Intelligent spraying technology based on digital model

Abstract

The invention discloses an intelligent spraying technology based on a digital model, which comprises the following steps of: converting a three-dimensional process model generated by a multi-CAD environment into a standard data format, and importing the standard data format into a digital model of a large curved surface component; a kinematic model of the robot is established and subjected to forward and inverse kinematic analysis, then trajectory planning research of the robot is completed on the basis, and finally global and overall trajectory planning of the robot is achieved. According to simulation and track optimization of the spraying process of the spraying robot, enveloping of the spraying face at the tail end of the spraying gun on the surface of the large-curved-surface component is completed, the process from simulation to actual spraying is achieved, and intelligent spraying of the robot on the large-curved-surface component is achieved based on real-time feedback control of a sensor at the tail end of the spraying gun.

Description

Technical Field

[0001] This invention relates to the field of intelligent spraying technology, and in particular to an intelligent spraying technology based on digital models. Background Technology

[0002] The planning of the painting trajectory for the ship's exterior is a crucial part of shipbuilding and plays a vital role. Traditional shipbuilding processes mostly rely on manual painting, which, due to factors such as worker experience, results in inconsistent painting quality. Furthermore, this method suffers from environmental pollution, harm to worker health, long working hours, and high costs.

[0003] There are two methods for trajectory planning of painting robots: manual teaching and offline programming. Manual teaching involves a worker guiding the robot's end effector and programming the robot to repeat expected actions. This method has a long programming cycle and cannot handle complex trajectory planning and control. Offline programming allows trajectory planning of painting robots to be independent of the robot itself. The painting task is completed in software through programming and simulation. This method saves time, improves painting efficiency, improves the working environment, and significantly improves painting quality.

[0004] However, current offline programming is mostly applied to small and medium-sized workpieces, primarily those that are planar. Research on automatic trajectory planning for painting robots on large ship facades still faces many challenges, mainly in the following aspects: The ship facade is large in scale, resulting in a massive amount of mesh model data. Designing a reasonable data structure to represent the model efficiently and complete the trajectory planning task is a pressing issue. The complex structure and varying curvature of the ship facade further complicate the design of the trajectory planning system based on the ship's geometric characteristics and the requirements of the painting process. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an intelligent spraying technology based on digital models, which aims to solve the technical problem that the existing technology is unable to achieve intelligent spraying on large curved surfaces.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: On the one hand, embodiments of this application provide an intelligent spraying technology based on a digital model, specifically including: In ship painting practice, the paint film model sprayed by the gun is an ellipse formed on a plane perpendicular to the gun axis. The coating thickness at different cross-sections in both the spray width and thickness directions follows a β distribution model. The formula is obtained by fitting experimental data. , If the air pressure of the spray gun, nozzle distance, spray flow rate, and mist cone angle are kept constant during the spraying process, then ellipse a and b are constant values. During uniform spraying, H... max For a constant value and inversely proportional to the moving speed v, a, b, and H max It is easy to measure in practice, and the distance x from the center can correspond to a unique coating thickness. Robot motion analysis is performed based on the improved DH method. Forward and inverse kinematics of the spraying robot are established, and forward and inverse kinematics analysis is conducted. Forward kinematics is verified using the robot toolbox in Matlab. Trajectory interpolation of the painting robot is performed using Cartesian space trajectory interpolation and joint space polynomial joint interpolation. An offline programming planning method based on a 3D digital model is adopted. The 3D model of the part to be painted is imported into the painting planning software. By setting the painting area on the outer surface of the component, the painting trajectory planning of the outer surface of the component is completed according to the painting process requirements and the movement range of the painting robot arm.

[0007] To further explain, in the practice of ship painting, the paint film model sprayed by the gun is an ellipse formed on a plane perpendicular to the axis of the spray gun. The major axis is the paint sweep width W, and the minor axis is perpendicular to the spraying speed ν. Here, β1 is the film thickness distribution along the major axis a, and β2 is the film thickness distribution along the minor axis b. The elliptical double β distribution of the finite-range model is closer to the mathematical model of the actual situation. Analysis yields the formula... .

