Flexible phased array element position determination method and flexible pulsed ultrasonic phased array transceiver

Abstract

The present invention discloses a method for determining the position of flexible phased array elements and a flexible pulsed ultrasonic phased array transceiver, belonging to the field of industrial inspection. When measuring a workpiece, the echo signals of each flexible phased array element when acting as a receiving element are synthesized into scan line data for all elements. The positions of the elements in the flexible ultrasonic phased array are determined using a relative element positioning algorithm based on the direct wave path of the i-th echo signal in the scan line data. Specifically, the direct wave path is analyzed to generate a propagation time dataset of the direct wave path as input. The positions of the transmitting array elements and the relative positions of the receiving array elements are continuously and iteratively adjusted until the objective function is minimized, thereby determining the final positions of the transmitting and receiving elements. The present invention can accurately determine the positions of the transmitting and receiving elements.

Description

Technical Field

[0001] The present invention belongs to the field of industrial detection, and in particular relates to a method for determining the position of flexible phased array elements and a flexible pulsed ultrasonic phased array transceiver. Background Art

[0002] Ultrasonic testing technology is suitable for detecting surface and internal defects in workpieces. It can quickly and accurately determine the location and size of defects, offering high sensitivity and environmental friendliness, making it suitable for defect detection and characterization on a wide range of workpieces. However, due to the geometry of curved surfaces, ultrasonic beam propagation can cause distortion, bending, and separation, complicating the accurate location, qualitative, and quantitative detection of defects. To improve defect detection accuracy, ultrasonic phased array technology has been developed based on ultrasonic nondestructive testing.

[0003] Ultrasonic phased array technology controls the ultrasonic signal emission of each array element to achieve continuous deflection and focusing of the sound waves. This allows for multiple scans and imaging of different inspection areas at the same location on the workpiece surface. This technology offers rapid inspection speeds, high sensitivity, and reliable results. Therefore, ultrasonic phased array technology offers significant advantages in inspecting complex curved components. This technology's ability to flexibly control the deflection and focusing of the sound beam through time delay mechanisms offers advantages such as a wide inspection range, high accuracy, and fast scanning speeds.

[0004] However, there are some technical difficulties with traditional rigid ultrasonic probes and rigid ultrasonic phased array probes:

[0005] First, rigid ultrasonic phased array probes cannot directly mate with complex curved test specimen surfaces. Water coupling or wedge coupling is typically required to propagate the sound waves. However, due to the acoustic impedance difference between the couplant and the test specimen, some acoustic field energy is lost during transmission, affecting the probe's sensitivity and leading to inaccurate defect location.

[0006] Secondly, rigid probes need to be adjusted to specific angles and positions during operation, and the detection angle is fixed, which may lead to reduced imaging quality and defect detection sensitivity.

[0007] In addition, the detection speed of rigid probes is slow. Traditional rigid probes need to scan point by point, which is inefficient, especially when detecting large areas, and the time cost is high. Summary of the Invention

[0008] The present invention provides a method for determining the position of flexible phased array elements and a flexible pulsed ultrasonic phased array transceiver. These methods aim to address technical issues existing in the prior art. Using a dataset of propagation times between direct wave paths as input, the method iteratively adjusts and optimizes the positions of the array's transmitting and receiving elements by comparing the errors between calibration data and synthesized data. First, a system of equations is used to relate the distance matrix to time and velocity, and this system of equations is used to solve for the unknown distance. The obtained distance values ​​are then used to calculate the signal arrival time and receiver time difference at each time point. Finally, the array element positions are optimized by minimizing the difference between these time differences and the actual measured values. This method accurately determines the positions of transmitting and receiving elements.

[0009] The present invention provides a method for determining the position of a flexible phased array element, comprising the following steps:

[0010] When measuring a workpiece, the echo signals of each flexible phased array element as a receiving element are synthesized into the scan line data of all elements;

[0011] The position of the array element in the flexible ultrasonic phased array is determined by using the relative array element positioning algorithm based on the direct wave path of the i-th echo signal in the scan line data. Specifically:

[0012] Analyze the direct wave path and generate a direct wave path propagation time dataset as input;

[0013] The positions of the transmitting array elements and the relative receiving array element positions are continuously adjusted iteratively until the objective function is minimized, and the final transmitting array element and receiving array element positions are determined.

[0014] Preferably, the propagation time dataset of the direct wave path is generated as input, and the positions of the transmitting array elements and the relative receiving array elements are iteratively adjusted until the objective function is minimized, specifically:

[0015] The propagation distance dataset of the direct wave path is generated using the scan line data as a generated dataset;

[0016] A calibration dataset of propagation distance of a calibrated direct wave path is obtained according to the experimental measurement of the propagation time of the direct wave path of the calibration sample, as the calibration dataset;

[0017] A synthetic dataset is obtained based on the generated dataset, and the objective function is minimized through iteration to minimize the difference between the calibration dataset and the synthetic dataset;

[0018] Determine the final transmit array element position based on the difference between the calibration data set and the synthetic data set;

[0019] The final receiving array element position is determined according to the final transmitting array element position.

[0020] Preferably, the objective function It is defined as half of the sum of the squared errors between the calibration dataset D and the synthetic dataset V. The specific expression is as follows:

[0021]

[0022] in,

[0023] V is a synthetic data set, in which the data is the Euclidean distance of the direct wave path when different array elements are used as transmitting array elements and other array elements are used as receiving array elements when measuring the workpiece; the jth element in V Among them, l j =||r T(j) -r R(j) ||2(1.1), l j is the ultrasonic wave propagation distance of the jth wave path of array element L, r T(j) and r R(j) are the transmitting array element position of the j-th wave path and the receiving array element position of the j-th wave path respectively;

[0024] j is the wave path index, j∈{1,...,Nw}, N w is the total number of wave paths;

[0025] T(j) is the transmit array element index of the j-th wave path, T(j) = floor((j-1) / N T )+1;

[0026] R(j) is the receiving array element index of the j-th wave path, R(j)=(j-1)%N R +1, N T is the number of transmitting array elements, N T =N w / N R , N R is the number of receiving array elements, “%” is the modulo operator;

[0027] is the objective function;

[0028] X is the set of transmitting array element position vectors, where the element of the j-th wave path is x j , t is the transmitting array element number;

[0029] Z is the set of receiving array element position vectors, where the element of the j-th wave path is z j , r is the receiving element number;

[0030] D is the calibration data set, where the data is the direct wave path propagation distance obtained by measuring the calibration sample;

[0031] e is the error vector, e=DV(1.2).

