Clock asynchronous inverse ultra-short baseline passive positioning method and system for unmanned underwater vehicle

Abstract

The invention relates to the technical field of underwater positioning of unmanned underwater vehicles, in particular to a clock asynchronous inverse ultra-short baseline passive positioning method and system for an unmanned underwater vehicle. The method comprises the following steps: firstly, calculating a beam incident angle and a horizontal azimuth angle by using attitude information provided by an inertial sensor carried on the unmanned underwater vehicle and direction information measured by an inverse ultra-short baseline (iUSBL) positioning system; converting data acquired in the diving process of the unmanned underwater vehicle into sound velocity profile data of the water area by using a sound velocity empirical formula; secondly, reversely tracking a sound wave propagation path by using a sound ray tracking algorithm on the basis of a beam incident angle, the depth of the unmanned underwater vehicle and sound velocity profile data, and calculating a horizontal distance between a sound source and the unmanned underwater vehicle; calculating a plane coordinate increment by using the horizontal azimuth angle and the horizontal distance; and finally, calculating the three-dimensional coordinate of the unmanned underwater vehicle by using the known sound source position and coordinate increment. According to the invention, the dependence of an iUSBL passive positioning technology on clock synchronization can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater positioning of unmanned underwater vehicles, and in particular to a clock asynchronous inverse ultra-short baseline passive positioning method and system for unmanned underwater vehicles. Background Art

[0002] At present, the underwater positioning of unmanned underwater vehicles (hereinafter referred to as UUVs) mainly adopts inertial navigation (INS) / Doppler odometer (DVL) combined navigation technology and hydroacoustic positioning technology. Among them, the error of INS / DVL combined navigation diverges over time, so it is not suitable for long-endurance UUVs. Traditional hydroacoustic positioning technologies mainly include long baseline (LBL), short baseline (SBL), and ultra-short baseline (USBL). As the military use of UUVs continues to become more prominent, single beacon navigation and positioning technology, inverse ultra-short baseline (iUSBL) positioning technology, etc. have become hot research directions in the field of underwater navigation and positioning in recent years. Among them, iUSBL positioning technology is similar to USBL positioning technology, and also has ranging and direction finding capabilities. Only single epoch observation data can achieve positioning. The difference is that it installs the acoustic transceiver on the UUV (or other underwater platform) that needs to be positioned, and the transponder is deployed on the seabed or surface buoys. When the transponder of the iUSBL positioning system is deployed on the seabed, the coordinates of the transponder need to be calibrated in advance, which requires high construction and maintenance costs and is easy to be discovered and destroyed by the enemy; when the transponder of the iUSBL positioning system is deployed on the sea surface buoy, its coordinates can be obtained in real time through GNSS positioning. Although it is still easy to be discovered and destroyed, its deployment is flexible and convenient, the maintenance cost is low, and it can be replenished in time. The iUSBL positioning technology in the response mode requires the UUV to actively transmit the interrogation signal, which increases the risk of UUV exposure, especially for military UUV. In recent years, the iUSBL passive positioning system based on clock synchronization has emerged, which can achieve passive positioning without transmitting signals to the outside, ensuring the concealment of UUV. However, long-term clock synchronization requires high-precision clock maintenance, which increases the manufacturing cost and volume of UUV, while low-precision clocks are not suitable for long-endurance UUVs. Summary of the invention

[0003] The present invention aims to solve the problem that the long-term clock synchronization of the iUSBL passive positioning system based on clock synchronization requires high-precision clock maintenance, which increases the manufacturing cost and volume of the UUV. A clock asynchronous inverse ultra-short baseline passive positioning method and system for unmanned underwater vehicles are proposed to provide method support for realizing a low-cost, small-volume, and highly concealed iUSBL passive underwater positioning system, so as to better serve the underwater covert activities of long-endurance UUVs and avoid the dependence of the iUSBL passive positioning technology on clock synchronization.

