocessing on the basis of scanning a shoe tree to obtain point cloud data, and obtaining a spatial motion track point mark and data; an approximate glue spraying attachment space track on the shoe tree is obtained through polynomial interpolation; then, orthogonal coordinate system NOA vectors corresponding to the glue spraying attachment space track points on all the shoe trees are sequentially solved, a mechanical arm tail end glue spraying space track obtained after the shoe tree glue spraying track NOA vector directions are offset by a certain distance is solved, and a mechanical arm tail end pose matrix is obtained through solving according to the orthogonal coordinate system NOA vectors and the mechanical arm tail end glue spraying space track; and finally, establishing an inverse kinematics mathematical model according to the D-H parameters of the robot, and substituting the inverse kinematics mathematical model into the tail end pose matrix of the mechanical arm for solving to obtain a shoe tree glue spraying movement track.

Description

Technical Field

[0001] The invention belongs to the technical field of shoe last manufacturing, and in particular relates to a method for automatically generating a shoe last glue spraying path based on point cloud data processing. Background Art

[0002] Traditional shoemaking technology relies heavily on manual operations. Gluing is the most important part of the shoemaking process, which not only involves the quality and production efficiency of the shoes, but also has a great negative impact on the health of the shoemakers themselves. For this reason, it is urgent to adopt an industrial robot intelligent glue spraying technology to replace the traditional manual glue coating process. At present, although the shoemaking industry already has intelligent glue spraying technology for industrial robots, the shoe styles change very quickly, and the motion trajectory of the industrial robot intelligent glue spraying requires manual learning (usually using a teaching pendant + manual operation judgment), which is time-consuming and labor-intensive, and it is difficult for workers to get started, making it difficult to meet the development needs of the industry. Traditional visual solutions are difficult to implement, robots learn slowly, and industrial cameras are prone to contaminants, affecting control accuracy. Summary of the invention

[0003] The difficulty in solving the above problem lies in how to obtain the data of the dynamic surface of the shoe last and keep the end of the robot arm always perpendicular to the trajectory surface of the shoe last and the glue spraying spacing unchanged. Therefore, it is necessary to synthesize the line finding, spacing, and orthogonal algorithms into a control algorithm and finally convert it into the motion posture of the end of the robot arm, which involves complex posture space transformation.

[0004] In view of this, the purpose of the present invention is to provide a method for automatically generating a shoe last spraying path based on point cloud data processing, so as to solve the problem of slow learning speed and low efficiency of the shoe last spraying path of the robot in the existing shoemaking spraying technology under the background of rapid changes in shoe styles.

[0005] The main process of the scheme includes: 1. Scan the shoe last with a 3D scanner to obtain point cloud data; 2. Preprocess the point cloud data; 3. Mark the points of the spatial motion trajectory and export the data; 4. Use polynomial interpolation to obtain the approximate spatial trajectory of the shoe last glue spraying; 5. Solve the NOA vector of the orthogonal coordinate system of the glue spraying posture; 6. Calculate the spatial trajectory of the glue spraying at the end of the manipulator after the NOA vector direction of the shoe last glue spraying trajectory is offset by a certain distance; 7. Obtain the position matrix of the end of the manipulator; 8. Establish an inverse kinematics mathematical model based on the robot DH parameters. The present invention can quickly realize the generation of motion trajectories for glue spraying of shoe lasts of different shoe styles, solve the problem that the traditional scheme relies on manual labor, has low efficiency and poor versatility, and can continuously meet the development needs of the industry.

[0006] The technical solution specifically adopted by the present invention to solve the technical problem is:

[0007] A method for automatically generating a shoe last glue spraying path based on point cloud data processing comprises the following steps: based on scanning the shoe last to obtain point cloud data, the point cloud data is preprocessed to obtain spatial motion trajectory point marks and data; then, the approximate glue spraying attachment spatial trajectory on the shoe last is obtained through polynomial interpolation; then, the orthogonal coordinate system NOA vectors corresponding to the glue spraying attachment spatial trajectory points on the shoe last are solved in turn, and the glue spraying spatial trajectory of the end of the robot arm after the direction of the NOA vector of the shoe last glue spraying trajectory is offset by a certain distance is solved, and the end posture matrix of the robot arm is obtained according to the orthogonal coordinate system NOA vector and the glue spraying spatial trajectory of the end of the robot arm; finally, an inverse kinematics mathematical model is established according to the robot DH parameters, and the end posture matrix of the robot arm is brought into the solution to obtain the shoe last glue spraying motion trajectory.

