A method for measuring the thickness of a solid under seawater based on an ultrasonic phased array

Abstract

The application provides a method for measuring the thickness of a solid under seawater based on an ultrasonic phased array, which comprises the following steps: acquiring at least two ultrasonic beams emitted into seawater by using an ultrasonic phased array; obtaining a first reflected echo time difference according to a first ultrasonic beam emitted into seawater by using a self-correlation algorithm; obtaining a second reflected echo time difference according to a second ultrasonic beam emitted into seawater; determining a first angle according to a first propagation time, a third propagation time and an emission angle; determining a second angle according to the first angle and the emission angle; determining a to-be-measured solid sound velocity value according to a second propagation time, a fourth propagation time, the first angle and the second angle based on a genetic algorithm; determining a to-be-measured solid thickness according to the to-be-measured solid sound velocity value, the second propagation time and the first angle, and obtaining a plurality of to-be-measured solid thicknesses; and obtaining a to-be-measured solid target thickness according to the plurality of to-be-measured solid thicknesses.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geological exploration and the technical field of solid thickness measurement, and particularly relates to a method for measuring the thickness of a solid under seawater based on an ultrasonic phased array. BACKGROUND

[0002] Ocean resources are of great significance to sustainable development, and reasonable utilization and development of ocean resources require high-precision marine geophysical underwater material detection technology, and measuring the thickness of underwater solids is an important part of this technology.

[0003] Currently, underwater solid thickness measurement mainly uses ultrasonic waves with good directivity and strong penetration to in-situ detect deep-sea solid material resources. Specifically, it mainly uses pulse echo type ultrasonic waves to calculate the thickness of solid materials. When the ultrasonic waves propagate in the solid material, they will be reflected when they encounter the bottom surface of the solid material. The round-trip time of ultrasonic waves in the solid material, combined with the propagation speed of ultrasonic waves in the solid material, can be used to calculate the thickness of the solid material. This method is low in cost and easy to implement, and is therefore widely used.

[0004] However, in the process of using pulse echo to measure the thickness of underwater solids, the angle between the ultrasonic signal incident direction and the horizontal direction of the solid material surface is generally assumed to be 90°, i.e., the ultrasonic incident direction is assumed to be perpendicular to the surface of the solid to be measured. However, due to the unevenness of the surface of the solid to be measured and the slope of the sea mountain, if the angle between the ultrasonic incident direction and the horizontal direction is simply assumed to be perpendicular, it will have a significant impact on the measurement results of the solid thickness. Moreover, often before measuring the thickness of a specific area, a sample of the material is collected and the sound speed of the area is measured or the existing sound speed value is used as a reference. Since the physical properties of deep-sea solids are unknown, the results of sound speed calculation are also different, resulting in different measurement results of the thickness of the solid material. SUMMARY

[0005] Therefore, the present application provides a method for measuring the thickness of a solid under seawater based on an ultrasonic phased array, to solve at least one of the above technical problems, to improve the measurement accuracy of the thickness of the solid, and to reduce measurement errors.

[0006] In order to achieve the above object, the application provides a method for measuring the thickness of a solid under seawater based on an ultrasonic phased array, which comprises the following steps: acquiring at least two ultrasonic beams emitted into seawater by using an ultrasonic phased array, wherein each ultrasonic beam can pass through seawater to reach the upper surface of a solid to be measured, and pass through the solid to be measured to reach the lower surface of the solid to be measured through the upper surface of the solid to be measured, the upper surface of the solid to be measured is the surface close to the ultrasonic phased array, the lower surface of the solid to be measured is the surface away from the ultrasonic phased array, any two ultrasonic beams of the at least two ultrasonic beams have different emission angles, and the any two ultrasonic beams comprise a first ultrasonic beam and a second ultrasonic beam; obtaining a first reflection echo time difference corresponding to the first ultrasonic beam according to the first ultrasonic beam emitted into seawater by using a self-correlation algorithm, wherein the first reflection echo time difference comprises a first propagation time of the first ultrasonic beam in seawater and a second propagation time of the first ultrasonic beam in the solid to be measured; obtaining a second reflection echo time difference corresponding to the second ultrasonic beam according to the second ultrasonic beam emitted into seawater by using the self-correlation algorithm, wherein the second reflection echo time difference comprises a third propagation time of the second ultrasonic beam in seawater and a fourth propagation time of the second ultrasonic beam in the solid to be measured; determining a first angle of the first ultrasonic beam after reaching the upper surface of the solid to be measured according to the first propagation time, the third propagation time and the emission angle; determining a second angle of the second ultrasonic beam after reaching the upper surface of the solid to be measured according to the first angle and the emission angle; determining a sound velocity value of the solid to be measured in seawater according to the second propagation time, the fourth propagation time, the first angle and the second angle based on a genetic algorithm; determining the thickness of the solid to be measured according to the sound velocity value of the solid to be measured in seawater, the second propagation time and the first angle, and obtaining the thicknesses of a plurality of solids to be measured; and obtaining a target thickness of the solid to be measured according to the thicknesses of the plurality of solids to be measured.

