Wheelset painting synchronization control device and method

Abstract

The present invention relates to the technical field of intelligent industrial equipment and discloses a synchronous control device for wheelset painting, comprising: a wheelset rotating platform, a paint supply system, a robotic arm, a visual guidance module and a control system; by integrating a pressure sensor, a servo motor and a PLC controller, precise synchronous control of wheelset rotation, paint brush control, paint supply and robotic arm position is achieved; based on the surface image information and curvature data provided by the visual guidance module, a painting trajectory is generated and the paint brush direction and paint supply are adjusted to achieve precise painting of complex curved surfaces.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent industrial equipment, and in particular to a synchronous control device and method for automatic painting of a wheelset. Background Art

[0002] Currently, traditional wheelset painting is mostly done manually, resulting in low efficiency, uneven coating quality, and potential for human error. With the development of automation technology, robotic arm spraying technology is gradually being applied to industrial production. However, existing technologies still face significant technical difficulties in synchronizing wheelset rotation, paint supply, and robotic arm movement, impacting painting quality and production efficiency.

[0003] The invention patent with application number "CN202111323921.8" discloses a wheelset painting equipment and a wheelset painting method. The wheelset painting equipment includes a rotary drive device, a robotic arm and a paint brush; the robotic arm is used to drive the paint brush close to or away from the wheelset to be painted, so that the paint brush abuts against any part to be painted of the wheelset to be painted or away from the wheelset that has been painted, and the robotic arm is used to drive the paint brush to move axially along the wheelset to be painted; the paint box is used to store anti-rust paint, and the paint box can be installed on the moving path of the robotic arm, so that the robotic arm can drive the paint brush to dip a sufficient amount of anti-rust paint to ensure the quality of painting.

[0004] According to the above, the wheelset painting equipment needs to use a robotic arm to drive the paint brush to dip in paint. Although automatic painting control can be achieved, due to the complex surface and variable curves of the wheelset, it is difficult to ensure the uniformity of the paint on the wheelset surface by painting with the paint brush along the same direction and angle. In addition, the method of dipping in paint can easily lead to missed spots and uneven painting, resulting in waste of paint materials and affecting the painting quality and production efficiency.

[0005] Therefore, it is particularly important to develop a painting system that can achieve precise synchronous control between wheelset rotation, paint supply and robot arm transposition. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a wheelset painting device and a painting method based on vision guidance, which aims to solve the problems of uneven painting and low efficiency on complex surfaces of wheelsets during the painting process.

[0007] The technical solution adopted in the present invention is:

[0008] A wheel set painting synchronization control device includes: a wheel set rotating platform, a paint supply system, a robotic arm, a visual guidance module and a control system, wherein:

[0009] The wheelset rotation platform is used to fix the wheelset and control it to rotate at a predetermined speed and angle;

[0010] The paint supply system includes a paint brush, a paint storage tank, a pumping device, a flow sensor and a piping system, which is used to adjust the paint supply to the paint brush in real time according to the painting progress to ensure uniform paint distribution;

[0011] The robotic arm has a multi-degree-of-freedom joint and is used to carry a paint brush to perform painting operations, and can accurately paint according to a set brushing trajectory;

[0012] The visual guidance module includes an industrial camera and an image processing unit, which are used to capture surface image information of the wheelset. The image processing unit performs curvature analysis on the surface image and generates curvature data for use by the control system.

[0013] The control system integrates pressure sensors, servo motors, and a PLC controller to achieve precise synchronous control of wheelset rotation, paint brush control, paint supply, and robotic arm position. Based on surface image information and curvature data provided by a visual guidance module, it generates a painting trajectory and adjusts the paint brush direction and paint supply, enabling precise painting of complex curved surfaces.

[0014] Preferably, the wheelset rotating platform is equipped with an adjustable clamping mechanism, which can adapt to wheelsets of different sizes and types.

[0015] Preferably, the end of the bristles of the paint brush is provided with a plurality of microporous channels, and the paint is pumped from the paint storage tank through the pipeline system and the flow sensor, and finally seeps out evenly from the root of the bristles through the microporous channels to prevent dripping or accumulation during the painting process.

