Flexible phased array element position determination method and flexible pulse type ultrasonic phased array transceiver

Abstract

The invention discloses a flexible phased array element position determination method and a flexible pulse type ultrasonic phased array transceiver, and belongs to the field of industrial detection. When a workpiece is measured, echo signals generated when the flexible phased array elements serve as receiving array elements are synthesized into scanning line data of all the array elements; the position of an array element in the flexible ultrasonic phased array is determined by utilizing an ith echo signal in scanning line data based on a direct wave path relative array element positioning algorithm, specifically, the direct wave path is analyzed, and a propagation time data set of the direct wave path is generated as input; and continuously iteratively adjusting the positions of the array elements for emission and the positions of the relative receiving array element elements until the target function is minimized, and determining the final positions of the emission array element and the receiving array element. According to the invention, the positions of the transmitting array element and the receiving array element can be accurately determined.

Description

Technical Field

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

[0002] Ultrasonic testing technology is suitable for the detection of surface and internal defects of workpieces. It can quickly and accurately detect the location and size of defects. It has high sensitivity and is environmentally friendly. It is suitable for defect detection and characterization of various workpieces. However, due to the influence of the geometric shape of the curved surface, the sound beam will be distorted, bent, and separated during propagation, which makes it difficult to accurately locate, qualitatively, and quantitatively detect defects. In order to improve the detection accuracy of defects, ultrasonic phased array technology has been developed based on ultrasonic nondestructive testing technology.

[0003] Ultrasonic phased array technology controls the ultrasonic signal emission of each array element to achieve continuous deflection and focusing of sound waves, and performs multiple scans and imaging of different detection areas at the same position on the workpiece surface. It has fast detection speed, high flaw detection sensitivity, and reliable detection results. Therefore, ultrasonic phased array technology has obvious advantages in the detection of complex curved surface components. This technology can flexibly control the deflection and focusing of the sound beam through the time delay law, so it has the advantages of wide detection range, high accuracy, and fast scanning speed.

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

[0005] First, the rigid ultrasonic phased array probe cannot directly match the surface of the complex curved test piece. In order to propagate the sound wave, water coupling or wedge coupling is usually required. However, due to the difference in acoustic impedance between the coupling agent and the test piece, the sound field energy will be lost during the transmission process, which will affect the sensitivity of the probe and lead to inaccurate defect positioning.

[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, rigid probes have slow detection speeds. 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 a flexible phased array element and a flexible pulse ultrasonic phased array transceiver, which aims to solve the technical problems existing in the prior art. The present invention uses the propagation time data set between the direct wave paths as input, and iteratively adjusts and optimizes the position of the array transmitting and receiving array elements by comparing the error between the calibration data and the synthetic data. First, a set of equations is used to link the distance matrix with time and speed, and the set of equations is used to solve the unknown distance. Then, the signal arrival time at each time point and the time difference of the receiver are calculated based on the obtained distance value. Finally, the position of the array element is optimized by minimizing the difference between these time differences and the actual measured values. The present invention can accurately determine the position of the transmitting array element and the receiving array element.

[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 propagation time dataset of the direct wave path as input;

[0013] The positions of the transmitting array elements and the relative receiving array element positions are 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, and as input, the position of the array element used for transmission and the position of the relative receiving array element are adjusted iteratively until the objective function is minimized, specifically:

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

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

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

[0018] Determine the final transmitting array element position according to 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 are the Euclidean distances of the direct wave paths 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 jth wave path, T(j) = floor((j-1) / N T )+1;

[0026] R(j) is the receiving array element index of the jth 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 array 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 square direct wave path length between all the 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 transmitting array element position vector matrix and the receiving array 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 the vectors in X and Z respectively;

[0041] Then the vector v in the synthetic dataset V is represented 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 synthetic 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 arr is the length of the transmitting element;

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

[0050]

[0051] At the beginning of the optimization of the transmitting array element position vector, the propagation time is set to 0, and then the gradient element in equation (1.9) is 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, is a weight matrix, in the present invention, related to the propagation time, which 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 that introduces 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 pulse 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, and 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 the host computer 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, as follows:

[0066] The hardware circuit control module controls the hardware circuit according to the parameters issued, wherein the controllable high-voltage source in the hardware circuit generates corresponding high voltage output to the pulse transmission circuit according to the configuration, and the transmission beam synthesis module in the FPGA controls each array element in the pulse transmission circuit to transmit a high-voltage pulse electrical signal, thereby stimulating 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 in the workpiece, if there is a defect in the workpiece, the ultrasonic wave will be reflected, and the generated echo will be received by the receiving element of the phased array through the receiving beam control module, and converted into an electrical signal by the piezoelectric effect. The echo signal is gain amplified and AD collected by the echo receiving circuit, and the collected digital signal is input into the FPGA for processing;

[0068] The RAEL positioning and array 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 emission time, transmitting array elements and receiving array 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.