[0007] According to the embodiments of the application, the ultrasonic phased array comprises a plurality of array elements, and the different emission angles of any two ultrasonic beams are realized by adjusting the excitation time of the plurality of array elements of the ultrasonic phased array.

[0008] According to the embodiments of the application, the first reflection echo time difference corresponding to the first ultrasonic beam is obtained according to the first ultrasonic beam emitted into seawater by using the self-correlation algorithm, which comprises the following steps: collecting a first emission wave signal of the first ultrasonic beam emitted into seawater and a first reflection echo signal of the first ultrasonic beam after reaching the upper surface of the solid to be measured; and obtaining the first reflection echo time difference corresponding to the first ultrasonic beam by using the first emission wave signal and the first reflection echo signal based on the self-correlation algorithm.

[0009] According to an embodiment of the present application, the method further comprises: determining a preset sound speed value range of the to-be-tested solid in seawater; and determining an initial population of the genetic algorithm according to the preset sound speed value range of the to-be-tested solid in seawater, the initial population including a preset number of preset sound speed values, each of which is an individual of the genetic algorithm.

[0010] According to an embodiment of the present application, the method further comprises: setting genetic algorithm parameters, the genetic algorithm parameters including an initial population size, a preset iteration number N, a selection rate, a crossover rate, and a mutation rate; for the i th iteration, determining a fitness function value of each individual of the (i-1) th iteration according to the second propagation time, the fourth propagation time, the first angle, and the second angle based on the genetic algorithm parameters; selecting a target individual of the i th iteration that meets a preset fitness function value according to the fitness function value of each individual; and recalculating the fitness function value of each individual of the i th iteration after a crossover and mutation operation between the target individuals of the i th iteration based on a crossover rule and a mutation rule, to obtain a sound speed value of the to-be-tested solid in seawater in the i th iteration, wherein 1≤i≤N-1.

[0011] According to an embodiment of the present application, after the sound speed value of the to-be-tested solid in seawater in the i th iteration is obtained by recalculating the fitness function value of each individual of the i th iteration, the method further comprises: performing selection, crossover, and mutation operations on each individual after the crossover and mutation operation based on the recalculated fitness function value of the i th iteration, and calculating a fitness function value of each individual of the (i+1) th iteration after the crossover and mutation operation, to obtain a sound speed value of the to-be-tested solid in seawater in the (i+1) th iteration.

[0012] According to an embodiment of the present application, the method further comprises: determining a thickness of the to-be-tested solid according to the sound speed value of the to-be-tested solid in seawater, the second propagation time, and the first angle, to obtain thicknesses of a plurality of to-be-tested solids.

[0013] According to an embodiment of the present application, the selection rate is 90%, the crossover rate is 70%, and the mutation rate is 50%.

[0014] According to an embodiment of the present application, the method further comprises: encoding each individual in the initial population to obtain a target code string; and decoding the target code string to calculate the fitness function value of each individual.

[0015] According to the embodiment of the present application, the target thickness of the solid to be measured is obtained according to the thicknesses of the plurality of solids to be measured, comprising: summing the thicknesses of the plurality of solids to be measured to obtain a sum result; and obtaining the target thickness of the solid to be measured according to the sum result.

[0016] According to the embodiment of the present application, the first propagation time of the first ultrasonic beam in seawater and the second propagation time of the first ultrasonic beam in the solid to be measured, and the second propagation time of the second ultrasonic beam in seawater and the third propagation time of the second ultrasonic beam in the solid to be measured are obtained by using the self-correlation algorithm for each of the first ultrasonic beam and the second ultrasonic beam of the at least two ultrasonic beams with different emission angles emitted into seawater based on an ultrasonic phased array, and the first angle after the first ultrasonic beam reaches the upper surface of the solid to be measured is determined based on the first propagation time and the third propagation time and the emission angle, the second angle after the second ultrasonic beam reaches the upper surface of the solid to be measured is determined based on the first angle and the emission angle, and the sound speed value of the solid to be measured in seawater is obtained according to the first round second propagation time, the first round fourth propagation time, the first round first angle and the first round second angle by combining the genetic algorithm, and the target thickness of the solid to be measured is obtained based on the sound speed value. By using the ultrasonic phased array to obtain ultrasonic beams with different emission angles and the genetic algorithm to measure the thickness of the underwater solid, the technical problem of inaccurate measurement of the thickness of the solid to be measured caused by the default ultrasonic incident direction perpendicular to the surface of the solid to be measured on the seabed and the determination of the sound speed value of the solid to be measured based on the solid sample or the existing sound speed value is solved, thereby achieving the technical effects of improving the measurement accuracy of the thickness of the solid and reducing the measurement error. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A flowchart of a method for measuring the thickness of a solid under seawater based on an ultrasonic phased array according to an embodiment of the present application is schematically shown;

[0018] Figure 2 A schematic diagram of emitting at least two ultrasonic beams with different emission angles by using an ultrasonic phased array according to an embodiment of the present application is schematically shown;

[0019] Figure 3 A flowchart of a method for determining the sound speed value of the solid to be measured in seawater based on a genetic algorithm according to an embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0020] In order to make the objects, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to specific embodiments and the accompanying drawings.

