Aircraft surface automatic spraying method based on heavy-load robot

Abstract

The invention belongs to the technical field of aircraft coating processing, and particularly relates to an aircraft surface automatic spraying method based on a heavy-load robot, which comprises the following steps: carrying out geometric modeling on an aircraft body workpiece; a spray gun tool coordinate system is calibrated, and TCP coordinate optimization calculation is carried out by fusing spray gun 3D model parameters and flame long distance values; constructing a global workpiece coordinate system dynamic database; automatic coverage of a multi-layer U-shaped reciprocating spraying path is achieved through a path planning algorithm; after a fixed spraying distance parameter is set, the spraying software process package generates a robot track, and path simulation is carried out; a robot movement track program is generated by combining parameters of coating types, plasma flame lengths, spraying angles and spraying speeds; and a low-speed transition point is inserted into a track alarm point, and dynamic smooth connection of a spraying path is achieved. The spraying efficiency of the large machine body workpiece is improved, and manual intervention is reduced; and the adaptability is high, and spraying objects of different shapes and sizes can be rapidly dealt with.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft coating processing, and specifically relates to an automated spraying method for aircraft surfaces based on a heavy-duty robot. Background Art

[0002] During the operation of an aircraft, the coating on the aircraft surface may be affected by various factors, such as wind, rain, climate change, external collisions, etc., resulting in damage to the coating, such as scratches, corrosion, peeling, etc. To ensure the appearance quality and aerodynamic performance of the aircraft, it is necessary to cover special coatings on the body surface or key parts during production. Traditional spraying methods have great limitations, such as complex operations, low precision, low efficiency, etc. Existing spraying robots usually need to set the spraying trajectory through manual teaching or programming. The irregular and diverse aircraft body parts and some process requirements for high-temperature spraying also limit the production output of the manual teaching mode. High temperatures and toxic dust will also pose hazards to the health of workers. When using traditional special-purpose machines or spraying robots to deal with such products with complex shapes or variable but high-precision requirements, there are problems such as low efficiency, poor precision, difficult robot adjustment, and the high cost and long construction period caused by the loss of special coatings and expensive body parts during the debugging process also seriously affect the output. Currently, aircraft coating spraying is mostly carried out manually. The traditional robot teaching mode is difficult to adapt to the rapid switching of different batches of products, and there are disadvantages such as low spraying precision, blurred boundaries, and long and difficult-to-modify robot programs. Summary of the Invention

[0003] The purpose of the present invention is to provide an automated spraying method for aircraft surfaces based on a heavy-duty robot to overcome the disadvantages of low spraying precision, high-temperature and toxic environments of special coatings, and heavy spraying tools that cannot be produced manually, and long and difficult-to-modify robot programs.

[0004] The technical solution adopted by the present invention to achieve the above purpose is: an automated spraying method for aircraft surfaces based on a heavy-duty robot, including the following steps:

[0005] 1) Geometrically model the aircraft body workpiece to generate a digital model including surface shape, size, and complexity;

[0006] 2) Based on the robot tool coordinate system calibration algorithm, establish a dynamic mapping model of multiple tool TCP points, calibrate the spray gun tool coordinate system by the four-point method, and perform TCP coordinate optimization calculation by integrating the 3D model parameters of the spray gun and the flame length distance value;

[0007] 3) Combine the three-point method calibration and the turntable pose parameters to construct a dynamic database of the global workpiece coordinate system;

[0008] 4) Generate the robot TCP trajectory based on a fixed spraying distance and the normal projection rule, and use the path planning algorithm to automatically cover the multi-layer U-shaped reciprocating spraying path;

[0009] 5) After setting a fixed spraying distance parameter, the spraying software process package generates the robot trajectory and performs visual simulation optimization. If the simulated robot trajectory can all be reached, execute step 6); otherwise, return to step 4);

[0010] 6) Combine the parameters of the coating type, plasma flame length, spraying angle, and speed to generate the robot motion trajectory program;

[0011] 7) Insert low-speed transition points at the trajectory alarm points through the kinematic interpolation algorithm to achieve dynamic smooth connection of the spraying path.

