A method and system for eliminating errors in external information of underwater gravity measurement

Abstract

The present invention relates to the field of gravity measurement data processing technology, and specifically discloses a method and system for eliminating errors in external information of underwater gravity measurement, the method comprising: obtaining external information of underwater gravity measurement; calculating a white noise standard deviation value according to the external information of underwater gravity measurement; stripping the measured wild value of the external information of underwater gravity measurement, and then performing Kalman filtering, and then calculating an estimated value of the change of the measurement value of the external information of underwater gravity measurement at any time relative to the measurement value at the initial time; constructing a random differential equation group according to the white noise standard deviation value and the estimated value of the change, solving the random differential equation group, and obtaining the external information of underwater gravity measurement with external errors eliminated. The present invention performs error separation on the external information containing errors referenced in underwater high-precision gravity measurement, and eliminates this part of the error to restore the real gravity field change underwater, and finally improve the accuracy of underwater gravity measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of gravity measurement data processing, and in particular to a method and system for eliminating errors of external information of underwater gravity measurement. Background Art

[0002] At present, the mainstream shipborne gravity measurement is mostly surface gravity measurement. The gravity anomaly signal caused by the seabed geological body will be rapidly attenuated by the water body, which will also lead to a decrease in the resolution of the gravity measurement equipment. Underwater gravity measurement technology came into being. It completes the underwater high-precision gravity measurement task by connecting the gravity measurement equipment with the autonomous underwater vehicle (AUV) and supplemented by external information correction such as inertial navigation system, Doppler velocimeter (DVL), depth sensor, etc.

[0003] The mathematical model of underwater gravity measurement is derived from Newton's second law. The vector mathematical model of underwater gravity measurement is shown in formula (1):

[0004] …(1)

[0005] In the formula, is the eastward gravity anomaly, is the northward gravity anomaly, It is the anomaly of celestial gravity; For the eastward force, For the northward force, Comparing strength with the heaven, , and Measured by gravity measuring equipment; is the depth of the gravity measuring device (positive in the celestial direction); is the Earth's rotation angular velocity, ; is the geographical latitude; is the east speed over the ground, is the ground speed to the north, It is the speed over the ground; for The first derivative of for The first derivative of for The first derivative of ; is the meridian radius, is the radius of the Maoyou circle; is the normal gravity upward.

[0006] In general, gravity measurement equipment is a scalar gravity measurement, which only estimates the vertical component of the gravity vector. In the third equation of equation (1), let , as well as , we can get the mathematical model of underwater gravity measurement (scalar form):

[0007] …(2)

[0008] In the formula, is the gravity anomaly, for The second-order derivative of Normal gravity.

[0009] In underwater gravity measurement, It is expressed as shown in formula (3):

[0010] …(3)

[0011] In the formula, is the free air gravity anomaly, ; is the gravitational constant, ; is the density of seawater, ; for Difference from nominal depth; is the normal gravity associated with the latitude.

[0012] The expression is shown in formula (4):

[0013] …(4)

[0014] When performing underwater gravity measurement tasks, the gravity measurement equipment is usually fixed to a remote-controlled AUV, which sails along longitude and latitude circles parallel to the meridian and azimuth circles, and sails straight at a constant speed on the same survey line. Figure 1 shown. Figure 1 The information flow of underwater gravity measurements is described as follows:

[0015] First, the gravity measuring equipment measures the celestial relative force at each point on the survey line. , and then Substitute into the underwater gravity measurement mathematical model of equation (2);

[0016] Then, the inertial navigation system, DVL, depth sensor and other equipment on the AUV are used to measure the latitude information, northeast speed information, depth information and other external auxiliary information of each point on the survey line, and then these external auxiliary information are brought into the underwater gravity measurement mathematical model of formula (2);

[0017] Finally, using various external auxiliary information, the celestial force is corrected through equations (2) to (4) to obtain the gravity anomaly values ​​of each point on the survey line. .

