Fiber optic vector hydrophone and array attitude calibration method and system thereof

Abstract

The present invention provides a method and system for calibrating the attitude of a fiber optic vector hydrophone and its array. The attitude calibration method includes: a sound source transmits a signal and rotates around the fiber optic vector hydrophone; an acoustic energy flow method is used to obtain the azimuth angle θ of the fiber optic vector hydrophone corresponding to the sound source; the X+ axis direction of the fiber optic vector hydrophone is determined based on the obtained azimuth angle; the deviation angle Δθ between the current attitude heading of the hydrophone and the X+ axis direction is determined based on the attitude sensor in the fiber optic vector hydrophone, and the fiber optic vector hydrophone is attitude calibrated so that the X+ axis direction of the fiber optic vector hydrophone coincides with the attitude heading. This solves the problem in the prior art of being unable to ensure that the X+ axis of the fiber optic vector hydrophone is consistent with the heading angle of the attitude sensor during navigation, thereby improving the application capability of the fiber optic vector hydrophone array in target azimuth measurement and the array azimuth estimation accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrophone array attitude calibration, and in particular to a fiber optic vector hydrophone and an array attitude calibration method and system thereof. Background Art

[0002] With the continuous advancement of technology, hydrophones are becoming increasingly important to meet the needs of shore-based station construction, support coastal warning sonar systems, and achieve remote detection and identification. Fiber-optic vector hydrophones utilize highly sensitive fiber-optic coherent detection technology to convert measured signals into optical signals, which are then transmitted via optical fiber to signal processing systems for information extraction. These devices offer numerous advantages, including high sensitivity and ease of multiplexing. Combining multiple fiber-optic vector hydrophones at a specific spacing to form a fiber-optic vector hydrophone array offers excellent array gain.

[0003] Each fiber-optic vector hydrophone in a fiber-optic vector hydrophone array corresponds to an attitude sensor, and the attitude sensor's heading angle is used to correct the vector hydrophone's azimuth estimation angle. Because the vector hydrophones are suspended by springs, the state of each suspended fiber-optic vector hydrophone varies, resulting in azimuth estimation errors. The attitude sensor is installed in a pressure-resistant and watertight sealed cavity. Mechanical structure limits ensure that the heading angle is consistent with the zero-degree direction of the fiber-optic vector hydrophone (i.e., the X+ axis of the fiber-optic vector hydrophone). However, engineering deviations exist during the assembly of the two, resulting in the X+ axis direction of the vector hydrophone and the heading angle direction not completely aligning, leading to inaccurate azimuth estimation. The fiber-optic vector hydrophones in the array are connected by flexible connections. During the actual assembly process, the deviation between the X+ axis direction and the heading angle of each vector hydrophone is not fixed, which weakens the array gain during array azimuth estimation. In severe cases, array azimuth estimation cannot be performed. Based on the sound intensity signals received by the fiber optic vector hydrophone along the X and Y axes, the attitude sensor heading angle is corrected so that the deviation between the vector hydrophone's X+ axis direction and the attitude sensor heading angle is within the error range, thereby achieving the accuracy of each heading sensor in the fiber optic vector hydrophone array and thus improving the array's azimuth estimation accuracy. However, at present, most of the corrections for the heading angle of the attitude sensors in the fiber optic vector hydrophone array are performed on the hydrophones themselves when not in navigation. Therefore, a method that can actually correct the heading angle of the attitude sensors during navigation is urgently needed as an alternative or supplement to achieve the accuracy of each heading sensor in the fiber optic vector hydrophone array and thus improve the array's azimuth estimation accuracy. Summary of the Invention

[0004] The purpose of the present invention is to provide a fiber optic vector hydrophone and its array attitude calibration method and system to solve the problem in the prior art that it is impossible to ensure that the X+ axis of the fiber optic vector hydrophone is consistent with the heading angle of the attitude sensor during navigation, thereby enhancing the application capability of the fiber optic vector hydrophone array in target azimuth measurement and improving the array azimuth estimation accuracy.