[0012] The specific content of step 2) is as follows:

[0013] 2-1) Define multiple tool TCP points according to the spray gun type and the properties of the spraying material, and generate the initial calibration point set in the robot working envelope space through the four-point method;

[0014] 2-2) Based on the Z-axis parameter of the tool system of the spray gun 3D model, use the flame length compensation algorithm to correct the TCP coordinates to meet the constraint condition that the flame length error ≤ 1 cm:

[0015] TCP 终 =TCP 初始 +ΔZ·R Z (θ)

[0016] where ΔZ is the flame length compensation amount, and R Z (θ) is the rotation matrix about the Z axis.

[0017] The specific content of step 3) is as follows:

[0018] 3-1) According to the workpiece coordinate system calibration method, obtain the workpiece clamping position through the turntable pose sensor, and establish a right-handed coordinate system with the workpiece surface feature point as the origin;

[0019] 3-2) Use the three-point method to calibrate the parameters to generate the workpiece coordinate system transformation matrix, that is:

[0020]

[0021] where R is the rotation matrix and t is the translation vector.

[0022] 3-3) Store different workpiece coordinate systems as global variables and match and call them, that is:

[0023] 3-3-1) When changing the workpiece, automatically call the corresponding coordinate system data according to the workpiece number;

[0024] 3-3-2) Monitor the pose offset of the turntable in real time. If the offset exceeds the tolerance range, trigger the recalibration of the coordinate system.

[0025] 3-3-3) Store the historical calibration data, predict the deviation trend of the calibration parameters through machine learning algorithms, and optimize the calibration efficiency.

[0026] The path planning algorithm performs the following steps:

[0027] 4-1) Extract the geometric information of the area to be sprayed from the 3D model, and generate a surface normal vector field based on the normal vector calculation module.

[0028] 4-2) Starting from the normal center of the tool end of the spray gun, generate an initial set of TCP points along the direction of the normal vector field at a fixed flame length distance.

[0029] 4-3) Use the curve fitting algorithm to smooth the discrete TCP points to form a continuous spraying path.

[0030] 4-4) Adjust the overlap rate of the U-shaped reciprocating motion of the heavy-duty robot according to the coating thickness distribution requirements.

[0031] The specific content of step 4-4) is as follows:

[0032] a. Calculate the local path spacing according to the curvature change rate of the surface:

[0033] d = d base ·(1 + k·|κ|)

[0034] where d base is the reference spacing, k is the curvature influence factor, and κ is the local curvature.

[0035] b. Automatically increase the U-shaped path density in the high-curvature area exceeding the curvature threshold to ensure the uniformity of the coating.

[0036] The visualization simulation optimization in step 5) specifically includes:

[0037] 5-1) In the simulation interface, display the matching degree between the spraying trajectory and the workpiece surface in real time, and identify the areas with abnormal coating thickness.

[0038] 5-1-1) Import the 3D model of the workpiece, TCP point positions and motion parameters into the simulation software interface.

[0039] 5-1-2) Based on the spraying parameters and coating properties, calculate the coating thickness distribution through a physical model.

[0040] 5-1-3) Intuitively display the thickness distribution on the surface of the 3D model in the form of color gradients or numerical annotations.

[0041] 5-1-4) Compare with the preset thickness threshold, mark the areas that exceed the allowable range, and generate a coordinate report of the abnormal areas;

[0042] 5-2) Automatically adjust the spraying speed or angle parameters according to the simulation results, and generate an optimized trajectory;

[0043] 5-2-1) Analyze the associated spraying parameters according to the position of the abnormal area and the thickness deviation direction;

[0044] 5-2-2) Dynamic adjustment rules:

[0045] The deviation direction leads to an over-thick area: reduce the spraying speed or increase the distance between the spray gun and the workpiece surface;

[0046] The deviation direction leads to an under-thin area: increase the spraying speed or reduce the tilt angle of the spray gun to increase the coverage area;

[0047] 5-2-3) The spraying software process package re-plans the spraying path based on the adjusted parameters, imports the new trajectory into the simulation module, and updates the coating thickness prediction result;

[0048] 5-3) Verify the optimization effect through iterative simulation until the coating uniformity meets the preset threshold.

[0049] The specific steps of step 7) are as follows:

[0050] 7-1) Generate a transition trajectory by using quintic polynomial interpolation in the robot joint space;

[0051] 7-2) Dynamically adjust the interpolation period according to the servo motor torque feedback to avoid overspeed or overload;

[0052] 7-3) Ensure the spraying integrity of the transition point connection area through the path coverage verification algorithm.