[0008] Furthermore, when the shoe last is scanned to obtain point cloud data, the fixed base integrated with the shoe last is scanned together to provide a relative position relationship between the workpiece coordinate system and the robot base coordinate system.

[0009] Furthermore, the point cloud data preprocessing includes cutting off redundant point cloud data, and then based on the known relative position of the shoe last base and the robot, setting the workpiece coordinate system and the origin on the fixed base, and the XY planes of the workpiece coordinate system and the robot base coordinate system are parallel, and the origin of the workpiece coordinate system is set at the center of the base geometric feature or a position where the parameters are known.

[0010] Furthermore, in the process of obtaining the approximate glue spraying attachment spatial trajectory on the shoe last through polynomial interpolation, the number of insertion points between every two derived marking points is not less than 4, so as to ensure that an approximate smooth glue spraying attachment trajectory L1 on the shoe last is obtained.

[0011] Furthermore, the method of solving the NOA vector of the orthogonal coordinate system corresponding to all the space trajectory points of the glue spraying attachment on the shoe last is specifically as follows: for all the trajectory points, the corresponding NOA vector Vectors, where vector N is obtained by the difference between adjacent points, vector O is solved by passing through corresponding points perpendicular to the approximate plane, and vector A is solved according to the right-hand rule.

[0012] Furthermore, the solution of the glue spraying trajectory of the shoe last NOA vector direction after a certain distance offset of the robot arm end glue spraying space trajectory is specifically: through the obtained The actual glue spraying space trajectory L2 at the end of the robot arm is obtained by using the vector and the glue spraying space trajectory on the shoe last: Where DIS is the offset glue spraying distance.

[0013] Furthermore, the solution to obtain the pose matrix of the end of the robotic arm is specifically to perform homogeneous transformation on the obtained pose and posture matrices, and multiply them to obtain the position matrix of the end of the robotic arm as the input of the inverse kinematics mathematical model of the robotic arm and solve the corresponding joint angle.

[0014] Furthermore, the inverse kinematics mathematical model established according to the robot DH parameters takes into account the end tool coordinate system.

[0015] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the method for automatically generating a shoe last glue spraying path based on point cloud data processing as described above are implemented.

[0016] A non-transitory computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for automatically generating a shoe last glue spraying path based on point cloud data processing as described above.

[0017] Compared with traditional manual teaching or visual methods, the present invention and its preferred embodiment have the following advantages: the robot's spraying path learning is obtained through preliminary three-dimensional scanning and theoretical calculation. Compared with manual or traditional visual methods, this method has the advantages of fast learning speed, low difficulty for workers to get started, and high cost performance. It can greatly shorten the learning cycle of learning the spraying trajectories of different shoe models, which can greatly improve the production capacity and competitiveness of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0019] Figure 1 is a method flow chart of an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of a physical object with feature points attached thereto according to an embodiment of the present invention;

[0021] Figure 3 Schematic diagram of point cloud before and after preprocessing according to an embodiment of the present invention;

[0022] Figure 4 is a schematic diagram of glue spraying path point marking according to an embodiment of the present invention;

[0023] Figure 5 is a schematic diagram of polynomial interpolation of a glue spraying path according to a simulation test result of an embodiment of the present invention;

[0024] Figure 6 is a trajectory point set of a simulation test result of an embodiment of the present invention Vector diagram;

[0025] Figure 7 is a schematic diagram of the glue spraying trajectory at the end of the robot arm according to the simulation test results of an embodiment of the present invention;

[0026] Figure 8It is a kinematic control schematic diagram of the simulation test results of an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the features and advantages of the present invention more clearly understood, the following embodiments are specifically described in detail as follows:

[0028] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0030] An embodiment of the present invention provides a method for automatically generating a shoe last glue spraying path based on point cloud data processing, comprising the following steps:

[0031] Step S1: Scan the shoe last using a 3D scanner to obtain point cloud data;

[0032] Step S2: point cloud data preprocessing;

[0033] Step S3: marking the spatial motion trajectory points and exporting the data in the point cloud processing software;

[0034] Step S4: obtaining an approximate glue spraying attachment spatial trajectory on the shoe last by polynomial interpolation;

[0035] Step S5: Solve the corresponding spatial trajectory points of the glue spraying attachment on all shoe lasts vector;

[0036] Step S6: solving the spatial trajectory of glue spraying at the end of the robot arm;

[0037] Step S7: Solve the end pose matrix of the robot arm;

[0038] Step S8: Establish an inverse kinematics mathematical model based on the robot DH parameters, and bring it into the posture matrix for solution;

[0039] As a preferred solution of this embodiment, in step S1, a high-precision feature point visual stitching method is adopted, and feature points need to be pasted on the scanned area. It is worth noting that in order to facilitate subsequent coordinate transformation, the fixed base of the shoe last also needs to be scanned.

[0040] As a preferred solution of this embodiment, in step S2, point cloud preprocessing can be performed in reverse engineering software such as Geomagic Studio, and the main operation steps include:

[0041] Step S21: trimming redundant point cloud data. Too much point cloud data will affect the running speed of the subsequent search algorithm.

[0042] Step S22: Set the workpiece coordinate system XY plane on the shoe last fixed base and parallel to the robot base coordinate system XY plane. At the same time, set the origin of the workpiece coordinate system at the center of the base geometric feature or a position with known parameters.

[0043] As a preferred solution of this embodiment, in step S3, according to the actual requirements of the glue spraying process, the trajectory marking and data export are manually performed in the point cloud processing software, and the number of marking points should be no less than 36.

[0044] As a preferred solution of this embodiment, in step S4, in order to obtain a smoother glue spraying trajectory curve, polynomial interpolation processing is performed on the derived data, and the number of insertion points between every two derived marking points should be no less than 4, and finally the glue spraying attachment trajectory L1 is obtained.

[0045] As a preferred solution of this embodiment, in step S5, after interpolation, each trajectory point O i is the coordinate origin of the i-th point, For the corresponding point Vector, we can get Furthermore, searching for the distance from O in the point cloud data i The nearest point B after offsetting 1-3cm in the vertical positive direction (the offset distance and direction can be determined according to the actual situation) i ,but According to its perpendicular and The conditions are obtained. According to the right-hand rule, and It should be noted that the calculated normal vector If there are situations where the directions are opposite, it is necessary to unify the directions through procedures.

[0046] As a preferred solution of this embodiment, in step S6, after obtaining the shoe last glue attachment trajectory obtained in step S4 and the shoe last glue attachment trajectory obtained in step S5, Under the premise of , the motion trajectory of the robot nozzle at a certain distance from the shoe last can be calculated, and the calculation formula is Where DIS is the offset glue spraying distance.

[0047] As a preferred solution of this embodiment, in step S7, the fourth-order pose matrix of the end of the robot arm is obtained by the position matrix obtained in step S6 and the position matrix obtained in step S5. The result of multiplying a vector matrix after homogeneous transformation.

[0048] As a preferred solution of this embodiment, in step S8, mathematical modeling is performed with reference to the DH parameters of the robot and the end tool parameters, and then the posture matrix obtained in step S7 is passed to the mathematical model for inverse kinematics solution.

[0049] Reference Figure 1 , the following provides a specific example of automatic generation of shoe last glue spraying path based on point cloud data processing, including the following steps:

[0050] Step S1: The shoe last with feature points attached is as follows Figure 2 As shown, the original point cloud data obtained by scanning with a 3D scanner is as follows Figure 3 As shown on the left, the shoe last is fixed on a rectangular thin plate base, and the base is also scanned together. Its significance lies in providing the relative position relationship between the workpiece coordinate system and the robot base coordinate system.