[0005] In a first aspect, the present invention provides a method for calibrating an optical fiber vector hydrophone attitude, comprising:

[0006] The sound source transmits a signal and rotates around the fiber optic vector hydrophone;

[0007] The acoustic energy flow method is used to obtain the azimuth angle θ of the sound source corresponding to the optical fiber vector hydrophone;

[0008] Determine the X+ axis direction of the fiber optic vector hydrophone through the obtained azimuth angle;

[0009] The deviation angle Δθ between the current attitude heading of the hydrophone and the X+ axis direction is determined according to the attitude sensor in the fiber optic vector hydrophone, and the fiber optic vector hydrophone is calibrated to make the X+ axis direction of the fiber optic vector hydrophone coincide with the attitude heading.

[0010] Furthermore, before the sound source transmits the signal, the method further includes: placing the optical fiber vector hydrophone vertically in water under far-field conditions.

[0011] Preferably, the fiber optic vector hydrophone is placed vertically by using a counterweight and a float to keep the fiber optic vector hydrophone in a straightened state.

[0012] Preferably, the sound source is rotated around the fiber optic vector hydrophone via a rotating stage.

[0013] Furthermore, the sound source rotates around the fiber optic vector hydrophone at a fixed preset speed.

[0014] Furthermore, the acoustic energy flow method includes:

[0015] According to the received sound source signal information, the fiber optic vector hydrophone estimates the azimuth angle, where the X-axis and Y-axis signals received by the fiber optic vector hydrophone are:

[0016]

[0017] Where s(t) represents the sound intensity at the location of the fiber optic vector hydrophone at time t; v x Indicates the sound intensity signal received on the X-axis; v y represents the sound intensity signal received on the Y axis; θ is the azimuth angle of the sound source signal in the XOY plane of the vector sphere;

[0018] The azimuth angle θ of the sound source signal in the XOY plane of the vector sphere is:

[0019]

[0020] In a second aspect, the present invention provides a method for calibrating an optical fiber vector hydrophone array attitude, comprising:

[0021] The sound source transmits a signal and rotates around the fiber optic vector hydrophone array;

[0022] The acoustic energy flow method is used to obtain the azimuth angle θ of the sound source corresponding to each fiber optic vector hydrophone in the fiber optic vector hydrophone array;

[0023] Determine the X+ axis direction of each fiber optic vector hydrophone using the acquired azimuth angle;

[0024] According to the attitude sensor in each fiber optic vector hydrophone, the deviation angle Δθ between the attitude heading of the current hydrophone and the X+ axis direction is determined, and each fiber optic vector hydrophone is attitude calibrated so that the X+ axis direction of each fiber optic vector hydrophone coincides with the attitude heading.

[0025] Furthermore, the sound source rotates around the optical fiber vector hydrophone array at a fixed preset speed.

[0026] Furthermore, the acoustic energy flow method includes:

[0027] According to the sound source signal information received by each fiber optic vector hydrophone in the fiber optic vector hydrophone array, the azimuth angle of each fiber optic vector hydrophone is estimated. The X-axis and Y-axis signals received by the fiber optic vector hydrophone are:

[0028]

[0029] Where s(t) represents the sound intensity at the location of the fiber optic vector hydrophone at time t; v x Indicates the sound intensity signal received on the X-axis; v y represents the sound intensity signal received on the Y axis; θ is the azimuth angle of the sound source signal in the XOY plane of the vector sphere;

[0030] The azimuth angle θ of the sound source signal in the XOY plane of the vector sphere is:

[0031]

[0032] In a third aspect, the present invention provides a fiber optic vector hydrophone array attitude calibration system, comprising: a sound source signal transmitting module, a sound source signal receiving module, a data processing module, and an attitude calibration module;

[0033] Sound source signal transmitting module: used for transmitting sound source signals and rotating around the fiber optic vector hydrophone array at a preset speed;

[0034] Sound source signal acquisition module: used to obtain the sound source signal received by each fiber optic vector hydrophone in the fiber optic vector hydrophone array and send it to the data processing module;

[0035] The data processing module is used to receive the sound source signal sent by the sound source signal acquisition module and use the acoustic energy flow method to obtain the azimuth angle of each fiber optic vector hydrophone in the fiber optic vector hydrophone array corresponding to the sound source; determine the X+ axis direction of each fiber optic vector hydrophone based on all the obtained azimuth angles; and determine the deviation angle between the current attitude and heading of the hydrophone and its corresponding X+ axis direction based on the attitude sensor in each fiber optic vector hydrophone;

[0036] Attitude calibration module: used to calibrate the attitude of each fiber optic vector hydrophone in the fiber optic vector hydrophone array so that the X+ axis direction of each fiber optic vector hydrophone in the array coincides with the attitude heading.