[0069] Preferably, the flexible phased array ultrasonic transducer comprises 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 a 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 non-planar flexible ultrasonic array elements. The algorithm uses the propagation time data set between direct wave paths as input, and iteratively adjusts and optimizes the positions of the array transmitting and receiving array elements by comparing the errors between the calibration data and the model calculation data until the objective function is minimized, thereby accurately determining the positions of the transmitting array elements and the receiving array 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 angle of the transmitting and receiving 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 a plane, and different transmitting array element-receiving array element combinations can be assigned (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 emit ultrasonic pulses and reach the defect at the same time, thereby focusing the ultrasonic wave at the defect 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, the propagation of sound waves in materials can be optimized, the ability to detect defects can be improved, and the propagation of sound waves can be optimized. 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 right side schematic diagram 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 of a method for determining positions of elements of 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 be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are 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 propagation time dataset of the direct wave path as input;

[0089] The positions of the transmitting array elements and the relative receiving array element positions are 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. The method is used to determine the position of array elements on a flexible phased array ultrasonic transducer on a surface of unknown geometric shape:

[0091] A 4×16 array of flexible phased array ultrasonic transducers is placed on the surface of a non-planar workpiece. The spatial position of each transducer array element of the flexible phased array ultrasonic transducer is unknown when it is working. Figure 3 Possible array surface configurations (curved solid black lines) are shown, along with the locations of several array elements as transmit elements (triangles) and receive elements (pentagons), as well as the ultrasonic direct path, interface (black line), and scattered wave paths. Further, given a uniform material and a particular transmit element-receive element combination, the arrival times or propagation times on different wave path types will differ due to different path lengths (e.g., between direct and scattered), and in some cases the wave speeds will also differ. The direct wave path is the straight path shown from the transmitter to the receiver. Interface waves propagate along the curved array and are expected to propagate at slower wave 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 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) to illustrate the ultrasonic wave propagation from a given transmitting array element r. 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.

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

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

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

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

[0097] Determine the final transmitting array element position according to 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 data set 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 work as 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 as the optimization process changes.

[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 are the Euclidean distances of the direct wave paths 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 jth wave path, T(j) = floor((j-1) / N T )+1;

[0106] R(j) is the receiving array element index of the jth 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 array 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 array elements are at their calibrated true positions, the value of e is equal to zero. It is used to solve the optimization problem by specifying an objective function of the propagation time related to the position of the array elements.

[0113] According to a specific embodiment of the present invention, the data in the calibration data set D is the square direct wave path length between all the 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 data set 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 transmitting array element position vector matrix and the receiving array 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 the vectors in X and Z respectively;

[0122] Then the vector v in the synthetic dataset V is represented 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 the squared components of the distances in all directions to get an overall squared distance component. This value can be used to evaluate the quality or superiority of different wave paths.

[0128] According to a specific embodiment of the present invention, determining the final transmit array element position according to the difference between the calibration data set and the synthetic 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 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. All other array coordinates are initialized to be drawn from a normal distribution The random number drawn from arr is the length of the array element.

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

[0133] Usually, without known relative array element positions, the positions of the individual elements in the array are 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 the ambiguity of 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. The purpose of this is to constrain the overall shape of the array, thereby avoiding too much freedom in the array shape when there are no 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., to be 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 other array coordinates:

[0137] First, the other array coordinates are initialized from a normal distribution: except for the first and last elements in the array, the positions of other elements are usually initialized to random numbers drawn from a normal distribution. Normally distributed random numbers are generated to simulate irregular and imperfect array layouts in reality, or to introduce some randomness during the optimization process. In this way, the initial distribution of array element positions can be avoided from being too regular or fixed, thus helping the algorithm find a solution that better meets the optimization goal.