[0053] In step 7-2), dynamically adjusting the interpolation period according to the servo motor torque feedback is specifically as follows:

[0054] 7-2-1) Real-time feedback torque and speed data of the servo motor through the robot controller; monitor whether the load of each joint is close to the safety threshold;

[0055] 7-2-2) Dynamic adjustment strategy:

[0056] Overspeed handling: If the speed of a certain joint exceeds the preset value, extend the interpolation period, that is, reduce the movement speed;

[0057] Overload handling: If the torque exceeds the limit, shorten the length of the transition section trajectory or reduce the acceleration;

[0058] 7-2-3) Adjust according to the interpolation period adjustment formula, that is:

[0059]

[0060] where T base is the base period, and Δτ is the difference between the current torque and the maximum allowable torque;

[0061] 7-2-4) Re-run the transition section after adjustment, continuously monitor the feedback data until the torque and speed are stable within the safe range.

[0062] The specific steps of step 7-3) are as follows:

[0063] 7-3-1) Superimpose the adjusted trajectory on the original planned path, and compare the projected areas of the two on the surface of the 3D model; use the rasterization algorithm to detect whether there are uncovered areas;

[0064] 7-3-2) Calculate the U-shaped path overlap rate of the transition section trajectory to ensure that the coating thickness requirement is met;

[0065] If the local density is insufficient, visually inspect the coating uniformity of the transition area through color mapping, mark the defective points, and after increasing the path point density of the transition section, execute step 6-3-2); otherwise, execute step 6-3-3);

[0066] 7-3-3) Load the new trajectory into the spraying software process package and run the coating thickness prediction model.

[0067] An automatic spraying system for an aircraft surface based on a heavy-duty robot, comprising: a spraying software process package, a laser scanner, a multi-axis motion controller, and a trajectory simulation module;

[0068] The spraying software process package includes: a 3D modeling module, a coordinate calibration module, and a trajectory planning module;

[0069] The 3D modeling module is used to perform geometric modeling on the aircraft body workpiece to generate a digital model including surface shape, size, and complexity;

[0070] The coordinate calibration module is used to establish a dynamic mapping model of multiple tool TCP points, calibrate the spray gun tool coordinate system by the four-point method, and at the same time, calibrate the workpiece coordinate system and manage the dynamic mapping model of TCP points and the global workpiece coordinate system database;

[0071] The trajectory planning module is used to generate the robot TCP trajectory based on a fixed spraying distance and a normal projection rule, and use the path planning algorithm to automatically cover the multi-layer U-shaped reciprocating spraying path;

[0072] The laser scanner is arranged near the tooling of the robot workstation so that its field of view covers the entire tooling, for three-dimensional data acquisition of the workpiece, and is sent to the spraying software process package for geometric modeling of the workpiece;

[0073] The multi-axis motion controller is used to execute the spraying parameter optimization algorithm and dynamically adjust the spraying speed and angle according to the optimization results; it also inserts low-speed transition points at the trajectory alarm points through the kinematic interpolation algorithm to achieve dynamic smooth connection of the spraying path;

[0074] The trajectory simulation module is used to perform interference simulation on the trajectory to avoid interference paths.

[0075] The present invention has the following beneficial effects and advantages:

[0076] 1. The present invention improves the spraying efficiency of large body workpieces and reduces manual intervention; moreover, it has strong adaptability and can quickly respond to spraying objects of different shapes and sizes.

[0077] 2. The present invention solves the problem that in the process of high-temperature plasma spraying production, through offline simulation, programming, and no-load testing, the operator can be kept away from the high-temperature and toxic environment, and the spraying process parameters can be safely and flexibly adjusted remotely to adapt to the changes of a variety of complex-shaped spraying objects.

[0078] 3. The method of the present aspect realizes the automated production of the spraying process for large aircraft components using a large-load robot under high-temperature and high-speed conditions, greatly reducing the loss of special coatings and expensive body components during the debugging and testing process in the traditional production mode, and improving production safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 It is a schematic flow chart of the robot calibration and path automatic generation system of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0080] The following further describes the present invention in detail with reference to the drawings and embodiments.