[0008] To further explain, the robot kinematics verification process is as follows: First, the Link, SerialLink, and teach functions in the robot toolbox are used to construct a simulation model of the gantry painting robot with the MDH parameter table. Second, the fkine function in the toolbox is used to calculate the forward kinematics. Finally, the settings of each joint are substituted into the forward kinematics equations to calculate the results and compared with the results obtained by the fkine function.

[0009] To further explain, TRIBON is used to construct the segmented 3D model, and the IGES and STEP formats allow for the transmission of various types of geometric object characteristics, achieving almost distortion-free data transmission between different systems. This is especially useful for very complex segmented 3D geometric models with curved surfaces that require high data transmission accuracy. These models can be imported into the spraying path planning system software as igs;iges or step;stp files. If it is a quasi-3D model from TRIBON, the DXF format can be used for planar views and vector images, and files transmitted in this way have the *.dxf extension.

[0010] To further explain, during the import of external CAD files, when importing simple structural files, the system uses a single-pass algorithm, which reads the file and simultaneously performs the geometric model formation. When importing files with complex data structures, a double-pass algorithm is used: in the first stage, the system reads the file and analyzes the model structure, and in the second stage, it creates the geometric model. All topological references between objects are precisely analyzed. Similarly, in a large number of components, complex objects such as solids and surfaces are formed, and all simple objects such as curves and points within even more complex objects are copied separately as independent objects.

[0011] Therefore, the total number of files loaded is actually greater than the number converted into models. Before importing the quasi-3D model by TRIBON, the internal structure of the segments is removed to greatly speed up the process of reconstructing the geometric model in the second stage.

[0012] To further explain, the painting trajectory planning requires building a robot library. First, a 3D model of the actual painting robot is created. During the drawing process, the painting robot is divided into external axes, robot base, and joint axes. Then, these parts are assembled, and a global coordinate system is established. Finally, each part is exported sequentially as an STL file, and then the STL file is converted into an OSD file. Then, the robot code for the multi-linkage painting robot is written. The program mainly includes the robot's DH information parameters, the coordinate axes of the external axes, robot base, and joint axes, joint types, position constraints, positive and negative directions of rotation, parent-child relationships, etc., thus obtaining a robot library corresponding to the actual painting robot. This paper describes the spraying tool for the end effector robot in offline programming software. The process involves drawing a spray gun model, defining the workpiece coordinate system, saving it as an STL file, defining the exported STL graphic file at the end effector of the robotic arm through code, and finally representing the structural dimensions of the spray gun model in the code to complete the creation of the spraying robot library.

[0013] To further explain, the Cartesian space trajectory interpolation is implemented in MATLAB: Assuming the coordinates of spray point 1 are (0,0,0) and the coordinates of spray point 2 are (x,y,z), and the spraying speed of the spray gun is v, the increments Δx, Δy, and Δz of the x, y, and z axes are calculated respectively, thereby completing the trajectory interpolation between spray point 1 and spray point 2.

[0014] An electronic device includes a processor and a memory, wherein the memory stores a computer program, the computer program being loaded and executed by the processor to implement the aforementioned intelligent spraying technology based on a digital model.

[0015] A computer-readable storage medium storing a computer program, which is loaded and executed by a processor to implement the above-described intelligent spraying technology based on a digital model.

[0016] In summary, the advantages of this invention compared to existing technologies are as follows: This research is based on a three-dimensional digital model of a large curved surface workpiece, and conducts research on path planning and intelligent spraying technology for automated robotic spraying. The three-dimensional process model generated by multiple CAD environments is converted into a standard data format and imported into the digital model of the large curved surface component. A kinematic model of the robot is established, and forward and inverse kinematic analysis is performed. Based on this, the robot's trajectory planning is studied, ultimately achieving global and overall trajectory planning for the robot. Based on the simulation and trajectory optimization of the spraying robot's spraying process, the envelope of the spraying surface at the end of the spray gun in different areas of the large curved surface component is completed, realizing the process from simulation to actual spraying. Based on real-time feedback control from the spray gun end sensor, intelligent spraying of the large curved surface component by the robot is achieved. Attached Figure Description

[0017] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of the invention are illustrated in the drawings by way of example and not limitation, wherein: Figure 1 This is a model diagram for spray painting. Figure 2 This is a schematic diagram of the spraying robot's machine bay. Detailed Implementation

[0018] The principles and spirit of the invention will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are given merely to enable those skilled in the art to better understand and implement the invention, and are not intended to limit the scope of the invention in any way. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art. The terms "embodiment" or "implementation" in this specification may refer to one embodiment or a combination of embodiments or implementations.

