Flexible phased array ultrasonic adaptive detection system and method based on multi-source wave field distortion compensation and conformal regulation

Abstract

The application discloses a flexible phased array ultrasonic adaptive detection system and method based on multi-source wave field distortion compensation and shape-preserving regulation, adopts a flexible ultrasonic array to excite full-matrix FMC ultrasonic waves to a variable-curvature workpiece, drives the flexible ultrasonic array to adaptively adhere to the workpiece through a shape-preserving driving mechanism, dynamically reconstructs array element coordinates in real time, calculates accurate time delay through cross-interface wave field distortion compensation of echo signals, completes workpiece internal structure imaging by using a TFM algorithm with correlation factor weighting, further jointly evaluates image quality, if imaging indexes do not meet the standards, issues a closed-loop control instruction to the shape-preserving driving mechanism to optimize the adhesion state of the flexible ultrasonic array, iterates the coordinate reconstruction, distortion compensation and imaging calculation steps again until the imaging quality meets the threshold requirement. The application solves the problems of sound energy loss and blind area caused by the fact that the probe cannot completely adhere, and significantly improves the defect positioning and imaging precision under dynamic deformation.

Description

Technical Field

[0001] This invention belongs to the field of nondestructive testing technology, and particularly relates to a flexible phased array ultrasonic adaptive detection system and method based on multi-source wavefield distortion compensation and conformal control. Background Technology

[0002] In the field of modern industrial nondestructive testing (NDT), especially in the quality assurance of core and critical components such as aerospace composite materials, complex nuclear power pipes, and wind turbine blades, ultrasonic phased array (PAUT) technology plays an irreplaceable role due to its strong penetrating power and sensitivity to internal defects. As industrial equipment develops towards larger, more complex, and irregularly shaped designs, traditional inspection of regular planes or standard cylindrical surfaces can no longer meet the demands. Efficient and high-precision detection of internal defects on non-standard, complex, variable curvature surfaces has become a current industry pain point.

[0003] Existing ultrasonic testing of complex curved surfaces mainly relies on two methods: one is to use a multi-axis robotic arm to carry a traditional rigid probe in combination with the immersion method for scanning; the other is to use the flexible ultrasonic phased array probe (Flexible PAUT), which has emerged in recent years. The advantage of the flexible ultrasonic phased array probe is that it can undergo physical deformation to conform to the workpiece surface, thereby achieving better detection results. Most existing imaging technologies are based on the total focusing method (TFM), which requires precise knowledge of the three-dimensional coordinates of each array element in space, and the calculation of the propagation time delay of the sound wave across the interface through the classical Fermat principle or Snell's law, thereby achieving focused imaging.