[0051] Step S2: After the point cloud data obtained in step S1 is processed in the reverse engineering software Geomagic studio, the point cloud data obtained is as follows: Figure 3 As shown on the right, the coordinate origin is set at the geometric center of the rectangle on the bottom of the fixed base. The XY plane of the point cloud data coincides with the bottom of the base, and the Z axis is perpendicular to the bottom and upward.

[0052] Step S3: The spatial motion trajectory points marked in the software are as follows Figure 4 As shown in Pt1-Pt36 in the figure; these points need to be marked in sequence according to the actual motion trajectory of the glue spraying; workers who are familiar with the process can mark them, and it is very easy to get started, and no professional knowledge is required; the glue spraying motion trajectory obtained by this marking is very simple, convenient and efficient, and can effectively replace traditional visual and manual methods.

[0053] Step S4: The approximate glue spraying attachment space trajectory on the shoe last is obtained by polynomial interpolation, as shown in Figure 4 As shown by the red line in the figure; the more interpolation points there are, the closer it is to the theoretical glue spraying curve; in order to improve the accuracy, the point closest to the interpolation point can also be searched in the point cloud and replaced with the interpolation point, but the amount of calculation will be greatly increased;

[0054] Step S5: Solve for all trajectory points corresponding to Vector Figure 6 shown; each The vector is the motion posture of the corresponding robot at the corresponding point. In order to prevent the inverse kinematics solution error, it is not converted into the RPY posture angle here. This step is to control the robot arm glue spraying actuator to always remain perpendicular to the glue spraying area of ​​the shoe last. The specific calculation steps are:

[0055] Step S51: The coordinate systems are perpendicular to each other Three unit vectors are composed. First, we can find the vector

[0056] For each trajectory point O i is the coordinate origin of the i-th point, For the corresponding point Vector, we can get Vector N i is the direction of motion of the robot end;

[0057] Step S52: Further, search for the point cloud data from O i The closest point B after offsetting a fixed distance in the Z direction i , the search distance and direction can be determined according to the actual situation. It is worth noting that the vector and are not perpendicular to each other, so Cannot replace and Can be found in and Then we get by the right-hand rule;

[0058] Step S53: Further, calculate and vector and vector The unit vectors are perpendicular It is worth noting that the first vector The direction may be either positive or negative, and all signs need to be uniformly adjusted to be the same with a point enclosed in the trajectory as the reference point;

[0059] Step S54: Further, since the required vector and It is not perpendicular, so we need to find the vector and The unit vectors are perpendicular After obtaining the three vectors, Vector matrix homogeneous transformation;

[0060] Step S6: Spray glue to attach the rails Figure 7 The thin black line in the figure shows the spatial trajectory of the glue spraying at the end of the robot arm after offsetting a certain distance. Figure 7 The thick black line in Figure 7As shown in the figure, under the same coordinate scale, according to the different DIS settings (DIS = 5, DIS = 10, DIS = 20), the motion trajectory of the end-arm glue spraying with different offset distances can be obtained. The calculation formula is: Where DIS is the offset glue spraying distance, L1 is the glue spraying attachment trajectory, and finally all the trajectory points (X, Y, Z) in L2 need to be homogeneously transformed into a fourth-order position matrix;

[0061] Step S7: The fourth-order pose matrix of the end of the robot arm is obtained by multiplying the position matrix obtained in step S6 by the pose matrix obtained in step S5;

[0062] Step S8: Establish a mathematical model based on the robot DH parameters and tool coordinate parameters, and then perform inverse kinematics solution. The six-axis robot arm has eight sets of solutions. The correct set of solutions needs to be selected according to the actual conditions. The final six-axis robot motion control simulation of the automatic generation method of the spraying path is as follows: Figure 8 shown.

[0063] Based on the same inventive concept, the present invention also provides a computer device, which includes: one or more processors, and a memory for storing one or more computer programs; the program includes program instructions, and the processor is used to execute the program instructions stored in the memory. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is used to implement one or more instructions, specifically for loading and executing one or more instructions in a computer storage medium to implement the above method.

[0064] It needs to be further explained that, based on the same inventive concept, the present invention also provides a computer storage medium, on which a computer program is stored, and the computer program is executed by a processor to execute the above method. The storage medium can adopt any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electrical, magnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present invention, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, device or device or used in combination with it.

