A method for calculating dynamic draft of a survey vessel based on shipborne GNSS geodetic height

Abstract

The present invention relates to the technical field of dynamic draft data processing for survey vessels, specifically disclosing a method for calculating the dynamic draft of a survey vessel based on shipborne GNSS geodetic height. The method comprises the following steps: S01, acquiring real-time shipborne GNSS geodetic height data; S02, correcting the GNSS geodetic height data based on synchronized data collected in real time by a multi-beam bathymetry system to obtain necessary data containing only the dynamic draft and water level of the survey vessel; S03, adding Gaussian white noise to the to-be-decomposed signal contained in the necessary data based on an ensemble empirical mode decomposition method to alter the distribution of extreme points in the original sequence, summing the IMF components obtained each time, and extracting the average value; S04, after ensemble empirical mode decomposition, extracting water level information based on the period of each characteristic component. This invention improves operational efficiency, reduces project production costs and the technical level requirements of technicians, is simple to operate, and achieves high accuracy in dynamic draft calculation.

Description

Technical Field

[0001] The present invention relates to the technical field of dynamic processing of survey ship draft data, and in particular to a method for calculating the dynamic draft of a survey ship based on ship-borne GNSS geodetic height. Background Art

[0002] The dynamic draft of a survey vessel refers to the varying degrees of overall draught caused by the displacement of the stern thrusters, from a stationary state to rapid motion. This draught is primarily influenced by vessel speed (the vessel's ground velocity minus the seawater velocity), vessel type, and water depth, and varies at different locations on the vessel. Multibeam bathymetry systems have become the mainstream equipment for bathymetry. Dynamic draft is a key correction parameter, and its results directly impact the final results of bathymetry measurements. Therefore, to obtain accurate and reliable bathymetry data and improve bathymetry accuracy, it is essential to precisely measure the vessel's dynamic draft and correct for its effects.

[0003] To solve this problem, China's "Hydrographic Specifications" (GB 12327-2022) provides a method for measuring the difference in depth of a vessel underway and a method for measuring the difference in height using high-precision GNSS altimetry. The measurement conditions are first specified as follows: (1) Select an open water area with a flat seabed, relatively hard bottom, and a water depth of approximately 7 times the draft of the survey vessel (if the water depth in the survey area is shallower, select a shallower area), ensuring that the survey vessel can sail at various speeds; (2) During the test, the sea conditions are good, the water level is observed, and the survey vessel drifts without power under the action of currents and other forces; (3) Ensure that the survey vessel drifts without power in a straight line, collects depth data or Global Navigation Satellite System (GNSS) altimetry data, and the straight-line drift distance is not less than 200m. Then, a survey line is laid out based on the straight-line drift track line, and extends to both ends by not less than 100m. When the above three conditions are met, the underway depth difference measurement method is based on the survey line laid out under the measurement conditions. The survey ship conducts depth measurement in the same direction and along the same survey line as the drift direction at different set speeds. The depth measurement data under drift and different ship speeds are then processed and corrected to obtain accurate depth data under different ship speeds. The depth data of the selected straight drift section is used as the quasi-static comparison reference depth, and the depths at other different speeds are compared with it. The positioning deviation of the comparison point is no more than 2m, and the comparison depth difference of the two survey lines is obtained. The average of the comparison depth difference is taken as the dynamic draft value under different ship speeds. The high-precision GNSS height difference measurement method also meets the above three conditions. It adopts high-precision GNSS measurement methods such as real-time kinematic carrier phase difference (RTK), network RTK, precise point positioning (PPP), and post-processed kinematic (PPK). The survey ship collects GNSS measurement data at different set speeds in the same direction and along the same survey line in the drift direction. The GNSS measurement data under drift and different ship speeds are processed and corrected to extract the plane coordinates and elevation data under different ship speeds. The selected straight drift segment positioning and height measurement data are used as quasi-static comparison benchmark data. The plane coordinates and elevation data under other different ship speeds are compared with others. The coordinate deviation of the comparison point is no more than 2m. The comparison elevation difference of the two survey lines is obtained, and the average of the comparison elevation difference is taken as the dynamic draft value at different ship speeds. In summary, it can be seen that the "Specifications for Hydrographic Surveying" (GB 12327-2022) provides two methods for measuring dynamic draft. Although they can accurately calculate the dynamic draft under a certain heading and speed, they are not easy to implement due to the influence of the measurement environment, and navigation tests are required before work, which increases the project production cost.

