Underwater gap spraying method and spraying robot

Abstract

This invention provides an underwater crevice painting method and a spraying robot, belonging to the field of spraying equipment technology. The robot comprises a three-jointed, six-degree-of-freedom robotic arm and a visual spray head. The distal end of the three-jointed, six-degree-of-freedom robotic arm is rotatably connected to the visual spray head. The visual spray head comprises a spray assembly, a binocular camera, and a laser radar, and employs image recognition technology based on the FCOS crevice detection algorithm to identify crevice underwater. The spray assembly generates an electrostatic spray operation. The robot's spray execution terminal is capable of autonomous spray trajectory planning, enabling autonomous spraying and providing excellent flexibility.

Description

Technical Field

[0001] The present invention relates to the technical field of spraying equipment, and in particular to an underwater crevice spraying method and a spraying robot. Background Art

[0002] With the continuous development of various industries such as shipping and electricity, the safety and lifespan of the underwater parts of water conservancy and hydropower steel structures have become issues that require our attention. The large number of metal components inside underwater steel structures are exposed to water and are easily corroded, affecting their safe operation and causing safety accidents. Therefore, these structural surfaces and tiny gaps must be spray-sealed.

[0003] The traditional solution involves manually using a handheld spray gun or draining the reservoir to lower the water level for spraying. This involves a large workload, severe economic losses, a harsh working environment, a small working space, and poor corrosion resistance of the paint. Autonomously controlled underwater crevice spraying robots, however, can disregard repetitive and extensive work, the complex and hazardous nature of the space, and can perform meticulous and accurate spraying in high-pressure, low-visibility environments, replacing manual labor and even being able to enter construction spaces that are inaccessible to humans. As the execution unit for spraying operations, the performance and intelligence of the spraying robot directly affect the quality of the sprayed surface. Spraying robots are a type of industrial robot, and the articulated robotic arm structure is widely used in spraying operations in industrial and agricultural production, transportation, aerospace, and other fields due to its high degree of freedom, ease of programming, and control.

[0004] In recent years, spray robots have evolved from hydraulic drives to electric motors, from bulky mechanical designs to integrated, lightweight mechanisms. Spraying operations have also evolved from single-robot operations to multi-robot collaboration, and from human-robot separation to human-robot collaboration. In the future, intelligent robots will independently complete highly complex tasks. However, existing spray robots lack flexibility, are mostly manually controlled, and have a low degree of automation. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides an underwater crevice spraying method and a spraying robot, wherein the spraying execution terminal of the robot can perform autonomous spraying trajectory planning, realize autonomous spraying, and have better flexibility. The present invention provides the following technical solutions.

[0006] The present invention provides an underwater gap spraying method, comprising:

[0007] The coordinate expression of the spraying actuator at the end of the spraying robot is obtained through the binocular camera and laser radar, and the posture relationship of the spraying actuator at the end of the spraying robot is obtained using the spatial posture transformation matrix;

[0008] By rotating the binocular camera and radar at equal angles, n scanning points are obtained for the workpiece calibration, and it is determined whether the distance between the first scanning point and the sprayed surface meets the spraying surface distance requirement; if not, it is adjusted to the required position according to the distance difference; if the distance requirement is met, the angle between the direction vector of the scanning point and the measuring beam is determined point by point. If the angle between the direction vector is less than or equal to 45°, it is determined whether this point is the nth scanning point; if this point is not the nth point, the rotation is stopped, and the scanning points are fitted with a quintic spline curve to obtain a smooth spraying trajectory line and spraying is carried out. The trajectory line is split into a dense point set at equal distances, and the coordinate point of the end effector movement target is calculated. The spraying actuator at the end of the spray robot moves point by point and completes the spraying;

[0009] After the above work is completed, the end effector is moved to the above end point and the posture is adjusted so that the normal distance from the point is the required distance from the spray surface for subsequent scanning and spraying work; if the number of scanning points reaches n points, a quintic spline curve is used to fit the n scanning points to obtain a smooth spraying trajectory line, and the trajectory splitting step is performed and the end effector is controlled to move and spray point by point;

[0010] When a scanning point or split point in the previous step appears during the scanning process, one round of spraying is completed and the scanning is stopped immediately. The remaining scanning points are fitted with a quintic spline curve and the trajectory points are split. After this part of the spraying work is completed, the spraying is ended.

