Calibration method for calibrating acoustic device based on differential Beidou

Abstract

The invention provides a calibration method for calibrating an acoustic device based on differential Beidou, and the method comprises the steps: firstly, judging the hydrological grade of a test sea area, so as to stipulate the specific navigation path of a test ship and a matching ship during the test; during a test, the course gamma of the test ship is kept unchanged, the original position is maneuvering, and the matching ship does uniform-speed circumferential sailing around the test ship with the radius of R. In the process, relevant data measured by a test ship Beidou antenna, a matching ship Beidou antenna and a test ship acoustic device are collected, then the real azimuth angle of the matching ship relative to the test ship is obtained through mathematical operation, the measured azimuth angle of the matching ship measured by the acoustic device is combined, the real azimuth angle and the measured azimuth angle are processed according to the statistical principle, and the real azimuth angle is obtained. And respectively calculating a direction finding precision system error, a random error and a second-order origin moment error of the acoustic device, and correcting a measured azimuth angle according to error values to enable the azimuth angle to be fit with a real azimuth angle, so that the direction finding precision calibration of the high-precision acoustic device is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of ship positioning instrument calibration, and in particular to a calibration method based on a differential Beidou calibration acoustic device. Background Art

[0002] The calibration of acoustic devices is an important key test for verifying the performance of acoustic devices during ship sea trials. Based on the application of advanced technologies such as big data processing and intelligent recognition, the detection performance of modern acoustic devices has made significant progress, and the direction-finding accuracy of acoustic devices has been significantly improved. Therefore, the requirements for the calibration of acoustic devices have also increased in adaptability. The traditional acoustic device calibration method uses optical equipment to observe the target to obtain the true value, compares it with the target azimuth value detected by the acoustic device, and calibrates the acoustic device. However, this method is slow in data processing and provides rough benchmark accuracy, which cannot meet the calibration requirements of modern acoustic devices. Therefore, a new set of acoustic device calibration methods needs to be developed. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present invention provides a calibration method for a differential Beidou calibration acoustic device, the calibration method comprising the following steps:

[0004] S1. Determine the current sound speed according to the hydrological conditions of the test sea area;

[0005] S2. Sailing the test ship and the supporting ship to the test sea area, the test ship is equipped with a test ship Beidou antenna and an acoustic device, the acoustic device is located at the front side of the test ship Beidou antenna close to the bow, and the supporting ship is equipped with a supporting ship Beidou antenna;

[0006] S3. The test ship maintains the heading γ unchanged and maneuvers at the original position, and the coordinating ship sails in a uniform circle with a radius of R around the test ship;

[0007] S4. Data Collection

[0008] a. Collecting position information, the Beidou antenna of the test ship and the Beidou antenna of the matching ship are timed to unify the time reference;

[0009] b. Collection of heading and azimuth information: During the test, the acoustic device on the test ship is turned on to collect the azimuth information of the cooperating ship detected by the acoustic device; at the same time, the heading information of the test ship is collected.

[0010] Optionally, the calibration method further comprises step S5, data processing:

[0011] a. Unify the positions and calculate the position between the acoustic device of the test ship and the Beidou antenna of the matching ship.

[0012]

[0013] L——the relative distance between the center of the acoustic device and the Beidou antenna of the test ship;

[0014] R——the relative distance between the BeiDou antenna of the test ship and the BeiDou antenna of the matching ship;

[0015] θ i =|γ-β i |

[0016] γ——the heading angle of the test ship, which is defined as the angle that the bow of the test ship turns clockwise relative to the true north direction;

[0017] βi is the azimuth angle of the Beidou antenna of the test ship and the Beidou antenna of the cooperation ship, which is defined as the angle that the line between the Beidou antenna of the test ship and the Beidou antenna of the cooperation ship rotates relative to the true north direction with the Beidou antenna of the test ship as the origin.

[0018] Optionally, step S5 further includes:

[0019] b. Time unification

[0020]

[0021] Among them, x 1 (t-Δt), y 1 (t-Δt) are the X and Y coordinates of the Beidou antenna of the ship at time t-Δt; 0 (t), y 0 (t) are the X and Y coordinates of the location of the acoustic device on the test ship at time t; Δt is the time it takes for the sound wave to reach the test ship from the matching ship.

