A method for monitoring ocean currents based on tracking and positioning of seabed anchored buoys

Abstract

The present invention discloses a method for monitoring ocean currents based on tracking and positioning a submarine anchored buoy. The method belongs to the field of underwater navigation and positioning technology and is used for ocean current monitoring. The method includes implementing attitude correction of a GNSS antenna to obtain the position of an acoustic signal emitted by a sea surface transducer; establishing a sea surface-seabed sonar observation equation based on acoustic timing data and sound velocity profile data between the sea surface and the submarine anchored buoy; establishing a submarine anchored buoy motion constraint equation based on a random walk model to form a positioning model that takes into account the motion characteristics of the submarine anchored buoy; performing adjustment and solving the positioning model that takes into account the motion characteristics of the submarine anchored buoy to obtain a coordinate sequence of the submarine anchored buoy; and smoothing the coordinate time series to obtain an ocean current motion trajectory. The present invention monitors the ocean current motion trajectory by tracking the motion time series of the positioning buoy, thereby achieving km-scale physical ocean environment monitoring based on marine geodetic technology.

Description

Technical Field

[0001] The invention discloses a method for monitoring ocean currents based on tracking and positioning of seabed anchored buoys, belonging to the technical field of underwater navigation and positioning. Background Art

[0002] Compared to fixed observation sites, moored observation sites are located higher above the seafloor, supporting a wider observation and navigation range and at a lower cost. Furthermore, moored buoys are highly flexible and can be equipped with specialized sensors, such as conductivity-temperature-depth (CTD) sensors, acoustic Doppler current profilers (ADCPs), or bio-related sensors, to collect time-series data on oceanographic and meteorological parameters in specific areas. Currently, moored buoys are widely used for real-time, continuous, and long-term observations, making significant contributions to the study of the mesoscale physical ocean environment, such as summer and winter monsoons and tropical cyclones. Given their advantages in observation range and capability, moored buoys equipped with acoustic beacons have potential for remote APN services. Similar to fixed beacons, moored beacons can be used for conventional acoustic range observations from surface platforms. However, due to the influence of ocean dynamics, their real-time motion makes obtaining the precise position of moored beacons a significant challenge.

[0003] Observational errors caused by spatiotemporal variations in the sound velocity structure are a key factor affecting the positioning of fixed and moored beacons. The understanding and processing of sound velocity information has evolved through three phases: single point, vertical profile, and spatiotemporal structure. First, a specific sound velocity value (such as weighted average or harmonic sound velocity) is selected and spatial intersection is used to convert time observations into range observations. This is used in scenarios where low positioning accuracy is required during marine activities. Subsequently, to correct for the effects of ray bending, a sound velocity profile (SSP) is typically used, and ray tracking is employed, assuming a vertically layered, uniformly gradient SSP. Furthermore, to meet the requirements of developing seafloor observation networks and monitoring seafloor deformation, a more refined modeling of the sound velocity structure is required. A time-varying linear spatial function sound velocity perturbation model has been proposed, based on the observation time and the spatial position of the surface platform and seafloor beacon. This model can optimize positioning accuracy to approximately 2-3 cm for the horizontal component and 4-9 cm for the vertical component. It is worth noting that these results are obtained for a seafloor array consisting of fixed beacons. Therefore, a matching sound velocity perturbation model is also crucial for positioning using hybrid seafloor constellations. The positioning model in the adjustment system is another key point for accurately locating submarine acoustic beacons. Traditional positioning models have improved positioning performance to varying degrees. However, all these studies are based on fixed submarine beacons and reasonably ignore the motion of the beacons, which is not applicable to the anchored beacons in the submarine hybrid constellation. Summary of the Invention

[0004] The purpose of the present invention is to provide a current monitoring method based on seabed anchored buoy tracking and positioning, so as to solve the problem in the prior art that the movement of beacons is often ignored in current monitoring, resulting in the unsuitability of anchored beacons in seabed hybrid constellations.