[0004] The above-mentioned existing technologies have limitations in multiple dimensions in practical engineering applications: First, at the level of physical coupling and hardware coordination, existing flexible probes mostly employ passive deformation (such as manual pressing or simple spring backing), lacking real-time adaptive active conformal control for complex surfaces with varying curvature. This often results in minute air gaps between the probe and the workpiece surface, severely impacting acoustic transmittance. Second, at the algorithmic calculation level, due to the constantly changing curvature of the workpiece surface, the relative spatial coordinates of each array element are no longer fixed constants after the flexible array deforms. Existing technologies often still use simplified fixed curvature models or planar models when calculating the propagation delay of sound beams across interfaces, failing to compensate in real-time for wave field distortion (phase defocus) caused by changes in array element coordinates and interface curvature. This calculation error leads to artifacts, reduced resolution, and even defect location shifts in the final 3D imaging. Finally, at the level of system closed-loop mechanism, existing scanning systems mostly operate in an "open-loop" mode, i.e., data is acquired first and then analyzed offline. If poor signal quality occurs during detection due to poor adhesion, the system cannot detect and correct it in real time, requiring rework and resulting in extremely low detection efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible phased array ultrasonic adaptive detection system and method based on multi-source wavefield distortion compensation and conformal control, so as to solve the problems existing in the background technology, such as poor fit between the existing flexible probe and complex curved surface, phase calculation error caused by array element deformation, and lack of real-time evaluation closed loop.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A flexible phased array ultrasonic adaptive detection system based on multi-source wavefield distortion compensation and conformal control includes a flexible ultrasonic array, a conformal drive mechanism, an ultrasonic host, a central processing computing platform, and a display terminal. The flexible ultrasonic array consists of a flexible insulating substrate and several embedded piezoelectric ultrasonic array elements, which are used to be deployed on the surface of the workpiece with variable curvature to be tested, to excite ultrasonic full-matrix capture signals to the workpiece, and to collect echo signals. The conformal drive mechanism includes a distributed micro servo push rod array, a drive control module, and a curvature sensing element. Each push rod of the micro servo push rod array is connected to the back of each element of the flexible ultrasonic array. The curvature sensing element is used to collect workpiece surface curvature information (including curvature radius and tangent angle). The drive control module is used to control the extension and retraction of each push rod of the micro servo push rod array based on the collected curvature information, thereby driving the flexible ultrasonic array to adaptively deform and actively conform to the workpiece surface. The ultrasound host is connected to the flexible ultrasound array and is used to drive the flexible ultrasound array to complete the transmission and reception of ultrasound full matrix capture signals. The central processing platform integrates a dynamic array element coordinate reconstruction unit, a wavefield distortion compensation unit, a PCF-weighted TFM imaging unit, and an image quality joint evaluation and closed-loop control unit. The dynamic array element coordinate reconstruction unit reconstructs the physical coordinates of each element of the flexible ultrasonic array based on curvature information collected by curvature sensing elements. The wavefield distortion compensation unit receives the collected echo signals, performs cross-interface wavefield distortion compensation and precise time-lapse calculation, eliminating wavefield defocusing errors caused by surface deformation. The PCF-weighted TFM imaging unit uses a phase coherence factor-weighted TFM algorithm to image the internal structure of the workpiece. The image quality joint evaluation and closed-loop control unit calculates the Shannon entropy and local contrast of the imaging results in real time, compares them with pre-stored imaging thresholds for quality assessment, and if the imaging indicators do not meet the standards, it sends closed-loop control commands to the conformal drive mechanism to optimize the flexible ultrasonic array's fit, iterates the coordinate reconstruction, distortion compensation, and imaging calculation steps again until the imaging quality meets the threshold requirements. The display terminal is connected to the central processing computing platform and is used to display array element coordinate parameters, compensation delay data, imaging results of internal defects in the workpiece, system closed-loop adjustment records, and image quality scoring data in real time.

[0007] Preferably, the dynamic array element coordinate reconstruction unit reconstructs the physical coordinates of each element of the flexible ultrasonic array in the following manner: Using the central element of the flexible ultrasonic array as the origin, the physical coordinates of each element are calculated by integrating the curvature along the arc length of the flexible insulating substrate. The calculation formula is as follows: ; ; in, Indicates array element physical coordinates Indicates array element The arc length distance along the flexible insulating substrate, This is the tangent angle of the curved surface; the model ensures a precise mapping between the underlying hardware deformation parameters and the acoustic computing platform. The real-time two-dimensional coordinates of all array elements are solved point by point to complete the dynamic reconstruction of the spatial position of array elements under deformation state.

[0008] Preferably, the wavefield distortion compensation unit performs cross-interface wavefield distortion compensation and accurate timekeeping calculation on the echo signal using the following calculation method: The wave field distortion compensation unit calculates the incident angle and refraction angle of each array element based on Snell's law and the sound velocity of the coupling layer and the workpiece. Substituting the coupling layer thickness and real-time curvature, the distortion compensation term is calculated. Then, the propagation delay from the array element to the target pixel is obtained through time travel. The calculation formula is as follows: ; ; ; in, Indicates the transmission / reception array element To the target pixel The propagation delay This is a distortion compensation term. Represents the target pixel. Physical coordinates; The sound velocity of the coupling layer, The sound velocity of the workpiece. The coupling layer thickness; and Representing array elements respectively The corresponding ultrasonic incident angle and refraction angle; For adaptive correction coefficients, Indicates array element The real-time radius of curvature at that location. This distortion compensation model eliminates phase defocus caused by surface undulations from the underlying physical equations.