[0081] As Figure 1 shown, it is a schematic flow chart of the robot calibration and path automatic generation system of the present invention; a method for automatic spraying on the surface of an aircraft based on a heavy-duty robot of the present invention includes the following steps:

[0082] 1) Geometrically model the aircraft body workpiece to generate a digital model including surface shape, size, and complexity;

[0083] 2) Based on the robot tool coordinate system calibration algorithm, establish a dynamic mapping model of multiple tool TCP points, calibrate the spray gun tool coordinate system by the four-point method, and perform TCP coordinate optimization calculation by integrating the spray gun 3D model parameters and the flame length distance value;

[0084] 2-1) Define multiple tool TCP points according to the spray gun type and the properties of the spraying material, and generate an initial set of calibration points in the robot working envelope space through the four-point method;

[0085] 2-2) Based on the Z-axis parameter of the tool system of the 3D model of the spray gun, use the flame length compensation algorithm to correct the TCP coordinates to meet the constraint condition that the flame length error ≤ 1 cm:

[0086] TCP 终 = TCP 初始 + ΔZ·R Z (θ)

[0087] where ΔZ is the flame length compensation amount, and R Z (θ) is the rotation matrix about the Z axis.

[0088] 3) Combine the three-point calibration and the turntable pose parameters to construct a dynamic database of the global workpiece coordinate system;

[0089] 3-1) According to the workpiece coordinate system calibration method, obtain the workpiece clamping position through the turntable pose sensor, and establish a right-handed coordinate system with the workpiece surface feature point as the origin;

[0090] 3-2) Use the three-point calibration parameters to generate the workpiece coordinate system transformation matrix, that is:

[0091]

[0092] where R is the rotation matrix and t is the translation vector.

[0093] 3-3) Store different workpiece coordinate systems as global variables and match and call them, that is:

[0094] 3-3-1) When replacing the workpiece, automatically call the corresponding coordinate system data according to the workpiece number;

[0095] 3-3-2) Real-time monitor the turntable pose offset. If the offset exceeds the tolerance range, trigger the coordinate system to be recalibrated;

[0096] 3-3-3) Store the historical calibration data, predict the deviation trend of the calibration parameters through the machine learning algorithm, and optimize the calibration efficiency.

[0097] 4) Generate the robot TCP trajectory based on the fixed spraying distance and the normal projection rule, and use the path planning algorithm to automatically cover the multi-layer U-shaped reciprocating spraying path;

[0098] For the path planning algorithm, perform the following steps:

[0099] 4-1) Extract the geometric information of the area to be sprayed from the 3D model, and generate a surface normal vector field based on the normal vector calculation module;

[0100] 4-2) Starting from the nozzle center of the spray gun, generate an initial TCP point set along the direction of the normal vector field at a fixed flame length distance;

[0101] 4-3) Use the curve fitting algorithm to smooth the discrete TCP points to form a continuous spraying path;

[0102] 4-4) According to the requirements of the coating thickness distribution, adjust the overlap rate of the U-shaped reciprocating motion of the heavy-duty robot.

[0103] a. Calculate the local path spacing according to the surface curvature change rate:

[0104] d = d base ·(1 + k·|κ|)

[0105] where d base is the reference spacing, k is the curvature influence factor, and κ is the local curvature;

[0106] b. Automatically increase the U-shaped path density in the high-curvature area beyond the curvature threshold to ensure the coating uniformity.

[0107] 5) After setting a fixed spraying distance parameter, the spraying software process package generates the robot trajectory and conducts visual simulation optimization. If the simulated robot trajectory can all reach, execute step 6); otherwise, return to step 4);

[0108] The visual simulation optimization specifically includes:

[0109] 5-1) Real-time display the matching degree between the spraying trajectory and the workpiece surface in the simulation interface, and identify the areas with abnormal coating thickness;

[0110] 5-1-1) Import the 3D model of the workpiece, TCP point positions and motion parameters into the simulation software interface;

[0111] 5-1-2) Based on the spraying parameters and coating properties, calculate the coating thickness distribution through the physical model;

[0112] 5-1-3) Intuitively display the thickness distribution on the surface of the 3D model in the form of color gradient or numerical annotation;

[0113] 5-1-4) Compare with the preset thickness threshold, mark the areas beyond the allowable range, and generate an abnormal area coordinate report;

[0114] 5-2) Automatically adjust the spraying speed or angle parameters according to the simulation results to generate an optimized trajectory;

[0115] 5-2-1) Analyze the associated spraying parameters according to the position of the abnormal area and the deviation direction of the thickness;

[0116] 5-2-2) Dynamic adjustment rules:

[0117] The deviation direction leads to an over-thick area: reduce the spraying speed or increase the distance between the spray gun and the workpiece surface;

[0118] The deviation direction leads to an under-thin area: increase the spraying speed or reduce the tilt angle of the spray gun to increase the coverage area;

[0119] 5-2-3) Based on the adjusted parameters, the spraying software process package re-plans the spraying path, imports the new trajectory into the simulation module, and updates the coating thickness prediction result;

[0120] 5-3) Verify the optimization effect through iterative simulation until the coating uniformity meets the preset threshold.