[0021] Figure 1A flow chart of a method for measuring thickness of a solid under sea water based on an ultrasonic phased array is shown.

[0022] As shown in Figure 1 The method can include operations S110-S180.

[0023] In operation S110, at least two ultrasonic beams emitted by the ultrasonic phased array into the sea water are acquired, wherein each first round ultrasonic beam can pass through the sea water to reach an upper surface of a solid to be measured, and pass through the upper surface of the first round solid to be measured to reach a lower surface of the first round solid to be measured, the upper surface of the first round solid to be measured being the surface close to the first round ultrasonic phased array, the lower surface of the first round solid to be measured being the surface away from the first round ultrasonic phased array, any two ultrasonic beams of the first round at least two ultrasonic beams having different emission angles, the any two ultrasonic beams of the first round including a first ultrasonic beam and a second ultrasonic beam.

[0024] According to an embodiment of the present application, the ultrasonic phased array can be a phased ultrasonic transducer, which can include a plurality of array elements arranged in one-dimensional linear. By adjusting the excitation time of the plurality of array elements of the ultrasonic phased array placed in the sea water and setting according to a certain delay rule, any two ultrasonic beams having different emission angles can be emitted. That is, the phased ultrasonic probe of the ultrasonic phased transducer can emit a plurality of ultrasonic waves with different angles by changing the delay of the array elements.

[0025] According to an embodiment of the present application, each ultrasonic beam of the at least two ultrasonic beams can pass through the sea water to reach the upper surface of the solid to be measured in the sea water, and then pass through the upper surface of the solid to be measured to reach the lower surface of the solid to be measured.

[0026] According to an embodiment of the present application, by changing the excitation time of a single array element of the ultrasonic phased array and setting according to a certain delay rule, the sound waves emitted by each array element will follow the Huygens principle and superimpose to form a new wave front phased array. By controlling the time of emitting and receiving ultrasonic wave signals by the probe array element of the ultrasonic phased array, the focusing rule is followed. Due to the time difference, the ultrasonic wave array emitted by each array element gradually converges into a point in space, thereby achieving the effect of sound beam focusing and deflection. Since the ultrasonic phased array is used to emit a plurality of ultrasonic beams with different emission angles, the emission angle of each ultrasonic beam can be different, thereby improving the measurement result of the thickness to be measured and reducing the influence on the thickness measurement result.

[0027] In operation S120, a first reflection echo time difference corresponding to the first ultrasonic beam is obtained according to the first ultrasonic beam emitted into the first seawater by using a self-correlation algorithm, wherein the first reflection echo time difference includes a first propagation time of the first ultrasonic beam propagating in the first seawater and a second propagation time of the first ultrasonic beam propagating in the first solid to be measured.

[0028] In operation S130, a second reflection echo time difference corresponding to the second ultrasonic beam is obtained according to the second ultrasonic beam emitted into the first seawater by using the first self-correlation algorithm, wherein the second reflection echo time difference includes a third propagation time of the second ultrasonic beam propagating in the first seawater and a fourth propagation time of the second ultrasonic beam propagating in the first solid to be measured.

[0029] According to an embodiment of the present application, the self-correlation algorithm is an algorithm used to describe signal characteristics in signal processing. The echo beam after the first ultrasonic beam reaching the upper surface of the solid to be measured and the echo beam after the first ultrasonic beam reaching the lower surface of the solid to be measured can be determined according to the first ultrasonic beam emitted by the ultrasonic phased array, that is, the first reflection echo time difference corresponding to the first ultrasonic beam can be determined.

[0030] According to an embodiment of the present application, the first propagation time of the first ultrasonic beam propagating in the seawater can be obtained by determining the echo beam after the first ultrasonic beam reaching the upper surface of the solid to be measured, and the second propagation time of the first ultrasonic beam propagating in the solid to be measured can be obtained by determining the echo beam after the first ultrasonic beam reaching the lower surface of the solid to be measured.

[0031] According to an embodiment of the present application, the echo beam after the second ultrasonic beam reaching the upper surface of the solid to be measured and the echo beam after the second ultrasonic beam reaching the lower surface of the solid to be measured can be determined according to the second ultrasonic beam emitted by the ultrasonic phased array, that is, the second reflection echo time difference corresponding to the second ultrasonic beam can be determined.

[0032] According to an embodiment of the present application, the third propagation time of the second ultrasonic beam propagating in the seawater can be obtained by determining the echo beam after the second ultrasonic beam reaching the upper surface of the solid to be measured, and the fourth propagation time of the second ultrasonic beam propagating in the solid to be measured can be obtained by determining the echo beam after the second ultrasonic beam reaching the lower surface of the solid to be measured.

[0033] In operation S140, a first angle of the first ultrasonic beam reaching the upper surface of the first solid to be measured is determined according to the first propagation time, the third propagation time and the first emission angle.