[0005] A method for monitoring ocean currents based on tracking and positioning of seabed anchored buoys comprises:

[0006] S1. Using an attitude sensor to obtain attitude observation data of the position of the GNSS antenna, performing attitude correction of the GNSS antenna, and obtaining the position of the acoustic signal emitted by the sea surface transducer;

[0007] S2. Based on the acoustic timing data and sound velocity profile data between the sea surface and the seabed anchored buoy, a sea surface-seabed sonar observation equation is established. Based on the random walk model, a motion constraint equation for the seabed anchored buoy is established to form a positioning model that takes into account the motion characteristics of the seabed anchored buoy.

[0008] S3. Perform adjustment calculation on the positioning model that takes into account the motion characteristics of the seabed anchored buoy to obtain the coordinate sequence of the seabed anchored buoy, and smooth the coordinate time series to obtain the ocean current motion trajectory.

[0009] S1 includes, S1.1, obtaining the position of the sea surface carrier GNSS receiver , 、 and are the components of the GNSS receiver position on the sea surface in the east, north and zenith directions respectively.

[0010] S1 includes, S1.2, obtaining the parameters required for GNSS antenna attitude correction through the attitude sensor carried by the sea surface transducer. The parameters required for GNSS antenna attitude correction include heading angle , pitch angle and roll angle , establish the coordinate transformation matrix :

[0011] .

[0012] S1 includes, S1.3, lever arm measurement information of the position of acoustic signal emission using GNSS receiver and sea surface transducer , calculate the emission position of the sea surface transducer acoustic signal :

[0013] ;

[0014] Where, 、 and are the components of the acoustic signal emission position of the sea surface transducer in the east, north and zenith directions respectively, 、 and are the components of the arm measurement information of the acoustic signal emission positions of the GNSS receiver and the sea surface transducer in the east, north and zenith directions, respectively.

[0015] Establishing the sea surface-seabed sonar observation equation includes:

[0016] ;

[0017] ;

[0018] ;

[0019] ;

[0020] ;

[0021] ;

[0022] Where, Observation vector, 、 are the two components of the observation vector, 、 、 is the design matrix, is the fixed beacon model parameter coefficient matrix and the diagonal design matrix composed of the parameter coefficient matrix of the seabed anchored buoy model, are unknown position parameters related to static beacons and seabed anchored buoys, is a parameter related to the location of the seabed static station, is the unknown parameter vector related to the position of the seabed anchor buoy, is the regularization parameter, is the regularization matrix, is the coefficient matrix of the constraint equation, is the differential operator matrix, is a parameter related to the sound velocity structure disturbance, 、 are two constraint parameters.

[0023] The two constraint parameters satisfy the following:

[0024] ;

[0025] Where, Indicates the variance, is the standard deviation, is the adjustment factor that controls the relative freedom of motion of the anchor beacon, for The power array, is the weight matrix of the constraint equation.

[0026] The motion constraint equations for the seabed anchored buoy are as follows:

[0027] ;

[0028] Where, During the observation period The location of the seabed anchor buoy, It is the number index of the seabed anchor buoy. is the random walk error, and the expectation of the random walk error is for:

[0029] ;

[0030] Variance of random walk error for:

[0031] ;

[0032] Where, The weight matrix representing the random walk error.

[0033] The matrix expression of the motion constraint equation of the seabed anchored buoy is:

[0034] ;

[0035] ;

[0036] ;

[0037] ;

[0038] Where, is the random walk error matrix.

[0039] Adjustment solution includes:

[0040] ;

[0041] Where, It is used for static beacon positioning dimensional observation vector, is the number of underwater ranging observations, is the Cholesky decomposition matrix, 、 is a random error;

[0042] Estimate the unknown parameters using the Gauss-Newton iteration formula:

[0043] ;

[0044] Where, It is Iteration valuation, It is Iteration The convergence condition is that the maximum difference between the two parameter estimates in two consecutive iterations is less than the set threshold.