[0022] Optionally, step S5 further includes:

[0023] c. Azimuth true value calculation: calculate the relative azimuth angle αi between the center of the test ship's acoustic device and the Beidou antenna of the matching ship. αi is defined as the angle of the line between the test ship's acoustic device and the matching ship's Beidou antenna relative to the bow direction, with the test ship's acoustic device as the origin;

[0024]

[0025] Among them, αi'>0° and αi'+θi<180°; |αi|=π-αi', when the matching ship is located on the left side of the test ship, αi takes a negative value;

[0026] When the matching ship is located on the right side of the test ship, αi takes a negative value;

[0027] Then the true azimuth angle αti of the cooperating ship is calculated; αti is defined as the angle of the line between the acoustic device of the test ship and the Beidou antenna of the cooperating ship rotated in the clockwise direction relative to the true north direction with the acoustic device of the test ship as the origin;

[0028] α ti ={αi+γ+360°}%(360°)

[0029] Among them, 0°≤αti≤360°.

[0030] Optionally, step S5 further includes:

[0031] d. Direction finding accuracy data processing

[0032] The measured azimuth α0i of the matching ship measured by the acoustic device and the calculated true azimuth αti are processed according to statistical principles, and the systematic error, random error and second-order origin moment error of the acoustic device direction finding accuracy are calculated respectively. The measured azimuth is corrected according to the error value to make it fit the true azimuth;

[0033] Systematic error:

[0034] Random Error:

[0035] Second-order origin moment error:

[0036] where Δα i =α 0i -αt i ; N means that the cooperating ship sails to N different locations to collect N sets of data.

[0037] Optionally, the range of the initial distance R between the test ship and the matching ship is:

[0038]

[0039] d——effective aperture of acoustic device;

[0040] S——Theoretical detection distance of acoustic device, related to hydrological conditions and matching ship noise level.

[0041] As described above, the present invention provides a calibration method for an acoustic device based on differential Beidou calibration. The calibration method first uses a portable sound velocity measuring instrument to quickly measure the propagation speed of sound waves at different depths of seawater in the test sea area, and calculates the sound velocity gradient; according to the sound velocity gradient, the hydrological level of the test sea area is determined, and then the specific navigation path of the test ship and the matching ship during the test is specified. During the test, the test ship keeps the heading γ unchanged and maneuvers at the original position, and the matching ship sails around the test ship in a uniform circular manner with a radius of R. During the process, the relevant data measured by the Beidou antenna of the test ship, the Beidou antenna of the matching ship, and the acoustic device of the test ship are collected, and then the true azimuth of the matching ship relative to the test ship is obtained through mathematical calculations, and the measured azimuth of the matching ship measured by the acoustic device is combined. The true azimuth and the measured azimuth are processed according to statistical principles, and the systematic error, random error, and second-order origin moment error of the acoustic device direction finding accuracy are calculated respectively, and the measured azimuth is corrected according to the error value to make it fit the true azimuth, thereby realizing the high-precision acoustic device direction finding accuracy calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Shown is a schematic diagram of the positions of the test ship and the matching ship in Example 1 of the present invention.

[0043] Figure 2 Shown is a schematic diagram of various azimuth angles of the test ship and the matching ship in Example 1 of the present invention.

[0044] Component number description

[0045] 11 Beidou antenna on test ship

[0046] 12 Acoustic Devices

[0047] 21 Cooperate with ship Beidou antenna DETAILED DESCRIPTION

[0048] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0049] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0050] For ease of description, spatial relational terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other directions of the device in use or operation in addition to the directions depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more intervening layers. As used herein, "between..." means including the end point values.

[0051] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0052] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0053] Embodiment 1

[0054] like Figure 1 to Figure 2 As shown, this embodiment provides a calibration method for an acoustic device based on differential Beidou calibration, comprising the following steps:

[0055] S1. Determine the current sound speed based on the hydrological conditions of the test sea area.

[0056] According to the principles of hydroacoustics, the sound velocity profile refers to the change of sound speed with depth, which has a great influence on the propagation of sound waves in seawater. The paths of sound lines with different sound velocity profiles are different. Therefore, it is necessary to measure the sound velocity profile to better understand the different paths of sound lines.