[0034] When operating S150, the second angle after the first ultrasonic beam reaches the upper surface of the solid to be tested is determined based on the first angle and the first emission angle of the first round.

[0035] According to an embodiment of the present invention, the first angle can be the angle between the emission direction of the first ultrasonic beam and the normal after the first ultrasonic beam reaches the upper surface of the solid to be tested, with the upper surface of the solid to be tested as the horizontal direction and the direction perpendicular to the upper surface of the solid to be tested as the first normal. Similarly, the angle between the emission direction of the second ultrasonic beam and the second normal is the second angle. The second normal can be the normal in the direction perpendicular to the upper surface of the solid to be tested, and the first normal and the second normal are parallel.

[0036] According to an embodiment of the present invention, the second angle can be determined based on the geometric relationship between any two ultrasonic beams, by using the first angle and the emission angles of any two ultrasonic beams.

[0037] For example, Figure 2 The diagram illustrates, according to an embodiment of the present invention, the use of an ultrasonic phased array to emit at least two ultrasonic beams at different emission angles.

[0038] like Figure 2 As shown, taking any two ultrasonic beams AM and AN from at least two ultrasonic beams with different emission angles as an example, two ultrasonic beams AM and AN with emission angles α are emitted into the seawater by an ultrasonic phased array A placed in seawater, with the direction of the solid to be tested. The first ultrasonic beam AM reflects the echo after reaching the upper surface of the solid to be tested, which determines the first propagation time tm1 of the first ultrasonic beam in the seawater. The second ultrasonic beam AM reflects the echo after reaching the lower surface of the solid to be tested, which determines the second propagation time tm2 of the first ultrasonic beam in the solid to be tested. Similarly, the second ultrasonic beam AN reflects the echo after reaching the upper surface of the solid to be tested, which determines the third propagation time tn1 of the second ultrasonic beam in the seawater. The fourth ultrasonic beam AN reflects the echo after reaching the lower surface of the solid to be tested, which determines the fourth propagation time tn2 of the second ultrasonic beam in the solid to be tested.

[0039] Based on, for example Figure 2 Given the geometry of any two ultrasonic beams shown, based on the first propagation time tm1, the third propagation time tn1, and the emission angle α, the first angle θ1 after the first ultrasonic beam reaches the upper surface of the solid to be tested can be determined. The first angle θ1 can be obtained using formula (1):

[0040] (1);

[0041] Based on such Figure 2The geometry of any two of the illustrated ultrasonic beams can determine a second angle θ3 of the second ultrasonic beam reaching the upper surface of the first round of the to-be-measured solid according to the first angle θ1 and the emission angle α. The second angle θ3 can be obtained by formula (2):

[0042] (2).

[0043] In operation S160, the sound speed value of the first round of the to-be-measured solid in the first round of seawater is determined based on the genetic algorithm according to the first round of the second propagation time, the first round of the fourth propagation time, the first round of the first angle and the first round of the second angle.

[0044] In operation S170, the thickness of the first round of the to-be-measured solid is determined according to the sound speed value of the first round of the to-be-measured solid in the first round of seawater, the first round of the second propagation time and the first round of the first angle, and the thicknesses of multiple first rounds of the to-be-measured solid are obtained.

[0045] In operation S180, the target thickness of the first round of the to-be-measured solid is obtained according to the thicknesses of the multiple first rounds of the to-be-measured solid.

[0046] According to the embodiments of the present application, the sound speed value of the to-be-measured solid in seawater after each iteration can be determined based on the set genetic algorithm parameters, the second propagation time tm2 and the fourth propagation time tn2, the first angle θ1 and the second angle θ3; the thickness of the to-be-measured solid after each iteration can be determined for the sound speed value of the to-be-measured solid in seawater after each iteration, in combination with the second propagation time tm2 and the first angle θ1 of the first round , and the thicknesses of the to-be-measured solid corresponding to the preset number of iterations are obtained. The corresponding operation is performed on the thicknesses of the to-be-measured solid corresponding to the preset number of iterations , and the thickness of the to-be-measured solid determined by using the arbitrary two ultrasonic beams is obtained. Thus, the thicknesses of the to-be-measured solid determined by using the arbitrary two ultrasonic beams are obtained, and the target thickness H2 of the to-be-measured solid can be obtained based on the multiple thicknesses of the to-be-measured solid .

