Non-destructive testing robot for rotating wheel and testing method of non-destructive testing robot

Abstract

The invention discloses a rotating wheel nondestructive testing robot and a testing method thereof, and belongs to the technical field of specialized robots and nondestructive testing. The rotating wheel nondestructive testing robot comprises a permanent magnet adsorption walking mechanism, a multi-degree-of-freedom mechanical arm, a module flaw detection unit, a multi-sensor positioning system and a central controller; the adsorption walking mechanism is used for realizing all-attitude stable crawling on the curved surface of the rotating wheel; the multi-degree-of-freedom mechanical arm is arranged above the middle part of the permanent magnet adsorption walking mechanism and is used for moving the module flaw detection unit to a specified position; the module flaw detection unit is used for performing high-resolution detection on the damage of the composite material on the rotating wheel; the multi-sensor positioning system is used for real-time pose feedback of the robot; the central controller is used for controlling all the components to work cooperatively. According to the nondestructive detection robot for the runner and the detection method thereof, the problems that in the prior art, detection of internal cracks of turbine runner blades depends on a manual frame erecting mode, the high-altitude operation risk is large, the number of detection blind areas is large, and efficiency is low can be effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of special robots and nondestructive testing, and specifically relates to a wheel nondestructive testing robot and a testing method thereof. Background Art

[0002] As the core equipment of hydropower generation systems, turbine runners (especially Francis runners) operate under complex conditions of high head and strong currents for long periods of time. This makes them susceptible to cracks within the blades due to fatigue and stress concentration. If these cracks are not detected promptly, they can continue to grow during operation, eventually leading to serious accidents such as blade breakage. This not only affects power generation efficiency but also causes significant economic losses and safety hazards. Therefore, regular and accurate nondestructive testing of internal cracks in turbine runner blades is crucial to ensuring safe and stable operation of the unit.

[0003] Existing technologies for crack detection within turbine runners (especially Francis turbines) have long relied on manual scaffolding, which presents three key challenges: high-altitude operation risks, numerous blind spots, and low efficiency. Existing wall-climbing robots also suffer from insufficient suction force, poor surface adaptability, and an inability to integrate multimodal flaw detection equipment. Summary of the Invention

[0004] The present invention aims to address the above-mentioned shortcomings by providing a runner nondestructive testing robot and method thereof, thereby resolving the existing problems of relying on manual scaffolding for detecting internal cracks in turbine runners (especially Francis type) blades, which presents high risks of high-altitude operations, numerous blind spots in detection, and low efficiency. To achieve the above-mentioned objectives, the present invention provides the following technical solutions: A nondestructive testing robot for a rotating wheel comprises a permanent magnetic adsorption walking mechanism, a multi-degree-of-freedom robotic arm, a modular flaw detection unit, a multi-sensor positioning system and a central controller; the permanent magnetic adsorption walking mechanism is used to achieve full-stance stable crawling on the curved surface of the rotating wheel; the multi-degree-of-freedom robotic arm is arranged above the middle of the permanent magnetic adsorption walking mechanism, and its end is equipped with a detection module mounting platform for connecting to the modular flaw detection unit. The multi-degree-of-freedom robotic arm is used to move the modular flaw detection unit to a specified position; the modular flaw detection unit is used for high-resolution detection of damage to composite materials on the rotating wheel; the multi-sensor positioning system is used for real-time posture feedback of the robot; and the central controller is used to control the permanent magnetic adsorption walking mechanism, the multi-degree-of-freedom robotic arm, the modular flaw detection unit and the multi-sensor positioning system to work together.

[0005] Furthermore, the permanent magnetic adsorption walking mechanism includes a base, a permanent magnetic adsorption array and a driving track; the driving track is arranged on both sides of the base and cooperates with the permanent magnetic adsorption array to achieve stable crawling on the wheel curved surface.