[0019] Those skilled in the art will recognize that embodiments of the present invention can be implemented as a system, apparatus, device, method, or computer program product. Therefore, this disclosure can be specifically implemented in the following forms: entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0020] This study investigates path planning and intelligent spraying technology for automated robotic spraying based on a 3D digital model of a large curved surface workpiece. The 3D process model generated from multiple CAD environments is converted to a standard data format and imported into the digital model of the large curved surface component. A kinematic model of the robot is established, and forward and inverse kinematics analyses are performed. Based on this, trajectory planning for the robot is studied, ultimately achieving global and overall trajectory planning. Through simulation and trajectory optimization of the spraying robot's spraying process, the envelope of the spraying surface at the end of the spray gun in different regions on the surface of the large curved surface component is determined, realizing the process from simulation to actual spraying. Based on real-time feedback control from the spray gun end sensor, intelligent spraying of the large curved surface component by the robot is achieved.

[0021] According to one embodiment of the present invention, a digital model-based intelligent spraying technology is proposed, specifically including: 1. Spraying Digital Model Analysis An ideal finite-range β-distribution model provides a coating thickness deposition model, meaning that the coating thickness at different cross-sections along both the spray width and spray thickness directions follows a β-distribution model, resulting in the following formula: , In the formula: H—coating thickness at any point; H max —Maximum thickness; W —Spray width; x —Distance between the center of the spray width and the center of the spray width, −w / 2≤x≤w / 2.

[0022] In ship painting practice, the paint film produced by the spray gun is an ellipse formed on a plane perpendicular to the axis of the spray gun, such as... Figure 1 As shown, the major axis is the paint sweep width W, and the minor axis is perpendicular to the spraying speed ν. Here, β1 represents the film thickness distribution along the major axis a, and β2 represents the film thickness distribution along the minor axis b. The elliptic double β distribution of the finite-range model is closer to the actual mathematical model, as shown in Formula 2 below: , Formula 3 was obtained by fitting the experimental data as follows: .

[0023] During the spraying process, the air pressure of the spray gun, the nozzle distance, the spray flow rate, and the mist cone angle are kept constant. When the ellipse a and b are constant values ​​and the spraying speed is uniform, H max It is a constant and inversely proportional to the moving speed v. a, b, H max It is easy to measure in practice, and the distance x from the center can correspond to a unique coating thickness.

[0024] 2. Robot Motion Analysis Based on the improved DH method, forward and inverse kinematics of the spraying robot were established, forward and inverse kinematics analysis was performed, and forward kinematics verification was carried out using the Robotics Toolbox in Matlab.

[0025] The verification process is as follows: First, the Link, SerialLink, and teach functions in the robot toolbox are used to construct a simulation model of the gantry painting robot with the MDH parameter table. Second, the fkine function in the toolbox is used to calculate the forward kinematics. Finally, the settings of each joint are substituted into the forward kinematics equations to calculate the results and compared with the results obtained by the fkine function.

[0026] Spraying trajectory planning The spraying path planning employs an offline programming planning method based on a 3D digital model. This involves importing the segmented 3D model generated from the shipyard's production design into intelligent spraying path planning software for the component's outer surface. By defining the coating area on the component's outer surface and considering coating process requirements (film thickness) and the movement range of the coating robotic arm, the software automatically plans the spraying trajectory using the 3D component digital model. Simultaneously, it automatically generates instructions for the controller to issue to each joint for coordinated movement and spraying operations.

[0027] If the movement trajectory may encounter situations such as collisions with segmented components, inaccessibility, or singularities, manual intervention can be used to optimize the movement trajectory of the robot's end spray gun and eliminate the aforementioned unreasonable situations such as collisions, inaccessibility, and singularities.