[0004] To achieve the above purpose, the technical solution adopted is:

[0005] A clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle comprises the following steps:

[0006] Firstly, the beam incidence angle and horizontal azimuth are calculated using the attitude information provided by the inertial sensor on the unmanned underwater vehicle and the direction information measured by the inverse ultra-short baseline positioning system.

[0007] Then, the data collected by the unmanned underwater vehicle during the dive is converted into the sound speed profile data of the water area using the sound speed empirical formula;

[0008] Then, based on the beam incident angle, the depth of the unmanned underwater vehicle and the sound velocity profile data, the sound wave propagation path is reversely tracked using the sound ray tracking algorithm to calculate the horizontal distance between the sound source and the unmanned underwater vehicle;

[0009] Then the plane coordinate increment is calculated using the horizontal azimuth and horizontal distance;

[0010] Finally, the three-dimensional coordinates of the unmanned underwater vehicle are calculated using the known sound source position and coordinate increments.

[0011] According to the clock asynchronous inverse ultra-short baseline passive positioning method for unmanned underwater vehicles of the present invention, further, when calculating the beam incidence angle and the horizontal azimuth angle, it is necessary to first obtain the direction vector observed by the inverse ultra-short baseline positioning system in the navigation coordinate system:

[0012] According to the direction information collected by the inverse ultra-short baseline positioning system and the attitude information provided by the inertial sensor, the direction vector observed by the inverse ultra-short baseline positioning system is converted from its own carrier coordinate system to the navigation coordinate system. The calculation formula is as follows:

[0013]

[0014] Where a represents the direction vector measured by iUSBL; C is the rotation matrix composed of the attitude information provided by IMU; the subscripts n and v represent the navigation coordinate system and the iUSBL carrier coordinate system respectively; η,κ represent the yaw angle, pitch angle and roll angle respectively.

[0015] According to the clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle of the present invention, further, the incident angle and horizontal azimuth angle of the receiving beam of the unmanned underwater vehicle are calculated, and the calculation formula is:

[0016] θ=arccos(||a(1:2)|| / ||a||)

[0017] α=arctan(a(2) / a(1))

[0018] Where θ represents the incident angle of the receiving beam of the unmanned underwater vehicle, α represents the horizontal azimuth of the receiving beam of the unmanned underwater vehicle, ||·|| represents the modulus of the vector, a(1:2) represents the first two dimensions of the intercepted vector, and a(i) represents the i-th element of the extracted vector.

[0019] According to the clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle of the present invention, further, the temperature, salinity and static pressure data collected during the diving of the unmanned underwater vehicle are converted into sound speed profile data of the water area using an empirical formula for the speed of sound.

[0020] According to the clock asynchronous inverse ultra-short baseline passive positioning method for unmanned underwater vehicles of the present invention, further, the plane coordinate increment is calculated using the horizontal azimuth and the horizontal distance, and the calculation formula is as follows:

[0021]

[0022] Where ΔX is the increment of the x-direction coordinate, ΔY is the increment of the y-direction coordinate, and D is the horizontal distance between the sound source and the unmanned underwater vehicle.

[0023] According to the clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle of the present invention, further, the three-dimensional coordinates of the unmanned underwater vehicle are calculated using the known sound source position (X, Y, H) and coordinate increments:

[0024]

[0025] In the formula, (X UUV ,Y UUV ,H UUV ) represents the calculated three-dimensional coordinates of the unmanned underwater vehicle.

[0026] According to the clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle of the present invention, further, a depth increment ΔH used in the process of calculating the three-dimensional coordinates of the unmanned underwater vehicle is provided by a temperature-salinity-depth sensor or a depth sensor.