[0037] Beneficial effects

[0038] The present invention provides a fiber-optic vector hydrophone and array attitude calibration method and system. Under far-field conditions, the fiber-optic vector hydrophones are placed vertically in water. A sound source transmits a broadband signal and rotates around each fiber-optic vector hydrophone. Using the acoustic energy flow method, the X+ axis orientation of each fiber-optic vector hydrophone is determined. Simultaneously, based on the heading angle of the attitude sensor, the deviation angle between the X+ axis of the fiber-optic vector hydrophone and the heading angle of the attitude sensor is calculated. This deviation angle is then calibrated to align the X+ axis orientation of the fiber-optic vector hydrophone with the heading of the attitude sensor. Testing in water ensures that the fiber-optic vector hydrophone can be calibrated even while underway.

[0039] The fiber optic vector hydrophones in the fiber optic vector hydrophone array are connected by flexible connections. During the actual assembly process, the deviation between the X+ axis direction and the attitude heading of each fiber optic vector hydrophone in the array is not a fixed value. The calibration method provided by the present invention can ensure that the X+ axis direction of each fiber optic vector hydrophone in the array coincides with the attitude sensor heading, ensuring efficient utilization of the array gain. The larger the array scale, the more consistency can be achieved in the array attitude by performing attitude calibration on each fiber optic vector hydrophone in the array. The greater the array gain, the larger the range of the array's target azimuth estimation and the higher the accuracy, thereby promoting the large-scale application of fiber optic vector hydrophone arrays. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 Schematic diagram of the calibration structure of the optical fiber vector hydrophone provided by the present invention;

[0042] Figure 2 This is a diagram of the azimuth estimation of the optical fiber vector hydrophone array provided by the present invention.

[0043] In the figure: 1-fiber optic vector hydrophone; 2-attitude sensor; 3-attitude heading; 4-X+ axis direction of fiber optic vector hydrophone; 5-XOY plane of vector sphere; 6-sound source; 7-fiber optic vector hydrophone array. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] Fiber optic vector hydrophone 1 Figure 1 As shown, an attitude sensor 2 is provided on the top of the fiber optic vector hydrophone 1, and the direction of the arrow in the attitude sensor 2 represents the attitude heading 3; a vector sphere is provided in the middle of the fiber optic vector hydrophone 1, and a vector sphere XOY plane 5 is provided inside the vector sphere, wherein the dotted line in the vector sphere XOY plane 5 represents the X-axis and Y-axis of the fiber optic vector hydrophone 1, and the direction of the solid arrow represents the X+ axis direction 4 of the fiber optic vector hydrophone.

[0047] like Figure 1-2 As shown in the figure, this case provides a method for calibrating the attitude of a fiber optic vector hydrophone, which includes:

[0048] Step 1: Under far-field conditions, the fiber optic vector hydrophone 1 is placed vertically in water and is kept in a straightened state by using a counterweight and a float.

[0049] Step 2: Set up a rotating platform so that the sound source 6 can rotate around the fiber optic vector hydrophone 1, and the distance between the sound source 6 and the fiber optic vector hydrophone 1 remains unchanged.

[0050] Step 3: The sound source 6 transmits a broadband signal and rotates around the fiber optic vector hydrophone 1 for one revolution, wherein the duration of one revolution is about 1 minute;

[0051] Step 4: Using the acoustic energy flow method, obtain the azimuth angle θ of the sound source 6 corresponding to the optical fiber vector hydrophone 1;

[0052] The acoustic energy flow method comprises:

[0053] According to the sound source signal information received by the optical fiber vector hydrophone 1, the optical fiber vector hydrophone 1 estimates the azimuth angle of the sound source 6, wherein the X-axis and Y-axis signals received by the optical fiber vector hydrophone 1 are:

[0054]

[0055] Where s(t) represents the sound intensity at the location of the optical fiber vector hydrophone 1 at time t; v x Indicates the sound intensity signal received on the X-axis; v y represents the sound intensity signal received on the Y axis; θ is the azimuth angle of the sound source signal in the XOY plane 5 of the vector sphere;

[0056] The azimuth angle θ of the sound source signal in the vector sphere XOY plane 5 is:

[0057]

[0058] Step 5: Determine the X+ axis direction 4 of the fiber optic vector hydrophone using the obtained azimuth angle. By obtaining the azimuth angle of the sound source 6 after one rotation, the position of the sound source 6 when the azimuth angle is zero degrees is determined, i.e., the X+ axis direction 4 of the fiber optic vector hydrophone.