[0032] Preferably, the data in the calibration data set D is the squared direct wave path lengths between all combinations of transmitting array elements and receiving array elements.

[0033] Preferably, the squared direct wave path length is obtained by multiplying the wave velocity c by the square of the direct wave path propagation time. In this case, the calibration data set is D(c, T), where the element of the j-th wave path is T is the direct wave path propagation time matrix obtained by measuring the calibration sample; τ j is the element in T, is the direct wave path propagation time of the jth wave path when measuring the calibration sample, and c is the wave velocity.

[0034] Preferably, the synthetic dataset V is obtained by:

[0035] Calculate the difference Δ between the transmitting array element and the receiving array element position vector of all wave path transmitting array element and receiving array element combinations:

[0036] Δ=A x xA z z (1.3)

[0037] in,

[0038]

[0039]

[0040] Among them, A x and A z are the transmit element position vector matrix and the receive element position vector matrix respectively, I is the identity matrix, the matrix subscripts are the row and column values ​​of each matrix, x and z are vectors in X and Z respectively;

[0041] Then the vector v in the synthetic dataset V is expressed as:

[0042] v=Cdiag(Δ)Δ (1.6)

[0043] in,

[0044]

[0045] Where C is the square distance component between the transmitting array element and the receiving array element that records all wave paths.

[0046] Preferably, determining the final transmit array element position according to the difference between the calibration data set and the synthesized data set specifically includes:

[0047] Assume that the position of the first array element as the transmitting array element is r1 = {0, 0} t , the position of the last array element as the transmitting array element is To eliminate the ambiguity of the final array shape, t here represents transpose;

[0048] Among them, the coordinates of all other array elements are initialized to be from the normal distribution The random number drawn from L arr is the length of the transmitting element;

[0049] Taking the derivative of the set of transmit element position vectors X in equation (1.8), we get:

[0050]

[0051] At the beginning of the optimization of the transmitting element position vector, the propagation time is set to 0, and then the gradient elements in Equation (1.9) are Set to zero to eliminate the weight of propagation time;

[0052] Add the regularization term to the objective function, and the modified objective function o is:

[0053]

[0054] Where Ψ is the lateral constraint matrix, which is a weight matrix that, in the present invention, is related to the propagation time and enforces the relationship between the elements x in X, q = Ψx, and γ is a parameter of the target optimization objective that balances the array shape and the lateral constraint by introducing the correction term θ;

[0055] According to formula (1.10), the gradient of the regularized objective function is as follows:

[0056]

[0057] in,

[0058] The lateral constraint matrix Ψ is a second-order finite difference matrix scaled by 1 / 4, and the regularization strength γ is 1e-5;

[0059] The BFGS optimization algorithm is used to implement regularized objective function gradient optimization to obtain the final transmitting array element position;

[0060] The final receiving array element position is determined according to the final transmitting array element position.

[0061] The present invention also provides a flexible pulsed ultrasonic phased array transceiver, comprising a flexible phased array ultrasonic transducer, a lower computer and an upper computer; the flexible phased array ultrasonic transducer and the upper computer are both connected to the lower computer;

[0062] The host computer performs parameter configuration and waveform display;

[0063] The lower computer includes a hardware circuit part and an FPGA, wherein the hardware circuit includes a power supply circuit, a pulse transmitting circuit, an echo receiving circuit and a communication circuit. The power supply circuit supplies power to the pulse transmitting circuit, the echo receiving circuit and the communication circuit.

[0064] The FPGA includes a system control module, a hardware circuit control module, a transmit beam synthesis module, a receive beam control module, a RAEL positioning and allocation array element module, a storage control module, and a communication control module.

[0065] During operation, the host computer selects parameters and sends the configured parameters to the FPGA of the slave computer through the communication interface. After receiving the parameter data, the slave computer performs configuration. The system control module in the FPGA controls the hardware circuit control module, the transmit beam synthesis module, the receive beam control module, the RAEL positioning and allocation array element module, the storage control module, and the communication control module to perform ultrasonic excitation work. The details are as follows:

[0066] The hardware circuit control module controls the hardware circuit according to the parameters issued. The controllable high-voltage source in the hardware circuit generates corresponding high voltage output to the pulse transmission circuit according to the configuration. The transmit beam synthesis module in the FPGA controls each array element in the pulse transmission circuit to transmit high-voltage pulse electrical signals, which stimulate the array elements in the ultrasonic flexible phased array to generate ultrasonic waves.

[0067] When the ultrasonic wave generated by the transmitting element of the ultrasonic flexible phased array propagates through the workpiece, if it encounters a defect in the workpiece, the ultrasonic wave will be reflected. The generated echo is received by the phased array receiving element through the receiving beam control module and converted into an electrical signal by the piezoelectric effect. The echo signal is then amplified and collected by the echo receiving circuit. The collected digital signal is input into the FPGA for processing.

[0068] The RAEL positioning and element allocation module uses the above-mentioned flexible phased array element position determination method to determine the flexible phased array element position, and allocates ultrasonic transmission time, transmitting elements and receiving elements. The processing results are stored in the storage control module and uploaded to the host computer from the communication interface through the communication control module.

[0069] Preferably, the flexible phased array ultrasonic transducer includes a retractable rubber array element base, an ultrasonic array element, and a flexible probe electrical adapter; the ultrasonic array element is arranged on the retractable rubber array element base, and the flexible probe electrical adapter is connected to the end of the retractable rubber array element base, and the flexible probe electrical adapter has a flexible phased array transmitting and receiving connection port.