[0018] It can be seen from the above process that the accuracy of external auxiliary information directly affects the accuracy of gravity measurement. In general, AUV can sail at almost a constant speed through remote control, so in theory, external auxiliary information changes linearly. However, due to the influence of ocean currents, undercurrents and irregular sudden terrain that often appear underwater, or the external auxiliary information is abnormal due to interference from electrical signals, and the noise carried by the signal transmission itself, the external auxiliary information received by the gravity measurement equipment often carries noise or has measurement wild values. These abnormal values, especially the measurement wild values, will bring errors to the measurement of gravity abnormal values, resulting in a decrease in the accuracy of gravity measurement. The existing external information error elimination method usually uses Kalman filtering for each physical quantity to achieve data smoothing, but Kalman filtering only suppresses the noise of certain frequency signals, and has poor processing effect on measurement wild values. Therefore, it is urgent to construct a method for eliminating external information errors containing noise and measurement wild values ​​in underwater gravity measurement, so as to improve the measurement accuracy of gravity measurement equipment when performing underwater gravity measurement tasks. Summary of the invention

[0019] The present invention aims to solve the problem of gravity anomaly calculation errors caused by noise and measurement wild values ​​in external auxiliary information. To this end, the present invention provides an error elimination method and system for underwater gravity measurement external information, which regards the measurement results of each external information physical quantity of the AUV on the survey line as a random process, and establishes a random differential equation group model containing white noise and measurement wild values ​​for the random process, and solves the random differential equation group to restore the actual physical process of each external information, so as to eliminate the errors caused by noise and measurement wild values ​​in the measurement of each external information. The present invention performs error separation on the external information containing errors referenced in underwater high-precision gravity measurement, and eliminates this part of the error to restore the real gravity field changes underwater, and finally improve the accuracy of underwater gravity measurement.

[0020] The present invention provides a method for eliminating errors in external information of underwater gravity measurement, and the technical scheme adopted is as follows:

[0021] Obtain external information of underwater gravity measurement;

[0022] The standard deviation of white noise is calculated based on the external information of underwater gravity measurement;

[0023] The measured wild values ​​of the external information of underwater gravity measurement are stripped, and then Kalman filtering is performed, and then the estimated value of the change of the measured value of the external information of underwater gravity measurement at any time relative to the measured value at the initial time is calculated;

[0024] A set of stochastic differential equations is constructed according to the standard deviation of white noise and the estimated value of variation. The stochastic differential equations are solved to obtain the external information of underwater gravity measurement with external errors eliminated.

[0025] Furthermore, the process of calculating the white noise standard deviation value based on the underwater gravity measurement external information is as follows: the underwater gravity measurement external information includes depth information, latitude information and northeast sky speed information. On the basis of retaining the measured wild value, according to the depth information, latitude information and northeast sky speed information, the standard deviation of the depth information, the standard deviation of the latitude information and the standard deviation of the northeast sky speed information are calculated respectively as the white noise standard deviation value of the depth information, the white noise standard deviation value of the latitude information and the white noise standard deviation value of the northeast sky speed information.

[0026] Furthermore, according to the depth information, latitude information and Northeast Skyspeed information, each time is divided into an interval, and we get

[0027]

[0028] in, Indicates The depth information of each interval, Indicates The latitude information of the interval, Indicates Northeast Skyspeed information for each section, Indicates time The depth information, Indicates time The latitude information, Indicates time Northeast Skyspeed Information, for Divide by The remainder of Indicates the total number of moments;

[0029] For each interval of underwater gravity measurement external information, the drift rate of the interval value is linearly fitted and the drift is removed. Then the mean and standard deviation of the underwater gravity measurement external information of each interval are calculated to obtain , , , , and ,in, Indicates The mean of the depth information of the intervals, Indicates The standard deviation of the depth information in each interval, Indicates The mean of the latitude information of the intervals, Indicates The standard deviation of the latitude information of each interval, Indicates The mean value of the Northeast Sky Speed ​​information in the interval, Indicates The standard deviation of the Northeast Skyspeed information in the interval;

[0030] Calculate the standard deviation of white noise using the following formula:

[0031]

[0032] in, The standard deviation of white noise representing depth information, The standard deviation of white noise representing latitude information, Represents the standard deviation of white noise of Northeast Skyspeed information.

[0033] Furthermore, the measurement interval of the depth information, latitude information and northeast sky speed information is 1s. is 60.

