A method, equipment, and storage medium for improving the imaging quality of rail defect detection.

Abstract

This invention relates to the field of rail inspection technology, and discloses a method, device, and storage medium for improving the imaging quality of rail defect detection. The method includes the following steps: obtaining the detection depth of the rail defect; determining the effective aperture at the current depth based on the F-number; determining the corresponding effective number of array elements based on the effective aperture and the element spacing; then, using the abscissa of the imaging point as the center of the synthetic aperture, determining the left and right boundary ranges of the aperture center; performing delay superposition on the array elements within the left and right boundary ranges; calculating the total sound path and time delay and extracting the amplitude superposition to obtain the initial pixel value of the imaging point; subsequently, extracting the complex signal at the delay time and performing basic weighting; calculating the phase coherence factor and performing secondary weighting on the initial pixel value; and traversing all imaging points to generate the final detection image. This invention can dynamically adapt to different detection depths by adjusting the aperture, and combined with phase coherence weighting to suppress artifacts, it achieves high-resolution, low-artifact defect imaging of the rail at all depths, improving detection accuracy and reliability.

Description

Technical Field

[0001] This invention relates to the field of rail inspection technology, specifically a method, equipment, and storage medium for improving the imaging quality of rail defect detection. Background Technology

[0002] Railway transportation safety heavily relies on the integrity of rails. Over long-term use, rails can develop hidden damage such as railhead defects, rail web cracks, and welding defects, requiring regular inspection. Current inspection methods involve an inspection trolley equipped with an ultrasonic detector traveling along the rail line to automatically detect internal defects using ultrasonic waves. However, conventional ultrasonic detection suffers from limited coverage and unintuitive imaging. To address these issues, traditional ultrasonic detection has been improved by employing an ultrasonic phased array detector combined with synthetic aperture focusing (SAP) imaging technology. SAP imaging technology performs time-delay superposition of ultrasonic signals from multiple transmitting and receiving apertures to obtain low-resolution images of each focal point. These low-resolution images are then reconstructed to obtain the overall imaging area. In rail defect detection, SAP imaging technology can significantly improve the resolution and detection effectiveness of ultrasonic probes.

[0003] However, traditional synthetic aperture focusing imaging typically uses a fixed aperture size, and its resolution is significantly affected by depth. In rail inspection, the rail head, rail web, and rail base are located at different depths. In the shallow region where the rail head is located, the wavefront curvature is large. If a large fixed aperture is used, there is a significant wavefront mismatch between the echo signals received by the edge elements and the center elements, resulting in phase errors during synthesis, causing image defocusing and artifacts, and reducing image sharpness. In the deep region where the rail base is located, the wavefront is approximately a plane wave. If a small fixed aperture is used, the potential of the array's synthetic aperture cannot be fully utilized. The diameter of the synthetic aperture is limited, resulting in no improvement in resolution and difficulty in detecting minute defects. Therefore, fixed-aperture synthetic aperture focusing imaging cannot achieve optimal image quality simultaneously at the rail head and rail base, and it is difficult to maintain high resolution across the entire depth range, limiting the accuracy and reliability of full-section rail inspection. Summary of the Invention

[0004] The purpose of this invention is to provide a method, device, and storage medium to improve the imaging quality of rail defect detection, in order to solve the problems of inaccuracy and unreliability in full-section rail inspection when using synthetic aperture focusing imaging with a fixed aperture to detect rails.

[0005] The technical solution of this invention is: A method, device, and storage medium for improving the imaging quality of rail defect detection, comprising the following steps: Obtain the detection depth of rail defects and determine the effective aperture at the current depth based on the preset F number; The number of effective array elements participating in imaging is determined based on the determined effective aperture and the array element spacing. For any imaging point on the imaging plane, the position of the array element corresponding to the horizontal coordinate of the imaging point is used as the center of the synthetic aperture and indexed to determine the range of the left and right boundaries of the synthetic aperture corresponding to each detection depth. The echo signals of the array elements within the left and right boundary ranges are delayed and superimposed to determine the total sound path and time delay from the transmitting array element to the imaging point and back to the receiving array element. The amplitude of each receiving array element at the corresponding time delay is extracted and superimposed. After amplitude mapping conversion, the initial pixel value of the imaging point is obtained. The complex signal at the delayed time is extracted from the original echo signal. The extracted complex signal is then weighted, and the phase coherence factor of the current imaging point is calculated. The initial pixel value of the current imaging point is then weighted a second time using the phase coherence factor. All imaging points on the imaging plane are traversed to generate the final detection image of the rail defect.