[0011] Preferably, the method further includes adopting an FCOS gap detection algorithm to identify gaps in the workpiece when calibrating the workpiece.

[0012] The present invention also provides a spraying robot that applies the underwater gap spraying method, comprising a three-joint six-degree-of-freedom robotic arm and a visual nozzle; the end of the three-joint six-degree-of-freedom robotic arm is rotatably connected to the visual waterproof nozzle; the visual nozzle includes a spraying assembly, a binocular camera and a laser radar; the spraying assembly is used to generate electrostatic spraying operations.

[0013] Preferably, the spraying assembly includes a rotary cup, a high-voltage electrostatic generating system, a paint supply system and an air supply system; the rotary cup is electrically connected to the high-voltage electrostatic generating system; the paint supply system and the air supply system are respectively connected to the rotary cup; wherein, an electrostatic field is formed at the nozzle of the rotary cup through the high-voltage electrostatic generating system, and an electrostatic spraying operation is formed through the paint supply system and the air supply system.

[0014] Preferably, the three-joint six-degree-of-freedom robotic arm includes a frame box, an upper arm, a lower arm and a wrist; the ends of the frame box, upper arm, lower arm and wrist are connected in sequence by two rotating joints whose rotation directions are perpendicular to each other; each of the rotating joints is provided with a servo motor, and the servo motor drives the rotating joint to rotate; the end of the wrist is provided with a rotary motor, the output shaft of the rotary motor is rotatably connected to one end of the visualization nozzle, and the rotary motor drives the visualization nozzle to rotate axially.

[0015] Preferably, the three-joint six-degree-of-freedom robotic arm is made of aluminum alloy.

[0016] Preferably, it also includes an explosion-proof purge system; the explosion-proof purge system includes a purge unit, a purge control unit and a purge sensor; the purge sensor is arranged inside the three-joint six-degree-of-freedom robotic arm; the purge unit is electrically connected to the purge control unit; the purge unit is connected to the bottom of the three-joint six-degree-of-freedom robotic arm through a hose; wherein, when the purge sensor detects explosive gas, the purge unit is pressurized by controlling the purge control unit, and then gas is supplied to the three-joint six-degree-of-freedom robotic arm through the hose to increase the internal pressure to prevent the explosive gas.

[0017] Preferably, it further comprises a traveling unit and a workpiece conveying unit; the traveling unit is arranged at the bottom of the frame box to drive the frame box to move.

[0018] Preferably, it also includes a workpiece transfer unit; the workpiece transfer unit is mounted in front of the three-joint six-degree-of-freedom robotic arm; the workpiece transfer unit includes a workpiece conveying device and a servo rotary table arranged below the workpiece conveying device; when the workpiece conveying device conveys the workpiece to the front of the three-joint six-degree-of-freedom robotic arm, the servo rotary table drives the workpiece to rotate to complete the coating.

[0019] Beneficial effects of the present invention:

[0020] The present invention proposes an underwater gap spraying method and a spraying robot. The spraying robot provides a multi-free spraying execution terminal, performs autonomous spraying trajectory planning, realizes autonomous spraying, has good flexibility, and a high degree of automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of a method for spraying gaps at the bottom of an underground cabinet according to an embodiment of the present invention;

[0022] Figure 2 Schematic diagram of the structure of a three-joint six-degree-of-freedom robotic arm and a visual spray head of a spray robot according to an embodiment of the present invention;

[0023] Figure 3Schematic diagram of the explosion-proof purge system of the spraying robot according to an embodiment of the present invention;

[0024] Figure 4 Schematic diagram of the structure of auxiliary peripheral equipment of the spraying robot according to an embodiment of the present invention;

[0025] Figure 5 Schematic diagram of the calibration principle of an embodiment of the present invention;

[0026] Figure 6 The invention relates to an underwater gap collection device according to an embodiment of the present invention.