[0028] 3.1 Importing 3D Models Production design can be completed using TRIBON or other software, constructing segmented 3D or quasi-3D models. The IGES and STEP formats allow for the transfer of various geometric object characteristics, achieving near-distortion data transmission between different systems. This is particularly useful for highly complex segmented 3D geometric models requiring high data transmission accuracy, which can be imported into the spraying path planning system software as .igs; .iges or .step; .stp files. For quasi-3D models using TRIBON, planar views and vector images can also be transmitted using the DXF format; these files have the *.dxf extension.

[0029] During the import of external CAD files, the system uses a one-pass algorithm when importing simple structural files, meaning it reads the file and simultaneously performs geometric model formation; when importing files with complex data structures, it uses a double-pass algorithm. In the first stage, the system reads the file and analyzes the model structure; in the second stage, it creates the geometric model. All topological references between objects are precisely analyzed. Similarly, in a large number of components, complex objects (solids, faces) are formed, and all simple objects (curves / points, etc.) within more complex objects are copied separately as independent objects. Therefore, the total number of objects loaded from the file is actually greater than the number converted into a model. Before importing the quasi-3D model from TRIBON, segmented internal structures are removed to significantly accelerate the process of reconstructing the geometric model in the second stage.

[0030] 3.2 Spray gun motion planning First, a 3D model of the painting robot is created. To minimize the parent-child relationships between parts, some parts can be simplified or omitted. During the drawing process, the painting robot is divided into external axes (X-axis, Y-axis, Z-axis, which can be expanded as needed), a robot base, and joint axes (J1, J2, J4, J5, J6 axes), as shown in the figure. These parts are then assembled, and a global coordinate system (base coordinate system) is established. Finally, each part is exported sequentially as an STL file. The STL file is then converted to an OSD file, and the robot code for the multi-linkage painting robot is written. The program mainly includes the robot's DH information parameters, the coordinate axes of the external axes, robot base, J1, J2, J4, J5, and J6 axes, joint types, position constraints, positive and negative directions of rotation, and parent-child relationships, thus obtaining a robot library corresponding to the actual painting robot.

[0031] This paper describes the spraying tool for the end effector robot in offline programming software. The process involves drawing a spray gun model, defining the workpiece coordinate system, saving it as an STL file, defining the exported STL graphic file at the end effector of the robotic arm through code, and finally representing the structural dimensions of the spray gun model in the code to complete the creation of the spraying robot library.

[0032] The trajectory calculation in the offline programming software uses functions such as obstacle avoidance and singularity avoidance to process the data and then export a post-processing file. Finally, the post-processing file is executed in the controller to verify the effectiveness and correctness of the method.

[0033] 3.3 Spraying trajectory optimization Based on the simulation and trajectory optimization results of the spraying robot, a polynomial joint interpolation method is used to connect each area, and problems such as obstacle avoidance, unreachable areas, and singularity avoidance are handled to complete the envelope of the spraying surface of the large curved component surface divided into areas by the spray gun end. The robot is given coordinate information, point-to-point, straight line planning, arc planning, dynamic parameters, spray gun on / off, point information, speed, acceleration and other information.

[0034] The trajectory interpolation of the painting robot is performed using Cartesian space trajectory interpolation and joint space polynomial joint interpolation. Cartesian space trajectory interpolation is implemented in MATLAB: assuming the coordinates of spray point 1 are (0,0,0) and the coordinates of spray point 2 are (x,y,z), and the spray gun speed is 100mm / s, the increments Δx, Δy, and Δz along the x, y, and z axes are calculated respectively, thus completing the trajectory interpolation between spray point 1 and spray point 2. Joint space polynomial joint interpolation is used for transitions between different regions. Since the multi-degree-of-freedom painting robot undergoes multi-axis coupled motion during movement, the load on each joint changes continuously with time. To ensure a smooth transition in these transitions, a higher-order polynomial method is used for joint space interpolation.