[0009] Preferably, the PCF-weighted TFM imaging unit is used to complete the imaging of the internal structure of the workpiece using a phase coherence factor-weighted TFM algorithm, including the following processing steps: (1) After propagation delay compensation, the echo signals of each transmit-receive channel are extracted at the target pixel. Calculate the phase variance of the echo signal in each transmit-receive channel based on the instantaneous phase at the given point: ; ; in, This indicates the echo signal of each transmit-receive channel at the target pixel. Phase variance at that point The total number of array elements. Indicates by Array element launch, The echo signal received by the array element is compensated for propagation delay at the target pixel. The instantaneous phase at that point, This indicates that all transmit-receive channel echo signals are at the target pixel. The average coherent phase at that point, This represents the phase angle extraction operation for complex numbers. Represents the imaginary unit. ; (2) Based on the echo signals of each transmit-receive channel at the target pixel point Calculate the phase variance of the target pixel. Phase coherence factor weights at: ; in, Represents the target pixel. Phase coherence factor weights at the location; The monotonically decreasing mapping function representing the phase variance to the phase coherence factor weights; (3) Calculate the imaging amplitude of the target pixel: ; in, Represents the target pixel. The imaging amplitude at that location, The amplitude of the full matrix echo signal; Indicates from the launch array element To the target pixel The propagation delay Indicates from the receiving array element To the target pixel The propagation delay This represents the angular frequency of the ultrasonic echo signal. This indicates the sampling time of the full matrix echo signal.

[0010] This invention further provides a method for detecting variable curvature workpieces based on the above-mentioned flexible phased array ultrasonic adaptive detection system, the method comprising the following steps: S1. The flexible ultrasonic array is attached to the surface of the workpiece with variable curvature by relying on the micro servo push rod array. The system is powered on and the basic acoustic parameters and image qualification threshold are initialized. The curvature sensing element collects the curvature information of the workpiece surface in real time. S2. The drive control module controls the movement of the micro servo push rod array based on the initial curvature data, drives the flexible ultrasonic array to adaptively fit the workpiece, and sends the curvature data into the dynamic array element coordinate reconstruction unit to complete the real-time coordinate solution of all array elements. S3. The ultrasonic host drives the flexible ultrasonic array to complete the full matrix acquisition and transmission of ultrasonic signals. The acquired echo data is transmitted to the wave field distortion compensation unit for cross-interface wave field distortion compensation and accurate travel time calculation. S4. The compensated time delay data is sent to the PCF weighted TFM imaging unit, and the phase correlation factor weighted TFM algorithm is used to complete the imaging of the internal structure of the workpiece. S5. The imaging results are sent to the image quality joint evaluation and closed-loop control unit to carry out the image quality joint evaluation. If the imaging index does not meet the standard, a closed-loop control command is sent to the conformal drive mechanism to optimize the flexible ultrasonic array fitting state and iterate the coordinate reconstruction, distortion compensation, and imaging calculation steps again until the imaging quality meets the threshold requirements. S6. The final imaging result after meeting the standard is transmitted to the display terminal for output display.

[0011] Compared with the prior art, the present invention has the following advantages: (1) It breaks through the acoustic coupling bottleneck of complex variable curvature interfaces. Through the conformal drive mechanism, the flexible ultrasonic array probe can adaptively fit the workpiece under test like "skin", which solves the problem of acoustic energy loss and blind zone caused by the inability of rigid probes or passive flexible probes to fit completely from the physical hardware level; (2) Significantly improves defect localization and imaging accuracy under dynamic deformation. To address the coordinate drift caused by the deformation of the flexible ultrasonic probe, this invention proposes a dynamic coordinate integral extraction model and a unique cross-interface wavefield distortion compensation algorithm. Compared with the traditional fixed curvature model, the present invention can eliminate phase calculation errors in real time, which greatly improves the true resolution and positioning accuracy of ultrasound imaging. (3) A closed-loop detection system, from blind scanning to intelligent feedback, has been achieved. The system breaks through the traditional open-loop detection mode and can automatically adjust the pose and pressure of the front-end hardware based on the evaluation results of real-time image coherence and entropy. This improvement greatly reduces the reliance on human experience, avoids the generation of poor-quality data, and significantly improves the efficiency and reliability of industrial field inspection. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall architecture of the flexible phased array adaptive detection system of the present invention; Figure 2 This is a cross-sectional view of the flexible phased array adaptive detection system of the present invention; Figure 3 This is a flowchart illustrating the workflow of the flexible phased array adaptive detection system of the present invention. Reference numerals: 1. Variable curvature workpiece; 2. Flexible ultrasonic array; 3. Miniature servo push rod array; 4. Curvature sensor and drive control integrated module; 5. Ultrasonic host; 6. Central processing computing platform; 61. Dynamic array element coordinate reconstruction unit; 62. Wave field distortion compensation unit; 63. PCF weighted TFM imaging unit; 64. Image quality joint evaluation and closed-loop control unit; 7. Display terminal; 8. Coupling agent layer; 9. Push rod support frame. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0014] This embodiment provides a flexible phased array ultrasonic adaptive detection system based on multi-source wavefield distortion compensation and conformal control. The structural framework and data flow relationship of this system are as follows: Figure 1 As shown, the system consists of a flexible ultrasonic array 2, a micro servo push rod array 3, a curvature sensor and drive control integrated module 4, an ultrasonic host 5, a central processing computing platform 6, and a display terminal 7. The central processing computing platform 6 integrates four functional units: a dynamic array element coordinate reconstruction unit 61, a wavefield distortion compensation unit 62, a PCF-weighted TFM imaging unit 63, and an image quality joint evaluation and closed-loop control unit 64.