[0006] Furthermore, the multi-degree-of-freedom robotic arm includes a base, a first arm body, a second arm body, and a third arm body, and five joints sequentially connecting the base, the first arm body, the second arm body, the third arm body, and the detection module mounting platform, three of which are rotational joints and two are translation joints; The rotary joint includes a rotary shaft, a bearing assembly and a rotary drive member. The axis direction of the rotary shaft is perpendicular to the relative motion plane of the two corresponding connected components. The rotary drive member can drive the rotary shaft to rotate around its own axis to achieve relative rotation between the two adjacent components. The movable joint includes a guide rail assembly, a slider and a linear drive component. The guide rail assembly is fixed on one of the components along a preset linear direction. The slider is fixedly connected to the other component and slides with the guide rail assembly. The linear drive component can drive the slider to move along the length direction of the guide rail assembly to achieve relative linear movement between two adjacent components; the working space of the detection module mounting platform covers a pitch angle of ±180 degrees, and the end positioning accuracy is ±0.5mm. Furthermore, the modular flaw detection unit includes a phased array ultrasonic probe, an eddy current probe and a coupling agent spraying device; the phased array ultrasonic probe is composed of multiple piezoelectric chips arranged in a regular pattern, and by controlling the delay time of each chip to emit ultrasonic waves, an overall wavefront is formed to realize sound beam scanning, deflection and focusing, and high-resolution detection of composite material damage is achieved through multimodal imaging technology; the eddy current probe monitors the key parameters of the equipment such as axial displacement and axial vibration in real time by measuring the relative position or motion state between the probe and the rotor; the coupling agent fills the tiny gap between the metal surface and the probe to eliminate the reflection and scattering of ultrasonic waves by air, so that the sound waves can enter the metal more smoothly, reducing the influence of acoustic resistance on the inspection results.

[0007] Furthermore, the multi-sensor positioning system integrates an encoder, an IMU inertial unit, a laser rangefinder and a visual camera for real-time posture feedback.

[0008] Furthermore, the central controller includes a built-in path planning algorithm module and a defect feature extraction module.

[0009] Furthermore, the permanent magnetic adsorption array adopts a Halbach magnet structure, with a magnetic flux density of ≥0.8T and an adsorption safety factor of ≥3.0.

[0010] Furthermore, the path planning algorithm module is based on the runner B-rep model and uses an adaptive grid method to generate a collision-free detection trajectory, and the trajectory point density can be adjusted in the range of 5-20mm.

[0011] Furthermore, the defect feature extraction module performs wavelet packet denoising on the PAUT signal and implements real-time classification of crack types based on the YOLOv5 architecture.

[0012] A method for detecting a rotary wheel nondestructive testing robot, using the aforementioned rotary wheel nondestructive testing robot, comprises the following steps: S1, load the wheel CAD model and divide the inspection area; S2, generating a Zigzag scanning path covering all leaves; S3, the robot moves along the path, and the multi-degree-of-freedom robotic arm dynamically adjusts the posture of the phased array ultrasound probe to maintain normal coupling; S4, multi-sensor positioning system integrates positioning and builds detection maps in real time; S5. Extract defect features and generate a three-dimensional digital report.

[0013] The beneficial effects of the present invention are: The present invention discloses a runner flaw detection robot and method, comprising a permanent magnetic adsorption walking mechanism, a multi-degree-of-freedom robotic arm with force control, a modular flaw detection unit, and a multi-sensor positioning system. Strong adsorption is achieved through a Halbach magnetic array (a magnetic structure that is a near-ideal engineering structure, aiming to generate the strongest magnetic field with a minimum number of magnets). The robotic arm dynamically maintains normal coupling with the probe, and combined with fusion positioning technology, millimeter-level defect location is achieved. This robot solves the industry challenges of incomplete inspection coverage and low efficiency in the confined space of a runner, and is particularly suitable for automated inspection of internal defects in turbine runner blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention; Figure 2 This is a schematic diagram of the three-dimensional structure of the present invention from another perspective; Figure 3 It is a schematic diagram of a partially exploded structure of the present invention; Figure 4 It is another partial exploded structural diagram of the present invention; In the attached figure: 1. Permanent magnetic adsorption walking mechanism; 2. Drive track; 3. Permanent magnetic adsorption array; 4. Multi-degree-of-freedom robotic arm; 5. Detection module installation platform; 7. Phased array ultrasonic probe; 8. Eddy current probe; 9. Couplant spray device; 10. Multi-sensor positioning system; 11. Encoder; 12. IMU inertial unit; 13. Laser rangefinder; 14. Visual camera; 15. Central controller; 16. Path planning algorithm module; 17. Defect feature extraction module. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0016] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0017] In the description of the present invention, "first feature" or "second feature" may include one or more of the features.