[0121] 6) Combine the parameters of the coating type, plasma flame length, spraying angle and speed to generate the robot motion trajectory program;

[0122] 7) Insert low-speed transition points at the trajectory alarm points through the kinematic interpolation algorithm to achieve dynamic smooth connection of the spraying path.

[0123] 7-1) Generate a transition trajectory by using quintic polynomial interpolation in the robot joint space;

[0124] 7-2) Dynamically adjust the interpolation period according to the servo motor torque feedback to avoid overspeed or overload;

[0125] 7-2-1) Real-time feedback the torque and speed data of the servo motor through the robot controller; monitor whether the load of each joint is close to the safety threshold;

[0126] 7-2-2) Dynamic adjustment strategy:

[0127] Overspeed handling: If the speed of a certain joint exceeds the preset value, extend the interpolation period, that is, reduce the movement speed;

[0128] Overload handling: If the torque exceeds the limit, shorten the length of the transition section trajectory or reduce the acceleration;

[0129] 7-2-3) Adjust according to the interpolation period adjustment formula, that is:

[0130]

[0131] where, T base is the basic period, and Δτ is the difference between the current torque and the maximum allowable torque;

[0132] 7-2-4) After adjustment, run the transition section again and continuously monitor the feedback data until the torque and speed are stable within the safe range.

[0133] 7-3) Ensure the spraying integrity of the transition point connection area through the path coverage verification algorithm.

[0134] 7-3-1) Overlay the adjusted trajectory with the original planned path and compare the projected areas of the two on the surface of the 3D model; use the rasterization algorithm to detect whether there are uncovered areas.

[0135] 7-3-2) Calculate the U-shaped path overlap rate of the transition section trajectory to ensure that the coating thickness requirement is met.

[0136] If the local density is insufficient, check the coating uniformity of the transition area through color mapping visualization, mark the defect points, and after increasing the path point density of the transition section, execute step 6-3-2); otherwise, execute step 6-3-3).

[0137] 7-3-3) Load the new trajectory in the spraying software process package and run the coating thickness prediction model.

[0138] An automated spraying system for an aircraft surface based on a heavy-duty robot according to the present invention includes: a spraying software process package, a laser scanner, a multi-axis motion controller, and a trajectory simulation module.

[0139] The spraying software process package includes: a 3D modeling module, a coordinate calibration module, and a trajectory planning module.

[0140] The 3D modeling module is used to perform geometric modeling on the aircraft body workpiece to generate a digital model including surface shape, size, and complexity.

[0141] The coordinate calibration module is used to establish a dynamic mapping model of multiple tool TCP points, calibrate the spray gun tool coordinate system by the four-point method, and at the same time, calibrate the workpiece coordinate system and manage the dynamic mapping model of TCP points and the global workpiece coordinate system database.

[0142] The trajectory planning module is used to generate the robot TCP trajectory based on the fixed spraying distance and the normal projection rule, and use the path planning algorithm to realize the automatic coverage of the multi-layer U-shaped reciprocating spraying path.

[0143] The laser scanner is arranged near the tooling of the robot workstation so that its field of view covers the entire tooling, and is used for three-dimensional data acquisition of the workpiece and sent to the spraying software process package for geometric modeling of the workpiece.

[0144] A multi-axis motion controller is used to execute a spraying parameter optimization algorithm and dynamically adjust the spraying speed and angle according to the optimization results. It also inserts low-speed transition points at trajectory alarm points through a kinematic interpolation algorithm to achieve dynamic smooth connection of the spraying path.

[0145] A trajectory simulation module is used to perform interference simulation on the trajectory to avoid interference paths.

[0146] Embodiment 1:

[0147] In this embodiment, the heavy-duty robot is a six-axis serial configuration manipulator, and the workpiece carrier is an external seventh axis controlled by the robot controller. The running direction of the external seventh axis is orthogonal to the base coordinate system of the six-axis robot body.