[0016] Preferably, the paint brush is rectangular, and a pressure sensor is connected to the rear of the paint brush, so that a constant contact force can be maintained along the surface of the wheelset during the brushing operation.

[0017] Preferably, the robotic arm is designed as an 8-degree-of-freedom joint structure, each joint is equipped with a servo motor and a high-precision reducer, and the end of the robotic arm adopts a modular design, which can quickly replace brush heads of different sizes or shapes to meet various brushing needs.

[0018] Preferably, the image processing unit performs curvature analysis on the surface image, divides the entire area of ​​the wheelset surface into several blocks, and extracts the regional point cloud {P i (x i ,y i ,z i )}, use the least squares method to fit the quadratic surface of the block area:

[0019] z=ax 2 +by 2 +cxy+dx+ey+f;

[0020] After obtaining the coefficients a, b, c, d, e, and f, the curvature index of each area, that is, the average curvature, is calculated:

[0021]

[0022] Preferably, the average curvature is: For the fitted quadratic surface, calculate the normal vector of each area: The direction of the normal vector is used to adjust the tilt angle of the paint brush to ensure that the paint brush forms a fixed angle with the surface, such as a right angle.

[0023] Preferably, the control system adjusts the direction of the paint brush and the paint supply according to the curvature data provided by the visual guidance module. When the average curvature is greater than or equal to a first threshold, the paint brush is adjusted to a vertical direction; when the average curvature is less than the first threshold, the paint brush is adjusted to a horizontal direction.

[0024] Preferably, a plurality of adjacent areas with the same curvature data range are connected by straight lines or smooth curves to generate a merged area planning path for the paint brush, thereby preventing the robot arm from frequently turning the paint brush.

[0025] Preferably, a boundary overlap is set for the merged area, and the overlap width is at least 20% of the paint brush width W, so as to avoid missing paint at the boundary of the merged area.

[0026] A wheelset painting synchronization control method is applied to any of the above-mentioned wheelset painting synchronization control devices, characterized in that the steps include:

[0027] S1: The wheelset rotating platform fixes the wheelset to be painted;

[0028] S2: Use the vision guidance module to capture the surface image of the wheelset and use the image processing unit to generate the surface data;

[0029] S3: Generate a painting path based on surface image information and surface curvature data;

[0030] S4: The robotic arm drives the paint brush to paint and adjusts the direction of the paint brush and the amount of paint supplied in real time;

[0031] S5: The wheelset rotating platform drives the wheelset to rotate a certain angle, and steps S1, S2, S3, and S4 are repeated until all positions of the wheelset to be painted are painted.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention uses a wheelset painting synchronization control device, which accurately obtains the wheelset surface curve information through a visual guidance module, adjusts the paint brush direction and paint supply in real time, and realizes precise painting of complex curved surfaces, thereby making the painting path and paint supply more intelligent; the coating uniformity is significantly improved, reducing manual adjustment and rework; based on the visual guidance module to obtain the wheelset surface, the degree of automation of the painting process is improved, and it is suitable for batch painting of wheelsets of various specifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 : Schematic diagram of the overall structure of the wheelset painting synchronization control device based on vision guidance;

[0036] Figure 2 : Schematic diagram of the paint brush in the vertical direction;

[0037] Figure 3 : Schematic diagram of the paint brush in the horizontal direction.

[0038] In the figure, 1, rack, 2, control system, 3, paint storage tank, 4, robotic arm, 5, visual guidance module, 6, paint brush, 7, wheelset rotation platform, 8, second designated position, 9, first designated position, 10, groove, 11, wheelset, DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] The present invention provides a synchronous control device and method for wheelset painting, which can effectively control wheelset rotation, paint supply and painting operation of a robotic arm, thereby improving painting uniformity and work efficiency.