[0047] According to the embodiment of the present application, by utilizing at least two ultrasonic beams with different emission angles emitted into seawater based on an ultrasonic phased array, a first propagation time of a first ultrasonic beam in seawater and a second propagation time of the first ultrasonic beam in a solid to be measured, and a second propagation time of a second ultrasonic beam in seawater and a third propagation time of the second ultrasonic beam in the solid to be measured are obtained by using a self-correlation algorithm, and then based on the first propagation time and the third propagation time and the emission angle, a first angle after the first ultrasonic beam reaches the upper surface of the solid to be measured is determined, based on the first angle and the emission angle, a second angle after the second ultrasonic beam reaches the upper surface of the solid to be measured is determined, and in combination with a genetic algorithm, a sound speed value of the solid to be measured in seawater is obtained according to the first second propagation time, the first fourth propagation time, the first first angle and the first second angle, and a target thickness of the solid to be measured is obtained based on the sound speed value. By using the ultrasonic phased array to obtain ultrasonic beams with different emission angles, and using the genetic algorithm to measure the thickness of the underwater solid, the technical problem of inaccurate measurement of the thickness of the solid to be measured caused by the default ultrasonic incident direction being perpendicular to the surface of the solid to be measured on the seabed, and the determination of the sound speed value of the solid to be measured based on a solid sample or by referring to an existing sound speed value is solved, thereby achieving the technical effects of improving the measurement accuracy of the thickness of the solid and reducing the measurement error.

[0048] According to the embodiment of the present application, a first reflection echo time difference corresponding to a first ultrasonic beam is obtained based on the first ultrasonic beam emitted into seawater by using a self-correlation algorithm, including: collecting a first emission wave signal of the first ultrasonic beam emitted into seawater and a first reflection echo signal after the first ultrasonic beam reaches the upper surface of the solid to be measured; based on the self-correlation algorithm, the first reflection echo time difference corresponding to the first ultrasonic beam is obtained by using the first emission wave signal and the first reflection echo signal.

[0049] According to an embodiment of the present application, when determining the first reflection time difference corresponding to the first ultrasonic beam by using the autocorrelation algorithm, the first transmission wave signal of the first ultrasonic wave can be collected to detect the time and amplitude of the first transmission wave signal; the first reflection wave information of the first ultrasonic wave can be collected to detect the time and amplitude of the first reflection wave information; by using the time and amplitude of the first transmission wave signal and the time and amplitude of the first reflection wave information, the first reflection time difference can be determined. Specifically, by using the time and amplitude of the first transmission wave signal reaching the surface of the solid to be measured and the time and amplitude of the reflection wave signal after the first ultrasonic beam reaches the upper surface of the solid to be measured, the first propagation time tm1 of the first ultrasonic beam propagating in seawater can be determined; by using the time and amplitude of the first ultrasonic beam after penetrating the solid to be measured from the upper surface of the solid to be measured to reach the lower surface of the solid to be measured and the time and amplitude of the reflection wave signal after the first ultrasonic beam reaches the lower surface of the solid to be measured, the second propagation time tm2 of the first ultrasonic beam propagating in the solid to be measured can be determined.

[0050] According to an embodiment of the present application, the method further comprises: determining a range of preset sound speed values of the solid to be measured in the first round of seawater that needs to be configured; and determining an initial population of the genetic algorithm according to the range of preset sound speed values of the solid to be measured in the first round of seawater, wherein the initial population of the first round includes a preset number of preset sound speed values, and each preset sound speed value of the first round is used as an individual of the genetic algorithm of the first round.

[0051] According to an embodiment of the present application, the range of preset sound speed values of the solid to be measured can be 1500-3000 m / s, and a preset number of preset sound speed values of the solid to be measured can be selected from the range of preset sound speed values of the solid to be measured as individuals of the initial population in the genetic algorithm based on a preset number of initial populations.

[0052] Figure 3 A flowchart of a method for determining the sound speed value of the solid to be measured in seawater based on a genetic algorithm according to an embodiment of the present application is schematically shown.

[0053] As shown in Figure 3 , the method comprises operations S310-S340.

[0054] In operation S310, the first round of genetic algorithm parameters are set, and the first round of genetic algorithm parameters include the initial population number, the preset iteration number N, the selection rate, the crossover rate, and the mutation rate.

[0055] In operation S320, for the i-th round of iteration, the fitness function value of each individual of the (i-1)-th round is determined based on the first round of genetic algorithm parameters and according to the first round of second propagation time, the first round of fourth propagation time, the first round of first angle, and the first round of second angle.

[0056] In operation S330, according to the fitness function value of each first round individual, the target individual of the i th round satisfying the preset fitness function value is selected.

[0057] In operation S340, based on the crossover rule and the mutation rule between individuals, after the crossover and mutation operations between the target individuals of the i th round are performed, the fitness function value of each individual after the crossover and mutation operations is recalculated, and the sound velocity value of the first round of the to-be-tested solid in seawater is obtained, wherein 1≤i≤N-1.

[0058] According to the embodiment of the present application, the initial population quantity can be set to 300, the preset iteration number N can be 2000, the selection rate can be 90%, the first round crossover rate can be 70%, and the first round mutation rate can be 50%.

[0059] According to the embodiment of the present application, the method for determining the sound velocity value of the to-be-tested solid in seawater by using the genetic algorithm further includes: encoding each first round individual in the initial population of the first round to obtain a target code string; and decoding the target code string of the first round to calculate the fitness function value of each first round individual.

[0060] According to the embodiment of the present application, each individual in the initial population can be binary coded to obtain a code string for each individual.