[0027] Furthermore, the present invention also provides a clock asynchronous inverse ultra-short baseline passive positioning system for an unmanned underwater vehicle, comprising a beam incident angle horizontal azimuth angle calculation module, a sound velocity profile data acquisition module, a horizontal distance calculation module, a coordinate increment calculation module and a three-dimensional coordinate calculation module, wherein:

[0028] The beam incidence angle and horizontal azimuth angle calculation module is used to calculate the beam incidence angle and horizontal azimuth angle using the attitude information provided by the inertial sensor carried by the unmanned underwater vehicle and the direction information measured by the inverse ultra-short baseline positioning system;

[0029] The sound velocity profile data acquisition module is used to convert the data collected during the diving process of the unmanned underwater vehicle into the sound velocity profile data of the water area using the sound velocity empirical formula;

[0030] The horizontal distance calculation module is used to calculate the horizontal distance between the sound source and the unmanned underwater vehicle by reversely tracking the sound wave propagation path using the sound ray tracking algorithm based on the beam incident angle, the depth of the unmanned underwater vehicle and the sound velocity profile data;

[0031] A coordinate increment calculation module, used for calculating plane coordinate increment using horizontal azimuth and horizontal distance;

[0032] The three-dimensional coordinate calculation module is used to calculate the three-dimensional coordinates of the unmanned underwater vehicle using the known sound source position and coordinate increments.

[0033] The beneficial effects achieved by adopting the above technical solution are:

[0034] UUV underwater navigation and positioning is an essential skill for its underwater activities, and passive underwater positioning can greatly improve the concealment of UUV. The present invention realizes UUV passive underwater positioning based on iUSBL without the need for clock synchronization, makes full use of the IMU and temperature-salinity-depth sensor (CTD) information carried by the UUV, and gives play to the role of the sound velocity profile data collected during the UUV dive. The use of the sound ray tracking algorithm to calculate the horizontal distance can weaken the influence of underwater sound velocity changes on positioning accuracy. The present invention provides a new idea for the development of a low-cost, small-volume, lightweight, and highly concealed iUSBL passive positioning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention, wherein the drawings are only used to illustrate some embodiments of the present invention, but not to limit all embodiments of the present invention thereto.

[0036] Figure 1 It is a flow chart of a clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle according to an embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of the horizontal azimuth angle of a receiving beam according to an embodiment of the present invention;

[0038] Figure 3 Schematic diagram of the incident angle of the receiving beam according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings of specific embodiments of the present invention to clearly and completely describe the exemplary scheme of the embodiment of the present invention. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field.

[0040] Under time asynchronous conditions, the iUSBL positioning system can only measure the direction of arrival of the sound waves emitted by the sound source to the receiving array, and cannot obtain ranging information, so it cannot be directly positioned. Considering that UUV underwater activities need to be equipped with temperature, salinity and depth sensors (CTD) to perceive the surrounding water environment information in real time, and inertial sensors (IMU) to obtain their own attitude information in real time to provide data support for its autonomous control. In other words, IMU and CTD are essential sensors for UUV. To this end, a clock asynchronous inverse ultra-short baseline passive positioning method for unmanned underwater vehicles is proposed based on IMU and CTD measurement data. Figure 1 As shown, the following steps are included:

[0041] Step S101, using the attitude information provided by the IMU carried by the UUV and the direction information measured by the iUSBL positioning system to calculate the beam incidence angle and the horizontal azimuth angle.

[0042] According to the direction information collected by the iUSBL positioning system and the attitude information provided by the IMU, the direction vector observed by the iUSBL positioning system is converted from its own carrier coordinate system to the navigation coordinate system (the local horizontal coordinate system is used as the navigation coordinate system). The calculation formula is as follows:

[0043]

[0044] Where a represents the direction vector measured by iUSBL; C is the rotation matrix composed of the attitude information provided by IMU; the subscripts n and v represent the navigation coordinate system and the iUSBL carrier coordinate system, respectively. For example: a v represents the projection vector of a in the v system, Represents the direction cosine matrix from the n system to the v system; η,κ represent the yaw angle, pitch angle and roll angle respectively.

[0045] (2) Figure 2 and Figure 3 As shown, the incident angle and horizontal azimuth of the UUV receiving beam are calculated using the following formula:

[0046] θ=arccos(||a(1:2)|| / ||a||)

[0047] α=arctan(a(2) / a(1))

[0048] Where θ represents the incident angle of the UUV receiving beam, α represents the horizontal azimuth of the UUV receiving beam, ||·|| represents the modulus of the vector, a(1:2) represents the first two dimensions of the intercepted vector, and a(i) represents the i-th element of the extracted vector.