[0057] Under good hydrological conditions, sound waves propagate over long distances; under medium hydrological conditions, the propagation distance is average; under severe hydrological conditions, the propagation effect is poor and the distance is short. Based on the propagation speed of sound in seawater, the hydrological conditions in shallow sea conditions are divided into isonic type, weak negative gradient type, and strong jump layer type. Among them, the isonic type belongs to good hydrological conditions, the weak negative gradient type belongs to medium hydrological conditions, and the strong jump type belongs to severe hydrological conditions.

[0058] The empirical formula for the speed of sound in seawater is as follows:

[0059] c=1450+4.2T-0.037T 2+1.14(S-35)+0.018H

[0060] Where T is temperature (℃); S is salinity (0.1%); H is depth (m). It can be seen that the speed of sound is a function related to depth, temperature and salinity.

[0061]

[0062] Before the acoustic device calibration test, it is necessary to measure the propagation speed of sound waves at different depths in the test sea area to determine the hydrological conditions.

[0063] When measuring the sound velocity, a portable sound velocity meter can be used on the test ship or the supporting ship to quickly measure the propagation speed of sound waves in the seawater in the test sea area. When in use, the sound velocity meter is slowly lowered into the water. During the sinking process, the sound velocity meter continuously measures the sound velocity and the corresponding water depth, and obtains a curve of the sound velocity at the measurement point changing with the depth, forming an ocean sound velocity profile, and then calculating the sound velocity attenuation gradient to determine the hydrological conditions.

[0064] S2. Sailing the test ship and the cooperating ship to the test sea area, the test ship is equipped with the test ship Beidou antenna 11 and the acoustic device 12, the acoustic device 11 is located at the front side of the test ship Beidou antenna 11 close to the bow, and the cooperating ship is equipped with the cooperating ship Beidou antenna 21.

[0065] S3. The propagation distance of sound waves varies under different hydrological conditions, which determines that the detection distance of acoustic devices is attenuated under different hydrological conditions. To ensure the calibration effect of the acoustic device, it must be carried out in an open far-field condition. The test ship maintains the same heading γ and maneuvers at the original position, and the supporting ship sails around the test ship in a uniform circular motion with a radius of R. The initial distance R between the test ship and the supporting ship should meet the following requirements:

[0066]

[0067] d——effective aperture of acoustic device;

[0068] S——Theoretical detection distance of acoustic device, which is related to hydrological conditions and the noise level of the matching ship.

[0069] A variety of routes can be set before the test. According to the sound speed measurement results and after determining the hydrological conditions, the appropriate navigation radius and navigation path can be selected.

[0070] S4. Data Collection

[0071] a. Location information collection

[0072] The Beidou antenna of the test ship is calibrated with the Beidou antenna of the cooperating ship to unify the time base. The Beidou antenna of the test ship is used to obtain the position information of the test ship; the Beidou antenna of the cooperating ship is used to obtain the position information of the cooperating ship.

[0073] b. Heading and azimuth information collection

[0074] During the test, the acoustic device on the test ship was turned on to collect the azimuth information of the cooperating ship detected by the acoustic device; at the same time, the heading information of the test ship was collected.

[0075] S5. Data processing

[0076] a. Unified location

[0077] The use of Beidou Beidou antenna in conjunction with GPS can measure the position and orientation between the test ship and the matching ship with high precision. However, there is a distance between the acoustic device on the test ship and the installation position of the Beidou antenna. In order to reduce the system error, the installation position of the acoustic device and the Beidou antenna needs to be unified, and the position a between the acoustic device of the test ship and the Beidou antenna of the matching ship needs to be calculated.

[0078]

[0079] L——Relative distance between the center of the acoustic device and the Beidou antenna of the test ship (m);

[0080] R——The satellite positioning distance between the Beidou antenna of the test ship and the Beidou antenna of the matching ship, measured by the Beidou antenna.

[0081] in:

[0082] θ i =|γ-β i |

[0083] γ——the heading angle of the test ship (°), that is, the angle that the bow of the test ship turns clockwise relative to the true north direction;

[0084] βi is the azimuth angle of the Beidou antenna of the test ship and the Beidou antenna of the matching ship, which is defined as the angle that the line between the Beidou antenna of the test ship and the Beidou antenna of the matching ship rotates relative to the true north direction with the Beidou antenna of the test ship as the origin, and is measured by the Beidou antenna.