[0061] According to the embodiment of the present application, the code string of each individual can be decoded, and the decoded string can be input into the fitness function for fitness calculation to obtain the fitness function value corresponding to each individual.

[0062] According to the embodiment of the present application, the fitness function value can be calculated by inputting the second propagation time tm2, the first round fourth propagation time tn2, the first angle θ1 and the second angle θ3 into the fitness function, and the fitness function can be represented by the following formula (3):

[0063] (3);

[0064] Wherein, C1 is the sound velocity value of the ultrasonic wave propagating in seawater, which is a constant and can be 1500 m / s; and C2 is the preset sound velocity value of each individual in the initial population, i.e., the to-be-tested solid in seawater.

[0065] According to the embodiment of the present application, in the case that the current iteration is the first iteration, based on the genetic algorithm parameters, the second propagation time tm2, the fourth propagation time tn2 of the first iteration, the first angle θ1, the second angle θ3 and each individual in the determined initial population are input into the above fitness function, the fitness function value of each individual can be determined; according to the fitness function value of each individual, the target individual of the first iteration meeting the preset fitness function value is selected; and based on the crossover rule and the mutation rule between individuals, the target individuals of the first iteration are subjected to the crossover and mutation operations according to the crossover rate and the mutation rate, and each target individual after the crossover and mutation operations is recalculated to obtain the fitness function value of each target individual of the first iteration, based on the recalculated fitness function value of the first iteration, the sound velocity value of the first iteration of the solid to be measured in seawater is determined, and the set of each target individual of the first iteration can be used as each individual in the new population to participate in the next iteration.

[0066] According to the embodiment of the present application, in the case that the current iteration is the first iteration, based on the genetic algorithm parameters, the second propagation time tm2, the fourth propagation time tn2 of the first iteration, the first angle θ1, the second angle θ3 and each individual in the determined initial population are input into the above fitness function, the fitness function value of each individual can be determined; according to the fitness function value of each individual, the target individual of the first iteration meeting the preset fitness function value is selected; and based on the crossover rule and the mutation rule between individuals, the target individuals of the first iteration are subjected to the crossover and mutation operations according to the crossover rate and the mutation rate, and each target individual after the crossover and mutation operations is recalculated to obtain the fitness function value of each target individual of the first iteration, based on the recalculated fitness function value of the first iteration, the sound velocity value of the first iteration of the solid to be measured in seawater is determined, and the set of each target individual of the first iteration can be used as each individual in the new population to participate in the next iteration.

[0067] According to the embodiment of the present application, in the case that the current iteration is the first iteration, based on the genetic algorithm parameters, the second propagation time tm2, the fourth propagation time tn2 of the first iteration, the first angle θ1, the second angle θ3 and each individual in the determined initial population are input into the above fitness function, the fitness function value of each individual can be determined; according to the fitness function value of each individual, the target individual of the first iteration meeting the preset fitness function value is selected; and based on the crossover rule and the mutation rule between individuals, the target individuals of the first iteration are subjected to the crossover and mutation operations according to the crossover rate and the mutation rate, and each target individual after the crossover and mutation operations is recalculated to obtain the fitness function value of each target individual of the first iteration, based on the recalculated fitness function value of the first iteration, the sound velocity value of the first iteration of the solid to be measured in seawater is determined, and the set of each target individual of the first iteration can be used as each individual in the new population to participate in the next iteration.

[0068] According to the embodiment of the present application, in the case that the current round is the i+1th round, based on the genetic algorithm parameters, the second propagation time tm2, the fourth propagation time tn2 of the first round, the first angle θ1, the second angle θ3 and the determined population of the i th round of each individual are input into the above fitness function, the fitness function value of each individual can be determined; according to the fitness function value of each individual, the target individual of the i+1th round meeting the preset fitness function value is selected; and based on the crossover rule and the mutation rule between individuals, the crossover and mutation operations are performed between the target individuals of the i+1th round according to the crossover rate and the mutation rate, and each target individual after the crossover and mutation operations is recalculated to obtain the fitness function value of each target individual of the i+1th round, based on the recalculated fitness function value of the i+1th round, the sound velocity value of the to-be-measured solid in seawater in the i+1th round is determined, wherein the set of each target individual of the i+1th round can be used as each individual in the new population to participate in the next round of iteration. In this way, the sound velocity value of the to-be-measured solid in seawater in the Nth round is obtained.

[0069] According to the embodiment of the present application, the thickness of the first round to-be-measured solid is determined according to the sound velocity value of the first round to-be-measured solid in the first round seawater, the first round second propagation time and the first round first angle, and the thickness of the plurality of first round to-be-measured solids is obtained, including: for the sound velocity value of the first round to-be-measured solid in the first round seawater obtained by the i th iteration, the thickness of the i th first round to-be-measured solid is determined according to the sound velocity value of the i th first round to-be-measured solid in the first round seawater, the first round second propagation time and the first round first angle, and the thickness of the plurality of first round to-be-measured solids is obtained.

