A method for recovering missing positioning data of an underwater unit in marine towed surveys

Abstract

The present invention discloses a method for recovering missing positioning data of an underwater unit in marine towed surveys, comprising the following steps: preprocessing the ship GPS position data and the existing positioning data of the underwater unit during the towed survey to establish a recovery model for the missing positioning data of the underwater unit; making multiple estimations of the positioning missing path of the underwater unit, and combining the seabed terrain data of the area where the towed survey is located and the regularly recorded cable length data to calculate the theoretical cable length at the position corresponding to the cable length recording time point on each estimated path; selecting the estimated path where the minimum error between the theoretical cable length and the recorded cable length is located as the recovery result of the positioning missing path of this survey line. The method created by the present invention provides an effective solution to the problem that it is impossible to track the movement path of the underwater unit due to partial loss of positioning data during the underwater towed survey.

Description

Technical Field:

[0001] The present invention relates to the technical field of underwater unit positioning in ocean surveys, and particularly to a method for recovering missing positioning data of underwater units in ocean towed surveys.

[0002] Problem Background:

[0003] In ocean towed surveys, an acoustic positioning system is a commonly used device for positioning and tracking underwater units. This system receives acoustic signals emitted by transponders carried by underwater units through a transducer array installed at the bottom of the survey ship, obtains the distance and azimuth angle between the underwater unit and the survey ship, and then calculates the geographical longitude and latitude coordinates of the underwater unit. In actual applications, situations often occur where positioning data is missing due to acoustic signal occlusion or equipment communication failures. The missing positioning data will make it difficult to accurately track underwater units during towed surveys, which will greatly reduce the reliability of the data obtained from towed surveys. Summary of the Invention:

[0004] In view of the common problem of missing positioning data of underwater units in underwater towed surveys, the present invention proposes a method for recovering missing positioning data of underwater units. By using the ship's GPS position data and the cable length data recorded at regular intervals during towing, a recovery model for missing positioning data of underwater units is established, and this model is used to recover the missing positioning data of underwater units.

[0005] The object of the present invention is achieved through the following technical solutions: A method for recovering missing positioning data of underwater units in ocean towed surveys, comprising the following steps:

[0006] (1) Establish a towed line information table, indicating the start and end times and longitude and latitude in the table;

[0007] (2) Perform standardized preprocessing on the ship's GPS position data and the existing positioning data of the underwater unit; the existing positioning data of the underwater unit includes longitude, latitude, and depth data;

[0008] (3) According to the standardized ship's GPS position data and the existing positioning data, draw a predicted baseline for the missing positioning data of the underwater unit. Based on this baseline, create an adjustment parameter set for the predicted baseline, generate multiple predicted paths for the missing part of the underwater unit's positioning data, and construct a recovery model for the missing positioning data of the underwater unit;

[0009] (4) Combine the multi-beam topography of the survey area and the cable length data recorded at regular intervals, calculate the theoretical cable lengths of each predicted path in the recovery model for the missing positioning data of the underwater unit, and compare them with the cable length data recorded at regular intervals to obtain the optimal predicted path, which is used as the recovery path for the missing part of the towed line positioning data.

[0010] Further, step (2) specifically includes the following steps:

[0011] (2-1) Use the hampel filtering standard algorithm to filter out outliers in the ship's GPS position data and existing positioning data. Convert the above two types of data into smooth data with a time interval of 1 second through the one-dimensional linear interpolation algorithm. Use the start and end times of the survey line recorded in the towed line information table as the near-bottom working time period, and intercept the smooth data of the above two types of data within the near-bottom working time period;

[0012] (2-2) Convert the time (in the format of YYYY-MM-DD HH:MM:SS) of the intercepted ship GPS data and existing positioning data into the number of days Time since January 1, 1 AD GPS and Time usbl , subtract their respective start times of near-bottom work Time GPSstart and Time usblstart , to obtain the input time data of the underwater unit missing positioning data recovery model and

[0013]

[0014] (2-3) Convert the ship GPS longitude and latitude data Lon GPS , Lat GPS and the existing positioning longitude and latitude data Lon usbl , Lat usbl through the following formula to obtain the input longitude and latitude data of the underwater unit missing positioning data recovery model and

[0015]

[0016] where Lon GPSstart and Lat GPSstart are the longitude and latitude values of the ship GPS position data at the start of near-bottom work, and Lon usblstart and Lat usblstart are the longitude and latitude values of the existing positioning data at the start of near-bottom work.