[0027] Among them, 1. Air supply system; 2. Paint supply system; 3. High-voltage electrostatic generation system; 4. Rotary cup; 5. Workpiece; 6. Forearm; 7. Wrist; 8. Visual nozzle; 9. Upper arm; 10. Rack box; 11. Purge unit; 12. Purge sensor; 13. Purge control unit; 14. Hose. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like, indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features referred to. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of such features; in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0031] Example

[0032] This embodiment proposes an underwater gap spraying method and a spraying robot. The specific flow chart of the spraying method is as follows: Figure 1 As shown, the structure diagram of the three-joint six-degree-of-freedom mechanical arm of the spraying robot and the visual nozzle 8 is as shown in FIG. Figure 2 As shown, a multi-degree-of-freedom, multi-joint underwater gap spraying method is employed. First, the spatial pose transformation matrix is ​​used to determine the pose relationship between the industrial robot end effector and the spray gun head, as well as the coordinates of the binocular camera and laser ranging sensor on the spray gun head. A path planning method is then designed to enable the end effector to autonomously adjust the spray path to avoid interference and collision.

[0033] like Figure 1 As shown, the specific steps include:

[0034] The coordinate expression of the spraying actuator at the end of the spraying robot is obtained through the binocular camera and laser radar, and the posture relationship of the spraying actuator at the end of the spraying robot is obtained using the spatial posture transformation matrix;

[0035] By rotating the binocular camera and radar at equal angles, n (n≤6) scanning points are obtained for the workpiece calibration. The calibration principle is as follows Figure 5 As shown, it is judged whether the distance between the first scanning point and the sprayed surface meets the spraying surface distance requirement; if not, it is adjusted to the required position according to the distance difference; if the distance requirement is met, the angle between the scanning point direction vector and the measuring beam is judged point by point, and if the direction vector angle is less than or equal to 45°, it is judged whether this point is the nth scanning point; if this point is not the nth point, the rotation is stopped, and the scanning point is fitted with a quintic spline curve to obtain a smooth spraying trajectory line and spraying is performed, the trajectory line is split into a dense point set at equal distances, the end effector motion target coordinate point is calculated, and the end spraying actuator of the spray robot moves point by point to complete the spraying;

[0036] After the above work is completed, the end effector is moved to the above end point and the posture is adjusted so that the normal distance from the point is the required distance from the spray surface for subsequent scanning and spraying work; if the number of scanning points reaches n points, a quintic spline curve is used to fit the n scanning points to obtain a smooth spraying trajectory line, and the trajectory splitting step is performed and the end effector is controlled to move and spray point by point;

[0037] When a scanning point or split point in the previous step appears during the scanning process, one round of spraying is completed and the scanning is stopped immediately. The remaining scanning points are fitted with a quintic spline curve and the trajectory points are split. After this part of the spraying work is completed, the spraying is ended.

[0038] Furthermore, for the special underwater environment, ordinary machine vision detection technology often has difficulty in identifying and accurately spraying underwater gaps with problems such as low contrast, overexposure, large noise interference, and insufficient brightness. This embodiment provides a gap recognition system that can overcome the above difficulties and realize underwater gap images. Specifically, it includes a series of image enhancement technologies, an improved FCOS gap recognition algorithm, a binocular camera, a laser radar, etc. The specific system architecture is as follows Figure 6 shown.

[0039] like Figure 2 As shown, in this embodiment, a three-joint six-degree-of-freedom robotic arm and a visual nozzle 8 are used as the basic spraying assembly, and the spraying assembly is placed in water to perform spraying. Specifically, the motors and reducers at the three joints provide the robotic arm with stable and controllable rotation and swing power. The overall robotic arm includes six degrees of freedom, including the longitudinal rotational freedom between the box and the arm frame, the vertical and joint swinging freedom between the upper arm 9 and the arm frame, and between the upper arm 9 and the lower arm 6, as shown in FIG. Figure 2 The connection between the forearm 6, wrist 7 and the visual nozzle 8 also has three degrees of freedom, namely the axial rotational freedom of the forearm 6 and wrist 7, the swinging freedom of the vertical joint of the wrist 7 and the axial rotational freedom of the nozzle, which facilitates more refined and sensitive control and operation.

[0040] Each robotic arm consists of six rotating joints connected in series, each of which requires a motor as a power source to achieve motion. The motors must be waterproof. Compared to stepper motors, servo motors have greater overload capacity and better acceleration performance, maintaining smooth motion even at low speeds. Furthermore, with the help of a driver and encoder, servo motors can achieve closed-loop control of the current loop, speed loop, and position loop, further improving control performance.