[0004] Furthermore, numerous scholars both domestically and internationally have conducted in-depth research on this topic. For example, Briggs argues that when a survey vessel navigates a channel, its descent is primarily affected by channel width, water depth, and ship speed. Varyani argues that in areas with unrestricted depth or greater depth, descent is primarily affected by ship speed. He has also conducted in-depth research on the descent caused by high-speed survey vessels in shallow water. Delefortrie et al. studied the dynamic draft of survey vessels in turbid waters and developed a dynamic draft correction model. Zeraatgar et al. conducted a detailed study of the relationship between descent and the aforementioned parameters in shallow waters and developed a calculation model. Most of these researchers employed specific methods to develop correction models for dynamic draft, but they did not accurately measure dynamic draft from a practical perspective, resulting in certain limitations. Guo Fabin proposed the feasibility of using a cylindrical pressure sensor and a pressure-sensitive method to measure the dynamic draft at the transducer center. However, dynamic draft is easily confused with heave and is affected by the Bernoulli effect, making practical measurements difficult. Wu Bingzhao et al. proposed using a single- or dual-vessel method using GNSS to measure the dynamic draft at the transducer center, but this method requires a relatively long test voyage. Ardalan et al. successfully determined the relationship between bow and stern dynamic draft and ship speed using three GNSS receivers. However, this method is essentially a dynamic draft correction model and does not accurately determine the dynamic draft at the transducer center. Matte et al. conducted extensive research on dynamic draft, using GNSS and an acoustic Doppler current profiler (ADCP) to determine the dynamic draft at the GNSS antenna location, achieving centimeter-level accuracy. However, the ADCP was required as an auxiliary sensor.

[0005] With the continuous development of GNSS technology and the maturation of methods such as RTK, PPK, and PPP, it can provide centimeter-level positioning accuracy in both vertical and horizontal directions, making it increasingly important in marine surveying and marine environmental monitoring. The shipboard GNSS antenna and the bathymetric transducer are fixedly mounted on the survey vessel. The high-precision geodetic height changes obtained by the GNSS antenna can reflect the comprehensive dynamic changes in the vertical direction of the survey vessel in real time, including dynamic draft, water level, and waves. If a specific method is adopted, dynamic draft can be directly extracted from the shipboard GNSS geodetic height data without heading tests and the addition of other auxiliary equipment, which has important practical significance.

[0006] In summary, the dynamic draft measurement method based on the "Hydrographic Specification" (GB 12327-2022) is practical, but requires navigational testing under certain conditions, increasing project production costs and making implementation difficult. Calculations based on an empirical dynamic draft model, on the other hand, are subject to model errors and place higher technical demands on technical personnel. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for calculating the dynamic draft of a survey ship based on ship-borne GNSS geodetic height, so as to solve the above-mentioned problems.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A method for calculating the dynamic draft of a survey vessel based on shipborne GNSS geodetic height comprises the following steps:

[0010] S01. Obtain real-time shipborne GNSS geodetic height data;

[0011] S02. Correct the GNSS geodetic height data based on the synchronized data collected in real time by the multi-beam bathymetry system to obtain the necessary data containing only the dynamic draft and water level of the survey vessel;

[0012] S03. Adding Gaussian white noise to the signal to be decomposed contained in the necessary data based on an ensemble empirical mode decomposition method to change the extreme value distribution of the original sequence, summing the IMF components obtained each time, and extracting the average value;

[0013] S04. After the ensemble empirical mode decomposition, the water level information is extracted according to the period of each characteristic component, and the water level information in the necessary data in step S02 is eliminated to obtain dynamic draft data.

[0014] Preferably, the GNSS geodetic height data provides GNSS precise positioning based on RTK, PPK and PPP.

[0015] Preferably, the GNSS geodetic height data includes total draft data of the survey vessel, high-frequency fluctuation data in the vertical direction caused by wave effects, and water depth data.

[0016] Preferably, the calculation of the shipborne GNSS geodetic height data in step S01 includes:

[0017] ;

[0018] but:

[0019] ;

[0020] Where: T G is the shipborne GNSS geodetic height, T S is the water level change caused by ocean tides, S is the vertical change caused by waves, D is the dynamic draft of the measuring ship, J is the draft of the measuring ship when it is stationary, and H G It is the shipborne GNSS geodetic height data after wave correction.