[0034] Furthermore, the measured wild values ​​of the external information of the underwater gravity measurement are stripped, and then Kalman filtering is performed, and then the estimated value of the change of the measured value of the external information of the underwater gravity measurement at any time relative to the measured value at the initial time is calculated. The process is as follows: the measured wild values ​​are respectively screened out from the depth information, latitude information and northeast sky speed information, and the measured wild values ​​are replaced with the mean to obtain the depth information, latitude information and northeast sky speed information without measured wild values; the depth information, latitude information and northeast sky speed information without measured wild values ​​are respectively Kalman filtered to obtain the measured values ​​of the depth information, latitude information and northeast sky speed information; and then the estimated value of the change of the measured value of the depth information, latitude information and northeast sky speed information at any time relative to the measured value at the initial time is calculated.

[0035] Furthermore, the measured wild values ​​of the underwater gravity measurement external information are stripped, and then Kalman filtering is performed, and then the estimated value of the change of the measurement value of the underwater gravity measurement external information at any time relative to the measurement value at the initial time is calculated as follows:

[0036] If the first The depth information within the interval is If it is not included, the depth information is determined to be a measurement outlier and replaced with ; The depth information of all intervals is stitched together in chronological order, and Kalman filtering is performed to obtain the measured value of the depth information ,in Indicates a moment, ; Using spline interpolation, Extend to , R represents the real number domain; calculate the estimated value of the change of the measured value of the depth information at any time relative to the measured value at the initial time , , Indicates time Depth information;

[0037] If the first The latitude information within the interval is If the latitude information is outside the range, it is determined to be a wild value and replaced by ; Splice the latitude information of all intervals together in chronological order, perform Kalman filtering, and obtain the measured value of the latitude information ,in ; Using spline interpolation, Extend to ; Calculate the estimated value of the change of the measured value of the latitude information at any time relative to the measured value at the initial time , , Indicates time Latitude information;

[0038] If the first Northeast Tiansu information in the interval is If the information is not included, the Northeast Skyspeed information is determined to be a wild value and replaced by ; Splice the Northeast Skyspeed information of all intervals together in chronological order, perform Kalman filtering, and obtain the measured value of the Northeast Skyspeed information ,in ; Using spline interpolation, Extend to ; Calculate the estimated value of the change of the measured value of the Northeast Skyspeed information at any time relative to the measured value at the initial time , , Indicates time Northeast Skyspeed Information.

[0039] Furthermore, a set of stochastic differential equations is constructed based on the standard deviation of white noise and the estimated value of the variation. The process of solving the set of stochastic differential equations to obtain the external information of underwater gravity measurement that eliminates the external error is as follows:

[0040] System of stochastic differential equations:

[0041]

[0042] in, is called the drift term of the stochastic differential equation system, is called the diffusion term of the stochastic differential equation system, represents the external information of underwater gravity measurement with external errors eliminated, represents the estimated value of the change, , ; It means that the mean is 0 and the standard deviation is , and Gaussian white noise random process;

[0043] The numerical format for constructing the stochastic differential equation system using the Euler-Mauryama method is:

[0044]

[0045] in, , For the general The time interval of the equally spaced grid; for At the moment The numerical solution at Indicates time The estimated change in is a Gaussian white noise random process at time With the moment The difference between the values;

[0046] make The value of gradually approaches 0 from 1, and the numerical format is used to solve the system of stochastic differential equations until , () represents the expected function, Indicates time The external information of underwater gravity measurement that eliminates external errors, then is the solution of the stochastic differential equation system, Zhongmei The expected value of the number is calculated to obtain the external information of underwater gravity measurement that eliminates external errors.

[0047] The present invention also provides an error elimination system for underwater gravity measurement external information, which adopts the following technical solution: comprising: a data acquisition module, a white noise calculation module, a change amount estimation calculation module and an external information calculation module, wherein the data acquisition module is respectively connected to the white noise calculation module and the change amount estimation calculation module, and the external information calculation module is respectively connected to the white noise calculation module and the change amount estimation calculation module.