[0015] 1. Flexible ultrasonic array and conformal drive mechanism The structure of the flexible ultrasonic array and conformal drive mechanism can be referred to Figure 2Specifically, the flexible ultrasonic array 2 is composed of piezoelectric ultrasonic elements embedded in a flexible insulating substrate, and is attached to the surface of the variable curvature workpiece 1 during operation. The conformal drive mechanism consists of a micro servo push rod array 3, a curvature sensor and drive control integrated module 4, and a push rod support frame 9. The micro servo push rod array 3 is mounted on the push rod support frame 9, and the push rods of the micro servo push rod array 3 are arranged one-to-one with the back of each element of the flexible ultrasonic array 2. Each push rod in the micro servo push rod array 3 can receive control signals from the curvature sensor and drive control integrated module 4, and achieve independent adjustment of single-point pressure by changing the extension length, thereby driving the flexible ultrasonic array to adaptively deform and eliminate the gap between the contact surface with the workpiece. The curvature sensor and drive control integrated module 4 integrates the curvature sensor element and the drive control circuit board. The curvature sensor element is arranged along the flexible ultrasonic array to collect the curvature radius of the workpiece contact surface in real time. Surface tangent angle The curvature sensor and drive control integrated module 4 transmits curvature data to the central processing computing platform 6 on the one hand, and receives closed-loop control commands issued by the image quality joint evaluation and closed-loop control unit 64 on the other hand, and adjusts the pressing stroke and output pressure of the corresponding push rods of the micro servo push rod array 3 in real time.

[0016] 2. Ultrasonic main unit Among them, the ultrasonic host 5 is a full-matrix FMC ultrasonic transceiver, with hardware matching the two-element channel of the flexible ultrasonic array. It can transmit excitation ultrasonic signals element by element according to the time sequence, and synchronously acquire the reflected echo of the workpiece through all channels, storing the original echo amplitude of the entire matrix in real time. After acquisition, the raw echo data is transmitted to the central processing computing platform 6 to provide raw data for subsequent wavefield distortion compensation and imaging calculations.

[0017] 3. Central Processing Unit The central processing computing platform 6 is equipped with an industrial computing processor, which integrates four functional units in sequence: dynamic array element coordinate reconstruction unit 61, wave field distortion compensation unit 62, PCF weighted TFM imaging unit 63, and image quality joint evaluation and closed-loop control unit 64. Each unit performs operations in sequence and realizes data communication.

[0018] (1) Dynamic array element coordinate reconstruction unit Because the probe deforms, the physical coordinates of each array element must be dynamically reconstructed. This unit receives the tangent angle transmitted by the curvature sensor and the drive control integrated module 4. The data, using the central element of the flexible ultrasonic array 2 as the coordinate origin, reconstructs the physical coordinates of each element based on the arc length integral formula. Real-time physical coordinates of each array element Precise derivation via the integral of curvature along the arc length of the flexible insulating substrate: ; ; in, Indicates array element The arc length distance along the flexible insulating substrate, This is the tangent angle of the surface at this point; The real-time two-dimensional coordinates of all array elements are solved point by point to complete the dynamic reconstruction of the spatial position of the array elements under deformation state. The output coordinate parameters are sent to the wave field distortion compensation unit 62 to participate in the delay calculation.