[0018] In the description of the present invention, "plurality" means two or more.

[0019] In the description of the present invention, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact with each other, or the first and second features not being in direct contact with each other but being in contact with each other via another feature therebetween.

[0020] In the description of the present invention, “on”, “above” and “above” a first feature of a second feature include the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0021] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," and "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0022] Example See attached Figures 1 to 4. This embodiment discloses a non-destructive testing robot for a runner, which is suitable for damage detection of composite materials of large runners such as water turbines and steam turbines, especially for runner blades with curved structures, and can realize fully automated and high-precision non-destructive testing operations. The robot consists of five major parts: a permanent magnetic adsorption walking mechanism 1, a multi-degree-of-freedom robotic arm 4, a modular flaw detection unit, a multi-sensor positioning system 10 and a central controller 15. Each part works together to complete the inspection task of the runner. The permanent magnetic adsorption walking mechanism 1 serves as the mobile carrier of the robot, assuming the overall support and walking functions; the multi-degree-of-freedom robotic arm 4 is responsible for accurately delivering the detection device to the inspection position; the modular flaw detection unit performs specific damage detection operations; the multi-sensor positioning system 10 provides real-time feedback on the position and posture of the robot; and the central controller 15 serves as the "brain" to coordinate and control the operation of each component.

[0023] In this embodiment, the permanent magnetic adsorption walking mechanism 1 includes a base, a permanent magnetic adsorption array 3 and a drive track 2. The base is made of high-strength aluminum alloy and has an overall flat rectangular structure, providing an installation base for other components. The permanent magnetic adsorption array 3 is embedded in the bottom of the base and is arranged in a Halbach magnet structure. The special magnet arrangement method enhances the single-sided magnetic field strength, and its magnetic flux density can reach more than 0.8T, ensuring that the robot can generate sufficient adsorption force on the vertical or inclined wheel surface. The adsorption safety factor is not less than 3.0, which can effectively prevent the robot from slipping. The drive track 2 is symmetrically arranged on both sides of the base. The track surface is covered with a rubber material with a high friction coefficient, which cooperates with the permanent magnetic adsorption array 3 to achieve reliable walking. The drive track 2 is driven by a servo motor, and the speed is adjusted by a reducer to meet the needs of different detection speeds.

[0024] In this embodiment, the multi-degree-of-freedom robotic arm 4 is installed on a base above the middle part of the permanent magnetic adsorption walking mechanism 1, and consists of a base, a first arm body, a second arm body, a third arm body and a detection module mounting platform 5. The components are connected in sequence through five joints, three of which are rotating joints and two are moving joints.

[0025] The rotary joint consists of a rotating shaft, a bearing assembly, and a rotary drive. The shaft is constructed of 45-gauge steel and surface-hardened for enhanced wear resistance. The bearing assembly utilizes high-precision cross-roller bearings to ensure rotational accuracy. The rotary drive utilizes a servo motor connected to the shaft via a harmonic reducer, enabling precise rotation of the shaft around its axis. The relative rotation angle between adjacent components can range from 0 to 360 degrees.