[0017] Further, step (3) specifically includes the following steps:

[0018] (3-1) Use and as the horizontal axis, Take the vertical axis, plot the time and position comparison chart of the ship's GPS position data and the existing positioning data, and draw a path consistent with the ship's towing trend according to the movement trends of the ship's GPS path and the existing positioning path. Its longitude and latitude values are respectively and as the estimation baseline of the underwater unit missing positioning data recovery model;

[0019] (3-2) Based on the longitude and latitude values and on the estimated baseline path, considering the accuracy and calculation efficiency of the fitting calculation, use the method of fifth-degree polynomial fitting to calculate its fitting with The obtained coefficient sets {P i} and {Q i}; these two parameter sets respectively satisfy:

[0020]

[0021] (3-3) Create an adjustment parameter set {α j} for the estimated baseline, and adjust the longitude and latitude values of the estimated baseline according to the following formula to generate K underwater unit estimated paths, and their coordinate longitude and latitude values are expressed as and

[0022]

[0023] The value range of the adjustment parameter α is: -0.1 < α1 < 0.1, -0.1 < α2 < 0.1, -0.2 < α3 < 0.2, -0.5 < α4 < 0.5, 5 < α5 < 5. At the same time, considering the calculation efficiency, K ≤ 50.

[0024] Furthermore, step (4) specifically includes the following steps:

[0025] (4-1) Select a coordinate point corresponding to the cable length recording time point on an estimated path, combine the multi-beam bathymetric data of the survey area, and obtain the water depth data of this coordinate point through two-dimensional linear interpolation. Calculate the theoretical cable length data L of the underwater unit at this coordinate point during the towing process according to the following formula:

[0026]

[0027] where H is the distance between this coordinate point and the ship's position, and d is the water depth at this coordinate point; calculate the water depth data of all coordinate points corresponding to the cable length recording time point on this estimated path, and obtain the theoretical cable length set {L m} of all corresponding coordinate points on this estimated path, where m is the number of cable length data recorded at regular intervals of the towing line;

[0028] (4-2) Select different parameter values from the set of adjusted parameters {a j}, calculate the set of theoretical cable lengths for each estimated path, and obtain K sets of theoretical cable length sets {L m}; Using the least squares criterion, calculate the sum of squared errors S between the theoretical cable length data and the timed recorded cable length data according to the following formula: K ; where L

[0029]

[0030] is the value of the timed recorded cable length data, and select the estimated path with the smallest S value among the K sets of S values as the optimal estimated path; record

[0031] (4-3) According to the following formula, convert the longitude and latitude coordinate points and of the optimal estimated path into the longitude and latitude values Lon usbl ″ and Lat usbl ″ of the geographical coordinates, and obtain the recovery path of the missing part of the positioning data of the survey line;

[0032]

[0033] Advantages of the present invention:

[0034] Based on the ship's GPS position data and the existing underwater unit positioning data, the present invention establishes a recovery model for the missing positioning data of the underwater unit, combines the seabed terrain data and the timed recorded cable length data in the area where the towed line is located, and recovers the missing positioning data of the underwater unit during the towing process. Through the verification of the embodiments, the underwater unit positioning data recovered by the method provided by the present invention is relatively accurate, greatly improving the reliability of the data collected in the marine towed survey. Description of the drawings:

[0035] Figure 1 is a schematic diagram of the specific process of the method of the present invention.

[0036] Figure 2 is a schematic diagram of the generation process of the estimated reference line and the estimated path of the underwater unit of the method of the present invention.

[0037] Figure 3 is a comparison diagram of the cable length value at a specified point on the optimal estimated path obtained by the method of the present invention and the timed recorded cable length value.

[0038] Figure 4 is a comparison effect diagram of the optimal estimated path obtained by the method of the present invention.