[0019] (2) Wavefield distortion compensation unit This unit first calculates the incident and refraction angles of each array element based on Snell's law, combined with the sound velocity of the coupling layer and the workpiece. Then, it substitutes the coupling layer thickness and real-time curvature to calculate the distortion compensation term. Finally, it obtains the distance from the array element to the target pixel through time travel. The precise propagation delay eliminates wavefield defocusing errors caused by surface deformation; the formula for calculating the precise propagation delay from array element to target pixel is: ; in, Indicates the transmission / reception array element To the target pixel The propagation delay This is a distortion compensation term. Represents the target pixel. physical coordinates The sound velocity of the workpiece; Distortion compensation item Real-time curvature and coupling layer thickness were taken into account. The coupling effect is calculated using the following formula: ; ; In the formula, The sound velocity of the coupling layer, and Representing array elements respectively The corresponding ultrasonic incident angle and refraction angle, For adaptive correction coefficients, Indicates array element The real-time radius of curvature at that location.

[0020] This distortion compensation model eliminates phase defocus caused by surface undulations from the underlying physical equations. The compensated time delay parameters are then transmitted to the PCF-weighted TFM imaging unit 63.

[0021] (3) 6.3PCF-weighted TFM imaging unit To further suppress background noise from complex materials, this invention introduces a phase coherence factor weight (PCF) into the traditional total focusing (TFM) algorithm. This method can suppress material clutter and significantly improve the signal-to-noise ratio of imaging for minute defects (such as microcracks and pores). The unit first calculates the coherence weight coefficients based on the phase variance of the echo signal, and then combines the full matrix echo amplitude with the compensated post-delay to complete the total focusing imaging pixel by pixel according to the imaging formula.

[0022] Specifically, the following steps are included: After propagation delay compensation, the echo signals from each transmit-receive channel are extracted at the target pixel. The instantaneous phase at the specified point is determined, and the phase variance of the echo signal in each transmit-receive channel is calculated: ; ; in, This indicates the echo signal of each transmit-receive channel at the target pixel. Phase variance at that point The total number of array elements. Indicates by Array element launch, The echo signal received by the array element is compensated for propagation delay at the target pixel. The instantaneous phase at that point, This indicates that all transmit-receive channel echo signals are at the target pixel. The average coherent phase (weighted average phase) at that point. This represents the phase angle extraction operation for complex numbers. Represents the imaginary unit. .

[0023] Based on the echo signals from each transmit-receive channel at the target pixel point Calculate the phase variance of the target pixel. Phase coherence factor weights at: ; in, Represents the target pixel. Phase coherence factor weights at the location; This represents a monotonically decreasing mapping function from phase variance to the weights of the phase coherence factor.

[0024] Calculate the imaging amplitude of the target pixel: ; in, Represents the target pixel. The imaging amplitude at that location, The amplitude of the full matrix echo signal. Indicates from the launch array element To the target pixel The propagation delay Indicates from the receiving array element To the target pixel The propagation delay This represents the angular frequency of the ultrasonic echo signal. This indicates the sampling time of the full matrix echo signal.

[0025] The generated raw image is simultaneously pushed to the image quality joint evaluation and closed-loop control unit 64 and the display terminal 7.

[0026] (4) Joint image quality assessment and closed-loop control unit This unit calculates the Shannon entropy and local contrast of the imaging results in real time and performs quality assessment by comparing them with the imaging thresholds stored in the system. When the image score is lower than the preset threshold, it is determined that the probe coupling is poor or the workpiece curvature changes abruptly. Then, a closed-loop control command is generated and sent to the curvature sensor and drive control integrated module 4 through the dotted line path. The curvature sensor and drive control integrated module 4 adjusts the downward pressure matrix of each pusher of the micro servo pusher array 3 to optimize the fitting state of the flexible ultrasonic array 2. After the adjustment is completed, the system automatically and repeatedly iterates the coordinate reconstruction, distortion compensation, and imaging calculation steps until the imaging quality meets the threshold requirements.