[0026] The mobile joint consists of a guide rail assembly, a slider, and a linear drive. The guide rail assembly utilizes a high-precision linear guide, fixed to the arm along a predetermined linear direction. The slider is fixedly connected to the adjacent arm and forms a sliding fit with the guide rail assembly. The linear drive utilizes a ball screw and nut mechanism, with the screw arranged parallel to the guide rail assembly and the nut rigidly connected to the slider. A servo motor drives the screw, which in turn drives the slider along the guide rail, achieving relative linear motion between adjacent components.

[0027] Through the coordinated movement of each joint, the working space of the detection module mounting platform 5 can cover a pitch angle of ±180 degrees, and the end positioning accuracy reaches ±0.5mm. The posture of the detection device can be flexibly adjusted to ensure the optimal detection angle with the wheel surface.

[0028] In this embodiment, the modular flaw detection unit is mounted on the inspection module mounting platform 5 and includes a phased array ultrasonic probe 7, an eddy current probe 8, and a coupling agent spray device 9. The phased array ultrasonic probe 7 is composed of multiple piezoelectric chips arranged in a linear array or other pattern. A central controller 15 controls the delay time of ultrasonic emission from each chip, forming a controllable overall wavefront. This enables electronic scanning, deflection, and focusing of the acoustic beam, enabling wide-area inspection without mechanical movement. The probe utilizes multimodal imaging technology, capable of simultaneously acquiring multiple images, including B-scan and C-scan, enabling high-resolution detection of composite material damage, such as delamination and cracks.

[0029] The eddy current probe 8 adopts a high-frequency coil design with an optional operating frequency of 100kHz-1MHz. By measuring the changes in the electromagnetic field between the probe and the surface of the rotor, it monitors the equipment's shaft displacement, shaft vibration and other parameters in real time, and assists in judging the flatness and minor defects of the rotor surface.

[0030] The couplant spray device 9, used in conjunction with the phased array ultrasonic probe 7, comprises a couplant storage tank, a micropump, and an atomizing nozzle. During operation, the micropump draws couplant from the storage tank and sprays it evenly over the detection area in the form of a mist through the atomizing nozzle. The couplant, made of a water-soluble polymer gel, quickly fills the tiny gaps between the metal surface and the probe, eliminating air reflection and scattering of ultrasonic waves, reducing the effects of acoustic resistance, and ensuring smooth ultrasonic penetration into the metal.

[0031] In this embodiment, the multi-sensor positioning system 10 integrates an encoder 11, an IMU (Inertial Measurement Unit) (IMU), a laser rangefinder 13, and a visual camera 14 to provide real-time position and posture feedback for the robot. The encoder 11 calculates travel distance by recording the number of revolutions of the motor driving the tracks 2. The IMU 12, comprising a three-axis accelerometer and a three-axis gyroscope, measures the robot's acceleration and angular velocity in real time to determine its posture. The laser rangefinder 13, mounted on the front of the base, emits a laser beam to measure the distance to the wheel surface, assisting in determining the surface curvature. The visual camera 14, which can be an industrial-grade CCD camera equipped with a wide-angle lens, captures feature points on the wheel surface and uses image recognition algorithms to achieve positioning. Multi-sensor data can be fused using a Kalman filter algorithm to improve positioning accuracy.

[0032] In this embodiment, the central controller 15 can be an industrial-grade embedded computer equipped with a multi-core processor, high-speed storage modules, and a real-time operating system. It has a built-in path planning algorithm module 16 and a defect feature extraction module 17, which communicate with other components via data cables. The path planning algorithm module 16 can load the B-rep model of the runner, use an adaptive grid method to divide the inspection area, and generate a collision-free inspection trajectory based on the wheel's surface features. The trajectory point density can be adjusted within the range of 5-20mm according to the required inspection accuracy. After receiving the PAUT signal acquired by the phased array ultrasonic probe 7, the defect feature extraction module 17 first performs wavelet packet denoising to remove noise interference, and then analyzes the processed signal based on the YOLOv5 architecture to achieve real-time classification of crack types.