[0048] Data acquisition module, used to obtain external information of underwater gravity measurement;

[0049] A white noise calculation module, used to calculate the white noise standard deviation value according to the external information of underwater gravity measurement;

[0050] The change amount estimation calculation module is used to strip the measured wild value of the underwater gravity measurement external information, then perform Kalman filtering, and then calculate the change amount estimation of the measurement value of the underwater gravity measurement external information at any time relative to the measurement value at the initial time;

[0051] The external information calculation module is used to construct a group of random differential equations according to the white noise standard deviation value and the estimated value of the variation, solve the group of random differential equations, and obtain the external information of underwater gravity measurement that eliminates the external error.

[0052] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0053] Compared with the single Kalman filtering method, the random differential equation group model containing white noise and measurement wild values ​​proposed in the present invention can consistently establish a random process for the physical quantities measured by external information. By solving the random differential equations and performing expectation estimation, the white noise and measurement wild values ​​in the measurement process are converted into expectations with overall properties. This can avoid the amplification of local external information errors caused by large deviations from outliers, which in turn has a negative impact on the accuracy of gravity measurements, thereby improving the accuracy of underwater gravity measurements.

[0054] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1 It is a schematic diagram of underwater gravity measurement information flow in the prior art.

[0057] Figure 2 It is a flow chart of the method provided by the present invention.

[0058] Figure 3 It is a structural block diagram of the system provided by the present invention.

[0059] Reference numerals:

[0060] 1. Data acquisition module; 2. White noise calculation module; 3. Change estimation calculation module; 4. External information calculation module. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0062] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0063] Combine the following Figure 2 and Figure 3 The present invention is further described in detail, and a method and system for eliminating errors of external information of underwater gravity measurement of the present invention are described as follows:

[0064] In this embodiment, Figure 2 As shown, a method for eliminating errors of external information of underwater gravity measurement is provided, comprising the following steps:

[0065] Step 1: Obtain external information of underwater gravity measurement.

[0066] The underwater gravity measurement external information includes depth information, latitude information and northeast sky speed information. Represents depth information, which is measured by a depth sensor. Indicates latitude information, which is measured by the inertial navigation system. Northeast sky speed information includes east speed relative to the ground , North speed and ground speed ,make ,but It represents the Northeast Sky Speed ​​information, which is measured by DVL. , Indicates a moment, Indicates the total number of moments.

[0067] Step 2: Calculate the standard deviation of white noise based on the external information of underwater gravity measurement.

[0068] On the basis of retaining the measured wild values, the standard deviation of the depth information, the standard deviation of the latitude information and the standard deviation of the northeast sky speed information are calculated respectively according to the depth information, the latitude information and the northeast sky speed information as the white noise standard deviation value of the depth information, the white noise standard deviation value of the latitude information and the white noise standard deviation value of the northeast sky speed information.

[0069] Since the underwater gravity measurement external information obtained is data from a long measurement period, if the standard deviation is calculated using the entire data, the calculation result will not be accurate enough. Therefore, it is necessary to first divide the underwater gravity measurement external information into multiple intervals of equal size, and then calculate the standard deviation of the data in each interval, and then calculate the standard deviation of the data in the entire time period as the white noise standard deviation value.

[0070] The specific process is:

[0071] According to the depth information, latitude information and Northeast Sky Speed ​​information, each time is divided into an interval, and we get

[0072] …(5)

[0073] in, Indicates The depth information of each interval, Indicates The latitude information of the interval, Indicates Northeast Skyspeed information for each section, Indicates time The depth information, Indicates time The latitude information, Indicates time Northeast Skyspeed Information, for Divide by The remainder of Indicates the total number of moments;

[0074] For each interval of underwater gravity measurement external information, the drift rate of the interval value is linearly fitted and the drift is removed. Then the mean and standard deviation of the underwater gravity measurement external information of each interval are calculated to obtain , , , , and ,in, Indicates The mean of the depth information of the intervals, Indicates The standard deviation of the depth information in each interval, Indicates The mean of the latitude information of the intervals, Indicates The standard deviation of the latitude information of each interval, Indicates The mean value of the Northeast Sky Speed ​​information in the interval, Indicates The standard deviation of the Northeast Skyspeed information in the interval;

[0075] Calculate the standard deviation of white noise using the following formula:

[0076] …(6)

[0077] in, The standard deviation of white noise representing depth information, The standard deviation of white noise representing latitude information, Represents the standard deviation of white noise of Northeast Skyspeed information.

