Position calibration method in bow-shaped operation of AUV (Autonomous Underwater Vehicle) based on one seabed acoustic beacon

Abstract

The invention provides a method for calibrating the position of an AUV (Autonomous Underwater Vehicle) in underwater bow-shaped navigation based on one seabed acoustic beacon, which comprises the following steps: step S101, in an underwater operation area of the AUV or an AUV cluster, laying one seabed acoustic beacon at the central position of the underwater operation area in advance by a test ship or a label-laying AUV, and calibrating the position of the seabed acoustic beacon, so as to calibrate the position of the seabed acoustic beacon; as a position reference; s102, the AUV carries out underwater bow-shaped navigation operation, m groups of underwater sound distance measurement are carried out on the seabed sound beacons before and after the course turns, and underwater sound distance measurement results are stored; and S103, based on the m groups of underwater acoustic ranging results, carrying out correction calculation on the stored m groups of longitudes and latitudes, calculating a position error correction amount, and compensating the position error correction amount to inertial navigation to realize AUV position error calibration. The problems that in the prior art, due to the fact that a USBL is limited by the orientation angle resolution, high-precision underwater acoustic positioning cannot be achieved in a long distance, and an LBL needs to be distributed and calibrated in advance to calibrate the position error of an AUV or an AUV cluster can be solved.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic position calibration, and more particularly to a position calibration method for AUVs navigating in an underwater "bow" shape based on a single seabed acoustic beacon. Background Technology

[0002] Autonomous underwater vehicles (AUVs) are playing an increasingly important role in marine development and national defense due to their numerous advantages, including small size, low operating costs, intelligent autonomous operation, convenient maintenance, and good stealth capabilities. As the application areas of AUVs gradually expand, the requirements for navigation systems are also becoming increasingly demanding.

[0003] Currently, most AUVs use an INS / GPS / DVL integrated navigation system. When AUVs operate underwater for extended periods, navigation errors increase over time, affecting the accuracy of operational results and the AUV's own navigation safety.

[0004] To solve the navigation and positioning problem of AUVs or AUV clusters operating underwater for extended periods, underwater PNT systems are typically used. However, how to achieve position error calibration of AUVs or AUV clusters within the operating area with the minimum number of seabed acoustic beacons has become a challenge. Summary of the Invention

[0005] This invention provides a position calibration method for AUV underwater "bow" shaped navigation based on a single seabed acoustic beacon, which solves the problem in the prior art that USBL is limited by directional angular resolution and cannot achieve high-precision underwater acoustic positioning at long distances, while LBL requires the pre-deployment and calibration of multiple seabed acoustic beacons to achieve position error calibration of AUV or AUV cluster.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] A method for position calibration during underwater "bow"-shaped navigation of an AUV based on a single seabed acoustic beacon, specifically including the following steps: Step S101: In the underwater operation area of ​​the test vessel or buoy AUV, one seabed acoustic beacon is deployed in advance at the center of the underwater operation area, and the position of the seabed acoustic beacon is calibrated as a position reference. Step S102: The AUV performs underwater "bow" shaped navigation operations, and performs m sets of underwater acoustic ranging on the seabed acoustic beacon before and after the course turn, and saves the underwater acoustic ranging results. Step S103: Based on the m sets of underwater acoustic ranging results, the saved m sets of latitude and longitude are corrected and calculated, the position error correction amount is calculated and compensated to the inertial navigation system, and the AUV position error calibration is realized.