[0070] Preferably, the parameter configuration includes the pulse type.

[0071] Compared with the prior art, the present invention has the following beneficial effects:

[0072] 1. The present invention provides an algorithm for determining the position of elements in a non-planar flexible ultrasonic array. The algorithm uses a dataset of propagation times between direct wave paths as input and iteratively adjusts and optimizes the positions of the array's transmitting and receiving elements by comparing the errors between calibration data and model calculation data until the objective function is minimized. This algorithm can accurately determine the positions of the transmitting and receiving elements.

[0073] 2. The present invention is flexible and adaptable: the flexible probe can adapt to different detection environments and geometries, especially in applications on curved surfaces or complex structures. In contrast, traditional probes are usually rigid and have poor adaptability.

[0074] 3. The present invention adopts phased array technology. Since each array element has a separate control line, the FPGA can individually control each array element in the flexible phased array ultrasonic probe to act as a transmitting array element or a receiving array element, so that the probe can adjust the angles of the transmitted and received waves, as well as the time when the transmitting array element transmits the ultrasonic pulse, so that they reach the defect at the same time, that is, the ultrasonic wave is focused at the defect, thereby improving the imaging resolution and detection accuracy with higher resolution.

[0075] 4. The present invention can perform multi-directional detection: each array element can be used as both a transmitting array element and a receiving array element, and the flexible probe is flat and can be assigned different transmitting array element-receiving array element combinations (not limited to a 1-to-1 combination, but can also be 1-to-many, or many-to-many, so that the transmitting array element can have multiple transmitting array elements to transmit ultrasonic pulses and reach the defect at the same time, so as to achieve the best effect). In this way, it is possible to achieve a similar distribution of multiple traditional probes on the workpiece and perform detection at the same time, that is, multi-angle and multi-directional detection can be performed simultaneously, reducing the time required for traditional probes to scan point by point.

[0076] 5. The present invention has better acoustic field characteristics: through phased array technology, it can optimize the propagation of sound waves in materials, improve the ability to detect defects, and optimize the propagation of sound waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 A schematic diagram of a flexible pulsed ultrasonic phased array transceiver device according to an embodiment of the present invention;

[0078] Figure 2a FIG. 1 is a bottom view schematic diagram of a flexible phased array transducer according to an embodiment of the present invention. Figure 1 Enlarged view of the dotted line;

[0079] Figure 2b is a schematic right side view of a flexible phased array transducer according to an embodiment of the present invention;

[0080] Figure 2c is a front view schematic diagram of a flexible phased array transducer according to an embodiment of the present invention;

[0081] Figure 3 A schematic diagram of a technical route for a method for determining the position of elements in a flexible phased array according to an embodiment of the present invention;

[0082] Figure 4 The calibration sample of one embodiment of the present invention is aluminum with a diameter of 760 mm and a thickness of 254 mm; a center hole diameter of c / (8.13×5 MHz) mm and a depth of 254 mm;

[0083] In the figure, 1-retractable rubber array element base; 2-ultrasonic array element; 3-flexible probe electrical adapter; 4-flexible phased array transmitting and receiving connection port. DETAILED DESCRIPTION

[0084] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0085] The present invention provides a method for determining the position of a flexible phased array element, comprising the following steps:

[0086] When measuring a workpiece, the echo signals of each flexible phased array element as a receiving element are synthesized into the scan line data of all elements;

[0087] The position of the array element in the flexible ultrasonic phased array is determined by using the relative array element positioning algorithm based on the direct wave path of the i-th echo signal in the scan line data. Specifically:

[0088] Analyze the direct wave path and generate a direct wave path propagation time dataset as input;

[0089] The positions of the transmitting array elements and the relative receiving array element positions are continuously adjusted iteratively until the objective function is minimized, and the final transmitting array element and receiving array element positions are determined.

[0090] The method of the present invention is used to determine the position of array elements in a flexible ultrasonic phased array on a surface of unknown geometric shape.

[0091] A 4×16 array of flexible phased array ultrasonic transducers is placed on a non-planar workpiece surface. The spatial position of each transducer element is unknown during operation. Figure 3 Possible array surface configurations (curved solid black lines) are shown, along with the locations of several array elements, representing transmitters (triangles) and receivers (pentagons), along with the direct, interface (black lines), and scattered wave paths for ultrasound. Furthermore, given a uniform material and a specific transmitter-receiver combination, the arrival times or propagation times for different wave path types will differ due to different path lengths (e.g., direct versus scattered), and in some cases, the wave velocities will also differ. The direct wave path is shown as a straight line from transmitter to receiver. Interface waves propagate along the curved array and are expected to propagate at slower speeds in solids (i.e., Rayleigh waves).

[0092] like Figure 3 As shown, the array of eight elements in the i-th row is distributed on an arbitrary surface, and the coordinate system is the Cartesian coordinate system O, x, y. The second array element (triangle) is at r T The transmitter is located at r, and all other elements are located at r R The ultrasonic wave propagation direct path, interface path, scattering path, and internal defects of the workpiece (circle) are used as receiving array elements (pentagons). T To the receiving array element r R There are multiple paths between them. The scattering path will reach r first. p Then return r R In most cases, the direct pulse that traverses the jth direct path will arrive earlier than the interface or scattered pulse, where c l 、c s 、c R They are the longitudinal wave velocity, shear wave velocity and Rayleigh wave velocity respectively.

[0093] According to a specific embodiment of the present invention, the propagation time dataset of the direct wave path is generated as input, and the positions of the array elements used for transmission and the relative positions of the receiving array elements are iteratively adjusted until the objective function is minimized, specifically:

[0094] The propagation distance dataset of the direct wave path is generated using the scan line data as a generated dataset;

[0095] A calibration dataset of propagation distance of a calibrated direct wave path is obtained according to the experimental measurement of the propagation time of the direct wave path of the calibration sample, as the calibration dataset;

[0096] A synthetic dataset is obtained based on the generated dataset, and the objective function is minimized through iteration to minimize the difference between the calibration dataset and the synthetic dataset;

[0097] Determine the final transmit array element position based on the difference between the calibration data set and the synthetic data set;

[0098] The final receiving array element position is determined according to the final transmitting array element position.