[0021] Preferably, the multi-beam echo sounding system in step S02 is equipped with at least an attitude indicator;

[0022] The synchronous data collected are attitude measurement values ​​of the roll, pitch and heave of the survey ship measured by the attitude meter;

[0023] Then perform correction on GNSS geodetic height data:

[0024] ;

[0025] Among them, r is the roll of the survey ship, p is the pitch of the survey ship, and h is the up and down heave of the survey ship.

[0026] Preferably, the steps of obtaining the IMF component in step S03 include:

[0027] S31, initialize the amplitude of the Gaussian white noise sequence to , the number of times is N j ;

[0028] S32. Add noise sequence n to the original signal x(t) i (t), then:

[0029] ;

[0030] S33, let a(t) and b(t) be x i The maximum and minimum values ​​of (t) are fitted into envelopes, and the mean of the two envelopes c(t) can be expressed as:

[0031] ;

[0032] ;

[0033] Among them, h i1 (t) is the amount after decomposition;

[0034] S34, h i1 (t) Determine compliance with the Implementing Regulations:

[0035] If the decomposed value is less than the threshold, then h i1 (t) = IMF i1 ;

[0036] If the decomposed value is greater than the threshold, it is not satisfied and h i1 (t) is treated as the original time series, and steps S31 to S33 are repeated. After k times of screening, we get , the remaining signal for:

[0037] ;

[0038] S35, for the remaining signal Repeat steps S33 to S44 until r n (t) is less than the preset threshold or monotonic function, and i IMF components and 1 residual component r are obtained. i (t), then:

[0039] ;

[0040] S36, repeat step S35 E times, take the average value of the corresponding IMF components, and the final IMF component IMF j (t) and the residual component r j (t) is:

[0041] ;

[0042] .

[0043] Preferably, the implementation regulations include:

[0044] S331. In the dataset of the necessary data, the number of extreme value points and the number of zero-crossing points must be equal or differ by at most 1;

[0045] S332. The mean value of the envelope formed by the local maximum and the envelope formed by the local minimum is 0.

[0046] As an example, the EMD in step S04 is a process of processing the original signal x(t) .

[0047] In the above technical solution, the present invention provides a method for calculating the dynamic draft of a survey vessel based on shipborne GNSS geodetic height, which has the following beneficial effects: after the acquired accurate shipborne GNSS geodetic height data is wave corrected, the ensemble modal empirical decomposition method is used to separate the dynamic draft and water level of the survey vessel from the shipborne GNSS geodetic height data, thereby achieving the purpose of extracting the dynamic draft while avoiding navigation tests and without other special operations, thereby reducing project production costs, improving production efficiency, and reducing the technical level requirements of water operation personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0049] Figure 1 A comparison chart of the GNSS geodetic high-water level wave correction before and after the correction is provided in an embodiment of the present invention;

[0050] Figure 2 A comparison chart of the GNSS geodetic high-water level wave correction before and after the correction is provided in an embodiment of the present invention;

[0051] Figure 3 An information graph of the water level variation period after the collective empirical mode decomposition provided by an embodiment of the present invention;

[0052] Figure 4 A diagram of the draft variation cycle information after the collective empirical mode decomposition provided by an embodiment of the present invention;

[0053] Figure 5 The embodiment of the present invention provides an ensemble empirical mode decomposition for extracting shipborne GNSS water level and dynamic draft diagrams. DETAILED DESCRIPTION

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] Example 1

[0056] like Figure 1 As shown, a method for calculating the dynamic draft of a survey vessel based on shipborne GNSS geodetic height includes the following steps:

[0057] S01. Obtain real-time shipborne GNSS geodetic height data:

[0058] The above-mentioned steps are based on the combined effects of the survey vessel's motion and ocean fluid dynamics. The GNSS geodetic height data in the above-mentioned steps provides GNSS precise positioning based on RTK, PPK, and PPP. The collected GNSS geodetic height data packet includes at least three components:

[0059] The first component is the high-frequency fluctuation in the vertical direction caused by the wave effect;

[0060] The second part is to measure the total draft of the ship, including static draft and dynamic draft;

[0061] The third part is the water level, then:

[0062] ;

[0063] but:

[0064] ;

[0065] Where: T G is the shipborne GNSS geodetic height, T S is the water level change caused by ocean tides, S is the vertical change caused by waves, D is the dynamic draft of the measuring ship, J is the draft of the measuring ship when it is stationary, and H G It is the shipborne GNSS geodetic height data after wave correction.