[0059] Step 6: Determine the deviation angle Δθ between the current attitude heading 3 of the hydrophone and the X+ axis direction based on the attitude sensor 2 in the fiber optic vector hydrophone 1. Perform attitude calibration on the fiber optic vector hydrophone 1 so that the X+ axis direction 4 of the fiber optic vector hydrophone coincides with the attitude heading 3. The deviation angle Δθ is the azimuth angle measured by the fiber optic vector hydrophone 1 when the sound source 6 is rotated to a position where the attitude sensor heading angle is 0 degrees.

[0060] Example 2

[0061] like Figure 1-2As shown, this case provides a method for calibrating the attitude of a fiber optic vector hydrophone array. The method of Example 1 is used to perform attitude calibration on each fiber optic vector hydrophone 1 in a fiber optic vector hydrophone array 7, so that the X+ axis direction 4 of each fiber optic vector hydrophone in the array coincides with the attitude heading 3. The calibration method of Example 2 differs from that of Example 1 in that the light source 6 rotates around the entire fiber optic vector hydrophone array 7 at a fixed preset speed. The fiber optic vector hydrophone array 7 is composed of a plurality of fiber optic vector hydrophones 1 arranged in a row, and the number of fiber optic vector hydrophones 1 in the fiber optic vector hydrophone array 7 can be set according to actual needs. Figure 2 This is an example of a fiber optic vector hydrophone array 7 consisting of 16 fiber optic vector hydrophones 1. When the posture of each fiber optic vector hydrophone 1 in the array is highly consistent, the greater the array gain, the larger the range of the array's target direction estimation and the higher the accuracy.

[0062] Example 3

[0063] like Figure 1-2 As shown, this case provides a fiber optic vector hydrophone array attitude calibration system, including: a sound source signal transmitting module, a sound source signal receiving module, a data processing module, and an attitude calibration module;

[0064] Sound source signal transmitting module: used for the sound source 6 to transmit broadband signals and rotate around the fiber optic vector hydrophone array 7 at a preset speed, with one rotation lasting 1 minute;

[0065] Sound source signal acquisition module: used to acquire the sound source signal received by each fiber optic vector hydrophone 1 in the fiber optic vector hydrophone array 7 and send it to the data processing module;

[0066] The data processing module is used to receive the sound source signal sent by the sound source signal acquisition module and use the acoustic energy flow method to obtain the azimuth angle of each fiber optic vector hydrophone 1 in the fiber optic vector hydrophone array 7 corresponding to the sound source; determine the X+ axis direction 4 of each fiber optic vector hydrophone based on all the obtained azimuth angles; and determine the deviation angle between the attitude heading 3 of the current hydrophone and its corresponding X+ axis direction based on the attitude sensor 2 in each fiber optic vector hydrophone 1;

[0067] Attitude calibration module: used to calibrate the attitude of each fiber optic vector hydrophone 1 in the fiber optic vector hydrophone array 7 so that the X+ axis direction 4 of each fiber optic vector hydrophone in the array coincides with the attitude heading 3.

[0068] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for calibrating the attitude of a fiber optic vector hydrophone, characterized in that: include: The sound source transmits a signal and rotates around the fiber optic vector hydrophone once; wherein the sound source rotates around the fiber optic vector hydrophone via a rotating platform, and the distance between the sound source and the fiber optic vector hydrophone remains unchanged; The acoustic energy flow method is used to obtain the azimuth angle of the fiber optic vector hydrophone corresponding to the sound source ; Determine the X+ axis direction of the fiber optic vector hydrophone using the acquired azimuth angle; Determine the current attitude heading of the hydrophone and the deviation angle of the X+ axis direction according to the attitude sensor in the fiber optic vector hydrophone , perform attitude calibration on the fiber optic vector hydrophone so that the X+ axis direction of the fiber optic vector hydrophone coincides with the attitude heading.