[0042] The technical solution adopted in the present invention is:

[0043] like Figure 1As shown, the wheelset painting synchronization control device includes: a wheelset rotating platform 7, a paint supply system, a robotic arm 4, a visual guidance module 5, and a control system 2, wherein:

[0044] The wheelset rotating platform 7 is used to fix the wheelset 11 and control it to rotate at a predetermined speed and a set angle;

[0045] The paint supply system includes a paint brush 6, a paint storage tank 3, a pumping device, a flow sensor and a piping system, which is used to adjust the paint supply of the paint brush in real time according to the painting progress to ensure uniform paint distribution;

[0046] The robotic arm 4 has a multi-degree-of-freedom joint and is used to carry a paint brush 6 to perform painting operations, and can accurately paint according to a set brushing trajectory;

[0047] The visual guidance module 5 includes an industrial camera and an image processing unit, which are used to capture the surface image information of the wheelset. The image processing unit performs curvature analysis on the surface image and generates curvature data for use by the control system.

[0048] The control system 2: realizes precise synchronous control of wheelset rotation, paint brush control, paint supply and robot arm position by integrating pressure sensors, servo motors and PLC controllers. Based on the surface image information and curvature data provided by the vision guidance module, it generates a brushing trajectory and adjusts the paint brush direction and paint supply to achieve precise painting of complex curved surfaces.

[0049] Preferably, the wheelset rotating platform is equipped with an adjustable clamping mechanism, which can adapt to wheelsets of different sizes and types.

[0050] Specifically, the wheelset rotation platform is equipped with a dual-sided adjustable clamping mechanism to stabilize the wheelset and prevent wobble during rotation. The clamping mechanism uses electric or hydraulic control, automatically adjusting the clamping force based on wheelset size to prevent damage caused by over-tightening. The platform also incorporates a high-strength rotating shaft and precision bearings to ensure smooth and low-friction rotation.

[0051] The wheelset rotation platform is driven by a servo motor and coupled with a reducer to achieve precise rotation control, ensuring the wheelset rotates stably at the desired speed. An integrated frequency converter supports stepless speed regulation to accommodate varying painting requirements (e.g., low-speed inspection versus high-speed painting).

[0052] The wheelset rotation platform integrates dynamic balancing sensors to detect eccentricity or imbalance during wheelset rotation in real time, compensating for this by adjusting the clamping position or weighting mechanism. If the wheelset's axis deviates, the servo motor controls the platform's adaptive adjustment to maintain alignment between the wheelset's rotation center and the robot's working center.

[0053] The wheelset rotation platform is equipped with a high-precision angle sensor that records the wheelset's rotation angle in real time, allowing the control system to synchronously generate the painting trajectory. The encoder outputs real-time wheelset position data, which, in conjunction with the vision guidance module, ensures that every surface is evenly coated with paint without omissions or overlaps.

[0054] The wheelset rotating platform is equipped with an overload detection module. If the rotating platform is subjected to abnormal force (such as insufficient clamping force or excessive wheelset mass), the operation will be stopped immediately and an alarm will be issued.

[0055] The wheelset rotating platform is connected to the control system via a communication interface (such as Modbus or EtherCAT). After controlling the wheelset to rotate a certain angle, the visual guidance module obtains image information to generate a painting path, and the robotic arm performs the painting operation. After the painting is completed, the wheelset rotating platform rotates the wheelset by a certain angle again, and the visual guidance module obtains image information again to generate a painting path, and the robotic arm performs the painting operation again until the painting is completed.

[0056] The paint supply system includes a paint brush 6, a paint storage tank 3, a pumping device, a flow sensor and a piping system, which is used to adjust the paint supply of the paint brush in real time according to the painting progress to ensure uniform paint distribution;

[0057] Preferably, the end of the bristles of the paint brush is provided with a plurality of microporous channels, and the paint is pumped from the paint storage tank through the pipeline system and the flow sensor, and finally seeps out evenly from the root of the bristles through the microporous channels to prevent dripping or accumulation during the painting process.