[0066] S02. Based on the synchronized data collected in real time by the multi-beam bathymetry system, the GNSS geodetic height data is corrected to obtain the necessary data containing only the dynamic draft and water level of the survey vessel:

[0067] In the above-mentioned step embodiment, the multi-beam echo sounder system is equipped with at least an attitude meter, and the synchronization data refers to the attitude measurement values ​​of the roll, pitch, and heave of the survey vessel measured by the attitude meter. It should be noted that when the shipborne GNSS geodetic height data and attitude measurement values ​​in step S01 of the embodiment are transmitted to the processing terminal, they need to be timestamped, that is, the shipborne GNSS geodetic height data and attitude measurement values ​​with the same time threshold are compared and modified. The GNSS geodetic height data is then corrected using the following formula:

[0068] ;

[0069] Among them, r is the roll of the survey ship, p is the pitch of the survey ship, and h is the up and down heave of the survey ship.

[0070] S03. Adding Gaussian white noise to the signal to be decomposed contained in the necessary data based on the ensemble empirical mode decomposition method to change the extreme value distribution of the original sequence, and summing the IMF components obtained each time and extracting the average value;

[0071] In the above-mentioned embodiment, the steps of adding Gaussian white noise to the signal to be decomposed to change the distribution of extreme points of the original sequence are:

[0072] S31, initialize the amplitude of the Gaussian white noise sequence to , the number of times is N j ;

[0073] S32. Add noise sequence n to the original signal x(t)i (t), then:

[0074] ;

[0075] S33, let a(t) and b(t) be x i The maximum and minimum values ​​of (t) are fitted into envelopes, and the mean of the two envelopes c(t) can be expressed as:

[0076] ;

[0077] ;

[0078] Among them, h i1 (t) is the amount after decomposition;

[0079] S34, h i1 (t) Determine compliance with the Implementing Regulations:

[0080] If the decomposed value is less than the threshold, then h i1 (t) = IMF i1 ;

[0081] If the decomposed value is greater than the threshold, it is not satisfied and h i1 (t) is treated as the original time series, and steps S31 to S33 are repeated. After k times of screening, we get , the remaining signal for:

[0082] ;

[0083] The above-mentioned implementing regulations include:

[0084] S331. In the dataset of required data, the number of extreme points and the number of zero crossing points must be equal or differ by at most 1;

[0085] S332. The mean value of the envelope formed by the local maximum and the envelope formed by the local minimum is 0.

[0086] Further, S35, for the remaining signal Repeat steps S33 to S44 until r n (t) is less than the preset threshold or monotonic function, and i IMF components and 1 residual component r are obtained. i (t), then: ;

[0087] S36, repeat step S35 E times, take the average value of the corresponding IMF components, and the final IMF component IMF j(t) and the residual component r j (t) is:

[0088] ;

[0089] .

[0090] S04. After the ensemble empirical mode decomposition, the water level information is extracted according to the period of each characteristic component, and the water level information in the necessary data in step S02 is eliminated to obtain dynamic draft data.

[0091] In the above steps, the original signal x(t) is expressed as follows after the ensemble empirical mode decomposition:

[0092] ;

[0093] Since the periods of dynamic draft and tide level are quite different, after ensemble empirical mode decomposition, water level information can be extracted according to the periods of each characteristic component, so as to realize the separation of dynamic draft and GNSS geodetic high water level, and then realize the extraction of dynamic draft.

[0094] Example 2

[0095] This example describes the method provided in Example 1. Figure 2-Figure 4 shown.

[0096] The test area has obvious seasonal variation characteristics. The prevailing wind is northerly in winter, southerly in summer, and the wind direction changes alternately in spring and autumn. The strong wind direction is NNW~NNE, and the common wind direction is N~NNW, among which NNW is the strongest, and the second common wind direction is SSE~S.

[0097] Tidal properties (H K1 +H O1 ) / H M2 The ratio is 0.36 to 0.40, which is less than 0.50, belonging to the regular semi-diurnal tide sea area; the shallow sea influence coefficient H M4 / H M2 Between 0.02 and 0.03, the sum of the amplitudes of the main shallow sea tides (H M4 +H MS4 +H M6 ) is between 0.06m and 0.16m. Generally speaking, the influence of shallow water tide is significant. Tidal property coefficient (W K1 +W O1 ) / W M2 The ratio of the vertical average W of the shallow water effect is less than 0.5. M4 / W M2 When the ratio is between 0.02 and 0.39, it is a regular semi-diurnal tide, and the tide is also greatly affected by shallow water.