[0033] The specific steps of using the rotary nondestructive testing robot for testing are as follows: S1, load the runner CAD model and divide the inspection area; The operator imports the CAD model of the runner into the central controller 15 through the host computer. The central controller 15 automatically divides the inspection area according to the geometric features of the model. The size of each area can be set according to the actual inspection requirements to ensure that all parts of the runner to be inspected are covered, especially key structures such as blades.

[0034] S2, generate a Zigzag scanning path covering all leaves; The path planning algorithm module 16 generates a zigzag scanning path based on the defined inspection area and the rotor B-rep model. This path ensures the inspection device covers all blades with an optimal trajectory. The spacing between path points can be adjusted within a range of 5-20 mm to meet the inspection accuracy requirements, while avoiding obstacles such as protrusions on the rotor to ensure collision-free operation.

[0035] S3, the robot moves along the path, and the robotic arm dynamically adjusts the probe posture to maintain normal coupling; Central controller 15 controls the movement of permanent magnetic adsorption walking mechanism 1 along the generated scanning path. During this movement, multi-sensor positioning system 10 collects real-time robot position information and feeds it back to central controller 15. Based on this feedback, central controller 15 dynamically adjusts the posture of detection module mounting platform 5 by controlling the movement of each joint of multi-degree-of-freedom robotic arm 4, ensuring that the phased array ultrasonic probe 7 maintains normal coupling with the wheel surface and ensuring the stability of the detection signal. Simultaneously, couplant spraying device 9 automatically sprays couplant according to the detection progress.

[0036] S4, multi-sensor fusion positioning and real-time construction of detection map; During the inspection process, the encoder 11, IMU inertial unit 12, laser rangefinder 13, and visual camera 14 operate simultaneously. The multi-sensor positioning system 10 integrates the data from each sensor to determine the robot's precise position in real time. The inspection data collected by the phased array ultrasonic probe 7 and eddy current probe 8 are transmitted to the central controller 15. The central controller 15 combines this positioning information to construct a real-time inspection map of the wheel. This map intuitively displays the distribution of damage within the inspection area.

[0037] S5. Extract defect features and generate a three-dimensional digital report; After inspection, the defect feature extraction module 17 processes the collected PAUT signals to extract characteristic information such as the defect's location, size, and type. The central controller 15 combines this information with the 3D model of the wheel to generate a 3D digital inspection report containing the defect's 3D coordinates, image, and classification results, facilitating subsequent analysis and evaluation by the operator.

[0038] Through the above structure and method, the wheel nondestructive testing robot can adapt to the curved surface structure of the wheel, realize fully automated and high-precision nondestructive testing, greatly improve the testing efficiency and accuracy, and reduce the labor intensity and safety risks of manual testing.

[0039] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that the technical solutions of the present invention may be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and such modifications or equivalents shall be encompassed by the claims of the present invention. Any techniques, shapes, and structures not described in detail herein are well known.

Claims

1. A wheel nondestructive testing robot, characterized by: The invention comprises a permanent magnetic adsorption walking mechanism (1), a multi-degree-of-freedom robotic arm (4), a module flaw detection unit, a multi-sensor positioning system (10) and a central controller (15); the permanent magnetic adsorption walking mechanism (1) is used to realize full-stance stable crawling on the rotating wheel curved surface; the multi-degree-of-freedom robotic arm (4) is arranged above the middle of the permanent magnetic adsorption walking mechanism (1), and the end thereof is equipped with a detection module installation platform (5) for connecting the module flaw detection unit, and the multi-degree-of-freedom robotic arm (4) is used to move the module flaw detection unit to a specified position; the module flaw detection unit is used for high-resolution detection of composite material damage on the rotating wheel; the multi-sensor positioning system (10) is used for real-time posture feedback of the robot; and the central controller (15) is used to control the permanent magnetic adsorption walking mechanism (1), the multi-degree-of-freedom robotic arm (4), the module flaw detection unit and the multi-sensor positioning system (10) to work together.