[0006] Preferably, as a further improvement of the present invention, the effective aperture is obtained by the following formula: , In the formula, z To detect depth, L ( z () represents the effective aperture used at the current detection depth. FN It is an F-number.

[0007] Preferably, as a further improvement of the present invention, the number of effective array elements is determined based on the following formula: , In the formula, For the effective number of array elements, p For the spacing between array elements, L ( z () represents the effective aperture used at the current detection depth. z To detect depth, FN It is an F-number.

[0008] Preferably, as a further improvement of the present invention, the left and right boundary ranges of the synthetic aperture corresponding to each detection depth are determined by the following formula: , , , In the formula, i left For the left boundary element index, i right For the right boundary matrix element index, For the effective number of array elements, i c For the central array element index, p For the spacing between array elements, x is the x-coordinate of the imaging point.

[0009] Preferably, as a further improvement of the present invention, the formula for calculating the total sound path is as follows: , In the formula, For the launch array element, To receive array elements, x The x-coordinate of the imaging point. z To detect depth, d total For total pitch; The formula for calculating the time delay is as follows: , In the formula, c The speed of sound in the medium. τ For time delay, d total For total pitch; The obtained echo signal is: , In the formula, For echo signal, To transmit pulses, A ( x ) is the amplitude attenuation factor; Signal alignment and superposition are performed to extract the signal with time delay from the echo signal of the receiving array element. τ The amplitude at a given point is calculated, and then all amplitudes are superimposed. After amplitude mapping transformation, the image point is obtained. x , z ) pixel values I ( x , z ): , In the formula, To receive array elements, i left For the left boundary element index, i right For the right boundary matrix element index, This is the superimposed imaging echo signal.

[0010] Preferably, as a further improvement of the present invention, the basic weighting of the extracted complex signal includes the following steps: From the original echo signal Extracting time delay τ Complex signal: , In the formula, A i For signal amplitude, It is the phase modulation function; Perform basic weighting on the obtained complex signal. , In the formula, For the basic weighting of dynamic aperture, I z_wi ( x , z The pixel values ​​of the image points after weighting based on the base. For the first i Each element has a time delay τ The signal value.

[0011] Preferably, as a further improvement of the present invention, the formula for calculating the phase coherence factor is: , , , In the formula, PCF ( z ) represents the phase coherence factor. To sum the magnitudes of the complex sums of the selected array element signals, The arithmetic sum of the complex sums of the selected array element signals. For amplitude, For phase; coherence factor PCF(z) Substitute into the following formula and perform a second weighting. , In the formula, For the basic weighting of dynamic aperture, i left For the left boundary element index, i right For the right boundary matrix element index, Let be the signal value of the i-th array element at delay τ. for PCF The pixel values ​​of the image after double weighting.

[0012] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the above-described method for improving the imaging quality of rail defect detection.

[0013] The present invention also provides a computer-readable storage medium storing a computer program that, when loaded by a processor, can execute the above-described method for improving the imaging quality of rail defect detection.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. A synthetic aperture focusing imaging method with different aperture sizes at different depths is adopted. The aperture size is dynamically adjusted for different depths. A small aperture is used in the near field to avoid wavefront mismatch and ensure image clarity, while a large aperture is used in the far field to improve resolution. From the near field to the far field, the overall resolution and image quality are optimized, thereby achieving high-precision imaging of the rail head, rail web and rail bottom across the entire depth range.

[0015] 2. Based on the dynamic adjustment of the aperture size, in order to further suppress phase inconsistency noise and artifacts, and at the same time enhance the focusing effect of the target signal, a phase coherence factor is added to the dynamic aperture to improve the coherent synthesis quality and make the imaging resolution and contrast at different depths more balanced, so as to ensure both aperture adaptation depth and signal phase consistency. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating a method for improving the imaging quality of rail defect detection according to the present invention. Detailed Implementation

[0017] The following is combined with Figure 1 The specific embodiments of the present invention will be described in detail below. In the description of the invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0018] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0019] Example like Figure 1 As shown, this embodiment of the invention provides a method for improving the imaging quality of rail defect detection, including the following steps: S1. Obtain the detection depth of rail defects and determine the effective aperture at the current depth based on the preset F number.