[0098] The steps for calculating the dynamic draft of the shipborne GNSS geodetic height measurement vessel are as follows:

[0099] S01. The survey vessel installed a GNSS antenna receiver directly above the transducer and simultaneously set up a base station on shore. The sampling interval for both the rover and base stations was set to 1s, and the elevation angle was 15°. The PPK technique was used to calculate the GNSS geodetic height for each epoch and eliminate errors caused by factors such as the ionosphere and multipath. For static draft changes, measurements were taken before and after the measurement, and then corrected using linear interpolation to obtain accurate shipborne GNSS geodetic height data ( Figure 2 ).

[0100] S02, the calculation formula provided by implementing step S03: The method given is used to correct the wave, and the effect before and after the wave correction ( Figure 2 colored thread).

[0101] S03, after filtering, the GNSS geodetic height is added with Gaussian white noise with a standard deviation of 0.2m, so the number N j Take 100. Then perform the ensemble empirical mode decomposition, and a total of 14 characteristic components are obtained after decomposition, such as Figure 3 and Figure 4 Since the water level change cycle is longer than the dynamic draft time, the characteristic component IMF 11 、IMF 12 、IMF 13 and the IMF 14 It is the water level variable characteristic, that is, the water level information measured by GNSS is the characteristic component IMF 11 、IMF 12 、IMF 13 and the IMF 14 The sum of reference Figure 5 (a) shows the change in water level.

[0102] S04, then subtract the characteristic component IMF from the GNSS geodetic height after wave correction 11 、IMF 12 、IMF 13 and the IMF 14 The sum of reference Figure 5 The dynamic draft changes shown in (b) in the figure can be used to obtain the dynamic draft measured by GNSS.

[0103] In summary, after wave correction, the precise shipborne GNSS geodetic height data is obtained, and then the ensemble modal empirical decomposition method is used to separate the dynamic draft and water level of the measuring vessel from the shipborne GNSS geodetic height data. This achieves the purpose of extracting the dynamic draft while avoiding navigation tests and requiring no other special operations, thereby reducing project production costs, improving production efficiency, and lowering the technical level requirements of water operators.

[0104] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0105] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0106] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0107] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0108] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

[0109] The embodiments of the present application also provide a specific implementation of an electronic device capable of implementing all steps of the method in the above embodiments. The electronic device specifically includes the following contents:

[0110] Processor, memory, communications interface, and bus;

[0111] The processor, memory, and communication interface communicate with each other via the bus.

[0112] The processor is used to call the computer program in the memory, and when the processor executes the computer program, all the steps in the method in the above embodiment are implemented.

[0113] The embodiments of the present application also provide a computer-readable storage medium capable of implementing all the steps of the method in the above embodiments. The computer-readable storage medium stores a computer program, which implements all the steps of the method in the above embodiments when executed by a processor.

[0114] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between the various embodiments can be referenced across them. Each embodiment focuses on the differences from other embodiments. In particular, for hardware + program embodiments, since they are generally similar to method embodiments, their description is relatively simple. For relevant parts, reference can be made to the description of the method embodiments. Although the embodiments in this specification provide method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive means. The order of steps listed in the embodiments is merely one of many possible execution sequences and does not represent the only execution sequence. When implemented in a practical device or end product, the methods shown in the embodiments or figures may be executed sequentially or in parallel (for example, in a parallel processor or multi-threaded processing environment, or even a distributed data processing environment). The terms "comprise," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, product, or apparatus comprising a set of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, product, or apparatus. Without further limitation, this does not preclude the presence of additional identical or equivalent elements in a process, method, product, or apparatus comprising the elements described. For ease of description, the above devices are described as functionally divided into various modules. Of course, when implementing the embodiments of this specification, the functions of each module can be implemented in the same or multiple software and / or hardware components, or a module implementing the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are merely illustrative. For example, the division of units described is merely a logical functional division. In actual implementation, other divisions may be used, such as combining or integrating multiple units or components into another system, or omitting or disabling some features. Furthermore, the coupling or direct coupling or communication connection shown or discussed between devices or units may be through interfaces, or indirect coupling or communication connection between devices or units, and may be electrical, mechanical, or other forms. The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce the instructions for implementing the process Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0115] Those skilled in the art will appreciate that the embodiments of this specification can be provided as methods, systems, or computer program products. Therefore, the embodiments of this specification may take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware. Furthermore, the embodiments of this specification may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk drives, CD-ROMs, optical storage devices, etc.) containing computer-usable program code. The various embodiments in this specification are described in a progressive manner, and similar parts between the various embodiments can be referenced across them. Each embodiment focuses on the differences from other embodiments. In particular, since the system embodiments are generally similar to the method embodiments, their description is relatively simple; for relevant parts, reference can be made to the description of the method embodiments. Throughout this specification, reference to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the embodiments of this specification.