[0027] 4. Display terminal The display terminal 7 is connected to the central processing computing platform 6, which provides real-time visualization of array element coordinate parameters, compensation delay data, imaging results of internal defects in the workpiece, system closed-loop adjustment records, and image quality scoring data, facilitating real-time observation of the detection status by staff.

[0028] The complete workflow of the flexible phased array ultrasonic adaptive detection system based on multi-source wavefield distortion compensation and conformal control is as follows: Figure 3 As shown, specifically: S1. The flexible ultrasonic array 2 is attached to the surface of the variable curvature workpiece 1 by relying on the micro servo push rod array 3. The system is powered on and the basic acoustic parameters and image qualification threshold are initialized. S2, the curvature sensor and drive control integrated module 4 collects the workpiece surface curvature information in real time, and controls the micro servo push rod array 3 to move according to the initial curvature data, drives the flexible ultrasonic array 2 to adaptively fit the workpiece, and sends the curvature data to the dynamic array element coordinate reconstruction unit 61 to complete the real-time coordinate solution of all array elements. S3. The ultrasonic host 5 drives the flexible ultrasonic array 2 to complete the full matrix acquisition and transmission of ultrasonic signals. The acquired echo data is transmitted to the wave field distortion compensation unit 62 for cross-interface wave field distortion compensation and accurate travel time calculation. S4. The compensated time delay data is sent to the PCF weighted TFM imaging unit 63, and the correlation factor weighted TFM algorithm is used to complete the imaging of the internal structure of the workpiece. S5. The imaging results are sent to the image quality joint evaluation and closed-loop control unit 64 to carry out image quality joint evaluation. If the imaging index does not meet the standard, a closed-loop control command is sent to the conformal drive mechanism to optimize the flexible ultrasonic array fitting state and iterate the coordinate reconstruction, distortion compensation, and imaging calculation steps again until the imaging quality meets the threshold requirements. S6. The final imaging result after meeting the standard is transmitted to the display terminal 7 for output display.

[0029] The above description is merely a preferred embodiment of the present invention and is 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 within the protection scope of the present invention.

Claims

1. A flexible phased array ultrasonic adaptive detection system based on multi-source wavefield distortion compensation and conformal control, characterized in that, include: A flexible ultrasonic array, comprising a flexible insulating substrate and several embedded piezoelectric ultrasonic elements, is used to be deployed on the surface of a workpiece with varying curvature to be tested, to excite a full-matrix ultrasonic capture signal to the workpiece, and to collect echo signals. The conformal drive mechanism includes a distributed micro servo push rod array, a drive control module, and a curvature sensing element. Each push rod of the micro servo push rod array is connected to the back of each element of the flexible ultrasonic array. The curvature sensing element is used to collect the curvature information of the workpiece surface. The drive control module is used to control the extension and retraction of each push rod of the micro servo push rod array based on the collected curvature information, so as to drive the flexible ultrasonic array to adaptively deform and actively conform to the workpiece surface. An ultrasound host, which is connected to the flexible ultrasound array, is used to drive the flexible ultrasound array to complete the transmission and reception of ultrasound full-matrix capture signals. The central processing computing platform integrates a dynamic array element coordinate reconstruction unit, a wavefield distortion compensation unit, a PCF-weighted TFM imaging unit, and an image quality joint evaluation and closed-loop control unit. The dynamic array element coordinate reconstruction unit reconstructs the physical coordinates of each element of the flexible ultrasonic array based on curvature information collected by curvature sensing elements. The wavefield distortion compensation unit receives the collected echo signals, performs cross-interface wavefield distortion compensation and precise time-lapse calculation, eliminating wavefield defocusing errors caused by surface deformation. The PCF-weighted TFM imaging unit uses a phase coherence factor-weighted TFM algorithm to image the internal structure of the workpiece. The image quality joint evaluation and closed-loop control unit jointly evaluates the imaging quality; if the imaging indicators do not meet the standards, it sends a closed-loop control command to the conformal drive mechanism to optimize the flexible ultrasonic array's bonding state and iterate the coordinate reconstruction, distortion compensation, and imaging calculation steps again until the imaging quality meets the threshold requirements. The display terminal is connected to the central processing computing platform and is used to display array element coordinate parameters, compensation delay data, imaging results of internal defects in the workpiece, system closed-loop adjustment records, and image quality scoring data in real time.