2. The method for calibrating the attitude of a fiber optic vector hydrophone according to claim 1, wherein: Before the sound source transmits a signal, the method further includes: Under far-field conditions, the fiber optic vector hydrophone is placed vertically in water.

3. The method for calibrating the attitude of a fiber optic vector hydrophone according to claim 2, wherein: The fiber optic vector hydrophone is placed vertically so that the fiber optic vector hydrophone is in a straightened state through a counterweight and a float.

4. The method for calibrating the attitude of a fiber optic vector hydrophone according to claim 1, wherein: The sound source rotates around the fiber optic vector hydrophone at a fixed preset speed.

5. The method for calibrating the attitude of a fiber optic vector hydrophone according to claim 1, wherein: The acoustic energy flow method comprises: According to the received sound source signal information, the fiber optic vector hydrophone estimates the azimuth angle, where the X-axis and Y-axis signals received by the fiber optic vector hydrophone are: ； Where s(t) represents the sound intensity at the location of the fiber optic vector hydrophone at time t; v x Indicates the sound intensity signal received on the X-axis; v y Indicates the sound intensity signal received on the Y axis; is the azimuth of the sound source signal in the XOY plane of the vector sphere; Azimuth of the sound source signal in the XOY plane of the vector sphere for: 。 6. A method for calibrating an optical fiber vector hydrophone array attitude, characterized in that: include: The sound source transmits a signal and rotates around the fiber optic vector hydrophone array for one revolution; wherein the sound source rotates around the fiber optic vector hydrophone via a rotating platform, and the distance between the sound source and the fiber optic vector hydrophone remains unchanged; The acoustic energy flow method is used to obtain the azimuth angle of the sound source corresponding to each fiber optic vector hydrophone in the fiber optic vector hydrophone array. ; Determine the X+ axis direction of each fiber optic vector hydrophone using the acquired azimuth angle; Determine the current attitude heading of the hydrophone and the deviation angle of the X+ axis direction according to the attitude sensor in each fiber optic vector hydrophone , perform attitude calibration on each fiber optic vector hydrophone so that the X+ axis direction of each fiber optic vector hydrophone coincides with the attitude heading.

7. The method for calibrating the attitude of a fiber optic vector hydrophone array according to claim 6, wherein: The acoustic energy flow method comprises: According to the sound source signal information received by each fiber optic vector hydrophone in the fiber optic vector hydrophone array, the azimuth angle of each fiber optic vector hydrophone is estimated. The X-axis and Y-axis signals received by the fiber optic vector hydrophone are: ； Where s(t) represents the sound intensity at the location of the fiber optic vector hydrophone at time t; v x Indicates the sound intensity signal received on the X-axis; v y Indicates the sound intensity signal received on the Y axis; is the azimuth of the sound source signal in the XOY plane of the vector sphere; Azimuth of the sound source signal in the XOY plane of the vector sphere for: 。 8. A fiber optic vector hydrophone array attitude calibration system, characterized in that: include: Sound source signal transmitting module, sound source signal receiving module, data processing module, attitude calibration module; Sound source signal transmitting module: used for transmitting a sound source signal and rotating around the fiber optic vector hydrophone array at a preset speed; wherein the sound source rotates around the fiber optic vector hydrophone via a rotating platform, and the distance between the sound source and the fiber optic vector hydrophone remains unchanged; Sound source signal acquisition module: used to obtain the sound source signal received by each fiber optic vector hydrophone in the fiber optic vector hydrophone array and send it to the data processing module; The data processing module is used to receive the sound source signal sent by the sound source signal acquisition module and use the acoustic energy flow method to obtain the azimuth angle of each fiber optic vector hydrophone in the fiber optic vector hydrophone array corresponding to the sound source; determine the X+ axis direction of each fiber optic vector hydrophone based on all the obtained azimuth angles; and determine the deviation angle between the current attitude and heading of the hydrophone and its corresponding X+ axis direction based on the attitude sensor in each fiber optic vector hydrophone; Attitude calibration module: used to calibrate the attitude of each fiber optic vector hydrophone in the fiber optic vector hydrophone array so that the X+ axis direction of each fiber optic vector hydrophone in the array coincides with the attitude heading.

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