[0065] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0066] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

[0067] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of a method for automatically generating a shoe last spraying path based on point cloud data processing under the inspiration of the present invention. All equal changes and modifications made within the scope of the invention application of the present invention should fall within the scope of the present invention.

Claims

1. A method for automatically generating a shoe last glue spraying path based on point cloud data processing, characterized in that: On the basis of scanning the shoe last to obtain point cloud data, the point cloud data is preprocessed to obtain the spatial motion trajectory point markers and data; then the approximate glue spraying attachment spatial trajectory on the shoe last is obtained through polynomial interpolation; then the orthogonal coordinate system NOA vectors corresponding to the glue spraying attachment spatial trajectory points on all shoe lasts are solved in turn, and the glue spraying spatial trajectory of the end of the robot arm after the NOA vector direction of the shoe last glue spraying trajectory is offset by a certain distance is solved, and the end posture matrix of the robot arm is obtained according to the orthogonal coordinate system NOA vector and the glue spraying spatial trajectory of the end of the robot arm; finally, the inverse kinematics mathematical model is established according to the robot DH parameters, and the end posture matrix of the robot arm is brought into the solution to obtain the glue spraying motion trajectory of the shoe last.

2. The method for automatically generating a shoe last glue spraying path based on point cloud data processing according to claim 1 is characterized in that: When the shoe last is scanned to obtain point cloud data, the fixed base integrated with the shoe last is scanned together to provide a relative position relationship between the workpiece coordinate system and the robot base coordinate system.

3. The method for automatically generating a shoe last glue spraying path based on point cloud data processing according to claim 1, characterized in that: The point cloud data preprocessing includes cutting off redundant point cloud data, and then setting the workpiece coordinate system and the origin on the fixed base based on the known relative position of the shoe last base and the robot, and the XY planes of the workpiece coordinate system and the robot base coordinate system are parallel, and the origin of the workpiece coordinate system is set at the center of the base geometric feature or at a position where the parameters are known.

4. The method for automatically generating a shoe last glue spraying path based on point cloud data processing according to claim 1, characterized in that: In the process of obtaining the approximate glue spraying attachment space trajectory on the shoe last by polynomial interpolation, the number of insertion points between every two derived marking points is not less than 4, so as to ensure that the approximate smooth glue spraying attachment trajectory on the shoe last is obtained. .

5. The method for automatically generating a shoe last glue spraying path based on point cloud data processing according to claim 1, characterized in that: The method of solving the NOA vector of the orthogonal coordinate system corresponding to all the space trajectory points of the glue spraying attachment on the shoe last is specifically as follows: vector, where vector N By using the difference between adjacent points, we can get the vector O The solution condition is that the vector passes through the corresponding point and is perpendicular to the approximate plane. A Then solve according to the right-hand rule.

6. The method for automatically generating a shoe last glue spraying path based on point cloud data processing according to claim 5, characterized in that: The specific solution of the glue spraying space trajectory of the end of the robot arm after the NOA vector direction of the shoe last glue spraying trajectory is offset by a certain distance is: The actual glue spraying space trajectory of the end of the robot arm is obtained by combining the vector and the glue spraying space trajectory on the shoe last. ,in DIS is the offset glue spraying distance.

7. The method for automatically generating a shoe last glue spraying path based on point cloud data processing according to claim 1, characterized in that: The solution to obtain the end position and posture matrix of the robot arm is specifically to perform homogeneous transformation on the obtained position and posture matrices, and multiply them to obtain the position matrix of the end of the robot arm, which is used as the input of the inverse kinematics mathematical model of the robot arm and solves the corresponding joint angle.

8. The method for automatically generating a shoe last glue spraying path based on point cloud data processing according to claim 1, characterized in that: The inverse kinematics mathematical model is established based on the robot DH parameters taking into account the end tool coordinate system.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the method for automatically generating a shoe last glue spraying path based on point cloud data processing as described in any one of claims 1 to 8 are implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for automatically generating a shoe last glue spraying path based on point cloud data processing as described in any one of claims 1 to 8 are implemented.

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