[0045] Smoothing includes estimating the Hurst exponent of each component and removing the previous indivual Components of the smoothed coordinate sequence :

[0046] ;

[0047] Where, is the number index of the submarine station, is the total number of seafloor stations, Indicates the coordinates, Indicates the The coordinates are decomposed by IMF. It's time, It's an error.

[0048] Compared with the existing technology, the present invention has the following beneficial effects: the present invention monitors the trajectory of ocean currents by tracking the timing of the movement of the positioning buoy, and realizes the physical ocean environment monitoring at the km scale based on marine geodetic technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is the result of decentralized processing of the motion trajectories of anchored buoys numbered No.1 to No.4;

[0050] Figure 2 It is the result of decentralized processing of the east-west movement trend of anchored buoys numbered No.1 to No.4;

[0051] Figure 3 It is the result of decentralized processing of the movement trend of anchored buoys No.1 to No.4 in the north-south direction;

[0052] Figure 4 It is the motion trajectory result of the anchored buoy of the time series of the navigation buoy position No.1;

[0053] Figure 5 This is the motion trajectory result of the anchored buoy of the navigation buoy position time series numbered No.2;

[0054] Figure 6 This is the motion trajectory result of the anchored buoy of the navigation buoy position time series numbered No.3;

[0055] Figure 7 This is the motion trajectory result of the anchored buoy in the time series of the navigation buoy position No. 4. DETAILED DESCRIPTION

[0056] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0057] A method for monitoring ocean currents based on tracking and positioning of seabed anchored buoys comprises:

[0058] S1. Using an attitude sensor to obtain attitude observation data of the position of the GNSS antenna, performing attitude correction of the GNSS antenna, and obtaining the position of the acoustic signal emitted by the sea surface transducer;

[0059] S2. Based on the acoustic timing data and sound velocity profile data between the sea surface and the seabed anchored buoy, a sea surface-seabed sonar observation equation is established. Based on the random walk model, a motion constraint equation for the seabed anchored buoy is established to form a positioning model that takes into account the motion characteristics of the seabed anchored buoy.

[0060] S3. Perform adjustment calculation on the positioning model that takes into account the motion characteristics of the seabed anchored buoy to obtain the coordinate sequence of the seabed anchored buoy, and smooth the coordinate time series to obtain the ocean current motion trajectory.

[0061] S1 includes, S1.1, obtaining the position of the sea surface carrier GNSS receiver , 、 and are the components of the GNSS receiver position on the sea surface in the east, north and zenith directions respectively.

[0062] S1 includes, S1.2, obtaining the parameters required for GNSS antenna attitude correction through the attitude sensor carried by the sea surface transducer. The parameters required for GNSS antenna attitude correction include heading angle , pitch angle and roll angle , establish the coordinate transformation matrix :

[0063] .

[0064] S1 includes, S1.3, lever arm measurement information of the position of acoustic signal emission using GNSS receiver and sea surface transducer , calculate the emission position of the sea surface transducer acoustic signal :

[0065] ;

[0066] Where, 、 and are the components of the acoustic signal emission position of the sea surface transducer in the east, north and zenith directions respectively, 、 and are the components of the arm measurement information of the acoustic signal emission positions of the GNSS receiver and the sea surface transducer in the east, north and zenith directions, respectively.

[0067] Establishing the sea surface-seabed sonar observation equation includes:

[0068] ;

[0069] ;

[0070] ;

[0071] ;

[0072] ;

[0073] ;

[0074] Where, Observation vector, 、 are the two components of the observation vector, 、 、 is the design matrix, is the fixed beacon model parameter coefficient matrix and the diagonal design matrix composed of the parameter coefficient matrix of the seabed anchored buoy model, are unknown position parameters related to static beacons and seabed anchored buoys, is a parameter related to the location of the seabed static station, is the unknown parameter vector related to the position of the seabed anchor buoy, is the regularization parameter, is the regularization matrix, is the coefficient matrix of the constraint equation, is the differential operator matrix, is a parameter related to the sound velocity structure disturbance, 、 are two constraint parameters.