[0078] Generally, the data files generated by underwater gravity measurement are mostly at 1s intervals, that is, , each minute can be divided into an interval, that is .

[0079] Step 3: stripping the measured wild values ​​of the underwater gravity measurement external information, and then performing Kalman filtering, and then calculating to obtain an estimated value of the change of the measured value of the underwater gravity measurement external information at any time relative to the measured value at the initial time.

[0080] The measured wild values ​​are respectively selected from the depth information, latitude information and northeast sky speed information, and the measured wild values ​​are replaced with the mean to obtain the depth information, latitude information and northeast sky speed information without measured wild values. The depth information, latitude information and northeast sky speed information without measured wild values ​​are respectively subjected to Kalman filtering to obtain the measured values ​​of the depth information, latitude information and northeast sky speed information, and then the estimated values ​​of the changes of the measured values ​​of the depth information, latitude information and northeast sky speed information at any time relative to the measured values ​​at the initial time are respectively calculated.

[0081] When screening and replacing measured wild values, in order to ensure the accuracy of the calculation, the underwater gravity measurement external information is divided into intervals using the same method as step 2, and the mean and standard deviation of the underwater gravity measurement external information in each interval are calculated. The specific process is not repeated here, and the , , , , and The specific process of this step is:

[0082] For depth information, each depth information is judged. If the The depth information within the interval is If it is not included, the depth information is determined to be a measurement outlier and replaced with After all the measured wild values ​​of the depth information are screened and replaced, the depth information of all intervals is spliced ​​together in chronological order and Kalman filtering is performed to obtain the measured value of the depth information. ,in ; Using spline interpolation, Extend to , R represents the real number domain; calculate the estimated value of the change of the measured value of the depth information at any time relative to the measured value at the initial time , , Indicates time depth information. is the first moment, i.e. the initial moment.

[0083] Similarly, for latitude information, each latitude information is judged. If the The latitude information within the interval is If the latitude information is outside the range, it is determined to be a wild value and replaced by After all the measured wild values ​​of the latitude information are screened and replaced, the latitude information of all intervals is spliced ​​together in chronological order, and Kalman filtering is performed to obtain the measured values ​​of the latitude information. ,in ; Using spline interpolation, Extend to ; Calculate the estimated value of the change of the measured value of the latitude information at any time relative to the measured value at the initial time , , Indicates time The latitude information.

[0084] For the Northeast Skyspeed information, each Northeast Skyspeed information is judged. If the Northeast Tiansu information in the interval is If the information is not included, the Northeast Skyspeed information is determined to be a wild value and replaced by After all the measured wild values ​​of the Northeast Skyspeed information are screened and replaced, the Northeast Skyspeed information of all intervals are spliced ​​together in chronological order, and Kalman filtering is performed to obtain the measured values ​​of the Northeast Skyspeed information ,in ; Using spline interpolation, Extend to ; Calculate the estimated value of the change of the measured value of the Northeast Skyspeed information at any time relative to the measured value at the initial time , , Indicates time Northeast Skyspeed Information.

[0085] Step 4: Construct a set of stochastic differential equations based on the white noise standard deviation and the estimated value of the variation, solve the set of stochastic differential equations, and obtain the external information of underwater gravity measurement that eliminates external errors.

[0086] Each underwater gravity measurement external information can be regarded as a random process consisting of two parts, one is the estimated value of the change obtained in step 3, and the other is the standard deviation of the white noise in the measurement process obtained in step 2. Based on the above idea, the following set of stochastic differential equations can be constructed for the underwater gravity measurement external information:

[0087] …(7)

[0088] in, is called the drift term of the stochastic differential equation system, is called the diffusion term of the stochastic differential equation system, represents the external information of underwater gravity measurement with external errors eliminated, represents the estimated value of the change, , ; It means that the mean is 0 and the standard deviation is , and (corresponding to , , ) is a Gaussian white noise random process.

[0089] The Euler-Mauryama method is used to construct the numerical format of formula (7):

[0090] …(8)

[0091] in, , For the general The time interval for equidistant grid division is: ; for At the moment The numerical solution at Indicates time The estimated change in is a Gaussian white noise random process at time With the moment The difference in values.