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

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

[0140]

[0141] At the beginning of the optimization of the transmitting array element position vector, the propagation time is set to 0, and then the gradient element in equation (1.9) is 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 to zero, since this determines the gradient strength for a given path in equation (1.9). If you wish to pre-determine the position of known elements at the start of the optimization, set them in the initialization and then replace the gradient elements 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. Then, 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, is a weight matrix, in the present invention, related to the propagation time, which 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 that introduces 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 pulse 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, and 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 the host computer 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, as follows:

[0158] The hardware circuit control module controls the hardware circuit according to the parameters issued, wherein the controllable high-voltage source in the hardware circuit generates corresponding high voltage output to the pulse transmission circuit according to the configuration, and the transmission beam synthesis module in the FPGA controls each array element in the pulse transmission circuit to transmit a high-voltage pulse electrical signal, thereby stimulating 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 in the workpiece, if there is a defect in the workpiece, the ultrasonic wave will be reflected, and the generated echo will be received by the receiving element of the phased array through the receiving beam control module, and converted into an electrical signal by the piezoelectric effect. The echo signal is gain amplified and AD collected by the echo receiving circuit, and the collected digital signal is input into the FPGA for processing;

[0160] The RAEL positioning and array 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 emission time, transmitting array elements and receiving array 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.

[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 an element of a flexible phased array 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 propagation time dataset of the direct wave path as input;

[0169] The positions of the transmitting array elements and the relative receiving array element positions are 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 an element of a flexible phased array 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 propagation time dataset of the direct wave path as input;

[0176] The positions of the transmitting array elements and the relative receiving array element positions are 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 generated as input, and the position of the array element used for transmission and the position of the relative receiving array element are adjusted iteratively until the objective function is minimized, specifically:

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

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

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

[0181] Determine the final transmitting array element position according to 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 are the Euclidean distances of the direct wave paths 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 jth wave path, T(j) = floor((j-1) / N T )+1;

[0189] R(j) is the receiving array element index of the jth 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 array 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 are the square direct wave path lengths 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 jth 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 transmitting array element position vector matrix and the receiving array 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 the vectors in X and Z respectively;

[0203] Then the vector v in the synthetic dataset V is represented 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] Further, determining the final transmitting array element position according to the difference between the calibration data set and the synthetic data set specifically includes:

[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 arr is the length of the transmitting element;

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

[0212]

[0213] At the beginning of the optimization of the transmitting array element position vector, the propagation time is set to 0, and then the gradient element in equation (1.9) is 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, is a weight matrix, in the present invention, related to the propagation time, which 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 that introduces 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 position of each element in the ultrasonic flexible phased array during detection, the positions of the transmitting element and the receiving element, the transmitting element and the receiving element, the number of the transmitting element and the receiving element, and the path between the internal defect of the workpiece and the transmitting element, and the defect and the receiving element are also determined, and further, the transmitting element-receiving element combination is determined. Furthermore, in this embodiment, the time for each transmitting element to emit a 5MHz ultrasonic pulse is determined so that it reaches the defect at the same time, that is, the ultrasonic wave is focused at the defect to achieve the best detection effect.

[0228] Example 3

[0229] According to a specific embodiment of the present invention, the flexible pulse 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, see Figure 1 , including 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, and 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 the host computer 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, as follows:

[0235] The hardware circuit control module controls the hardware circuit according to the parameters issued, wherein the controllable high-voltage source in the hardware circuit generates corresponding high voltage output to the pulse transmission circuit according to the configuration, and the transmission beam synthesis module in the FPGA controls each array element in the pulse transmission circuit to transmit a high-voltage pulse electrical signal, thereby stimulating 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 in the workpiece, if there is a defect in the workpiece, the ultrasonic wave will be reflected, and the generated echo will be received by the receiving element of the phased array through the receiving beam control module, and converted into an electrical signal by the piezoelectric effect. The echo signal is gain amplified and AD collected by the echo receiving circuit, and the collected digital signal is input into the FPGA for processing;

[0237] The RAEL positioning and array 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 emission time, transmitting array elements and receiving array 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.

[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, and the flexible probe electrical adapter 3 has a flexible phased array transmitting and receiving connection port 4.

[0239] The array element is made of SC1-3 flexible composite material, which has flexible softness, appropriate acoustic impedance, and scalable performance. The relative bandwidth of the ultrasonic pulse is about 65%, the center frequency is 5.0MHz, the number of array elements is 4x16, each array element has a separate transceiver line, a total of 4x16x1 lines (including one ground line), and finally connected to the flexible phased array transmit and receive connection port and the lower computer. The purpose of this design is to use the proposed RAEL method to dynamically locate each array element and allocate ultrasonic emission time, used as a transmitting array element and each array element as a receiving array element for accurate ultrasound emission and focusing.