[0041] The spraying part mainly includes the paint supply system 2, the coating process and the nozzle design. The paint supply system 2 is composed of a paint unit control panel, an air supply system 1, a flow regulator, a gear pump, a paint mixer, a color-changing valve, a paint and air supply pipeline and a monitoring pipeline. The coating process uses electrostatic coating. When the paint spraying robot is running, the paint sprayed out of the manual spray gun, the spray plate and the rotary cup 4 of the electrostatic spraying is positively charged, and the tooling part of the equipment is negatively charged. Under the influence of the large current generated by the high-voltage power supply, an electrostatic field is generated at the very end of the manual spray gun or the spray plate, the rotary cup 4 and the equipment installation part. In this embodiment, the spraying assembly includes a rotary cup 4, a high-voltage electrostatic generating system 3, a paint supply system 2 and an air supply system 1; the rotary cup 4 is electrically connected to the high-voltage electrostatic generating system 3; the paint supply system 2 and the air supply system 1 are respectively connected to the rotary cup 4; wherein, an electrostatic field is formed at the nozzle of the rotary cup 4 through the high-voltage electrostatic generating system 3, and an electrostatic spraying operation is formed through the paint supply system 2 and the air supply system 1. As Figure 3This is the working principle diagram of the high-speed rotary cup electrostatic spray gun.

[0042] like Figure 4 As shown, the explosion-proof purge system includes a purge unit 11, a purge control unit 13, and a purge sensor 12. The purge sensor 12 is located inside a three-joint, six-degree-of-freedom robotic arm. The purge unit 11 is electrically connected to the purge control unit 13, which is connected to the bottom of the three-joint, six-degree-of-freedom robotic arm via a hose 14. When the purge sensor 12 detects explosive gas, the purge control unit 13 controls the purge unit 11 to increase pressure, which is then supplied to the three-joint, six-degree-of-freedom robotic arm via the hose 14, raising the internal pressure to prevent the explosive gas. Furthermore, the purge control unit 13 monitors the internal pressure of the manipulator and the air pressure in the spray booth, immediately shutting off the manipulator servo power supply if an abnormality occurs.

[0043] Furthermore, the underwater manipulator aims to achieve spraying operations while suspended or under water impact. However, due to the dynamic coupling between the manipulator and the underwater robot, the movement of the manipulator will cause the movement of the underwater robot. To minimize the impact of the manipulator's movement on the floating underwater robot, the manipulator's underwater mass should be kept as small as possible from a design perspective. Furthermore, due to the manipulator's unique operating environment, the selection of materials is also crucial. The structural material of the manipulator must possess a certain degree of corrosion resistance. Therefore, aluminum alloy with low density and high stability can be selected for the manipulator's exterior.

[0044] In addition, the painting robot's auxiliary equipment includes a robot travel unit and a workpiece transfer unit. The robot travel unit and workpiece transfer unit include a servo turntable, a servo shuttle, and a conveyor system that complete the transfer and rotation of the workpiece 5, and a travel unit that completes the robot's up, down, left, and right sliding movements. The travel unit is installed at the bottom of the frame housing 10 and drives the frame housing 10 to move. The operating mode is dynamic / static. In dynamic / static mode, the workpiece 5 is first transferred to the painting chamber by the servo shuttle or conveyor system, and the servo turntable completes the rotation of the workpiece 5. After that, the painting robot itself or a robot equipped with a travel unit completes the painting operation.

[0045] The spraying robot of this embodiment can provide a multi-free spraying execution terminal, perform autonomous spraying trajectory planning, and realize autonomous spraying, with better flexibility and a higher degree of automation.