[0058] Specifically, paint brushes generally use flexible bristle materials (such as polymer fibers) that can adapt to surfaces of different curvatures to achieve uniform painting. Microporous channels are provided at the end of the bristles to ensure that the paint seeps out evenly from the roots of the bristles to prevent dripping or accumulation during the painting process. The paint brush is rectangular (length L, width W, where L>W) and is fixed to the end of the robotic arm by a detachable clamping device. Brush heads of different sizes or shapes can also be replaced as needed. A pressure sensor is connected to the rear of the paint brush to maintain a constant contact force along the wheelset surface during the painting operation.

[0059] The storage tank is designed with a capacity of 5 to 10 liters to meet continuous working requirements. It also adopts a vacuum-sealed structure to prevent paint volatilization and contamination. It supports the storage of a variety of paints (such as water-based paint and solvent-based paint), and is equipped with an internal anti-corrosion coating and a stirring device to ensure uniform paint composition.

[0060] The pumping device uses a precision metering pump (such as a gear pump or peristaltic pump) to ensure high-precision control of paint flow. Equipped with a variable frequency speed regulation function, the pumping speed can be adjusted in real time according to flow demand to avoid oversupply or under-application.

[0061] The flow sensor uses a built-in ultrasonic or electromagnetic flow sensor to monitor the flow of paint in real time. The flow sensor feedback signal is used to correct the output flow of the pumping device to ensure uniform distribution during the painting process.

[0062] The piping system uses Teflon or polytetrafluoroethylene (PTFE) flexible piping that can adapt to the range of motion of the robotic arm, is resistant to high pressure and corrosion, and ensures long-term use without leakage. A microfilter is installed in the main paint delivery channel to filter impurities in the paint and prevent clogging of the microporous channels of the brush bristles.

[0063] The robotic arm 4 has a multi-degree-of-freedom joint and is used to carry a paint brush 6 to perform painting operations, and can accurately paint according to a set brushing trajectory;

[0064] Specifically, the robotic arm 4 features an 8-degree-of-freedom joint structure, with each joint equipped with a servo motor and a high-precision reducer to ensure stable and accurate movement. The joints utilize harmonic or RV reducers, offering high torque, rigidity, and repeatability, meeting the demands of complex painting trajectories.

[0065] The end of the robotic arm adopts a modular design, which allows for quick replacement of brush heads of different sizes or shapes to suit various painting needs.

[0066] The main body of the robotic arm is made of aluminum alloy or carbon fiber, which is both light and high-strength, reducing inertia and improving movement efficiency.

[0067] A hollow channel is reserved inside the robotic arm to accommodate paint delivery pipes and cables to avoid interference caused by dragging of external cables.

[0068] The robotic arm generates the optimal painting trajectory based on the wheelset surface information provided by the visual guidance module and combined with the surface curvature data.

[0069] The visual guidance module 5 includes an industrial camera and an image processing unit, which are used to capture the surface image information of the wheelset. The image processing unit performs curvature analysis on the surface image and generates curvature data for use by the control system.

[0070] Specifically, the visual guidance module 5 includes an industrial camera and an image processing unit. The industrial camera obtains high-definition two-dimensional images of the wheelset surface at the first designated position 9 and the second designated position 8 on both sides of the wheelset. The image processing unit uses Gaussian filtering or median filtering to remove noise in the image and uses the Canny algorithm or Sobel operator to extract surface contour features.

[0071] Specifically, the image processing unit performs curvature analysis on the surface image and generates curvature data in the following steps:

[0072] Using structured light or stereo vision methods, the two-dimensional image is converted into a surface depth map, which represents the distribution of surface height;

[0073] Divide the entire wheelset surface into several blocks. The size (L, W) of each block should be consistent with the size of the paint brush. You can also use a reduced size (for example, 0.5L, 0.5W) to improve calculation accuracy.

[0074] For each area, extract the height information of the center point and its neighboring points, and extract the regional point cloud {P i (x i ,y i ,z i )};

[0075] Use the least squares method to fit the quadratic surface of the local area: z = ax 2 +by 2 +cxy+dx+ey+f;

[0076] Get the curvature index of each area:

[0077] Mean curvature:

[0078] For the fitted quadratic surface, calculate the normal vector of each area:

[0079]

[0080] The direction of the normal vector is used to adjust the tilt angle of the paint brush to ensure that the paint brush forms a fixed angle with the surface, such as a right angle.