[0020] Specifically, the F-number (F-Number) originates from optics and is defined as the ratio of focal length to aperture diameter. A smaller F-N results in a larger aperture and higher theoretical resolution, but also a greater risk of sidelobes and artifacts in the near field. To maintain optimal focusing performance across the entire depth range, the F-number is preset as a constant, typically determined through simulation or experimentation. A smaller F-value leads to higher resolution but also greater sensitivity to errors. Generally, the F-value starts at 2 and is adjusted sequentially based on the calculated aperture and detection results until a balance between good imaging resolution and low error is achieved.

[0021] According to the definition of F-number: , It can be deduced that at the detection depth z The effective aperture to be used: , In the formula, z For the depth of the image, L ( z () represents the effective aperture used at the current detection depth. FN F-number is the ratio of focal length to aperture diameter.

[0022] S2. Determine the number of effective array elements participating in imaging based on the determined effective aperture and array element spacing.

[0023] Specifically, the effective aperture used at the current detection depth can be determined in step S1. L ( z If ), then the corresponding number of effective array elements is: , In the formula, For the effective number of array elements, p The element spacing is determined by known parameters provided by the ultrasonic phased array probe hardware. L ( z () represents the effective aperture used at the current detection depth. z To detect depth, FN It is an F-number; The +1 in the above formula is because it needs to include the central array element. Since the number of array elements must be an integer, it is necessary to adjust the value accordingly. Perform the rounding operation.

[0024] Important limitations: It cannot exceed the total number of array elements N.

[0025] .

[0026] S3. Determine each detection depth z The center and left and right boundaries of the synthetic aperture at the location, for an imaging point on the imaging plane ( x , z ), with imaging points ( x , z x-coordinate x The location is used as the aperture center and indexed to determine the left and right boundary ranges of the synthetic aperture corresponding to each detection depth.

[0027] Central array element index: , In the formula, i c For the central array element index, p For the spacing between array elements, x The x-coordinate of the imaging point; Left boundary element index: , In the formula, i left For the left boundary element index, i c For the central array element index, For the effective number of array elements, Right boundary matrix element index: , In the formula, i right For the right boundary matrix element index, i c For the central array element index, The effective number of array elements.

[0028] S4. Perform delay superposition processing on the echo signals of the array elements within the range of the left and right boundaries, calculate the total sound path and time delay from the transmitting array element to the imaging point and back to the receiving array element, extract the amplitude of each receiving array element at the corresponding time delay and superimpose it, and obtain the initial pixel value of the imaging point after amplitude mapping conversion.

[0029] Specifically, delay stacking (beamforming) for depth z The point at ( x , z Only for indexes from arrive The array elements are stacked with a delay.

[0030] Calculate from the transmitting array element To the imaging point ( x , zThen return to the receiving array element. The total sound path is: , In the formula, For the launch array element, For receiving array elements; x The x-coordinate of the imaging point. z To detect depth, also referring to the ordinate of the imaging point. d total For total pitch; The formula for calculating time delay is as follows: , In the formula, c The speed of sound in the medium. τ For time delay; The obtained echo signal is: , In the formula, For echo signal, To transmit pulses, A ( x ) is the amplitude attenuation factor; Then, signal alignment and superposition are performed to extract the signal with time delay from the echo signal of the receiving array element. τ The amplitude at a given point is calculated, and then all amplitude values ​​are superimposed. A normalized amplitude mapping transformation is then performed on the superimposed amplitude signal to obtain the imaging point. x , z ) pixel values I ( x , z ): , In the formula, To receive array elements, i left For the left boundary element index, i right For the right boundary matrix element index, This is the superimposed imaging echo signal.

[0031] S5. Extract the complex signal at the delayed time from the original echo signal, perform basic weighting on the extracted complex signal, then calculate the phase coherence factor of the current imaging point, use the phase coherence factor to perform secondary weighting on the initial pixel value of the current imaging point, traverse all imaging points on the imaging plane, and generate the final detection image of the rail defect.