[0099] Since the calibration dataset D consists of the squared path lengths between all pairs of transmit and receive elements, and each element in the array has the opportunity to function as either a transmit or receive element, optimizing the position of any transmitter or receiver is arbitrary. In this case, the transmit element position is determined first, while the receive element position changes during the optimization process.

[0100] According to a specific embodiment of the present invention, the objective function It is defined as half of the sum of the squared errors between the calibration dataset D and the synthetic dataset V. The specific expression is as follows:

[0101]

[0102] in,

[0103] V is a synthetic data set, in which the data is the Euclidean distance of the direct wave path when different array elements are used as transmitting array elements and other array elements are used as receiving array elements when measuring the workpiece; the jth element in V Among them, l j =||r T(j) -r R(j) ||2(1.1), l j is the ultrasonic wave propagation distance of the jth wave path of array element L, r T(j) and r R(j) are the transmitting array element position of the j-th wave path and the receiving array element position of the j-th wave path respectively;

[0104] j is the wave path index, j∈{1,...,Nw}, N w is the total number of wave paths;

[0105] T(j) is the transmit array element index of the j-th wave path, T(j) = floor((j-1) / N T )+1;

[0106] R(j) is the receiving array element index of the j-th wave path, R(j)=(j-1)%N R +1, N T is the number of transmitting array elements, N T =N w / N R , N R is the number of receiving array elements, “%” is the modulo operator;

[0107] is the objective function;

[0108] X is the set of transmitting array element position vectors, where the element of the j-th wave path is x j , t is the transmitting array element number;

[0109] Z is the set of receiving array element position vectors, where the element of the j-th wave path is z j , r is the receiving element number;

[0110] D is the calibration data set, where the data is the direct wave path propagation distance obtained by measuring the calibration sample;

[0111] e is the error vector, e=DV(1.2).

[0112] When the transmitting and receiving elements are at their calibrated true positions, the value of e is equal to zero. An objective function of the propagation time related to the position of the array elements is specified to solve the optimization problem.

[0113] According to a specific embodiment of the present invention, the data in the calibration data set D is the squared direct wave path lengths between all combinations of transmitting array elements and receiving array elements.

[0114] According to a specific embodiment of the present invention, the squared direct wave path length is obtained by multiplying the wave velocity c by the square of the direct wave path propagation time. In this case, the calibration data set is D(c, T), where the element of the j-th wave path is T is the direct wave path propagation time matrix obtained by measuring the calibration sample; τ j is the element in T, is the direct wave path propagation time of the jth wave path when measuring the calibration sample, and c is the wave velocity. Near the array, the wave velocity c is uniform, and is obtained by multiplying cτ j The calibrated path length can be obtained.

[0115] According to a specific embodiment of the present invention, the synthetic dataset V is obtained by:

[0116] Calculate the difference Δ between the transmitting array element and the receiving array element position vector of all wave path transmitting array element and receiving array element combinations:

[0117] Δ=A x xA z z (1.3)

[0118] in,

[0119]

[0120]

[0121] Among them, A x and A z are the transmit element position vector matrix and the receive element position vector matrix respectively, I is the identity matrix, the matrix subscripts are the row and column values ​​of each matrix, x and z are vectors in X and Z respectively;

[0122] Then the vector v in the synthetic dataset V is expressed as:

[0123] v=Cdiag(Δ)Δ (1.6)

[0124] in,

[0125]

[0126] Where C is the square distance component between the transmitting array element and the receiving array element that records all wave paths.

[0127] C calculates the distance between two points in each wave path direction and squares it. Then, for each wave path, C adds up the squared components of the distance in all directions to obtain an overall squared distance component. This value can be used to assess the quality or superiority of different wave paths.

[0128] According to a specific embodiment of the present invention, determining the final transmit element position according to the difference between the calibration data set and the synthesized data set specifically includes:

[0129] Assume that the position of the first array element as the transmitting array element is r1 = {0, 0} t , the position of the last array element as the transmitting element is To eliminate the ambiguity of the final array shape, t here represents transpose;

[0130] Among them, the coordinates of all other array elements are initialized to be from the normal distribution The random number drawn from L arr is the length of the transmitting element;

[0131] Since there is no known relative array element position, and the relative position is sought, the position of the first array element is assumed to be r1 = {0, 0} t and the last array element position is To eliminate the ambiguity of the final array shape, the y position of the final element is constrained to be zero. Among them, all other array coordinates are initialized to be drawn from the normal distribution The random number drawn from L arr is the length of the array element.

[0132] Design considerations to eliminate ambiguity in array shape:

[0133] Usually, when there is no known relative array element position, the position of each element in the array is unknown, and their relative positions need to be determined in some way.

[0134] The present invention assumes that the positions of the first and last array elements are known: To resolve ambiguity in the array layout, the position of the first array element is assumed to be a fixed value, while the position of the last array element is set to a known value. This is done to constrain the overall shape of the array, thus avoiding the excessive freedom of the array shape that would occur without boundary conditions.

[0135] The y-coordinate of the final element is constrained to be zero: The last element of the array is assumed to have a y-coordinate of zero (i.e., it is located at some reference position). This helps define the structure of the entire array and ensures that the layout of the entire array makes sense.

[0136] Designs that randomly initialize the coordinates of other arrays:

[0137] First, the remaining array coordinates are initialized using a normal distribution. With the exception of the first and last elements in the array, the positions of all elements are typically initialized to random numbers drawn from a normal distribution. Normally distributed random numbers are generated to simulate irregular, imperfect array layouts in reality or to introduce some randomness during the optimization process. This prevents the initial distribution of array element positions from being too regular or fixed, helping the algorithm find a solution that better meets the optimization objective.