[0092] According to the strong convergence theorem, when Enough hours to have: , is greater than 0 and does not depend on The constant, () represents the expected function. Therefore, let The value of gradually approaches 0 from 1, and the numerical format of formula (8) is used to solve the stochastic differential equation system until , Indicates time The external information of underwater gravity measurement that eliminates external errors, then is the solution of the stochastic differential equation system. Zhongmei By finding the expected value of the number of (data length is 1s), the external information of underwater gravity measurement with external errors eliminated can be obtained.

[0093] Substituting the external information of underwater gravity measurement with external errors eliminated calculated in step 4 into formula (2) can calculate the gravity anomaly value.

[0094] The present invention calculates the standard deviation of each minute data of each underwater gravity measurement external information (latitude, depth, northeast sky speed, etc.) on the basis of retaining the measured wild values, and averages all one-minute measurement standard deviations obtained from the same data, and regards the result as the white noise standard deviation of the physical quantity measurement, as the diffusion term of the subsequent stochastic differential equation model; at the same time, the measured wild values ​​of each underwater gravity measurement external information are stripped, and the underwater gravity measurement external information after the measured wild values ​​are stripped is Kalman filtered to obtain the change of the measured value of each underwater gravity measurement external information at any time relative to the measured value at the initial time The estimated value is used as the drift term of the subsequent stochastic differential equation model; finally, the external information of underwater gravity measurement is regarded as a random process containing white noise, and the random process is regarded as the quantity to be solved, and a stochastic differential equation is established for it. The Euler-Mauryama method is used to establish the numerical solution format of the stochastic differential equation. By numerically solving the above stochastic differential equations and making an expected estimate of the external information of underwater gravity measurement every second in the numerical solution, the actual physical process of each underwater gravity measurement external information is restored to eliminate the errors caused by noise and measurement wild values ​​during the measurement of each underwater gravity measurement external information. Compared with the single Kalman filtering method adopted in the prior art, the random differential equation group model containing white noise and measurement wild values ​​proposed in the present invention can consistently establish a random process for the physical quantities measured by the external information of underwater gravity measurement. By solving the random differential equations and performing expectation estimation, the white noise and measurement wild values ​​in the measurement process are converted into expectations with overall properties, which can avoid the amplification of local external information errors caused by large deviations from outliers, thereby negatively affecting the accuracy of gravity measurements.

[0095] In this embodiment, Figure 3 As shown, there is also provided an error elimination system for external information of underwater gravity measurement, and the technical scheme adopted is as follows: comprising: a data acquisition module 1, a white noise calculation module 2, a change estimation calculation module 3 and an external information calculation module 4, wherein the data acquisition module 1 is respectively connected to the white noise calculation module 2 and the change estimation calculation module 3, and the external information calculation module 4 is respectively connected to the white noise calculation module 2 and the change estimation calculation module 3.

[0096] The data acquisition module 1 is used to obtain underwater gravity measurement external information and send the underwater gravity measurement external information to the white noise calculation module 2 and the change amount estimation calculation module 3. The underwater gravity measurement external information includes depth information, latitude information and northeast sky speed information.

[0097] The white noise calculation module 2 is used to calculate the white noise standard deviation value according to the underwater gravity measurement external information; and send the white noise standard deviation value to the external information calculation module 4.

[0098] The change amount estimation calculation module 3 is used to strip the measured wild value of the underwater gravity measurement external information, and then perform Kalman filtering, and then calculate the estimated value of the change of the measured value of the underwater gravity measurement external information at any time relative to the measured value at the initial time; and send the estimated value of the change to the external information calculation module 4.