[0039] Figure 5 is a comparison effect diagram of the water depth of the optimal estimated path obtained by the method of the present invention.​ Detailed implementation manners:

[0040] To describe the present invention more specifically, the technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0041] In this embodiment, to better test the effect of the present invention on the recovery of missing positioning data of underwater units, a marine towed survey line with complete positioning data is selected in the embodiment, and a part of the positioning data at the beginning section is intercepted as the input data of the underwater unit missing positioning data recovery model. The optimal estimated path is calculated by the underwater unit missing positioning data recovery model, and the result is compared with the complete positioning data of this survey line.

[0042] Embodiment:

[0043] As Figure 1 shown, the present invention provides a method for recovering missing positioning data of underwater units in towed surveys. The specific embodiments mainly include the following steps:

[0044] Step 1: Establish a towed survey line information table, and mark the start and end times, longitudes and latitudes of the survey line in the table;

[0045] Step 2: Use the hampel filtering standard algorithm to filter out the outliers in the ship's GPS position data and the existing positioning data, and convert the above two types of data into smooth data with a time interval of 1 second through the one-dimensional linear interpolation algorithm. Use the start and end times of the survey line recorded in the towed survey line information table as the near-bottom working time period. According to the towed survey line information table, intercept the data values of the above two types of data within the near-bottom working time period of the underwater unit as the input data of the underwater unit positioning missing positioning data recovery model;

[0046] Step 3: Convert the time (in the format of YYYY-MM-DD HH:MM:SS) of the ship's GPS data and the existing positioning data into the number of days Time GPS and Time usbl since the first year of the AD, and subtract their respective start times Time GPSstart and Time usblstart of the near-bottom work to obtain the input time data of the underwater unit positioning missing positioning data recovery model and

[0047]

[0048] Step 4: The ship's GPS longitude and latitude data Lon GPS , Lat GPS and the existing positioning longitude and latitude data Lon usbl , Lat usblThe following formula is used to convert the input latitude and longitude data of the underwater unit missing positioning data recovery model: and

[0049]

[0050] Among them, Lon GPSstart and Lat GPSstart Lon is the latitude and longitude value of the ship's GPS position data at the beginning of the near-bottom work. usblstart and Lat usblstart It is the latitude and longitude value of the positioning data available when the near-bottom work begins.

[0051] Step 5: Draw a time and position comparison chart of the ship's GPS position data and the existing positioning data (in and is the horizontal axis, As the vertical axis), according to the movement trend of the ship's GPS path and the existing positioning path, a path consistent with the ship's towing trend is drawn, and its latitude and longitude values ​​are and Serves as an estimated baseline for the model to recover missing positioning data of underwater units;

[0052] Step 6: Estimate the latitude and longitude values ​​on the baseline path and Based on The coefficient set obtained by fitting {P i} and {Q i Considering the accuracy and efficiency of the fitting calculation, this step recommends the use of a fifth-order polynomial fitting method. The two parameter sets satisfy:

[0053]

[0054] Step 7: Create a set of adjustment parameters for the estimated baseline {α j}, adjust the longitude and latitude values ​​of the estimated baseline according to the following formula to generate K underwater unit estimated paths, whose coordinate longitude and latitude values ​​are expressed as and

[0055]

[0056] The recommended value range of the adjustment parameter α is: -0.1<α1<0.1, -0.1<α2<0.1, -0.2<α3<0.2, -0.5<α4<0.5, 5<α5<5. Considering the computational efficiency, it is recommended that K≤50;

[0057] Step 8: Select a coordinate point corresponding to the cable length recording time point on a predicted path. Combine the multi-beam topographic data of the survey area, and obtain the water depth data of this coordinate point through two-dimensional linear interpolation. Calculate the theoretical cable length L of the underwater unit at this coordinate point during the towing process according to the following formula:

[0058]

[0059] where H is the distance between this coordinate point and the ship's position, and d is the water depth at this coordinate point. Calculate the water depth data of the coordinate points corresponding to all cable length recording time points on this predicted path, and obtain the set of theoretical cable lengths {L m} of all corresponding coordinate points on this predicted path, where m is the number of cable length data recorded at regular intervals along the towing line;