[0075] The two constraint parameters satisfy the following:

[0076] ;

[0077] Where, Indicates the variance, is the standard deviation, is the adjustment factor that controls the relative freedom of motion of the anchor beacon, for The power array, is the weight matrix of the constraint equation.

[0078] The motion constraint equations for the seabed anchored buoy are as follows:

[0079] ;

[0080] Where, During the observation period The location of the seabed anchor buoy, It is the number index of the seabed anchor buoy. is the random walk error, and the expectation of the random walk error is for:

[0081] ;

[0082] Variance of random walk error for:

[0083] ;

[0084] Where, The weight matrix representing the random walk error.

[0085] The matrix expression of the motion constraint equation of the seabed anchored buoy is:

[0086] ;

[0087] ;

[0088] ;

[0089] ;

[0090] Where, is the random walk error matrix.

[0091] Adjustment solution includes:

[0092] ;

[0093] Where, It is used for static beacon positioning dimensional observation vector, is the number of underwater ranging observations, is the Cholesky decomposition matrix, 、 is a random error;

[0094] Estimate the unknown parameters using the Gauss-Newton iteration formula:

[0095] ;

[0096] Where, It is Iteration valuation, It is Iteration The convergence condition is that the maximum difference between the two parameter estimates in two consecutive iterations is less than the set threshold.

[0097] Smoothing includes estimating the Hurst exponent of each component and removing the previous indivual Components of the smoothed coordinate sequence :

[0098] ;

[0099] Where, is the number index of the submarine station, is the total number of seafloor stations, Indicates the coordinates, Indicates the The coordinates are decomposed by IMF. It's time, It's an error.

[0100] The embodiment of the present invention uses the real observation data during the operation process. In order to evaluate the consistency of the motion between different anchored buoys, a differential processing method is adopted, and the position at the first moment is used as a reference to perform motion decentralization processing. Figure 1 As shown in the figure, the movement amplitude in the east-west direction is kept within 4 meters, while the movement amplitude in the north-south direction does not exceed 3 meters, and the trajectory shape is approximately a closed curve. Figure 2 and Figure 3 As shown in Figure 1, the motion of the anchored buoy shows a sine wave shape similar to a cosine wave. Different buoys show roughly similar periods, peaks, and valleys. However, some sections of the curve lack the expected smoothness, mainly due to discontinuous observation data. The position of the anchored buoy solved by the current monitoring method, the motion trajectory is Figure 4 、 Figure 5 、 Figure 6 、 Figure 7 The main movement direction of the anchored buoys is clearly shown, which is mainly dominated by the east-west movement. Among all anchored buoys, the initial eastward movement range is 2 meters, and then the westward movement range is 1.5 meters. Figure 5 The arrows in show this trend. The color bar represents the time series change from the start moment to the end moment, and the gradually changing orange arrows show the approximate movement direction of the anchored buoys. Specifically, navigation buoys No. 1 and No. 3 mainly show a movement trend in the east-west direction, while navigation buoys No. 2 and No. 4 show an approximate movement trend in the northeast-southwest direction. However, the current tracking results do not follow any standard or ideal trajectory, which is due to the limitations of the current motion constraint model in the present invention in the smoothness description, and the fact that the entire anchored buoy position sequence corresponds to three discontinuous time intervals. The use of spline basis functions can provide smoother and more realistic navigation buoy trajectories.