[0046] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An underwater gap spraying method, characterized in that: include: The coordinate expression of the spraying actuator at the end of the spraying robot is obtained through the binocular camera and laser radar, and the posture relationship of the spraying actuator at the end of the spraying robot is obtained using the spatial posture transformation matrix; By rotating the binocular camera and the radar at equal angles, n scanning points are obtained for the workpiece (5) and calibrated to determine whether the distance between the first scanning point and the sprayed surface meets the sprayed surface distance requirement; if not, the distance is adjusted to the required position according to the distance difference; if the distance requirement is met, the angle between the direction vector of the scanning point and the measuring beam is determined point by point, and if the angle between the direction vector is less than or equal to 45°, it is determined whether this point is the nth scanning point; if this point is not the nth point, the rotation is stopped, and a quintic spline curve is used to fit the scanning point to obtain a smooth spraying trajectory line and spraying is performed, the trajectory line is split into a dense point set at equal distances, and the coordinate point of the end effector movement target is calculated, and the end effector of the spraying robot moves point by point to complete the spraying; After the above work is completed, the end effector is moved to the above end point and the posture is adjusted so that the normal distance from the point is the required distance from the spray surface for subsequent scanning and spraying work; if the number of scanning points reaches n points, a quintic spline curve is used to fit the n scanning points to obtain a smooth spraying trajectory line, and the trajectory splitting step is performed and the end effector is controlled to move and spray point by point; When a scanning point or split point in the previous step appears during the scanning process, one round of spraying is completed and the scanning is stopped immediately. The remaining scanning points are fitted with a quintic spline curve and the trajectory points are split. After this part of the spraying work is completed, the spraying is ended.

2. The underwater gap spraying method according to claim 1, characterized in that: The method also includes using an FCOS gap detection algorithm to identify gaps in the workpiece (5) when calibrating the workpiece (5).

3. A spraying robot using the underwater crevice spraying method according to claim 1, characterized in that: The invention comprises a three-joint six-degree-of-freedom mechanical arm and a visualization spray head (8); the end of the three-joint six-degree-of-freedom mechanical arm is rotatably connected to the visualization spray head (8); the visualization spray head (8) comprises a spray assembly, a binocular camera and a laser radar; the spray assembly is used to generate an electrostatic spraying operation.

4. The spraying robot according to claim 3, characterized in that: The spraying assembly comprises a rotary cup (4), a high-voltage electrostatic generating system (3), a paint supply system (2) and an air supply system (1); the rotary cup (4) is electrically connected to the high-voltage electrostatic generating system (3); the paint supply system (2) and the air supply system (1) are respectively connected to the rotary cup (4); wherein, an electrostatic field is formed at the nozzle of the rotary cup (4) through the high-voltage electrostatic generating system (3), and an electrostatic spraying operation is formed through the paint supply system (2) and the air supply system (1).

5. The spraying robot according to claim 3, characterized in that: The three-joint six-degree-of-freedom robotic arm comprises a frame box 10, an upper arm (9), a lower arm (6) and a wrist (7); the ends of the frame box (10), the upper arm (9), the lower arm (6) and the wrist (7) are connected in sequence by two rotating joints whose rotation directions are perpendicular to each other; each rotating joint is provided with a servo motor, and the servo motor drives the rotating joint to rotate; the end of the wrist (7) is provided with a rotary motor, the output shaft of the rotary motor is rotatably connected to one end of the visualization nozzle (8), and the rotary motor drives the visualization nozzle (8) to rotate along the axial direction.

6. The spraying robot according to claim 5, characterized in that: The three-joint six-degree-of-freedom robotic arm is made of aluminum alloy.

7. The spraying robot according to claim 3, characterized in that: The invention also includes an explosion-proof purge system; the explosion-proof purge system includes a purge unit (11), a purge control unit (13) and a purge sensor (12); the purge sensor is arranged inside the three-joint six-degree-of-freedom robotic arm; the purge unit (11) is electrically connected to the purge control unit (13); the purge unit (11) is connected to the bottom of the three-joint six-degree-of-freedom robotic arm through a hose (14); wherein, when the purge sensor (12) detects explosive gas, the purge control unit (13) controls the purge unit (11) to increase pressure, and then supplies gas to the three-joint six-degree-of-freedom robotic arm through the hose (14), thereby increasing the internal pressure to prevent the explosive gas.

8. The spraying robot according to claim 5, characterized in that: It also includes a running unit and a workpiece conveying unit; the running unit is arranged at the bottom of the frame box (10) and drives the frame box (10) to move.

9. The spraying robot according to claim 4, characterized in that: It also includes a workpiece transfer unit; the workpiece transfer unit is mounted in front of the three-joint six-degree-of-freedom robotic arm; the workpiece transfer unit includes a workpiece conveying device and a servo rotary table arranged below the workpiece conveying device; when the workpiece conveying device conveys the workpiece to the front of the three-joint six-degree-of-freedom robotic arm, the servo rotary table drives the workpiece to rotate to complete the coating.

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