[0060] Step 9: Select different parameter values from the set of adjustment parameters {a j}, calculate the set of theoretical cable lengths for each predicted path, and obtain K sets of theoretical cable lengths {L m}. Use the least squares criterion to calculate the sum of squared errors S between the theoretical cable length data and the regularly recorded cable length data according to the following formula: K . where L

[0061]

[0062] where L record is the value of the regularly recorded cable length data. Select the predicted path with the smallest S value among the K sets of S values as the optimal predicted path;

[0063] Step 10: Convert the longitude and latitude coordinate points and of the optimal predicted path into the longitude and latitude values Lon usbl ″ and Lat usbl ″ of the geographic coordinates to obtain the recovery path of the missing part of the positioning data for this survey line.

[0064]

[0065] Figure 2 is a schematic diagram of the generation process of the underwater unit prediction reference line and the predicted path of the method of the present invention. Figure 2 In (a1) and (b1), the thin dotted lines represent the ship's GPS position data, and the thick solid lines represent the partially missing positioning data; Figure 2 In (a2) and (b2), the manually drawn underwater unit prediction path reference line (thick dashed line) is shown according to the changing trends of the two lines in (a1) and (b1); Figure 2 In (a3) and (b3), the manually drawn underwater unit prediction path reference line (thick dashed line) is shown according to the changing trends of the two lines in (a1) and (b1); Figure 2 In (a3) and (b3), the manually drawn underwater unit prediction path reference line (thick dashed line) is shown according to the changing trends of the two lines in (a1) and (b1); Figure 2The estimated path baseline of the underwater unit in (a1) and (b1) in it, and 30 estimated paths of the underwater unit (thin solid lines) are generated.

[0066] Figure 3 The comparison chart of the cable length value at a specified point on the optimal estimated path calculated by the underwater unit missing positioning data recovery model of the method of the present invention and the cable length value recorded at regular intervals. Among them, the solid triangle is the theoretical cable length value of the specified point on the optimal estimated path, and the hollow square is the cable length value recorded at regular intervals of the towing survey line at the same time point.

[0067] Figure 4 It shows the optimal estimated path calculated by the underwater unit missing positioning data recovery model. Among them, the thick dotted line represents the optimal estimated path of the underwater unit, the thick solid line represents the ship's movement path, and the thin dotted line represents the underwater unit path obtained by complete positioning. It can be seen from the figure that under the condition that the input data is partially missing positioning data, the optimal estimated path of the recovered underwater unit is basically the same as the path obtained from the positioning data.

[0068] Figure 5 It shows the graph of the change of the water depth value of the optimal estimated path calculated by the underwater unit missing positioning data recovery model over time. Among them, the thick dotted line represents the change of the water depth of the optimal estimated path of the underwater unit, the thick solid line represents the change of the water depth along the ship's towing path, and the thin dotted line represents the change of the water depth of the complete positioning data. It can be seen from the figure that under the condition that the input data is partially missing positioning data, the water depth value of the optimal estimated path of the recovered underwater unit has a small difference from the water depth value of the complete positioning data and is consistent with the change trend of the water depth along the ship's towing path.

[0069] The above specific embodiments have described in detail the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, supplements, equivalent replacements, etc. made within the scope of the principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recovering missing positioning data of an underwater unit in marine towed surveys, characterized in that, It includes the following steps: (1) Establish a towing survey line information table, and mark the start and end times, longitude and latitude in the table; (2) Perform standardized preprocessing on the ship's GPS position data and the existing positioning data of the underwater unit; the existing positioning data of the underwater unit includes longitude, latitude and depth data; (3) According to the standardized ship's GPS position data and the existing positioning data, draw a predicted baseline for the missing positioning data of the underwater unit. Based on this baseline, create an adjustment parameter set for the predicted baseline, generate multiple predicted paths for the missing part of the underwater unit's positioning data, and construct a recovery model for the missing positioning data of the underwater unit; (4) Combine the multi-beam topography of the survey area and the cable length data recorded at regular intervals, calculate the theoretical cable length of each predicted path in the recovery model of the missing positioning data of the underwater unit, and compare it with the cable length data recorded at regular intervals to obtain the optimal predicted path as the recovery path for the missing part of the towing survey line positioning data.