[0008] This invention also discloses a position calibration system for implementing the above method, comprising: a high-precision satellite navigation / inertial navigation / Doppler velocimeter integrated navigation system; a high-precision timekeeping device capable of being timed by satellite navigation; an underwater acoustic ranging and underwater acoustic communication system capable of being timed externally and hard-synchronized by a clock; a seabed acoustic beacon with satellite navigation timekeeping, high-precision timekeeping, underwater acoustic response, and underwater acoustic communication functions; and a depth gauge. First, one of the seabed acoustic beacons completes satellite navigation timekeeping on the deck of the test vessel or on shore and is in a high-precision timekeeping state. The seabed acoustic beacon is deployed at the center point of the underwater operation area, and its position is calibrated after it lands on the seabed. The AUV performs underwater "bow"-shaped navigation operations, and performs m underwater acoustic ranging measurements on the seabed acoustic beacon before and after the course turn, and saves the results. Based on the m sets of underwater acoustic ranging results, the corrected latitude and longitude are calculated, the position error correction is calculated and compensated to the inertial navigation system, thereby calibrating the AUV's position error.

[0009] The beneficial effects of this invention are: 1. This invention utilizes an AUV equipped with a high-precision satellite navigation / inertial navigation / Doppler velocimeter combined navigation system. Based on a known seabed acoustic beacon at the center of the operation area, and combined with an "arch"-shaped operation path, underwater acoustic ranging is performed on the known acoustic beacon to complete the calibration of the AUV's own navigation position error. 2. This invention solves the problem of AUV accumulating a certain position error during long-term underwater navigation. It achieves self-position error calibration at a long distance based on a known acoustic beacon deployed in the center of the operation area and its own integrated navigation system, which has high engineering application value. 3. This invention utilizes the high-precision INS / GPS / DVL integrated navigation system configured on the AUV itself, combined with the AUV's "bow"-shaped operation, to achieve long-distance calibration of the AUV's position error by measuring the underwater acoustic distance of a known seabed acoustic beacon at the center of the operation area, thus solving the technical problem of long-distance AUV position error calibration based on a single seabed acoustic beacon. Detailed Implementation

[0010] The present invention will now be described in detail with reference to the embodiments.

[0011] The present invention discloses a position calibration method for AUV underwater "bow"-shaped navigation based on a single seabed acoustic beacon, which specifically includes the following steps: Step S101: In the underwater operation area of ​​the test vessel or buoy AUV, one seabed acoustic beacon is deployed in advance at the center of the underwater operation area, and the position of the seabed acoustic beacon is calibrated as a position reference. In specific implementation, the coordinate system involved in the position reference is defined as follows: System: Inertial measurement unit coordinate system; System: DVL carrier coordinate system; System: Navigation coordinate system, which is East-North-Sky; System: Earth coordinate system The axis lies in the equatorial plane and points towards the prime meridian. The axis is parallel to the Earth's axis of rotation. Determined by a right-handed coordinate system; Planar Cartesian coordinate system: with the latitude and longitude of the pre-deployed and position-calibrated No. 0 seabed acoustic beacon as the origin, the X-axis points eastward, and the Y-axis points northward.

[0012] Step S102: The AUV performs underwater "bow" shaped navigation operations, and performs m sets of underwater acoustic ranging on the seabed acoustic beacon before and after the course turn, and saves the underwater acoustic ranging results. In this embodiment, m ≥ 3.