[0081] The visual guidance module obtains the generated curvature data of the surface, thereby optimizing the painting direction and angle of the paint brush, thereby achieving better and more uniform painting effects, reducing missed and repeated painting, and being able to efficiently adapt to wheelsets of different sizes and shapes, thereby improving painting efficiency.

[0082] The control system 2: realizes precise synchronous control of wheelset rotation, paint brush control, paint supply and robot arm position by integrating pressure sensors, servo motors and PLC controllers. Based on the surface image information and curvature data provided by the vision guidance module, it generates a brushing trajectory and adjusts the paint brush direction and paint supply to achieve precise painting of complex curved surfaces.

[0083] The control system is the core part of the entire device. Through precise hardware integration and advanced control algorithms, it coordinates the linkage between modules to achieve accurate coating of complex surfaces.

[0084] Specifically, the control system adopts a high-performance PLC (such as Siemens S series or Omron NJ series), has multi-axis synchronous control and real-time communication capabilities, supports multiple communication protocols (EtherCAT, CANopen, Modbus), and seamlessly connects with vision guidance modules, pressure sensors and other equipment; PLC coordinates wheelset rotation, robotic arm movement, paint supply and paint brush angle adjustment to ensure multi-task synchronization.

[0085] Specifically, the control system connects the bottom of the paint brush and multiple high-sensitivity pressure sensors at the end of the robotic arm to monitor the brushing pressure in real time and provide feedback on the contact force between the paint brush and the wheelset surface to avoid insufficient coverage due to too light a brushing or surface damage due to too heavy a brushing.

[0086] The control system is connected to the servo motors equipped with the robot arm joints, wheelset rotating platform, and paint brush angle adjustment mechanism to achieve precise control of position, speed, and acceleration, and adapt to complex brushing trajectories.

[0087] Preferably, the control system adjusts the direction of the paint brush and the amount of paint supplied according to the curvature data provided by the visual guidance module, and adjusts the paint brush to be vertical when the curvature is greater than or equal to a first threshold value, see the attached Figure 2 When the curvature is less than the first threshold, adjust the paint brush to the horizontal direction, see the attached Figure 3 .

[0088] Specifically, when the curvature data H provided by the visual guidance module represents the degree of curvature of the local surface, its size determines the selection of the brushing direction.

[0089] H ≥ first threshold (significant bending area):

[0090] The paint brush is adjusted to a vertical position with the long axis parallel to the painting direction, so that the bristles can fit closely to the curved surface and improve the uniformity of painting.

[0091] H<second threshold (flat regular area):

[0092] The paint brush is adjusted to a horizontal position with the long axis perpendicular to the painting direction, making it easier to paint a larger area each time and improving painting efficiency.

[0093] Global path planning: This method connects multiple adjacent areas with the same curvature data range, i.e., multiple adjacent significantly curved areas or multiple flat regular areas, with straight lines or smooth curves to generate a merged area planning path for the paint brush, thus preventing the robot arm from frequently turning the paint brush.

[0094] Furthermore, a boundary overlap is set for the merged area, and the overlap width is at least 20% of the paint brush width W, so as to avoid missing paint at the boundary of the merged area.

[0095] Specifically, according to the planned path area and the brushing speed of the robot arm, the paint supply is adjusted in real time. The specific formula is as follows:

[0096] Q=A·v·k

[0097] Among them, Q is the paint flow rate, A is the painting contact area corresponding to the planned path area, v is the robot arm speed, and k is the painting thickness coefficient.

[0098] A wheelset painting synchronization control method, applied to any of the above-mentioned wheelset painting synchronization control devices, is characterized by comprising:

[0099] S1: The wheelset rotating platform fixes the wheelset to be painted;

[0100] S2: Use the vision guidance module to capture the surface image of the wheelset and use the image processing unit to generate the surface data;

[0101] S3: Generate a painting path based on surface image information and surface curvature data;

[0102] S4: The robotic arm drives the paint brush to paint and adjusts the direction of the paint brush and the amount of paint supplied in real time;

[0103] S5: The wheelset rotating platform drives the wheelset to rotate a certain angle, and steps S1, S2, S3, and S4 are repeated until all positions of the wheelset to be painted are painted.