[0032] Specifically, the basic weighting of the extracted complex signal includes the following steps: From the original echo signal Extracting time delay τ Complex signal: , In the formula, A i For signal amplitude, It is the phase modulation function; Perform basic weighting on the obtained complex signal. , In the formula, For the basic weighting of dynamic aperture, I z_wi ( x , z The pixel values ​​of the image points after weighting based on the base. For the i-th array element in time delay τ The signal value.

[0033] The initial pixel values ​​of the imaging points are weighted twice using a phase coherence factor, as follows: Calculate the sum of the magnitudes of the complex sums of the selected array element signals: , In the formula, To sum the magnitudes of the complex sums of the selected array element signals, For amplitude, For phase.

[0034] It should be noted that selecting array elements refers to all array element signals participating in the synthesis. i left to i right ).

[0035] Calculate the arithmetic sum of the complex sums of the selected array element signals: , In the formula, The arithmetic sum of the complex sums of the selected array element signals. This refers to the amplitude.

[0036] Delay the extraction time τ Substituting the complex signal, the amplitude, and the arithmetic sum of the complex sum into the following formula, we obtain the coherence factor of the current imaging point. PCF(z) With depth z Dynamic changes: , coherence factor PCF(z) Substitute into the following formula for secondary weighting , In the formula, For the basic weighting of dynamic aperture,i left For the left boundary element index, i right For the right boundary matrix element index, For the first i Each element is delayed τ The signal value at that location, for PCF The pixel values ​​of the image after double weighting.

[0037] Finally, iterate through all imaging points ( x , z This process generates a final high-resolution, low-artifact image that ensures both aperture-fit depth and signal phase consistency.

[0038] This invention employs different aperture sizes at different depths to significantly improve defect detection at various locations on rails. Using a larger aperture at deeper depths increases the synthetic gain of the received signal, aiding in the detection of weak echo signals at greater depths and thus improving the lateral resolution of deep targets. At shallower depths, using a smaller aperture effectively suppresses defocusing and raster lobe artifacts, ensuring resolution uniformity while improving the quality of ultrasonic imaging and enhancing the accuracy of rail defect detection. Furthermore, the rational use of array elements for synthesis reduces computational load, thereby lowering the overall computational burden and improving detection efficiency.

[0039] Phase coherence factor (PCF) enhances lateral resolution by weighted amplification of phase-consistent signals and suppression of phase-discrete signals, resulting in a more focused signal. Dynamic aperture switching between shallow (small aperture) and deep (large aperture) layers is prone to sidelobes due to unbalanced array element excitation; in rail inspection, surface roughness or uneven coupling agent can also introduce artifacts. PCF screening reduces sidelobe levels, significantly minimizing artifact interference with defect identification. PCF accurately identifies the phase correlation of defect echoes, amplifying effective signals while suppressing noise and improving the contrast between defects and the background. Ultimately, the fusion of dynamic aperture and PCF represents a dual optimization of "spatial adaptation + signal purification," offering high technical feasibility, simple engineering implementation, and significantly improved accuracy and reliability in rail defect detection. This solution requires no hardware replacement, only the addition of a PCF calculation module to the existing signal processing workflow, making it highly adaptable to rail inspection.

[0040] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the steps in the embodiment of the method for improving the imaging quality of rail defect detection. Specific implementation methods can be found in the method embodiments, and will not be repeated here.

[0041] The present invention also provides a non-transitory computer-readable storage medium containing instructions on which a computer program is stored. For example, a memory containing instructions that can be executed by a processor of a computer device to perform the above-described method. For example, the non-transitory computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc. When the computer program is executed by the processor, it can implement the steps in the embodiments of the method for improving the imaging quality of rail defect detection. Specific implementation methods can be found in the method embodiments, which will not be repeated here.

[0042] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0043] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0044] These computer program instructions can also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0045] It should be noted that the specific embodiments described above enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. Therefore, although the present invention has been described in detail in this specification and embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention are covered within the protection scope of the present invention patent. No reference numerals in the claims should be construed as limiting the scope of the claims. Any simple variations or equivalent substitutions of technical solutions that can be readily obtained by those skilled in the art within the scope of the technology disclosed in the present invention are within the protection scope of the present invention.