[0138] Secondly, the role of the normal distribution: the normal distribution generates values ​​that are mostly concentrated near a certain mean, and the probability of the generated value gradually decreases as the distance from the mean increases. This helps to concentrate the positions of most array elements in a single area during initial layout, while also retaining a certain degree of variability and avoiding excessive restrictions on the array layout.

[0139] Taking the derivative of the set X of transmit element position vectors in equation (1.8), we get:

[0140]

[0141] At the beginning of the optimization of the transmitting element position vector, the propagation time is set to 0, and then the gradient elements in Equation (1.9) are Set to zero to eliminate the weight of propagation time;

[0142] Equation (1.8) can be used to convert the error e of a specific wave path into j Set it to zero to eliminate, as this determines the gradient strength in equation (1.9) for a given path. If you want to pre-determine the position of the known element at the beginning of the optimization, set it in the initialization and then replace the gradient element by Set to zero to eliminate its weight.

[0143] In the method of the present invention, when the propagation time is set to zero to delete the optimization weight from the wave path where no data exists, the error element is automatically set to zero. Therefore, when the propagation time is set to zero, the corresponding error element is also set to zero.

[0144] Add the regularization term to the objective function, and the modified objective function o is:

[0145]

[0146] Where Ψ is the lateral constraint matrix, which is a weight matrix that, in the present invention, is related to the propagation time and enforces the relationship between the elements x in X, q = Ψx, and γ is a parameter of the target optimization objective that balances the array shape and the lateral constraint by introducing the correction term θ;

[0147] According to formula (1.10), the gradient of the regularized objective function is as follows:

[0148]

[0149] in,

[0150] The lateral constraint matrix Ψ is a second-order finite difference matrix scaled by 1 / 4, and the regularization strength γ is 1e-5;

[0151] The BFGS optimization algorithm is used to implement regularized objective function gradient optimization to obtain the final position of the transmitting array element;

[0152] The final receiving array element position is determined according to the final transmitting array element position.

[0153] The present invention also provides a flexible pulsed ultrasonic phased array transceiver, comprising a flexible phased array ultrasonic transducer, a lower computer and an upper computer; the flexible phased array ultrasonic transducer and the upper computer are both connected to the lower computer;

[0154] The host computer performs parameter configuration and waveform display;

[0155] The lower computer includes a hardware circuit part and an FPGA, wherein the hardware circuit includes a power supply circuit, a pulse transmitting circuit, an echo receiving circuit and a communication circuit. The power supply circuit supplies power to the pulse transmitting circuit, the echo receiving circuit and the communication circuit.

[0156] The FPGA includes a system control module, a hardware circuit control module, a transmit beam synthesis module, a receive beam control module, a RAEL positioning and allocation array element module, a storage control module, and a communication control module.

[0157] During operation, the host computer selects parameters and sends the configured parameters to the FPGA of the slave computer through the communication interface. After receiving the parameter data, the slave computer performs configuration. The system control module in the FPGA controls the hardware circuit control module, the transmit beam synthesis module, the receive beam control module, the RAEL positioning and allocation array element module, the storage control module, and the communication control module to perform ultrasonic excitation work. The details are as follows:

[0158] The hardware circuit control module controls the hardware circuit according to the parameters issued. The controllable high-voltage source in the hardware circuit generates corresponding high voltage output to the pulse transmission circuit according to the configuration. The transmit beam synthesis module in the FPGA controls each array element in the pulse transmission circuit to transmit high-voltage pulse electrical signals, which stimulate the array elements in the ultrasonic flexible phased array to generate ultrasonic waves.

[0159] When the ultrasonic wave generated by the transmitting element of the ultrasonic flexible phased array propagates through the workpiece, if it encounters a defect in the workpiece, the ultrasonic wave will be reflected. The generated echo is received by the phased array receiving element through the receiving beam control module and converted into an electrical signal by the piezoelectric effect. The echo signal is then amplified and collected by the echo receiving circuit. The collected digital signal is input into the FPGA for processing.

[0160] The RAEL positioning and element allocation module uses the above-mentioned flexible phased array element position determination method to determine the flexible phased array element position, and allocates ultrasonic transmission time, transmitting elements and receiving elements. The processing results are stored in the storage control module and uploaded to the host computer from the communication interface through the communication control module.

[0161] According to a specific embodiment of the present invention, a flexible phased array ultrasonic transducer includes a retractable rubber array element base 1, an ultrasonic array element 2, and a flexible probe electrical adapter 3; the ultrasonic array element 2 is arranged on the retractable rubber array element base 1, and the flexible probe electrical adapter 3 is connected to the end of the retractable rubber array element base 1, and the flexible probe electrical adapter 3 has a flexible phased array transmitting and receiving connection port 4.

[0162] According to a specific embodiment of the present invention, the parameter configuration includes a pulse type.

[0163] Example 1

[0164] According to a specific embodiment of the present invention, the method for determining the position of a flexible phased array element of the present invention is described in detail below.

[0165] The present invention provides a method for determining the position of a flexible phased array element, comprising the following steps:

[0166] When measuring a workpiece, the echo signals of each flexible phased array element as a receiving element are synthesized into the scan line data of all elements;

[0167] The position of the array element in the flexible ultrasonic phased array is determined by using the relative array element positioning algorithm based on the direct wave path of the i-th echo signal in the scan line data. Specifically:

[0168] Analyze the direct wave path and generate a direct wave path propagation time dataset as input;

[0169] The positions of the transmitting array elements and the relative receiving array element positions are continuously adjusted iteratively until the objective function is minimized, and the final transmitting array element and receiving array element positions are determined.

[0170] Example 2

[0171] According to a specific embodiment of the present invention, the method for determining the position of a flexible phased array element of the present invention is described in detail below.