[0104] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A wheelset painting synchronization control device, comprising: Wheel set rotation platform, paint supply system, robotic arm, vision guidance module and control system, among which, The wheelset rotation platform is used to fix the wheelset and control it to rotate at a predetermined speed and angle; The paint supply system includes a paint brush, a paint storage tank, a pumping device, a flow sensor and a piping system, which is used to adjust the paint supply of the paint brush in real time according to the painting progress; The robotic arm has a multi-degree-of-freedom joint and is used to carry a paint brush to perform painting operations, and can accurately paint according to a set brushing trajectory; The visual guidance module includes an industrial camera and an image processing unit, which are used to capture surface image information of the wheelset. The image processing unit performs curvature analysis on the surface image and generates curvature data for use by the control system. The control system integrates pressure sensors, servo motors, and PLC controllers to achieve precise synchronous control of wheel rotation, paint brush control, paint supply, and robotic arm position. Based on surface image information and curvature data provided by the visual guidance module, it generates a painting trajectory and adjusts the paint brush direction and paint supply. The image processing unit performs curvature analysis on the surface image, divides the entire area of ​​the wheelset surface into several blocks, and extracts a regional point cloud {P i (x i ,y i ,z i )}, the quadratic surface formula for fitting the block area using the least squares method is: z=ax 2 +by 2 +cxy+dx+ey+f; After obtaining the coefficients a, b, c, d, e, and f, the curvature index of each area, that is, the average curvature, is calculated:

2. The wheelset painting synchronization control device according to claim 1, characterized in that: The wheelset rotating platform is equipped with an adjustable clamping mechanism.

3. The wheelset painting synchronization control device according to claim 1, characterized in that: The end of the bristles of the paint brush is provided with a plurality of microporous channels. The paint is pumped by a pumping device from a paint storage tank through a pipeline system and a flow sensor, and finally evenly seeps out from the roots of the bristles through the microporous channels.

4. The wheel set painting synchronization control device according to claim 1, characterized in that: The paint brush is rectangular, with a length of L and a width of W, wherein L>W. The rear of the paint brush is connected to a pressure sensor.

5. The wheel set painting synchronization control device according to claim 4, characterized in that: For the fitted quadratic surface, calculate the normal vector of each area: The direction of the normal vector is used to adjust the tilt angle of the paint brush.

6. The wheel set painting synchronization control device according to claim 4, characterized in that: The control system adjusts the direction of the paint brush according to the curvature data provided by the visual guidance module. When the average curvature is greater than or equal to a first threshold, the paint brush is adjusted to a vertical direction; when the average curvature is less than the first threshold, the paint brush is adjusted to a horizontal direction.

7. The wheelset painting synchronization control device according to claim 6, characterized in that: The merged area planning path of the paint brush is generated by connecting multiple adjacent areas with the same curvature data range with straight lines or smooth curves.

8. The wheel set painting synchronization control device according to claim 7, characterized in that: A boundary overlap is set for the merged area, and the overlap width is at least 20% of the width W of the paint brush.

9. A method for synchronous control of wheelset painting, applied to any one of the wheelset painting synchronous control devices according to claims 1-8, characterized in that the steps include: S1: The wheelset rotating platform fixes the wheelset to be painted; S2: Use the vision guidance module to capture the surface image of the wheelset and use the image processing unit to generate the surface data; S3: Generate a painting path based on surface image information and surface curvature data; S4: The robotic arm drives the paint brush to paint and adjusts the direction of the paint brush and the amount of paint supplied in real time; S5: The wheelset rotating platform drives the wheelset to rotate a certain angle, and steps S1, S2, S3, and S4 are repeated until all positions of the wheelset to be painted are painted.

Images