[0013] In practice, when the AUV performs underwater "bow"-shaped navigation operations, if the positioning error increases beyond the position calibration threshold, it uses its own configured underwater acoustic ranging system to perform real-time underwater acoustic ranging of the A# seabed acoustic beacon and caches the ranging results. The ranging results include the ranging time. AUV latitude and longitude ( ), distance of AUV relative to A# seabed acoustic beacon Navigation depth When the cached results reach 2m (m≥3) sets of ranging results, the real-time ranging results overwrite the oldest set of ranging results using a data loop. Simultaneously, the following processing is performed on this 2m set of underwater acoustic ranging results: (1) Divide the 2m group of underwater acoustic ranging results into m groups before the route turning and m groups after the route turning; For the 2m sets of distance measurement results, the first m sets of distance measurement results are denoted as: distance measurement time. AUV latitude and longitude ( ), distance of AUV relative to A# seabed acoustic beacon Navigation depth The following m sets of distance measurement information are recorded as: distance measurement time. AUV latitude and longitude ( ), distance of AUV relative to A# seabed acoustic beacon Navigation depth ; (2) Convert the latitude and longitude in the geographic coordinate system to Cartesian coordinates in the plane; Convert the AUV latitude and longitude coordinates from the 2m group of underwater acoustic ranging results of A# seabed acoustic beacon and the queried A# seabed acoustic beacon latitude and longitude coordinates to a plane Cartesian coordinate system, using the A# seabed acoustic beacon latitude and longitude coordinates ( Taking the origin as the x-axis and the direction east as the y-axis, then the latitude and longitude ( (Transformed to Descartes' seating system) The formula is as follows: (1) The location and depth of the converted A# seabed acoustic beacon are denoted as follows: and After converting the first m sets of ranging information from the A# seabed acoustic beacon: ranging time AUV position Distance of AUV relative to A# seabed acoustic beacon Navigation depth The last m sets of ranging information for the A# seabed acoustic beacon are saved as: ranging time. AUV location ( ), distance of AUV relative to A# seabed acoustic beacon Navigation depth Where Re is the Earth's radius; (3) Determine whether the first m sets of ranging tracks and the last m sets of ranging tracks are before or after the route turning point. Record the position of the first group of the first m groups ( Let E be the position of the m-th group ( ) is the position of the first group of the last m groups (F) Let G be the position of the m-th group ( Let H be the vector dot product formula. The angle θ between the two segments of the trajectory EF and trajectory GH is calculated using the formula as follows: (2) like If the AUV stops measuring the underwater acoustic distance and caching the distance results for the A# seabed acoustic beacon, it will use the cached 2m set of distance results to calculate the AUV's position using subsequent methods, thereby achieving inertial navigation position error calibration; otherwise, the AUV will continue to measure the underwater acoustic distance and cache the distance results for the A# seabed acoustic beacon.

[0014] Step S103: Based on the 2m set of underwater acoustic ranging results, correct and calculate the saved 2m set of latitude and longitude coordinates, calculate the position error correction amount and compensate it to the inertial navigation system to achieve AUV position error calibration. The specific steps are as follows: (1) Based on the known location and depth of the A# seabed acoustic beacon and the 2m set of underwater acoustic ranging results, the location of the buffered AUV is calculated; specifically: Record the AUV position (inertial navigation position) for the first ranging of the A# seabed acoustic beacon as: Let the corrected position of this point be denoted as . Then the AUV-corrected positions of the first m groups and the last m groups of distance measurement results. and This can be represented as: the location of the AUV during the first ranging of the A# seabed acoustic beacon. Adding the distances traveled by the AUV eastward and northward during that period, i.e.: (3) (4) Taking the i-th ranging result of the first m groups and the i-th ranging result of the last m groups for the known acoustic beacon A#, we have the following from plane geometry: (5) Due to the latitude and longitude of A# seabed acoustic beacon ( ( ) is used as the origin of the Cartesian coordinate system. for Then we have: (6) Substituting equations (3) and (4) into equation (6), the two equations in equation (5) are subtracted: (7) Then the m sets of distance measurement results can be written as: (8) Written in matrix form: (9) in: (10) (11) (12) The first AUV position measured from the A# seabed acoustic beacon is the corrected position to be solved. It can be calculated using the least squares method: (13) In order to ensure that equation (13) has a solution and is unique, the route of the AUV during underwater acoustic ranging should follow a "bow" shaped path and satisfy the angle judgment condition of the two segments of the track in the aforementioned steps.

[0015] Solving Then, the position of the m-th inertial navigation system in the buffer can be corrected using equations (3) and (4) to obtain the corrected AUV position. and .

[0016] (2) Calculate the inertial navigation error correction and calibrate the inertial navigation position error. AUV actual flight location from cache and underwater acoustic localization solution The inertial navigation position error of the AUV is calculated as follows: (14) Position error The compensation is transferred to the inertial navigation system, thus completing the position error correction of the AUV.