[0035] In the actual spraying process, the robot relies on external sensor information and the control system to form a closed-loop control, which adjusts the robot in real time to maintain the best spraying posture, avoid spraying collisions, and maintain the best parameters such as spraying distance, spray gun angle, spraying speed and spraying pressure, so as to realize the intelligent spraying of complex surfaces by the multi-degree-of-freedom intelligent spraying system equipment for large curved surfaces.

[0036] According to another embodiment of the present invention, a trajectory planning method for continuous zoned automatic spraying is proposed, specifically including: Based on the 3D model of large curved surface components, offline programming software is used to divide large curved surface components such as ships into several single-area surfaces. Then, trajectory planning is performed on each single-area surface, and finally, the trajectory planning of the whole area is formed by connecting the single areas.

[0037] (1) A robot spraying simulation system was used to carry out the spraying simulation of robots for large curved surface components. The three-dimensional CAD model of the ultra-long curved surface component was input, and the spraying area of ​​the component was divided into zones. Through graphical programming, editing, optimization and debugging, the spraying trajectory of the robot in each zone was generated, and then the zones were connected to form a global trajectory plan. The spraying paths were classified in space. The robot end pose on each type of path is a relatively fixed value. By establishing a user coordinate system consistent with reality, the robot end pose values ​​on all paths can be obtained.

[0038] (2) When the spraying robot reaches the designated station, control the robot to move its end to the marker point of the designated spraying area. Based on the measurement information of the sensor system equipped at the end of the spray gun, ensure that the direction of the spray gun coincides with the normal vector of the workpiece through linear positioning. Transmit the program and base parameters to the robot controller through OPC UA communication to complete the verification and compensation of the robot spatial coordinate system and the workpiece coordinate system, and improve the rationality of the host computer program scheme.

[0039] (3) The robot spraying trajectory is simulated and optimized. Seventh-order polynomial joint interpolation is used to connect the various areas, and obstacle avoidance and singularity avoidance are performed. When the robot is running, the robot control system converts the coordinates of the program path points into the joint angle vectors of each axis of the robot through motion inverse operation. At the same time, the peripheral ranging and obstacle avoidance sensors monitor the robot end posture and workpiece position in real time. The host computer sets the spatial error limit by monitoring the end posture and calculates the robot's three-dimensional spatial coordinate compensation by combining the origin of the base coordinate system. The compensation value is transmitted to the robot system background scanning program through the robot system's underlying API interface. During the operation, the robot dynamically adjusts the end posture through offset commands to meet the spraying process requirements and make the robot run along the optimal operation path.

[0040] According to another embodiment of the present invention, an electronic device is provided, the electronic device including a processor and a memory, the memory storing a computer program, the computer program being loaded and executed by the processor to realize the above-described intelligent spraying technology based on digital models.

[0041] According to another embodiment of the present invention, a computer-readable storage medium is provided, wherein a computer program is stored in the storage medium, and the computer program is loaded and executed by a processor to realize the above-described intelligent spraying technology based on a digital model.

[0042] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the scope of protection of the present invention, which is determined by the appended claims.

Claims

1. A digital model-based intelligent spraying technology, characterized in that, Specifically, it includes: In ship painting practice, the paint film model sprayed by the gun is an ellipse formed on a plane perpendicular to the gun axis. The coating thickness at different cross-sections in both the spray width and thickness directions follows a β distribution model. The formula is obtained by fitting experimental data. ， If the air pressure of the spray gun, nozzle distance, spray flow rate, and mist cone angle are kept constant during the spraying process, then ellipse a and b are constant values. During uniform spraying, H... max For a constant value and inversely proportional to the moving speed v, a, b, and H max It is easy to measure in practice, and the distance x from the center can correspond to a unique coating thickness. Robot motion analysis is performed based on the improved DH method. Forward and inverse kinematics of the spraying robot are established, and forward and inverse kinematics analysis is conducted. Forward kinematics is verified using the robot toolbox in Matlab. Trajectory interpolation of the painting robot is performed using Cartesian space trajectory interpolation and joint space polynomial joint interpolation. An offline programming planning method based on a 3D digital model is adopted. The 3D model of the part to be painted is imported into the painting planning software. By setting the painting area on the outer surface of the component, the painting trajectory planning of the outer surface of the component is completed according to the painting process requirements and the movement range of the painting robot arm.