[0172] The present invention provides a method for determining the position of a flexible phased array element, comprising the following steps:

[0173] When measuring a workpiece, the echo signals of each flexible phased array element as a receiving element are synthesized into the scan line data of all elements;

[0174] The position of the array element in the flexible ultrasonic phased array is determined by using the relative array element positioning algorithm based on the direct wave path of the i-th echo signal in the scan line data. Specifically:

[0175] Analyze the direct wave path and generate a direct wave path propagation time dataset as input;

[0176] The positions of the transmitting array elements and the relative receiving array element positions are continuously adjusted iteratively until the objective function is minimized, and the final transmitting array element and receiving array element positions are determined.

[0177] The propagation time dataset of the direct wave path is used as input to iteratively adjust the position of the transmitting array element and the relative position of the receiving array element until the objective function is minimized, specifically:

[0178] The propagation distance dataset of the direct wave path is generated using the scan line data as a generated dataset;

[0179] According to the experimental measurement calibration sample (such as Figure 4 The propagation distance calibration data set of the calibrated direct wave path is obtained by using the direct wave path propagation time of the calibrated direct wave path as the calibration data set;

[0180] A synthetic dataset is obtained based on the generated dataset, and the objective function is minimized through iteration to minimize the difference between the calibration dataset and the synthetic dataset;

[0181] Determine the final transmit array element position based on the difference between the calibration data set and the synthetic data set;

[0182] The final receiving array element position is determined according to the final transmitting array element position.

[0183] Furthermore, the objective function It is defined as half of the sum of the squared errors between the calibration dataset D and the synthetic dataset V. The specific expression is as follows:

[0184]

[0185] in,

[0186] V is a synthetic data set, in which the data is the Euclidean distance of the direct wave path when different array elements are used as transmitting array elements and other array elements are used as receiving array elements when measuring the workpiece; the jth element in V Among them, l j =||r T(j) -r R(j) ||2(1.1), l j is the ultrasonic wave propagation distance of the jth wave path of array element L, r T(j) and r R(j) are the transmitting array element position of the j-th wave path and the receiving array element position of the j-th wave path respectively;

[0187] j is the wave path index, j∈{1,...,Nw}, N w is the total number of wave paths;

[0188] T(j) is the transmit array element index of the j-th wave path, T(j) = floor((j-1) / N T )+1;

[0189] R(j) is the receiving array element index of the j-th wave path, R(j)=(j-1)%N R +1, N T is the number of transmitting array elements, N T =N w / N R , N R is the number of receiving array elements, “%” is the modulo operator;

[0190] is the objective function;

[0191] X is the set of transmitting array element position vectors, where the element of the j-th wave path is x j , t is the transmitting array element number;

[0192] Z is the set of receiving array element position vectors, where the element of the j-th wave path is z j , r is the receiving element number;

[0193] D is the calibration data set, where the data is the direct wave path propagation distance obtained by measuring the calibration sample;

[0194] e is the error vector, e=DV(1.2).

[0195] The data in the calibration data set D is the square direct wave path length between all the transmitting array elements and the receiving array element combinations. The square direct wave path length is obtained by multiplying the wave velocity c by the square of the direct wave path propagation time. At this time, the calibration data set is D(c, T), where the element of the j-th wave path is T is the direct wave path propagation time matrix obtained by measuring the calibration sample; τ j is the element in T, is the direct wave path propagation time of the jth wave path when measuring the calibration sample, and c is the wave velocity.

[0196] Furthermore, the synthetic dataset V is obtained as follows:

[0197] Calculate the difference Δ between the transmitting array element and the receiving array element position vector of all wave path transmitting array element and receiving array element combinations:

[0198] Δ=A x xA z z (1.3)

[0199] in,

[0200]

[0201]

[0202] Among them, A x and A z are the transmit element position vector matrix and the receive element position vector matrix respectively, I is the identity matrix, the matrix subscripts are the row and column values ​​of each matrix, x and z are vectors in X and Z respectively;

[0203] Then the vector v in the synthetic dataset V is expressed as:

[0204] v=Cdiag(Δ)Δ (1.6)

[0205] in,

[0206]

[0207] Where C is the square distance component between the transmitting array element and the receiving array element that records all wave paths.

[0208] Furthermore, the final transmit element position is determined based on the difference between the calibration data set and the synthesized data set, specifically including:

[0209] Assume that the position of the first array element as the transmitting array element is r1 = {0, 0} t , the position of the last array element as the transmitting array element is To eliminate the ambiguity of the final array shape, t here represents transpose;

[0210] Among them, the coordinates of all other array elements are initialized to be from the normal distribution The random number drawn from L arr is the length of the transmitting element;

[0211] Taking the derivative of the set of transmit element position vectors X in equation (1.8), we get:

[0212]

[0213] At the beginning of the optimization of the transmitting element position vector, the propagation time is set to 0, and then the gradient elements in Equation (1.9) are Set to zero to eliminate the weight of propagation time;

[0214] Add the regularization term to the objective function, and the modified objective function o is:

[0215]

[0216] Where Ψ is the lateral constraint matrix, which is a weight matrix that, in the present invention, is related to the propagation time and enforces the relationship between the elements x in X, q = Ψx, and γ is a parameter of the target optimization objective that balances the array shape and the lateral constraint by introducing the correction term θ;

[0217] According to formula (1.10), the gradient of the regularized objective function is as follows:

[0218]

[0219] in,

[0220] The lateral constraint matrix Ψ is a second-order finite difference matrix scaled by 1 / 4, and the regularization strength γ is 1e-5;

[0221] The BFGS optimization algorithm is used to implement regularized objective function gradient optimization to obtain the final transmitting array element position;

[0222] The final receiving array element position is determined according to the final transmitting array element position.

[0223] Furthermore, the BFGS optimization algorithm can be used to implement the regularized objective function gradient optimization. The pseudo code of the following two methods can be used. When the iterator is k, the initial estimate x 0 It is iterated until the objective function o(x) falls below the preset cutoff level ε or reaches the preset maximum number of iterations N k The step direction is determined by the gradient of the objective function and an estimated Hessian matrix, which helps to smooth the descent trajectory in the solution space.