2. The wheel nondestructive testing robot according to claim 1, characterized in that: The permanent magnetic adsorption walking mechanism (1) comprises a base, a permanent magnetic adsorption array (3) and a driving crawler (2); the driving crawler (2) is arranged on both sides of the base and cooperates with the permanent magnetic adsorption array (3) to achieve stable crawling on the wheel curved surface.

3. The wheel nondestructive testing robot according to claim 2, characterized in that: The multi-degree-of-freedom robotic arm (4) comprises a base, a first arm body, a second arm body and a third arm body, and five joints sequentially connecting the base, the first arm body, the second arm body, the third arm body and the detection module mounting platform (5), three of which are rotational joints and two are moving joints; The rotary joint includes a rotary shaft, a bearing assembly and a rotary drive member. The axis direction of the rotary shaft is perpendicular to the relative motion plane of the two corresponding connected components. The rotary drive member can drive the rotary shaft to rotate around its own axis to achieve relative rotation between the two adjacent components. The movable joint comprises a guide rail assembly, a slider and a linear drive member, wherein the guide rail assembly is fixed on one of the components along a preset linear direction, the slider is fixedly connected to the other component and slides with the guide rail assembly, and the linear drive member can drive the slider to move along the length direction of the guide rail assembly to achieve relative linear movement between two adjacent components; the working space of the detection module mounting platform (5) covers a pitch angle of ±180 degrees, and the end positioning accuracy is ±0.5mm.

4. The wheel nondestructive testing robot according to claim 3, characterized in that: The modular flaw detection unit comprises a phased array ultrasonic probe (7), an eddy current probe (8) and a coupling agent spraying device (9); the phased array ultrasonic probe (7) is composed of a plurality of piezoelectric chips arranged in a regular pattern, and forms an overall wavefront by controlling the delay time of each chip emitting ultrasonic waves, thereby realizing the device of sound beam scanning, deflection and focusing, and realizing high-resolution detection of composite material damage by multimodal imaging technology; the eddy current probe (8) monitors the key parameters of the shaft displacement and shaft vibration of the equipment in real time by measuring the relative position or motion state between the probe and the rotating wheel; the coupling agent eliminates the reflection and scattering of ultrasonic waves by air by filling the tiny gap between the metal surface and the probe, so that the sound waves can enter the metal more smoothly, thereby reducing the influence of acoustic resistance on the inspection results.

5. The wheel nondestructive testing robot according to claim 4, characterized in that: The multi-sensor positioning system (10) is integrated with an encoder (11), an IMU inertial unit (12), a laser rangefinder (13) and a visual camera (14) for real-time posture feedback.

6. The wheel nondestructive testing robot according to claim 5, characterized in that: The central controller (15) includes a built-in path planning algorithm module (16) and a defect feature extraction module (17).

7. The wheel nondestructive testing robot according to claim 6, characterized in that: The permanent magnetic adsorption array (3) adopts a Halbach magnet structure, with a magnetic flux density of ≥0.8T and an adsorption safety factor of ≥3.

0.

8. The wheel nondestructive testing robot according to claim 7, characterized in that: The path planning algorithm module (16) is based on the wheel B-rep model and uses an adaptive grid method to generate a collision-free detection trajectory, and the trajectory point density can be adjusted in the range of 5-20 mm.

9. The wheel nondestructive testing robot according to claim 8, characterized in that: The defect feature extraction module (17) performs wavelet packet noise reduction processing on the PAUT signal and implements real-time classification of crack types based on the YOLOv5 architecture.

10. A method for detecting a wheel nondestructive testing robot, characterized in that: The nondestructive testing robot for a rotary wheel according to claim 9 is used, comprising the following steps: S1, load the wheel CAD model and divide the inspection area; S2, generating a Zigzag scanning path covering all leaves; S3, the robot moves along the path, and the multi-degree-of-freedom robotic arm (4) dynamically adjusts the posture of the phased array ultrasonic probe (7) to maintain normal coupling; S4, multi-sensor positioning system (10) integrates positioning and constructs detection maps in real time; S5. Extract defect features and generate a three-dimensional digital report.

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