[0085] b. Time unification

[0086] During the test, the distance between the test ship and the supporting ship was greater than that under far-field test conditions, but the propagation speed of sound waves in seawater is about 1450m / s, so it takes several seconds for the noise of the supporting ship to propagate to the vicinity of the test ship, with an obvious time delay. In order to improve the calibration accuracy, the sound wave propagation time correction is performed based on the measured sound speed information in the test sea area, which is used to uniformly correct the relative distance R between the Beidou antenna of the supporting ship and the Beidou antenna of the test ship at the same time, and then converted into the relative distance a between the acoustic device of the test ship and the Beidou antenna of the supporting ship as the true value of the acoustic device calibration.

[0087]

[0088] Among them, x 1 (t-Δt), y 1 (t-Δt) are the X and Y coordinates of the position of the Beidou antenna of the ship at time t-Δt; 0 (t), y 0 (t) are the X and Y coordinates of the location of the acoustic device on the test ship at time t. Δt is the time taken for the sound wave to reach the test ship from the matching ship, which can be obtained by R / the speed of sound in seawater.

[0089] c. Calculation of true position value

[0090] After unifying the time position and correcting the time, the relative azimuth angle αi between the center of the test ship's acoustic device and the Beidou antenna of the cooperating ship can be accurately calculated. αi is defined as the angle that the line between the test ship's acoustic device and the cooperating ship's Beidou antenna rotates relative to the test ship's navigation direction (bow direction) with the test ship's acoustic device as the origin; when the cooperating ship is located on the left side of the test ship, αi takes a negative value; when the cooperating ship is located on the right side of the test ship, αi takes a negative value.

[0091]

[0092] Among them, αi'>0° and αi'+θi<180°; |αi|=π-αi', when the matching ship is located on the left side of the test ship, αi takes a negative value; when the matching ship is located on the right side of the test ship, αi takes a negative value.

[0093] Then, according to the heading information of the test ship collected during the test, the true azimuth αti of the cooperating ship is calculated; αti is defined as the angle of the line between the test ship acoustic device and the cooperating ship Beidou antenna rotated in the clockwise direction relative to the true north direction with the test ship acoustic device as the origin; 0°≤αti≤360°.

[0094] α ti ={αi+γ+360°}%(360°)

[0095] d. Direction finding accuracy data processing

[0096] The measured azimuth angle α0i of the cooperating ship measured by the acoustic device (the angle definition of α0i is the same as the angle definition of αti, the difference is that one is the measured value and the other is the true value) and the calculated true azimuth angle αti are processed according to statistical principles, and the systematic error, random error and second-order origin moment error of the acoustic device direction finding accuracy are calculated respectively.

[0097] Systematic error:

[0098] Random Error:

[0099] Second-order origin moment error:

[0100] where Δα i =α 0i -α ti ; N means the cooperating ships sail to N different locations.

[0101] Through this method, the ship's Beidou and differential Beidou are jointly used for high-precision data collection, the position information is unified and the time delay is eliminated to reduce the system error. On the basis of large-scale data processing, the high-precision acoustic device direction finding accuracy calibration is achieved.

[0102] In summary, the present invention provides a calibration method for an acoustic device based on differential Beidou calibration. The calibration method first uses a portable sound velocity measuring instrument to quickly measure the propagation speed of sound waves at different depths of seawater in the test sea area, and calculates the sound velocity gradient; according to the sound velocity gradient, the hydrological level of the test sea area is determined, and then the specific navigation paths of the test ship and the matching ship during the test are specified. During the test, the test ship keeps the heading γ unchanged and maneuvers at the original position, and the matching ship sails around the test ship in a uniform circular manner with a radius of R. During the process, the relevant data measured by the Beidou antenna of the test ship, the Beidou antenna of the matching ship, and the acoustic device of the test ship are collected, and then the true azimuth of the matching ship relative to the test ship is obtained through mathematical calculations, and the measured azimuth of the matching ship measured by the acoustic device is combined. The true azimuth and the measured azimuth are processed according to statistical principles, and the systematic error, random error, and second-order origin moment error of the acoustic device direction finding accuracy are calculated respectively, and the measured azimuth is corrected according to the error value to make it fit the true azimuth, thereby realizing the high-precision acoustic device direction finding accuracy calibration.