[0017] This invention also discloses a position calibration system for implementing the above method, specifically comprising: a high-precision satellite navigation / inertial navigation / Doppler velocimeter integrated navigation system; a high-precision timekeeping device capable of being timed by satellite navigation; an underwater acoustic ranging and underwater acoustic communication system capable of being timed externally and hard-synchronized by a clock; a seabed acoustic beacon with satellite navigation timekeeping, high-precision timekeeping, underwater acoustic response, and underwater acoustic communication functions; and a depth gauge. First, one of the seabed acoustic beacons completes satellite navigation timekeeping on the deck of the test vessel or on shore, and is in a high-precision timekeeping position. The process involves: deploying the seabed acoustic beacon at the center of the underwater operation area; calibrating the beacon's position after it lands on the seabed; conducting underwater "bow"-shaped navigation operations, performing m (m≥3) underwater acoustic ranging measurements on the seabed acoustic beacon before and after each course turn, and saving the results (including the current AUV's latitude and longitude, navigation depth, relative slant distance, etc.); based on the 2m sets of underwater acoustic ranging results, calculating the corrected latitude and longitude, calculating the position error correction amount, and compensating it to the inertial navigation system, thereby calibrating the AUV's position error.

[0018] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for position calibration during underwater "bow"-shaped navigation of an AUV based on a single seabed acoustic beacon, characterized in that, Includes the following steps: Step S101: In the underwater operation area of ​​the test vessel or buoy AUV, one seabed acoustic beacon is deployed in advance at the center of the underwater operation area, and the position of the seabed acoustic beacon is calibrated as a position reference. Step S102: The AUV performs underwater "bow" shaped navigation operations, and performs m sets of underwater acoustic ranging on the seabed acoustic beacon before and after the course turn, and saves the underwater acoustic ranging results. Step S103: Based on the m sets of underwater acoustic ranging results, the saved m sets of latitude and longitude are corrected and calculated, the position error correction amount is calculated and compensated to the inertial navigation system, and the AUV position error calibration is realized.

2. The method as described in claim 1, characterized in that, When the AUV performs underwater "bow"-shaped navigation operations, if the positioning error increases beyond the position calibration threshold, it uses its own configured underwater acoustic ranging system to perform real-time underwater acoustic ranging of the A# seabed acoustic beacon and caches the ranging results. The ranging results include the ranging time. AUV latitude and longitude, distance of AUV relative to A# seabed acoustic beacon Navigation depth When the cached results reach 2m sets of ranging results, the real-time ranging results will overwrite the oldest set of ranging results in a data loop manner.

3. The method as described in claim 2, characterized in that, The following processing was performed on the 2m group of underwater acoustic ranging results: (1) Divide the 2m group of underwater acoustic ranging results into m groups before the route turning and m groups after the route turning; For the 2m sets of distance measurement results, the first m sets of distance measurement results are denoted as: distance measurement time. AUV latitude and longitude ( ), distance of AUV relative to A# seabed acoustic beacon Navigation depth The following m sets of distance measurement information are recorded as: distance measurement time. AUV latitude and longitude ( ), distance of AUV relative to A# seabed acoustic beacon Navigation depth ; (2) Convert the latitude and longitude in the geographic coordinate system to Cartesian coordinates in the plane; Convert the AUV latitude and longitude coordinates from the 2m group of underwater acoustic ranging results of A# seabed acoustic beacon and the queried A# seabed acoustic beacon latitude and longitude coordinates to a plane Cartesian coordinate system, using the A# seabed acoustic beacon latitude and longitude coordinates ( The origin is defined by the x-axis, with the east direction as the x-axis and the north direction as the y-axis. Then latitude and longitude ( (Transformed to Descartes' seating system) The formula is as follows: （1） The location and depth of the converted A# seabed acoustic beacon are denoted as follows: and After converting the first m sets of ranging information from the A# seabed acoustic beacon: ranging time AUV position Distance of AUV relative to A# seabed acoustic beacon Navigation depth The last m sets of ranging information for the A# seabed acoustic beacon are saved as: ranging time. AUV location ( ), distance of AUV relative to A# seabed acoustic beacon Navigation depth Where Re is the Earth's radius; (3) Determine whether the first m sets of ranging tracks and the last m sets of ranging tracks are before or after the route turning point; Record the position of the first group of the first m groups ( Let E be the position of the m-th group ( ) is the position of the first group of the last m groups (F) Let G be the position of the m-th group ( Let H be the vector dot product formula. The angle θ between the two segments of the trajectory EF and trajectory GH is calculated using the formula as follows: （2） like If the AUV stops measuring the underwater acoustic distance and caching the distance results for the A# seabed acoustic beacon, it will use the cached 2m set of distance results to calculate the AUV's position using subsequent methods, thereby achieving inertial navigation position error calibration; otherwise, the AUV will continue to measure the underwater acoustic distance and cache the distance results for the A# seabed acoustic beacon.