2. The intelligent spraying technology based on a digital model according to claim 1, characterized in that, In ship painting practice, the paint film model sprayed by the spray gun is an ellipse formed on a plane perpendicular to the spray gun axis. The major axis is the paint sweep width W, and the minor axis is perpendicular to the spraying speed ν. Here, β1 represents the film thickness distribution along the major axis a, and β2 represents the film thickness distribution along the minor axis b. The elliptical double β distribution of the finite-range model is closer to the mathematical model of the actual situation. Analysis yields the formula... 。 3. The intelligent spraying technology based on a digital model according to claim 1, characterized in that, The robot kinematics verification process is as follows: First, the Link, SerialLink, and teach functions in the robot toolbox and the MDH parameter table are used to construct a simulation model of the gantry painting robot. Second, the fkine function in the toolbox is used to calculate the forward kinematics. Finally, the settings of each joint are substituted into the forward kinematics equations to calculate the results and compared with the results obtained by the fkine function.

4. The intelligent spraying technology based on a digital model according to claim 1, characterized in that, The segmented 3D model is constructed using TRIBON, and the IGES and STEP formats allow the transmission of various types of geometric object characteristics, achieving almost distortion-free data transmission between different systems. This is especially useful for very complex segmented 3D geometric models with curved surfaces that require high data transmission accuracy, using igs; iges or step; Import files with the .stp extension into the spray path planning system software; if it is a quasi-3D model of TRIBON, it can be transmitted as a plan view and vector image using DXF format. Files transmitted in this way have the *.dxf extension.

5. The intelligent spraying technology based on a digital model according to claim 1, characterized in that, During the import of external CAD files, the system uses a single-pass algorithm when importing simple structural files, which reads the file and simultaneously performs geometric model formation. When importing files with complex data structures, a double-pass algorithm is used: in the first stage, the system reads the file and analyzes the model structure; in the second stage, it creates the geometric model. All topological references between objects are precisely analyzed. Similarly, in a large number of components, complex objects such as solids and surfaces are formed, and all simple objects such as curves and points in more complex objects are copied separately as independent objects. Therefore, the total number of objects loaded from the file is actually greater than the number converted into a model. Before importing the quasi-3D model from TRIBON, the segmented internal structure is removed to greatly accelerate the process of reconstructing the geometric model in the second stage.

6. The intelligent spraying technology based on a digital model according to claim 1, characterized in that, The painting trajectory planning process requires building a robot library. First, a 3D model of the actual painting robot is created. During the modeling process, the painting robot is divided into external axes, robot base, and joint axes. These parts are then assembled, and a global coordinate system is established. Finally, each part is exported sequentially as an STL file, and the STL file is converted to an OSD file. Then, the robot code for the multi-linkage painting robot is written. The program mainly includes the robot's DH information parameters, the coordinate axes of the external axes, robot base, and joint axes, joint types, position constraints, positive and negative directions of rotation, and parent-child relationships, thus obtaining a robot library corresponding to the actual painting robot. This paper describes the spraying tool for the end effector robot in offline programming software. The process involves drawing a spray gun model, defining the workpiece coordinate system, saving it as an STL file, defining the exported STL graphic file at the end effector of the robotic arm through code, and finally representing the structural dimensions of the spray gun model in the code to complete the creation of the spraying robot library.

7. The intelligent spraying technology based on a digital model according to claim 1, characterized in that, The Cartesian space trajectory interpolation is implemented in MATLAB: Assuming the coordinates of spray point 1 are (0,0,0) and the coordinates of spray point 2 are (x,y,z), and the spraying speed of the spray gun is v, the increments Δx, Δy, and Δz of the x, y, and z axes are calculated respectively, thereby completing the trajectory interpolation between spray point 1 and spray point 2.

8. An electronic device, characterized in that, include: It includes a processor and a memory, wherein the memory stores a computer program, which is loaded and executed by the processor to implement the intelligent spraying technology based on a digital model as described in any one of claims 1-7.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which is loaded and executed by a processor to implement the intelligent spraying technology based on a digital model as described in any one of claims 1-7.

Images