[0148] This embodiment specifically includes the following steps:

[0149] 1) Perform 3D modeling on the body workpiece to be sprayed.

[0150] 2) Calibrate the robot tool coordinate system for the spraying mechanism at the end of the robot.

[0151] A. Define multiple tool TCP points of the robot according to the spraying distance or flame length of the spray gun and different spraying materials, and pre-store them in the upper software system for quick call during simulation of different workpieces.

[0152] B. When defining the robot tool TCP, the calibration reference point should be located within the working area of the robot's work envelope space, and the calibration is performed by the four-point method.

[0153] C. To improve the TCP calibration accuracy, the robot controller should re-calculate the tool TCP coordinates by adding the flame length distance value in the Z direction of the tool system according to the 3D model of the spray gun. The flame length error value should not be higher than 1 centimeter.

[0154] 3) After the large body workpiece is clamped, perform robot workpiece coordinate system calibration on it, and import the obtained workpiece spatial pose and tool model into the spraying software process package of the upper system. Specifically:

[0155] A. The large body workpiece should be reliably clamped on the turntable driven by the external axis of the robot. Take a point on the surface of the workpiece to be sprayed as the origin of the robot workpiece coordinate system, and define the coordinate system direction by the right-hand rule. Calibrate the robot workpiece coordinate system of various workpieces by the three-point method.

[0156] B. The workpiece coordinate systems of different workpieces should be named as global variables and imported into the upper system respectively. When simulating or producing different workpieces, the upper system directly selects the corresponding workpiece coordinate system.

[0157] 4) After setting a fixed spraying distance parameter, the spraying software process package of the upper system generates a robot trajectory and conducts path simulation on the generated robot trajectory. Specifically:

[0158] A. Extract the geometric information of the workpiece to be sprayed from the 3D model;

[0159] B. By combining the fixed spraying flame length distance with the geometric information of the workpiece that needs coating repair, a straight-line distance perpendicular to the workpiece surface starting from the normal center of the robot spray gun tool end is used to generate the TCP point trajectory of the robot spraying;

[0160] Among them, the geometric information of the workpiece that needs coating repair includes: the surface shape, size, and complexity of the workpiece that needs coating repair;

[0161] C. Keep the fixed spraying parameter distance, and combine the generated TCP points of the robot to complete the set of spatial points passed during multiple U-shaped reciprocating spraying actions, that is, the robot trajectory.

[0162] During the simulation process, monitor the collision detection results to check whether there is a collision between the trajectory and the workpiece or equipment model; if a collision or interference is found, record the trajectory points and the collision positions, and return to step 3) for subsequent analysis and adjustment of the 3D model parameters; and re-perform the interference simulation until it is ensured that the generated motion trajectory will not collide or interfere during actual operation, and then execute step 5).

[0163] 5) Input the spraying distance, angle, and speed parameters, and the software process package optimizes the robot spraying trajectory for visual simulation;

[0164] 6) Import the tool coordinate system and workpiece coordinate system obtained in steps 2) and 3) into and download them to the robot controller;

[0165] 7) Combine the upper system spraying process package with the path planning algorithm to generate a G-code format robot program and download it to the robot controller for verification of the robot's automatic mode no-load operation. If all spraying points can be reached at the specified spraying speed of the robot and there is no alarm during operation, then start the spray gun for spraying production. If an overload or overspeed alarm occurs, return to step 5) to reset the robot trajectory generation mode, and insert low-speed transition points at the robot alarm stop position. The transition points need to include the original complete path and cover the entire area to be sprayed;

[0166] 8) If there is no interference in the simulation, import it into the robot controller for spraying.

[0167] In summary, during the spraying process of large workpieces, the present invention conducts two trajectory simulations in the robot workpiece coordinate calibration stage and the robot offline spraying program generation stage to ensure the safety of the process, greatly reducing the consumption of special coatings and expensive body components during the debugging and testing process in the traditional production mode, and improving the production safety and automation level.