4. The method as described in claim 1, 2, or 3, characterized in that, Step S103 is as follows: (1) Based on the known location and depth of the A# seabed acoustic beacon and the 2m set of underwater acoustic ranging results, the location of the buffered AUV is calculated; specifically: Record the AUV position (inertial navigation position) for the first ranging of the A# seabed acoustic beacon as: Let the corrected position of this point be denoted as . Then the AUV-corrected positions of the first m groups and the last m groups of distance measurement results. and This can be represented as: the location of the AUV during the first ranging of the A# seabed acoustic beacon. Adding the distances traveled by the AUV eastward and northward during that period, i.e.: （3） （4） Taking the i-th ranging result of the first m groups and the i-th ranging result of the last m groups for the known acoustic beacon A#, we have the following from plane geometry: （5） Due to the latitude and longitude of A# seabed acoustic beacon ( ( ) is used as the origin of the Cartesian coordinate system. for Then we have: （6） Substituting equations (3) and (4) into equation (6), the two equations in equation (5) are subtracted: （7） Then the m sets of distance measurement results can be written as: （8） Written in matrix form: （9） in: （10） （11） （12） The first AUV position measured from the A# seabed acoustic beacon is the corrected position to be solved. It can be calculated using the least squares method: （13） In order to ensure that equation (13) has a solution and is unique, the route of the AUV during underwater acoustic ranging should follow a "bow" shaped path and satisfy the angle judgment condition of the two segments of the track in the aforementioned steps. Solving Then, the position of the m-th inertial navigation system in the buffer can be corrected using equations (3) and (4) to obtain the corrected AUV position. and ; (2) Calculate the inertial navigation error correction and calibrate the inertial navigation position error; AUV actual flight location from cache and underwater acoustic localization solution The inertial navigation position error of the AUV is calculated as follows: （14） Position error The compensation is transferred to the inertial navigation system, thus completing the position error correction of the AUV.

5. The method as described in claim 1, 2, or 3, characterized in that, The m≥3.

6. A position calibration system for implementing the above method, characterized in that, include: The system comprises a high-precision satellite navigation / inertial navigation / Doppler velocimeter integrated navigation system, a high-precision timekeeping device with satellite navigation timing, an underwater acoustic ranging and communication system with external timing and clock hard synchronization, a seabed acoustic beacon with satellite navigation timing, high-precision timekeeping, underwater acoustic response, and underwater acoustic communication functions, and a depth gauge. First, one of the seabed acoustic beacons is placed on the deck of the test vessel or on shore to complete satellite navigation timing and maintain high-precision timekeeping. The beacon is then deployed at the center point of the underwater operation area, and its position is calibrated after landing on the seabed. The AUV performs underwater "bow"-shaped navigation operations, performing m underwater acoustic ranging measurements on the seabed acoustic beacon before and after each course turn, and saving the results. Based on the m sets of underwater acoustic ranging results, the corrected latitude and longitude are calculated, the position error correction is calculated and compensated to the inertial navigation system, thereby calibrating the AUV's position error.

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