[0103] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A calibration method for an acoustic device based on differential Beidou calibration, characterized in that: The calibration method comprises the following steps: S1. Determine the current sound speed according to the hydrological conditions of the test sea area; S2. Sailing the test ship and the supporting ship to the test sea area, the test ship is equipped with a test ship Beidou antenna and an acoustic device, the acoustic device is located at the front side of the test ship Beidou antenna close to the bow, and the supporting ship is equipped with a supporting ship Beidou antenna; S3. The test ship maintains the heading γ unchanged and maneuvers at the original position, and the coordinating ship sails in a uniform circle with a radius of R around the test ship; S4. Data Collection a. Collecting position information, the Beidou antenna of the test ship and the Beidou antenna of the matching ship are timed to unify the time reference; b. Collection of heading and azimuth information: During the test, the acoustic device on the test ship is turned on to collect the azimuth information of the cooperating ship detected by the acoustic device; at the same time, the heading information of the test ship is collected.

2. The calibration method based on differential Beidou calibration acoustic device according to claim 1, characterized in that: The calibration method further comprises step S5, data processing: a. Unify the positions and calculate the position between the acoustic device of the test ship and the Beidou antenna of the matching ship. L——the relative distance between the center of the acoustic device and the Beidou antenna of the test ship; R——the relative distance between the BeiDou antenna of the test ship and the BeiDou antenna of the matching ship; i i =|γ-β i | γ——the heading angle of the test ship, which is defined as the angle that the bow of the test ship turns clockwise relative to the true north direction; βi is the azimuth angle of the Beidou antenna of the test ship and the Beidou antenna of the cooperation ship, which is defined as the angle that the line between the Beidou antenna of the test ship and the Beidou antenna of the cooperation ship rotates relative to the true north direction with the Beidou antenna of the test ship as the origin.

3. The calibration method based on differential Beidou calibration acoustic device according to claim 2, characterized in that: Step S5 also includes: b. Time unification Among them, x1(t-Δt) and y1(t-Δt) are the X and Y coordinates of the Beidou antenna of the cooperation ship at time t-Δt; x0(t) and y0(t) are the X and Y coordinates of the acoustic device of the test ship at time t; Δt is the time taken for the sound wave to reach the test ship from the cooperation ship.

4. The calibration method based on differential Beidou calibration acoustic device according to claim 3, characterized in that: Step S5 also includes: c. Azimuth true value calculation: calculate the relative azimuth angle αi between the center of the test ship's acoustic device and the Beidou antenna of the matching ship. αi is defined as the angle of the line between the test ship's acoustic device and the matching ship's Beidou antenna relative to the bow direction, with the test ship's acoustic device as the origin; Among them, αi'>0° and αi'+θi<180°; |αi|=π-αi', when the matching ship is located on the left side of the test ship, αi takes a negative value; When the matching ship is located on the right side of the test ship, αi takes a negative value; Then the true azimuth angle αti of the cooperating ship is calculated; αti is defined as the angle of the line between the acoustic device of the test ship and the Beidou antenna of the cooperating ship rotated in the clockwise direction relative to the true north direction with the acoustic device of the test ship as the origin; a ti ={αi+γ+360°}%(360°) Among them, 0°≤αti≤360°.

5. The calibration method based on differential Beidou calibration acoustic device according to claim 4, characterized in that: Step S5 also includes: d. Direction finding accuracy data processing The measured azimuth α0i of the matching ship measured by the acoustic device and the calculated true azimuth αti are processed according to statistical principles, and the systematic error, random error and second-order origin moment error of the acoustic device direction finding accuracy are calculated respectively. The measured azimuth is corrected according to the error value to make it fit the true azimuth; Systematic error: Random Error: Second-order origin moment error: where Δα i =α 0i -α ti ; N means that the cooperating ship sails to N different locations to collect N sets of data.

6. The calibration method based on differential Beidou calibration acoustic device according to claim 1, characterized in that: The range of the initial distance R between the test ship and the matching ship is: d——effective aperture of acoustic device; S——Theoretical detection distance of acoustic device, related to hydrological conditions and matching ship noise level.

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