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

[0241] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope 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 propagation time dataset of the direct wave path as input; The positions of the transmitting array elements and the relative receiving array element positions are adjusted iteratively until the objective function is minimized, and the final transmitting array element and receiving array element positions are determined.

2. The method for determining the position of a flexible phased array element according to claim 1, characterized in that: The propagation time dataset of the direct wave path is generated as input, and the position of the array element used for transmission and the position of the relative receiving array element are adjusted iteratively until the objective function is minimized, specifically: Using the scan line data, a propagation distance dataset of the direct wave path is generated as a generated dataset; A calibration data set of propagation distance of a calibrated direct wave path is obtained according to the experimental measurement of the direct wave path propagation time of the calibration sample, as the calibration data set; A synthetic data set is obtained based on the generated data set, and the objective function is minimized through iteration, so as to minimize the difference between the calibration data set and the synthetic data set; Determine the final transmitting array element position according to the difference between the calibration data set and the synthetic data set; The final receiving array element position is determined according to the final transmitting array element position.

3. The method for determining the position of a flexible phased array element according to claim 2, characterized in that: 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: in, V is a synthetic data set, in which the data are the Euclidean distances of the direct wave paths 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; j is the wave path index, j∈{1,...,Nw}, N w is the total number of wave paths; T(j) is the transmit array element index of the jth wave path, T(j) = floor((j-1) / N T )+1; R(j) is the receiving array element index of the jth 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; is the objective function; 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; 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 array 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, e=DV (1.2).

4. The method for determining the position of a flexible phased array element according to claim 3, characterized in that: The data in the calibration data set D are the square direct wave path lengths between all combinations of transmitting array elements and receiving array elements.

5. The method for determining the position of flexible phased array elements according to claim 4, characterized in that: 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 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.

6. The method for determining the position of flexible phased array elements according to claim 3, characterized in that: The synthetic dataset V is obtained as follows: 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: Δ=A x x-A z z (1.3) in, Among them, A x and A z are the transmitting array element position vector matrix and the receiving array 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 the vectors in X and Z respectively; Then the vector v in the synthetic dataset V is represented as: v=Cdiag(Δ)Δ (1.6) in, Where C is the square distance component between the transmitting array element and the receiving array element that records all wave paths.

7. The method for determining the position of flexible phased array elements according to claim 6, characterized in that: The final transmitting array element position is determined based on the difference between the calibration data set and the synthetic data set, including: 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 remove ambiguity about the final array shape, t here means transpose; Among them, the coordinates of all other array elements are initialized to be from the normal distribution The random number drawn from arr is the length of the transmitting element; Taking the derivative of the set X of the transmitting array element position vectors in equation (1.8), we get: At the beginning of the optimization of the transmitting array element position vector, the propagation time is set to 0, and then the gradient element in equation (1.9) is Set to zero to eliminate the weight of propagation time; Add the regularization term to the objective function, and the modified objective function o is: Where Ψ is the lateral constraint matrix, is a weight matrix, in the present invention, related to the propagation time, which 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 that introduces the correction term θ; According to formula (1.10), the gradient of the regularized objective function is as follows: in, The 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.

8. 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, and 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 the host computer 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, as follows: The hardware circuit control module controls the hardware circuit according to the parameters issued, wherein the controllable high-voltage source in the hardware circuit generates corresponding high voltage output to the pulse transmission circuit according to the configuration, and the transmission beam synthesis module in the FPGA controls each array element in the pulse transmission circuit to transmit a high-voltage pulse electrical signal, thereby stimulating 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 in the workpiece, if there is a defect in the workpiece, the ultrasonic wave will be reflected, and the generated echo will be received by the receiving element of the phased array through the receiving beam control module, and converted into an electrical signal by the piezoelectric effect. The echo signal is gain amplified and AD collected by the echo receiving circuit, and the collected digital signal is input into the FPGA for processing; The RAEL positioning and array element allocation module uses the flexible phased array array element position determination method described in any one of claims 1 to 7 to determine the flexible phased array array element position, and allocates ultrasonic emission time, transmitting array elements and receiving array 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.

9. The flexible pulse ultrasonic phased array transceiver according to claim 8, characterized in that: The flexible phased array ultrasonic transducer comprises 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.

10. The flexible pulse ultrasonic phased array transceiver according to claim 9, characterized in that: Parameter configuration includes pulse type.

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