Claims

1. A method for improving the imaging quality of rail defect detection, characterized in that, Includes the following steps: Obtain the detection depth of rail defects and determine the effective aperture at the current depth based on the preset F number; The number of effective array elements participating in imaging is determined based on the determined effective aperture and the array element spacing. For any imaging point on the imaging plane, the position of the array element corresponding to the horizontal coordinate of the imaging point is used as the center of the synthetic aperture and indexed to determine the range of the left and right boundaries of the synthetic aperture corresponding to each detection depth. The echo signals of the array elements within the left and right boundary ranges are delayed and superimposed to determine the total sound path and time delay from the transmitting array element to the imaging point and back to the receiving array element. The amplitude of each receiving array element at the corresponding time delay is extracted and superimposed. After amplitude mapping conversion, the initial pixel value of the imaging point is obtained. The complex signal at the delayed time is extracted from the original echo signal. The extracted complex signal is then weighted, and the phase coherence factor of the current imaging point is calculated. The initial pixel value of the current imaging point is then weighted a second time using the phase coherence factor. All imaging points on the imaging plane are traversed to generate the final detection image of the rail defect.

2. The method for improving the imaging quality of rail defect detection according to claim 1, characterized in that, The effective aperture is obtained using the following formula: ， In the formula, z To detect depth, L ( z () represents the effective aperture used at the current detection depth. FN It is an F-number.

3. The method for improving the imaging quality of rail defect detection according to claim 2, characterized in that, The number of effective array elements is determined based on the following formula: ， In the formula, For the effective number of array elements, p For the spacing between array elements, L ( z () represents the effective aperture used at the current detection depth. z To detect depth, FN It is an F-number.

4. The method for improving the imaging quality of rail defect detection according to claim 3, characterized in that, The left and right boundary ranges of the synthetic aperture corresponding to each detection depth are determined by the following formula: ， ， ， In the formula, i left For the left boundary element index, i right For the right boundary matrix element index, For the effective number of array elements, i c For the central array element index, p For the spacing between array elements, x is the x-coordinate of the imaging point.

5. The method for improving the imaging quality of rail defect detection according to claim 1, characterized in that, The formula for calculating the total sound path is as follows: ， In the formula, For the launch array element, To receive array elements, x The x-coordinate of the imaging point. z To detect depth, d total For total pitch; The formula for calculating the time delay is as follows: ， In the formula, c The speed of sound in the medium. τ For time delay, d total For total pitch; The obtained echo signal is: ， In the formula, For echo signal, To transmit pulses, A ( x ) is the amplitude attenuation factor; Signal alignment and superposition are performed to extract the signal with time delay from the echo signal of the receiving array element. τ The amplitude at a given point is calculated, and then all amplitudes are superimposed. After amplitude mapping transformation, the image point is obtained. x , z ) pixel value I ( x , z ): ， In the formula, To receive array elements, i left For the left boundary element index, i right For the right boundary matrix element index, This is the superimposed imaging echo signal.

6. The method for improving the imaging quality of rail defect detection according to claim 5, characterized in that, The basic weighting of the extracted complex signal includes the following steps: From the original echo signal Extracting time delay τ Complex signal: ， In the formula, A i For signal amplitude, It is the phase modulation function; Perform basic weighting on the obtained complex signal. ， In the formula, For the basic weighting of dynamic aperture, I z_wi ( x , z The pixel values ​​of the image points after weighting based on the base. For the first i Each element has a time delay τ The signal value.

7. The method for improving the imaging quality of rail defect detection according to claim 6, characterized in that, The formula for calculating the phase coherence factor is as follows: ， ， ， In the formula, PCF ( z ) represents the phase coherence factor. To sum the magnitudes of the complex sums of the selected array element signals, The arithmetic sum of the complex sums of the selected array element signals. For amplitude, For phase; coherence factor PCF(z) Substitute into the following formula and perform a second weighting. ， In the formula, For the basic weighting of dynamic aperture, i left For the left boundary element index, i right For the right boundary matrix element index, Let be the signal value of the i-th array element at delay τ. for PCF The pixel values ​​of the image after double weighting.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the method for improving the imaging quality of rail defect detection as described in any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is loaded by the processor, it is able to execute the method for improving the imaging quality of rail defect detection as described in any one of claims 1 to 7.

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