2. The method for recovering the missing positioning data of the underwater unit in marine towed surveys according to claim 1, wherein The specific steps of step (2) include the following steps: (2-1) Use the hampel filtering standard algorithm to filter out the outliers in the ship's GPS position data and the existing positioning data, convert the above two types of data into smooth data with a time interval of 1 second through the one-dimensional linear interpolation algorithm, and use the start and end times of the survey line recorded in the towing survey line information table as the near-bottom working time period, and intercept the smooth data of the above two types of data during the near-bottom working time period; (2-2) Convert the time of the intercepted ship GPS data and the existing positioning data into the number of days since the first year of the AD, Time GPS and Time usbl , subtract their respective start times of near-bottom work, Time GPSstart and Time usblstart , to obtain the input time data of the underwater unit missing positioning data recovery model and (2-3) The ship's GPS longitude and latitude data Lon GPS , Lat GPS and the existing positioning longitude and latitude data Lon usbl , Lat usbl are transformed by the following formula to obtain the input longitude and latitude data of the underwater unit missing positioning data recovery model and Among them, Lon GPSstart and Lat GPSstart are the longitude and latitude values of the ship's GPS position data at the start of near-bottom operation. Lon usblstart and Lat usblstart are the longitude and latitude values of the existing positioning data at the start of near-bottom operation.

3. The method for recovering the missing positioning data of the underwater unit in marine towed surveys according to claim 2, wherein, The specific steps of step (3) include the following steps: (3-1) With and as the horizontal axis, as the vertical axis, draw a time and position comparison chart of the ship's GPS position data and the existing positioning data. According to the movement trends of the ship's GPS path and the existing positioning path, draw a path that is consistent with the ship's towing trend, and its latitude and longitude values are respectively and as the estimation baseline for the underwater unit missing positioning data recovery model; (3-2) Based on the longitude and latitude values on the estimated reference route and as the basis, use the method of fifth-order polynomial fitting to calculate its relationship with The coefficient sets {P i} and {Q i} obtained by fitting; these two parameter sets respectively satisfy: (3-3) Create an adjustment parameter set {α j} for the estimated baseline. Adjust the longitude and latitude values of the estimated baseline according to the following formula to generate K estimated paths for underwater units, and their coordinate longitude and latitude values are expressed as and The value range of the adjustment parameter α is: -0.1 < α1 < 0.1, -0.1 < α2 < 0.1, -0.2 < α3 < 0.2, -0.5 < α4 < 0.5, 5 < α5 < 5, K ≤ 50.

4. The method for recovering the missing positioning data of the underwater unit in marine towed surveys according to claim 3, characterized in that, The specific steps of step (4) include the following steps: (4-1) Select a coordinate point corresponding to the cable length recording time point on a predicted path, combine the multi-beam topography data of the survey area, obtain the water depth data of this coordinate point through two-dimensional linear interpolation, and calculate the theoretical cable length data L of the underwater unit at this coordinate point during towing according to the following formula: where H is the distance between the coordinate point and the ship's position, and d is the water depth at the coordinate point; calculate the water depth data of all coordinate points corresponding to the cable length recording time points on the estimated path, and obtain the theoretical cable length set {L m} of all corresponding coordinate points on the estimated path, where m is the number of cable length data recorded at regular intervals of the towed line; (4-2) Select different parameter values from the set of adjusted parameters {a j}, calculate the set of theoretical cable lengths for each estimated path, and obtain K sets of theoretical cable length sets {L m} K ; Using the least squares criterion, calculate the sum of squared errors S between the theoretical cable length data and the timed recorded cable length data according to the following formula: where L record is the value for timing and recording the cable length data, and the estimated path with the smallest S value among the K groups of S values is selected as the optimal estimated path; (4-3) Convert the longitude and latitude coordinate points of the optimal estimated path and into the longitude and latitude values Lon usbl ” and Lat usbl ” of the geographic coordinates, and obtain the recovery path of the missing part of the positioning data of this survey line;

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