2. The flexible phased array ultrasonic adaptive detection system according to claim 1, characterized in that, The wavefield distortion compensation unit performs cross-interface wavefield distortion compensation and accurate timekeeping calculation on the echo signal, including: The wave field distortion compensation unit calculates the incident angle and refraction angle of each array element based on Snell's law and the sound velocity of the coupling layer and the workpiece. Substituting the coupling layer thickness and real-time curvature, the distortion compensation term is calculated. Then, the propagation delay from the array element to the target pixel is obtained through time travel. The calculation formula is as follows: ； ； ； in, Indicates the transmission / reception array element To the target pixel The propagation delay This is a distortion compensation term. Indicates array element physical coordinates Represents the target pixel. Physical coordinates; The sound velocity of the coupling layer, The sound velocity of the workpiece. The coupling layer thickness; and Representing array elements respectively The corresponding ultrasonic incident angle and refraction angle; For adaptive correction coefficients, Indicates array element The real-time radius of curvature at that location.

3. The flexible phased array ultrasonic adaptive detection system according to claim 2, characterized in that, The PCF-weighted TFM imaging unit uses a phase coherence factor-weighted TFM algorithm to complete the imaging of the internal structure of the workpiece, including the following steps: (1) After propagation delay compensation, extract the instantaneous phase of the echo signal of each transmit-receive channel at the target pixel, and calculate the phase variance of the echo signal of each transmit-receive channel: ； ； in, This indicates the echo signal of each transmit-receive channel at the target pixel. Phase variance at that point, The total number of array elements, Indicates by Array element launch, The echo signal received by the array element is compensated for propagation delay at the target pixel. The instantaneous phase at that point, This indicates that all transmit-receive channel echo signals are at the target pixel. The average coherent phase at that point, This represents the phase angle extraction operation for complex numbers. Represents the imaginary unit. ; (2) Calculate the target pixel. Phase coherence factor weights at: ； in, Represents the target pixel. Phase coherence factor weights at the location; The monotonically decreasing mapping function representing the phase variance to the phase coherence factor weights; (3) Calculate the imaging amplitude of the target pixel: ； in, Represents the target pixel. The imaging amplitude at that location, The amplitude of the full matrix echo signal; Indicates from the launch array element To the target pixel The propagation delay Indicates from the receiving array element To the target pixel The propagation delay This represents the angular frequency of the ultrasonic echo signal. This indicates the sampling time of the full matrix echo signal.

4. The flexible phased array ultrasonic adaptive detection system according to claim 1, characterized in that, The imaging metrics include Shannon entropy and local contrast.

5. A method for detecting variable curvature workpieces based on a flexible phased array ultrasonic adaptive detection system according to any one of claims 1 to 4, characterized in that, The method includes the following steps: S1. The flexible ultrasonic array is attached to the surface of the workpiece with variable curvature by relying on the micro servo push rod array. The system is powered on and the basic acoustic parameters and image qualification threshold are initialized. The curvature sensing element collects the curvature information of the workpiece surface in real time. S2. The drive control module controls the movement of the micro servo push rod array based on the initial curvature data, drives the flexible ultrasonic array to adaptively fit the workpiece, and sends the curvature data into the dynamic array element coordinate reconstruction unit to complete the real-time coordinate solution of all array elements. S3. The ultrasonic host drives the flexible ultrasonic array to complete the full matrix acquisition and transmission of ultrasonic signals. The acquired echo data is transmitted to the wave field distortion compensation unit for cross-interface wave field distortion compensation and accurate travel time calculation. S4. The compensated time delay data is sent to the PCF weighted TFM imaging unit, and the phase correlation factor weighted TFM algorithm is used to complete the imaging of the internal structure of the workpiece. S5. The imaging results are sent to the image quality joint evaluation and closed-loop control unit to carry out the image quality joint evaluation. If the imaging index does not meet the standard, a closed-loop control command is sent to the conformal drive mechanism to optimize the flexible ultrasonic array fitting state and iterate the coordinate reconstruction, distortion compensation, and imaging calculation steps again until the imaging quality meets the threshold requirements. S6. The final imaging result after meeting the standard is transmitted to the display terminal for output display.

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