[0168] Those skilled in the art can understand that the above description is only the preferred embodiment of the present invention. The features described in each embodiment and / or claim of the present disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. It is not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0169] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention. Obviously, those skilled in the art can make various changes and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. An automated spraying method for aircraft surfaces based on a heavy-duty robot, characterized in that, It includes the following steps: 1) Geometrically model the aircraft body workpiece to generate a digital model including surface shape, dimensions, and complexity; 2) Based on the robot tool coordinate system calibration algorithm, establish a dynamic mapping model of multiple tool TCP points, calibrate the spray gun tool coordinate system by the four-point method, and perform TCP coordinate optimization calculation by integrating the spray gun 3D model parameters and the flame length distance value; 3) Combine the three-point calibration method and the turntable pose parameters to construct a dynamic database of the global workpiece coordinate system; 4) Generate the robot TCP trajectory based on the fixed spraying distance and the normal projection rule, and use the path planning algorithm to automatically cover the multi-layer U-shaped reciprocating spraying path; 5) After setting a fixed spraying distance parameter, the spraying software process package generates the robot trajectory and performs visual simulation optimization. If the simulated robot trajectory can all reach, execute step 6); otherwise, return to step 4); 6) Combine the parameters of paint type, plasma flame length, spraying angle, and speed to generate the robot motion trajectory program; 7) Insert low-speed transition points at the trajectory alarm points through the kinematic interpolation algorithm to achieve dynamic smooth connection of the spraying path.

2. The automated aircraft surface spraying method based on a heavy-duty robot according to claim 1, wherein, The specific content of step 2) is as follows: 2-1) Define multiple tool TCP points according to the spray gun type and the properties of the spraying material, and generate an initial calibration point set in the robot working envelope space by the four-point method; 2-2) Based on the tool system Z-direction parameter of the spray gun 3D model, use the flame length compensation algorithm to correct the TCP coordinates to meet the constraint condition that the flame length error ≤ 1 cm: TCP 终 = TCP 初始 + ΔZ·R Z (θ) where ΔZ is the flame length compensation amount, and R Z (θ) is the rotation matrix about the Z-axis.

3. A method for automatic spraying on the surface of an aircraft based on a heavy-duty robot according to claim 1, characterized in that The specific content of step 3) is as follows: 3-1) According to the workpiece coordinate system calibration method, obtain the workpiece clamping position through the turntable pose sensor, and establish a right-handed coordinate system with the workpiece surface feature point as the origin; 3-2) Use the three-point calibration method to generate the workpiece coordinate system transformation matrix, that is: where, R is the rotation matrix and t is the translation vector. 3-3) Store different workpiece coordinate systems as global variables and match and call them, that is: 3-3-1) When changing the workpiece, automatically call the corresponding coordinate system data according to the workpiece number; 3-3-2) Real-time monitor the turntable pose offset. If the offset exceeds the tolerance range, trigger the coordinate system to be recalibrated; 3-3-3) Store the historical calibration data, predict the deviation trend of the calibration parameters through the machine learning algorithm, and optimize the calibration efficiency.

4. A method for automated spraying on the surface of an aircraft based on a heavy-duty robot according to claim 1, wherein The path planning algorithm performs the following steps: 4-1) Extract the geometric information of the area to be sprayed from the 3D model, and generate a surface normal vector field based on the normal vector calculation module; 4-2) Take the normal center of the spray gun tool end as the starting point, and generate an initial TCP point set along the direction of the normal vector field at a fixed flame length distance; 4-3) Use the curve fitting algorithm to smooth the discrete TCP points to form a continuous spraying path; 4-4) According to the coating thickness distribution requirements, adjust the overlap rate of the heavy-duty robot U-shaped reciprocating motion.

5. The automated aircraft surface spraying method based on a heavy-duty robot according to claim 4, wherein The specific content of step 4-4) is as follows: a. Calculate the local path spacing according to the surface curvature change rate: d = d base ·(1 + k·|κ|) where d base is the reference spacing, k is the curvature influence factor, and κ is the local curvature; b. Automatically increase the U-shaped path density in the high-curvature area exceeding the curvature threshold to ensure the coating uniformity.