[0070] According to the embodiment of the present application, the thickness of the first round to-be-measured solid can be determined according to the sound velocity value C2 of the to-be-measured solid in the first round seawater, the first round second propagation time tm2 and the first round first angle θ1 , which can be specifically expressed as the following formula (4):

[0071] (4).

[0072] According to the embodiment of the present application, for the obtained sound velocity of the to-be-measured solid in seawater in the i th round , the sound velocity value of the to-be-measured solid in seawater in the i th round, the second propagation time tm2 and the first round first angle θ1 can be input into the above formula, and the thickness of the to-be-measured solid in the i th round can be determined . In this way, the thickness of the to-be-measured solid in the Nth round can be obtained , and thus the thicknesses of the N to-be-measured solids are obtained.

[0073] According to an embodiment of the present application, the target thickness of the first round of the to-be-measured solid is obtained according to the thicknesses of the first round of the to-be-measured solids, including: summing the thicknesses of the first round of the to-be-measured solids to obtain a sum result; and obtaining the target thickness of the first round of the to-be-measured solids according to the sum result.

[0074] According to an embodiment of the present application, for any two ultrasonic beams, the thicknesses of the N to-be-measured solids are summed and averaged according to the obtained thicknesses of the N to-be-measured solids, so that the thicknesses of the to-be-measured solids calculated for the two ultrasonic beams are obtained .

[0075] According to an embodiment of the present application, the ultrasonic phased array emits a plurality of ultrasonic beams with different emission angles, and the thicknesses of the to-be-measured solids for any two ultrasonic beams are obtained based on the above method , and the target thickness H2 of the to-be-measured solid under the sea is obtained by summing and averaging the thicknesses of the to-be-measured solids .

[0076] According to an embodiment of the present application, in combination with Figure 2 , taking two ultrasonic beams as an example, the formula (4) can be determined, specifically, according to the geometric structure and the ray acoustic propagation theory, the time tm1 of the ultrasonic beam AM propagating in the sea and the time tm2 of the ultrasonic beam AM propagating in the to-be-measured solid are formula (5) and formula (6) respectively:

[0077] (5);

[0078] (6);

[0079] Wherein, C1 is the sound speed value of the ultrasonic wave propagating in the sea; H1 is the distance between the position of the ultrasonic phased array in the sea and the upper surface of the to-be-measured solid; H2 is the target thickness of the to-be-measured solid; θ1 is the first angle; θ2 is the angle between the emitted ultrasonic beam and the first normal line when the ultrasonic beam AM passes through the to-be-measured solid.

[0080] According to an embodiment of the present application, similarly, the time tn1 of the ultrasonic beam AN propagating in the sea and the time tn2 of the ultrasonic beam AN propagating in the to-be-measured solid are formula (7) and formula (8) respectively:

[0081] (7);

[0082] (8);

[0083] Wherein, θ3 is the second angle; θ4 is the angle between the emitted ultrasonic beam and the second normal line when the ultrasonic beam AN passes through the to-be-measured solid.

[0084] According to the Snell law formula (9) and formula (10):

[0085] (9);

[0086] (10);

[0087] And the geometric structure relationship formula (11):

[0088] (11);

[0089] Wherein, a is the emission angle between any two of the plurality of ultrasonic beams.

[0090] According to the embodiments of the present application, the calculation formula (12) of the sound speed value C2 of the solid to be measured in seawater and the calculation formula (4) of the thickness of the solid to be measured in each iteration can be determined based on the above-mentioned formulas (5)-(11).

[0091] (12).

[0092] According to the embodiments of the present application, the fitness function (3) of the genetic algorithm can be constructed from the above-mentioned formulas (5)-(12), so as to determine the target thickness of the solid to be measured based on the genetic algorithm and in combination with formula (4).

[0093] It should be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only the directions of the drawings and are not intended to limit the scope of protection of the present application. Throughout the drawings, the same elements are represented by the same or similar reference numerals. When it is possible to cause confusion in the understanding of the present application, the conventional structures or configurations will be omitted. Moreover, the shapes and sizes of the components in the drawings do not reflect the true size and ratio, but only illustrate the content of the embodiments of the present application. Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" before an element does not exclude the presence of multiple such elements.

[0094] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above first round is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.​