[0101] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for monitoring ocean currents based on tracking and positioning of seabed anchored buoys, characterized in that: include: S1. Using an attitude sensor to obtain attitude observation data of the position of the GNSS antenna, performing attitude correction of the GNSS antenna, and obtaining the position of the acoustic signal emitted by the sea surface transducer; S2. Based on the acoustic timing data and sound velocity profile data between the sea surface and the seabed anchored buoy, a sea surface-seabed sonar observation equation is established. Based on the random walk model, a motion constraint equation for the seabed anchored buoy is established to form a positioning model that takes into account the motion characteristics of the seabed anchored buoy. S3. performing adjustment calculation on the positioning model that takes into account the motion characteristics of the seabed anchored buoy to obtain the coordinate sequence of the seabed anchored buoy, and smoothing the coordinate time series to obtain the ocean current motion trajectory; Establishing the sea surface-seabed sonar observation equation includes: ； ； ； ； ； ； Where, Observation vector, 、 are the two components of the observation vector, 、 、 is the design matrix, is the fixed beacon model parameter coefficient matrix and the diagonal design matrix composed of the parameter coefficient matrix of the seabed anchored buoy model, are unknown position parameters related to static beacons and seabed anchored buoys, is a parameter related to the location of the seabed static station, is the unknown parameter vector related to the position of the seabed anchor buoy, is the regularization parameter, is the regularization matrix, is the coefficient matrix of the constraint equation, is the differential operator matrix, is a parameter related to the sound velocity structure disturbance, 、 are two constraint parameters; The two constraint parameters satisfy the following: ； Where, Indicates the variance, is the standard deviation, is the adjustment factor that controls the relative freedom of motion of the anchor beacon, for The power array, is the weight matrix of the constraint equation; The motion constraint equations for the seabed anchored buoy are as follows: ； Where, During the observation period The location of the seabed anchor buoy, It is the number index of the seabed anchor buoy. is the random walk error, and the expectation of the random walk error is for: ； Variance of random walk error for: ； Where, The weight matrix representing the random walk error; The matrix expression of the motion constraint equation of the seabed anchored buoy is: ； ； ； ； Where, is the random walk error matrix; Adjustment solution includes: ； Where, It is used for static beacon positioning dimensional observation vector, is the number of underwater ranging observations, is the Cholesky decomposition matrix, 、 is a random error; Estimate the unknown parameters using the Gauss-Newton iteration formula: ； Where, It is Iteration valuation, It is Iteration The convergence condition is that the maximum difference between the two parameter estimates in two consecutive iterations is less than the set threshold; Smoothing includes estimating the Hurst exponent of each component and removing the previous indivual Components of the smoothed coordinate sequence : ； Where, is the number index of the submarine station, is the total number of seafloor stations, Indicates the coordinates, Indicates the The coordinates are decomposed by IMF. It's time, It's an error.

2. The ocean current monitoring method based on seabed anchored buoy tracking and positioning according to claim 1, characterized in that: S1 includes, S1.1, obtaining the position of the sea surface carrier GNSS receiver , 、 and are the components of the GNSS receiver position on the sea surface in the east, north and zenith directions respectively.

3. The ocean current monitoring method based on seabed anchored buoy tracking and positioning according to claim 2, characterized in that: S1 includes, S1.2, obtaining the parameters required for GNSS antenna attitude correction through the attitude sensor carried by the sea surface transducer. The parameters required for GNSS antenna attitude correction include heading angle , pitch angle and roll angle , establish the coordinate transformation matrix : 。 4. The ocean current monitoring method based on seabed anchored buoy tracking and positioning according to claim 3 is characterized in that: S1 includes, S1.3, lever arm measurement information of the position of acoustic signal emission using GNSS receiver and sea surface transducer , calculate the emission position of the sea surface transducer acoustic signal : ； Where, 、 and are the components of the acoustic signal emission position of the sea surface transducer in the east, north and zenith directions respectively, 、 and are the components of the arm measurement information of the acoustic signal emission positions of the GNSS receiver and the sea surface transducer in the east, north and zenith directions, respectively.

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