6. The automated aircraft surface spraying method based on a heavy-duty robot according to claim 1, characterized in that The visual simulation optimization in step 5) specifically includes: 5-1) In the simulation interface, the matching degree between the spraying trajectory and the workpiece surface is displayed in real time, and the abnormal coating thickness area is identified; 5-1-1) Import the three-dimensional model of the workpiece, TCP point positions and motion parameters into the simulation software interface; 5-1-2) Based on the spraying parameters and coating characteristics, calculate the coating thickness distribution through a physical model; 5-1-3) Intuitively display the thickness distribution on the surface of the three-dimensional model in the form of color gradient or numerical annotation; 5-1-4) Compare with the preset thickness threshold, mark the areas beyond the allowable range, and generate a coordinate report of the abnormal area; 5-2) Automatically adjust the spraying speed or angle parameters according to the simulation results, and generate an optimized trajectory; 5-2-1) Analyze the related spraying parameters according to the position of the abnormal area and the thickness deviation direction; 5-2-2) Dynamic adjustment rules: The deviation direction leads to an over-thick area: reduce the spraying speed or increase the distance between the spray gun and the workpiece surface; The deviation direction leads to an under-thin area: increase the spraying speed or reduce the tilt angle of the spray gun to increase the coverage area; 5-2-3) Based on the adjusted parameters, the spraying software process package re-plans the spraying path, imports the new trajectory into the simulation module, and updates the coating thickness prediction result; 5-3) Verify the optimization effect through iterative simulation until the coating uniformity meets the preset threshold.

7. A method for automatic spraying on the surface of an aircraft based on a heavy-duty robot according to claim 1, characterized in that, The specific content of step 7) is as follows: 7-1) Generate a transition trajectory by using quintic polynomial interpolation in the robot joint space; 7-2) Dynamically adjust the interpolation period according to the servo motor torque feedback to avoid overspeed or overload; 7-3) Ensure the spraying integrity of the transition point connection area through a path coverage verification algorithm.

8. A method for automatic spraying on the surface of an aircraft based on a heavy-duty robot according to claim 7, characterized in that, In step 7-2), dynamically adjusting the interpolation period according to the servo motor torque feedback is specifically: 7-2-1) Real-time feedback torque and speed data of the servo motor through the robot controller; monitor whether the load of each joint is close to the safety threshold; 7-2-2) Dynamic adjustment strategy: Overspeed handling: If the speed of a certain joint exceeds the preset value, extend the interpolation period, that is, reduce the movement speed; Overload handling: If the torque exceeds the limit, shorten the trajectory length of the transition section or reduce the acceleration; 7-2-3) Adjust according to the interpolation period adjustment formula, that is: where T base is the base period and Δτ is the difference between the current torque and the maximum allowable torque; 7-2-4) After adjustment, re-run the transition section, continuously monitor the feedback data until the torque and speed are stable within the safe range.

9. The automated aircraft surface spraying method based on a heavy-duty robot according to claim 7, wherein The specific content of step 7-3) is as follows: 7-3-1) Superimpose the adjusted trajectory on the original planned path, and compare the projected areas of the two on the surface of the three-dimensional model; use the rasterization algorithm to detect whether there are uncovered areas; 7-3-2) Calculate the U-shaped path overlap rate of the transition section trajectory to ensure that the coating thickness requirements are met; If the local density is insufficient, visually check the coating uniformity of the transition area through color mapping, mark the defect points, and after increasing the path point density of the transition section, execute step 6-3-2); otherwise execute step 6-3-3); 7-3-3) Load the new trajectory in the spraying software process package and run the coating thickness prediction model.

10. An automated spraying system for an aircraft surface automated spraying method based on a heavy-duty robot according to any one of claims 1 to 9, characterized in that, It includes: Spraying software process package, laser scanner, multi-axis motion controller and trajectory simulation module; The spraying software process package includes: three-dimensional modeling module, coordinate calibration module, trajectory planning module; A 3D modeling module for geometrically modeling the aircraft body workpiece to generate a digital model including surface shape, dimensions, and complexity; A coordinate calibration module for establishing a dynamic mapping model of multiple tool TCP points, calibrating the spray gun tool coordinate system by the four-point method, and at the same time, calibrating the workpiece coordinate system and managing the dynamic mapping model of TCP points and the global workpiece coordinate system database; A trajectory planning module for generating the robot TCP trajectory based on a fixed spraying distance and a normal projection rule, and automatically covering the multi-layer U-shaped reciprocating spraying path by using a path planning algorithm; The laser scanner is arranged near the tooling of the robot workstation so that its field of view covers the entire tooling, for three-dimensional data acquisition of the workpiece and sending it to the spraying software process package for geometric modeling of the workpiece; A multi-axis motion controller for executing a spraying parameter optimization algorithm and dynamically adjusting the spraying speed and angle according to the optimization result; also inserting low-speed transition points at the trajectory alarm points through a kinematic interpolation algorithm to achieve dynamic smooth connection of the spraying path; The trajectory simulation module for performing interference simulation on the trajectory to avoid interference paths.

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