[0224]

[0225]

[0226]

[0227] After determining the relative positions of each element in the ultrasonic flexible phased array during testing, the positions and numbers of the transmitting and receiving elements, as well as the paths between the internal defects of the workpiece and the transmitting elements, and between the defects and the receiving elements, are also determined. Furthermore, the transmitting and receiving element combinations are determined. Furthermore, in this embodiment, the timing of each transmitting element's 5MHz ultrasonic pulse emission is determined so that they simultaneously reach the defect, focusing the ultrasonic waves at the defect for optimal detection results.

[0228] Example 3

[0229] According to a specific embodiment of the present invention, the flexible pulsed ultrasonic phased array transceiver of the present invention is described in detail below.

[0230] The present invention also provides a flexible pulse ultrasonic phased array transceiver device, see Figure 1 , comprising a flexible phased array ultrasonic transducer, a lower computer and an upper computer; the flexible phased array ultrasonic transducer and the upper computer are both connected to the lower computer;

[0231] The host computer performs parameter configuration and waveform display;

[0232] The lower computer includes a hardware circuit part and an FPGA, wherein the hardware circuit includes a power supply circuit, a pulse transmitting circuit, an echo receiving circuit and a communication circuit. The power supply circuit supplies power to the pulse transmitting circuit, the echo receiving circuit and the communication circuit.

[0233] The FPGA includes a system control module, a hardware circuit control module, a transmit beam synthesis module, a receive beam control module, a RAEL positioning and allocation array element module, a storage control module, and a communication control module.

[0234] During operation, the host computer selects parameters and sends the configured parameters to the FPGA of the slave computer through the communication interface. After receiving the parameter data, the slave computer performs configuration. The system control module in the FPGA controls the hardware circuit control module, the transmit beam synthesis module, the receive beam control module, the RAEL positioning and allocation array element module, the storage control module, and the communication control module to perform ultrasonic excitation work. The details are as follows:

[0235] The hardware circuit control module controls the hardware circuit according to the parameters issued. The controllable high-voltage source in the hardware circuit generates corresponding high voltage output to the pulse transmission circuit according to the configuration. The transmit beam synthesis module in the FPGA controls each array element in the pulse transmission circuit to transmit high-voltage pulse electrical signals, which stimulate the array elements in the ultrasonic flexible phased array to generate ultrasonic waves.

[0236] When the ultrasonic wave generated by the transmitting element of the ultrasonic flexible phased array propagates through the workpiece, if it encounters a defect in the workpiece, the ultrasonic wave will be reflected. The generated echo is received by the phased array receiving element through the receiving beam control module and converted into an electrical signal by the piezoelectric effect. The echo signal is then amplified and collected by the echo receiving circuit. The collected digital signal is input into the FPGA for processing.

[0237] The RAEL positioning and element allocation module uses the above-mentioned flexible phased array element position determination method to determine the flexible phased array element position, and allocates ultrasonic transmission time, transmitting elements and receiving elements. The processing results are stored in the storage control module and uploaded to the host computer from the communication interface through the communication control module.

[0238] Furthermore, if Figure 2a-2c As shown, the flexible phased array ultrasonic transducer includes a retractable rubber array element base 1, an ultrasonic array element 2, and a flexible probe electrical adapter 3; the ultrasonic array element 2 is arranged on the retractable rubber array element base 1, and the flexible probe electrical adapter 3 is connected to the end of the retractable rubber array element base 1. The flexible probe electrical adapter 3 has a flexible phased array transmitting and receiving connection port 4.

[0239] The array elements are made of SC1-3 flexible composite material, which offers flexibility, appropriate acoustic impedance, and scalability. The relative bandwidth of the ultrasonic pulse is approximately 65%, with a center frequency of 5.0 MHz. The array consists of 4x16 elements, each with a separate transmit and receive line, for a total of 4x16x1 lines (including one ground line). These lines are then connected to the flexible phased array transmit and receive ports and to the host computer. This design aims to dynamically locate each element using the proposed RAEL method and allocate ultrasonic emission time, using the transmitting element and the receiving element of each element for precise ultrasound transmission and focusing.

[0240] Furthermore, the parameter configuration includes a pulse type.

[0241] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for determining the position of a flexible phased array element, characterized in that: The steps include: When measuring a workpiece, the echo signals of each flexible phased array element as a receiving element are synthesized into the scan line data of all elements; The position of the array element in the flexible ultrasonic phased array is determined by using the relative array element positioning algorithm based on the direct wave path of the i-th echo signal in the scan line data. Specifically, Analyze the direct wave path and generate a direct wave path propagation time dataset as input; Iteratively adjust the position of the transmitting array element and the relative position of the receiving array element until the objective function is minimized, and determine the final transmitting array element and receiving array element positions; The propagation time dataset of the direct wave path is used as input to iteratively adjust the position of the transmitting array element and the relative position of the receiving array element until the objective function is minimized, specifically: The propagation distance dataset of the direct wave path is generated using the scan line data as a generated dataset; A calibration dataset of propagation distance of a calibrated direct wave path is obtained according to the experimental measurement of the propagation time of the direct wave path of the calibration sample, as the calibration dataset; A synthetic dataset is obtained based on the generated dataset, and the objective function is minimized through iteration to minimize the difference between the calibration dataset and the synthetic dataset; Determine the final transmit array element position based on the difference between the calibration data set and the synthetic data set; Determine the final receiving array element position according to the final transmitting array element position; Among them, the objective function It is defined as half of the sum of the squared errors between the calibration dataset D and the synthetic dataset V. The specific expression is as follows: (1.8) in, V is a synthetic data set, in which the data is the Euclidean distance of the direct wave path when different array elements are used as transmitting array elements and other array elements are used as receiving array elements when measuring the workpiece; the first j Elements ,in, (1.1), l j For array element L No. j The ultrasonic wave propagation distance of a wave path, and Respectively j The transmitting array element position of each wave path and the j The receiving array element position of each wave path; j is the wave path index, , is the total number of wave paths; T ( j ) is the j The transmit array element index of the wave path, ; R ( j ) is the j The receiving array element index of the wave path, , N T is the number of transmitting array elements, , is the number of receiving array elements, %” is the modulo operator; is the objective function; X is the set of transmitting element position vectors, where j The elements of the wave path are , , t is the transmitting element serial number; Z is the set of receiving element position vectors, where j The elements of the wave path are , , r is the receiving element number; D is the calibration data set, where the data is the direct wave path propagation distance obtained by measuring the calibration sample; e is the error vector, (1.2).