[0049] Step S102: Based on the temperature, salinity and static pressure data collected during the UUV dive, the data are converted into a sound velocity profile using an empirical sound velocity formula and used as a representative sound velocity profile of the water area.

[0050] Step S103: Use the incident angle of the UUV receiving beam, the UUV depth and the sound velocity profile to perform reverse sound ray tracking until the water surface sound source is reached, thereby calculating the horizontal distance D of the UUV relative to the water surface sound source (beacon).

[0051] Step S104: Calculate the plane coordinate increment using the horizontal azimuth angle α and the horizontal distance D. The calculation formula is as follows:

[0052]

[0053] Where ΔX is the increment of the x-coordinate and ΔY is the increment of the y-coordinate.

[0054] Step S105: Calculate the three-dimensional coordinates of the unmanned underwater vehicle using the self-position (X, Y, H) broadcast by the sound source and the coordinate increment:

[0055]

[0056] In the formula, (X UUV ,Y UUV ,H UUV ) represents the calculated three-dimensional coordinates of the UUV, and the depth increment ΔH adopts the output value of the CTD or depth sensor.

[0057] Corresponding to the above method, this embodiment also proposes a clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle, comprising a beam incident angle horizontal azimuth angle calculation module, a sound velocity profile data acquisition module, a horizontal distance calculation module, a coordinate increment calculation module and a three-dimensional coordinate calculation module, wherein:

[0058] The beam incidence angle and horizontal azimuth angle calculation module is used to calculate the beam incidence angle and horizontal azimuth angle using the attitude information provided by the inertial sensor carried on the unmanned underwater vehicle and the direction information measured by the inverse ultra-short baseline positioning system.

[0059] The sound speed profile data acquisition module is used to convert the data collected by the unmanned underwater vehicle during the diving process into the sound speed profile data of the water area using the sound speed empirical formula.

[0060] The horizontal distance calculation module is used to calculate the horizontal distance between the sound source and the unmanned underwater vehicle by reversely tracking the sound wave propagation path based on the beam incident angle, the depth of the unmanned underwater vehicle and the sound speed profile data using the sound ray tracking algorithm.

[0061] The coordinate increment calculation module is used to calculate the plane coordinate increment using the horizontal azimuth and horizontal distance.

[0062] The three-dimensional coordinate calculation module is used to calculate the three-dimensional coordinates of the unmanned underwater vehicle using the known sound source position and coordinate increments.

[0063] The present invention can realize UUV passive underwater positioning based on iUSBL without clock synchronization, so as to better serve the underwater covert activities of long-endurance UUV and avoid the dependence of iUSBL passive positioning technology on clock synchronization.

[0064] Unless otherwise specifically stated, the relative steps, numerical expressions and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0065] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0066] The units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person of ordinary skill in the art may use different methods to implement the described functions for each specific application, but such implementation is not considered to be beyond the scope of the present invention.

[0067] Those skilled in the art will appreciate that all or part of the steps in the above method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, a disk or an optical disk. Optionally, all or part of the steps in the above embodiment can also be implemented using one or more integrated circuits, and accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or in the form of software function modules. The present invention is not limited to any specific form of combination of hardware and software.

[0068] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A clock asynchronous inverse ultra-short baseline passive positioning method for unmanned underwater vehicles, characterized in that: The following steps are involved: Firstly, the beam incidence angle and horizontal azimuth are calculated using the attitude information provided by the inertial sensor on the unmanned underwater vehicle and the direction information measured by the inverse ultra-short baseline positioning system. Then, the data collected by the unmanned underwater vehicle during the dive is converted into the sound speed profile data of the water area using the sound speed empirical formula; Then, based on the beam incident angle, the depth of the unmanned underwater vehicle and the sound velocity profile data, the sound wave propagation path is reversely tracked using the sound ray tracking algorithm to calculate the horizontal distance between the sound source and the unmanned underwater vehicle; Then the plane coordinate increment is calculated using the horizontal azimuth and horizontal distance; Finally, the three-dimensional coordinates of the unmanned underwater vehicle are calculated using the known sound source position and coordinate increments.