Claims

1. A method for measuring the thickness of underwater solids based on ultrasonic phased array, comprising: At least two ultrasonic beams emitted into seawater using an ultrasonic phased array are obtained, wherein each ultrasonic beam can penetrate the seawater to reach the upper surface of a solid under test, and pass through the upper surface of the solid under test to reach the lower surface of the solid under test. The upper surface of the solid under test is the side closer to the ultrasonic phased array, and the lower surface of the solid under test is the side farther away from the ultrasonic phased array. Any two of the at least two ultrasonic beams have an emission angle between them, and the any two ultrasonic beams include a first ultrasonic beam and a second ultrasonic beam. Using an autocorrelation algorithm, a first reflected echo time difference corresponding to the first ultrasonic beam is obtained based on the first ultrasonic beam emitted into the seawater. The first reflected echo time difference includes the first propagation time of the first ultrasonic beam in the seawater and the second propagation time in the solid under test. Using the autocorrelation algorithm, a second reflected echo time difference corresponding to the second ultrasonic beam is obtained based on the second ultrasonic beam emitted into the seawater, wherein the second reflected echo time difference includes the third propagation time of the second ultrasonic beam in the seawater and the fourth propagation time in the solid under test. Based on the first propagation time, the third propagation time, and the emission angle, determine the first angle after the first ultrasonic beam reaches the upper surface of the solid to be tested; Based on the first angle and the emission angle, determine the second angle after the second ultrasonic beam reaches the upper surface of the solid to be tested; Based on a genetic algorithm, the sound speed of the solid under test in the seawater is determined according to the second propagation time, the fourth propagation time, the first angle, and the second angle. The thickness of the solid under test is determined based on the sound velocity value of the solid under test in the seawater, the second propagation time, and the first angle, thereby obtaining the thicknesses of multiple solids under test. The target thickness of the solid to be tested is obtained based on the thickness of the plurality of solids to be tested.

2. The method according to claim 1, wherein, The ultrasonic phased array includes multiple array elements, and the emission angle between any two ultrasonic beams is achieved by adjusting the excitation time of the multiple array elements of the ultrasonic phased array.

3. The method according to claim 1, wherein, The step of using an autocorrelation algorithm to obtain the first reflected echo time difference corresponding to the first ultrasonic beam emitted into the seawater includes: The system collects the first transmitted wave signal of the first ultrasonic beam emitted into the seawater, the first reflected echo signal after the first ultrasonic beam reaches the upper surface of the solid under test, and the reflected echo signal after the first ultrasonic beam passes through the upper surface of the solid under test and reaches the lower surface of the solid under test. Based on the autocorrelation algorithm, the first propagation time of the first ultrasonic beam in the seawater is determined using the first transmitted wave signal and the first reflected echo signal; the second propagation time of the first ultrasonic beam in the solid under test is determined using the first reflected echo signal and the reflected echo signal after the first ultrasonic beam passes through the upper surface of the solid under test and reaches the lower surface of the solid under test. Based on the first propagation time and the second propagation time, the first reflected echo time difference corresponding to the first ultrasonic beam is obtained.

4. The method according to claim 1, further comprising: Determine the preset sound velocity range of the solid to be tested in the seawater that needs to be configured; Based on the preset sound velocity range of the solid to be tested in the seawater, the initial population of the genetic algorithm is determined. The initial population includes a preset number of preset sound velocity values, and each preset sound velocity value serves as an individual of the genetic algorithm.

5. The method according to claim 4, wherein, The determination of the sound velocity of the solid under test in seawater based on the genetic algorithm, according to the second propagation time, the fourth propagation time, the first angle, and the second angle, includes: The genetic algorithm parameters are set, including the initial population size, the preset number of iterations N, the selection rate, the crossover rate, and the mutation rate. For the i-th iteration, based on the genetic algorithm parameters, and according to the second propagation time, the fourth propagation time, the first angle, and the second angle, the fitness function value of each individual in the (i-1)-th round is determined; Based on the fitness function value of each individual, select the target individual that satisfies the preset fitness function value in the i-th round; Based on the crossover and mutation rules between individuals, after performing crossover and mutation operations on the target individuals in the i-th round, the fitness function value of each individual in the i-th round after the crossover and mutation operations is recalculated to obtain the sound speed value of the solid to be tested in the seawater in the i-th round, where 1≤i≤N-1.

6. The method according to claim 5, wherein, After recalculating the fitness function value of each individual in the i-th round following the crossover and mutation operations, and obtaining the sound velocity value of the solid under test in the seawater in the i-th round, the method further includes: Based on the recalculated fitness function value of the i-th round, after performing selection, crossover, and mutation operations on each individual after the crossover and mutation operations, the fitness function value of each individual after the crossover and mutation operations in the (i+1)-th round is calculated to obtain the sound speed value of the solid to be tested in the seawater in the (i+1)-th round.

7. The method according to claim 6, wherein, The process of determining the thickness of the solid under test based on the sound velocity in the seawater, the second propagation time, and the first angle, thereby obtaining multiple thicknesses of the solid under test, includes: For the sound velocity value of the solid under test in the seawater obtained in the i-th iteration, the thickness of the solid under test in the i-th iteration is determined based on the sound velocity value of the solid under test in the seawater in the i-th iteration, the second propagation time, and the first angle, thus obtaining the thickness of multiple solids under test.

8. The method according to claim 5, wherein, The selection rate is 90%, the crossover rate is 70%, and the mutation rate is 50%.

9. The method according to claim 5, wherein, The method further includes: Encode each individual in the initial population to obtain the target encoded string; After decoding the target encoded string, the fitness function value of each individual is calculated.

10. The method according to claim 1, wherein, The step of obtaining the target thickness of the solid to be tested based on the thicknesses of the plurality of solids to be tested includes: The thicknesses of multiple solids to be measured are summed to obtain the summation result; The target thickness of the solid to be measured is obtained based on the summation result.

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