2. The method for determining the position of a flexible phased array element according to claim 1, wherein: The data in the calibration data set D are the squared direct wave path lengths between all combinations of transmitting array elements and receiving array elements.

3. The method for determining the position of flexible phased array elements according to claim 2, wherein: The squared direct wave path length is obtained by multiplying the wave velocity c by the square of the direct wave path propagation time. At this time, the calibration data set is D(c, T), where j The elements of the wave path are , T is the direct wave path propagation time matrix obtained by measuring the calibration sample; is the element in T, which is the first element when measuring the calibration sample. j The direct wave path propagation time of the wave path, c is the wave speed.

4. The method for determining the position of flexible phased array elements according to claim 1, wherein: The synthetic dataset V is obtained as follows: Calculate the difference between the transmit array element and receive array element position vectors for all wave path transmit array element and receive array element combinations : (1.3) in, (1.4) (1.5) in, A x and A z are the transmitting element position vector matrix and the receiving element position vector matrix respectively, I Is the identity matrix, the subscript of the matrix is ​​the value of each row and column of the matrix, x and z are vectors in X and Z respectively; Then the vector in the synthetic dataset V v Expressed as: (1.6) in, (1.7) in, C To record the square distance component between the transmitting array element and the receiving array element of all wave paths.

5. The method for determining the position of flexible phased array elements according to claim 4, wherein: The final transmit element position is determined based on the difference between the calibration dataset and the synthetic dataset, specifically including: Assume that the position of the first array element as the transmitting array element is , the position of the last array element as the transmitting array element is , to eliminate the ambiguity of the final array shape, t Here it means transpose; Among them, the coordinates of all other array elements are initialized to be from the normal distribution The random number drawn from is the length of the transmitting element; Taking the derivative of the set X of transmit element position vectors in equation (1.8), we get: (1.9) At the beginning of the optimization of the transmitting array element position vector, the propagation time is set to 0, and then the gradient elements in Equation (1.9) are Set to zero to eliminate the weight of propagation time; Add the regularization term to the objective function, the modified objective function for: (1.10) in, Ψ is the lateral constraint matrix, which is a weight matrix related to the propagation time, and it enforces the elements in X x The relationship between q = Ψx , and γ is the equilibrium array shape and the correction term introduced θ The lateral constraint is a parameter of the target optimization objective; According to formula (1.10), the gradient of the regularized objective function is as follows: (1.11) in, Lateral constraint matrix Ψ is a second-order finite difference matrix scaled by 1 / 4, and the regularization strength γ is 1e-5; The BFGS optimization algorithm is used to implement regularized objective function gradient optimization to obtain the final transmitting array element position; The final receiving array element position is determined according to the final transmitting array element position.

6. A flexible pulsed ultrasonic phased array transceiver, characterized in that: It includes a flexible phased array ultrasonic transducer, a lower computer and an upper computer; the flexible phased array ultrasonic transducer and the upper computer are both connected to the lower computer; The host computer performs parameter configuration and waveform display; The lower computer includes a hardware circuit part and an FPGA, wherein the hardware circuit includes a power supply circuit, a pulse transmitting circuit, an echo receiving circuit and a communication circuit. The power supply circuit supplies power to the pulse transmitting circuit, the echo receiving circuit and the communication circuit. The FPGA includes a system control module, a hardware circuit control module, a transmit beam synthesis module, a receive beam control module, a RAEL positioning and allocation array element module, a storage control module, and a communication control module. During operation, the host computer selects parameters and sends the configured parameters to the FPGA of the slave computer through the communication interface. After receiving the parameter data, the slave computer performs configuration. The system control module in the FPGA controls the hardware circuit control module, the transmit beam synthesis module, the receive beam control module, the RAEL positioning and allocation array element module, the storage control module, and the communication control module to perform ultrasonic excitation work. The details are as follows: The hardware circuit control module controls the hardware circuit according to the parameters issued. The controllable high-voltage source in the hardware circuit generates corresponding high voltage output to the pulse transmission circuit according to the configuration. The transmit beam synthesis module in the FPGA controls each array element in the pulse transmission circuit to transmit high-voltage pulse electrical signals, which stimulate the array elements in the ultrasonic flexible phased array to generate ultrasonic waves. When the ultrasonic wave generated by the transmitting element of the ultrasonic flexible phased array propagates through the workpiece, if it encounters a defect in the workpiece, the ultrasonic wave will be reflected. The generated echo is received by the phased array receiving element through the receiving beam control module and converted into an electrical signal by the piezoelectric effect. The echo signal is then amplified and collected by the echo receiving circuit. The collected digital signal is input into the FPGA for processing. The RAEL positioning and element allocation module uses the flexible phased array element position determination method according to any one of claims 1 to 5 to determine the flexible phased array element position, and allocates ultrasonic transmission time, transmitting elements and receiving elements, and stores the processing results in the storage control module, and uploads them to the host computer from the communication interface through the communication control module.

7. The flexible pulsed ultrasonic phased array transceiver according to claim 6, characterized in that: The flexible phased array ultrasonic transducer includes a retractable rubber array element base, an ultrasonic array element, and a flexible probe electrical adapter; the ultrasonic array element is arranged on the retractable rubber array element base, and the flexible probe electrical adapter is connected to the end of the retractable rubber array element base. The flexible probe electrical adapter has a flexible phased array transmitting and receiving connection port.

8. The flexible pulsed ultrasonic phased array transceiver according to claim 7, characterized in that: Parameter configuration includes pulse type.

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