2. The clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle according to claim 1, characterized in that: When calculating the beam incidence angle and horizontal azimuth, it is first necessary to obtain the direction vector observed by the inverse ultra-short baseline positioning system in the navigation coordinate system: According to the direction information collected by the inverse ultra-short baseline positioning system and the attitude information provided by the inertial sensor, the direction vector observed by the inverse ultra-short baseline positioning system is converted from its own carrier coordinate system to the navigation coordinate system. The calculation formula is as follows: Where a represents the direction vector measured by iUSBL; C is the rotation matrix composed of the attitude information provided by IMU; the subscripts n and v represent the navigation coordinate system and the iUSBL carrier coordinate system respectively; η,κ represent the yaw angle, pitch angle and roll angle respectively.

3. The clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle according to claim 2, characterized in that: Calculate the incident angle and horizontal azimuth of the receiving beam of the unmanned underwater vehicle. The calculation formula is: θ=arccos(||a(1:2)|| / ||a||) α=arctan(a(2) / a(1)) Where θ represents the incident angle of the receiving beam of the unmanned underwater vehicle, α represents the horizontal azimuth of the receiving beam of the unmanned underwater vehicle, ||·|| represents the modulus of the vector, a(1:2) represents the first two dimensions of the intercepted vector, and a(i) represents the i-th element of the extracted vector.

4. The clock asynchronous inverse ultra-short baseline passive positioning method for unmanned underwater vehicles according to claim 1, characterized in that: The temperature, salinity and static pressure data collected by the unmanned submersible during the dive are converted into sound speed profile data of the water area using the empirical formula of sound speed.

5. The clock asynchronous inverse ultra-short baseline passive positioning method for unmanned underwater vehicles according to claim 3, characterized in that: The plane coordinate increment is calculated using the horizontal azimuth and horizontal distance. The calculation formula is as follows: Where ΔX is the increment of the x-direction coordinate, ΔY is the increment of the y-direction coordinate, and D is the horizontal distance between the sound source and the unmanned underwater vehicle.

6. The clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle according to claim 5, characterized in that: Calculate the three-dimensional coordinates of the unmanned underwater vehicle using the known sound source position (X, Y, H) and coordinate increments: In the formula, (X UUV ,Y UUV ,H UUV ) represents the calculated three-dimensional coordinates of the unmanned underwater vehicle.

7. The clock asynchronous inverse ultra-short baseline passive positioning method for an unmanned underwater vehicle according to claim 6, characterized in that: The depth increment ΔH used in calculating the three-dimensional coordinates of the unmanned underwater vehicle is provided by a temperature-salinity-depth sensor or a depth sensor.

8. A clock asynchronous inverse ultra-short baseline passive positioning system for unmanned underwater vehicles, characterized in that: It includes a beam incident angle horizontal azimuth calculation module, a sound velocity profile data acquisition module, a horizontal distance calculation module, a coordinate increment calculation module and a three-dimensional coordinate calculation module, wherein: The beam incidence angle and horizontal azimuth angle calculation module is used to calculate the beam incidence angle and horizontal azimuth angle using the attitude information provided by the inertial sensor carried by the unmanned underwater vehicle and the direction information measured by the inverse ultra-short baseline positioning system; The sound velocity profile data acquisition module is used to convert the data collected during the diving process of the unmanned underwater vehicle into the sound velocity profile data of the water area using the sound velocity empirical formula; The horizontal distance calculation module is used to calculate the horizontal distance between the sound source and the unmanned underwater vehicle by reversely tracking the sound wave propagation path using the sound ray tracking algorithm based on the beam incident angle, the depth of the unmanned underwater vehicle and the sound velocity profile data; A coordinate increment calculation module, used for calculating plane coordinate increment using horizontal azimuth and horizontal distance; The three-dimensional coordinate calculation module is used to calculate the three-dimensional coordinates of the unmanned underwater vehicle using the known sound source position and coordinate increments.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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