[0116] In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless they contradict each other. The above is only an embodiment of the embodiment of this specification and is not intended to limit the embodiment of this specification. For those skilled in the art, the embodiment of this specification may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiment of this specification shall be included within the scope of the claims of the embodiment of this specification.

Claims

1. A method for calculating the dynamic draft of a survey vessel based on shipborne GNSS geodetic height, characterized in that: The following steps are involved: S01. Obtain real-time shipborne GNSS geodetic height data; S02. Correct the GNSS geodetic height data based on the synchronized data collected in real time by the multi-beam bathymetry system to obtain the necessary data containing only the dynamic draft and water level of the survey vessel; S03. Adding Gaussian white noise to the signal to be decomposed contained in the necessary data based on an ensemble empirical mode decomposition method to change the extreme value distribution of the original sequence, summing the IMF components obtained each time, and extracting the average value; S04. After performing ensemble empirical mode decomposition, extract water level information based on the period of each characteristic component, and remove the water level information from the necessary data in step S02 to obtain dynamic draft data; The calculation of the shipborne GNSS geodetic height data in step S01 includes: ； but: ； in: T G For shipborne GNSS geodetic height, T S is the change in water level caused by ocean tides, S is the vertical change caused by the wave, D To measure the dynamic draft of the ship, J To measure the draft of a ship at rest, H G The shipborne GNSS geodetic height data after wave correction; The multi-beam echo sounder system in step S02 is equipped with at least an attitude indicator; The synchronous data collected are attitude measurement values ​​of the roll, pitch and heave of the survey ship measured by the attitude meter; Then perform correction on GNSS geodetic height data: ； in, r To measure the ship's roll, p To measure the pitch of the ship, h To measure the heave and sinking of the ship; The steps of obtaining the IMF component in step S03 include: S31, initialize the amplitude of the Gaussian white noise sequence to , the number of times is N j ; S32, in the original signal x ( t ) is added to the noise sequence n i ( t ),but: ； S33, let a( t ) and b( t ) are x i ( t ) is fitted into an envelope with the maximum and minimum values, then the mean of the two envelopes c( t ) can be expressed as: ； ； in, h i1 (t) is the amount after decomposition; S34, yes h i1 (t) Determine compliance with the Implementing Regulations: If the decomposed value is less than the threshold, then it is satisfied. h i1 ( t )=IMF i1 ; If the decomposed value is greater than the threshold, it is not satisfied and the h i1 ( t ) as the original time series, and repeat steps S31 to S33. After k times of screening, we get h ik ( t )=IMF il ( t ), the remaining signal r 1( t )for: ； S35, for the remaining signal r 1( t ) Repeat steps S33 to S44 until N decompositions are completed. r N ( t ) is less than the preset threshold or monotonic function, we get i IMF components and 1 residual component r i ( t ),but: ； S36, repeat step S35 E times, take the average value of the corresponding IMF components, and the final IMF component IMF j ( t ) and the remaining amount r j ( t )for: ； ； The implementing regulations include: S331. In the dataset of the necessary data, the number of extreme value points and the number of zero-crossing points must be equal or differ by at most 1; S332, the mean value of the envelope formed by the local maximum value and the envelope formed by the local minimum value is 0; In step S04, the ensemble empirical mode decomposition is performed on the original signal x ( t ) .

2. The method for calculating the dynamic draft of a survey vessel based on shipborne GNSS geodetic height according to claim 1, characterized in that: The GNSS geodetic height data provides GNSS precise positioning based on RTK, PPK and PPP.

3. The method for calculating the dynamic draft of a survey vessel based on shipborne GNSS geodetic height according to claim 1, characterized in that: The GNSS geodetic height data includes the total draft data of the survey vessel, high-frequency fluctuation data in the vertical direction caused by wave effects, and water depth data.

4. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the method for calculating the dynamic draft of a survey ship based on ship-borne GNSS geodetic height as described in any one of claims 1 to 3 are implemented.

5. 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 for calculating the dynamic draft of a survey vessel based on ship-borne GNSS geodetic height as described in any one of claims 1 to 3 are implemented.

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