[0099] The external information calculation module 4 is used to construct a group of random differential equations based on the white noise standard deviation value and the estimated value of the variation, solve the group of random differential equations, and obtain the external information of underwater gravity measurement that eliminates the external error. The external information of underwater gravity measurement that eliminates the external error includes depth information, latitude information, and northeast sky speed information that eliminates the white noise and measurement wild value errors. The external information calculation module 4 outputs the external information of underwater gravity measurement that eliminates the external error to the mathematical model (scalar form) of underwater gravity measurement, and combines the celestial specific force in the mathematical model (scalar form) of underwater gravity measurement. , and calculate the gravity anomaly value.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for eliminating errors in external information of underwater gravity measurement, characterized in that: include: Obtain external information of underwater gravity measurement; The standard deviation of white noise is calculated based on the external information of underwater gravity measurement; The measured wild values ​​of the external information of underwater gravity measurement are stripped, and then Kalman filtering is performed, and then the estimated value of the change of the measured value of the external information of underwater gravity measurement at any time relative to the measured value at the initial time is calculated; A set of stochastic differential equations is constructed according to the standard deviation of white noise and the estimated value of variation. The stochastic differential equations are solved to obtain the external information of underwater gravity measurement with external errors eliminated.

2. A method for eliminating errors in external information of underwater gravity measurement according to claim 1, characterized in that: The process of calculating the white noise standard deviation value according to the external information of underwater gravity measurement is as follows: the underwater gravity measurement external information includes depth information, latitude information and northeast sky speed information. On the basis of retaining the measured wild value, according to the depth information, latitude information and northeast sky speed information, the standard deviation of the depth information, the standard deviation of the latitude information and the standard deviation of the northeast sky speed information are calculated respectively as the white noise standard deviation value of the depth information, the white noise standard deviation value of the latitude information and the white noise standard deviation value of the northeast sky speed information.

3. A method for eliminating errors in external information of underwater gravity measurement as claimed in claim 2, characterized in that: According to the depth information, latitude information and Northeast Sky Speed ​​information, each time is divided into an interval, and we get in, Indicates The depth information of each interval, Indicates The latitude information of the interval, Indicates Northeast Skyspeed information for the interval, Indicates time The depth information, Indicates time The latitude information, Indicates time Northeast Skyspeed Information, for Divide by The remainder of Indicates the total number of moments; For each interval of underwater gravity measurement external information, the drift rate of the interval value is linearly fitted and the drift is removed. Then the mean and standard deviation of the underwater gravity measurement external information of each interval are calculated to obtain , , , , and ,in, Indicates The mean of the depth information of the intervals, Indicates The standard deviation of the depth information of the interval, Indicates The mean of the latitude information of the intervals, Indicates The standard deviation of the latitude information of each interval, Indicates The mean value of the Northeast Sky Speed ​​information in the interval, Indicates The standard deviation of the Northeast Skyspeed information in the interval; Calculate the standard deviation of white noise using the following formula: in, The standard deviation of white noise representing depth information, The standard deviation of white noise representing latitude information, Represents the standard deviation of white noise of Northeast Skyspeed information.

4. A method for eliminating errors in external information of underwater gravity measurement as claimed in claim 3, characterized in that: The measurement interval of the depth information, latitude information and northeast sky speed information is 1s. is 60.

5. The method for eliminating errors in external information of underwater gravity measurement according to claim 1, characterized in that: The process of stripping the measured wild values ​​of the external information of underwater gravity measurement, then performing Kalman filtering, and then calculating the estimated value of the change of the measured value of the external information of underwater gravity measurement at any time relative to the measured value at the initial time is as follows: respectively filter out the measured wild values ​​from the depth information, latitude information and northeast sky speed information, replace the measured wild values ​​with the mean value, and obtain the depth information, latitude information and northeast sky speed information without measured wild values; perform Kalman filtering on the depth information, latitude information and northeast sky speed information without measured wild values ​​to obtain the measured values ​​of the depth information, latitude information and northeast sky speed information, and then respectively calculate the estimated value of the change of the measured value of the depth information, latitude information and northeast sky speed information at any time relative to the measured value at the initial time.

6. A method for eliminating errors in external information of underwater gravity measurement as claimed in claim 3, characterized in that: The process of stripping the measured wild value of the external information of underwater gravity measurement, performing Kalman filtering, and then calculating the estimated value of the change of the measured value of the external information of underwater gravity measurement at any time relative to the measured value at the initial time is as follows: If the first The depth information within the interval is If it is not included, the depth information is determined to be a measurement outlier and replaced with ; The depth information of all intervals is stitched together in chronological order, and Kalman filtering is performed to obtain the measured value of the depth information ,in Indicates a moment, ; Using spline interpolation, Extend to , R represents the real number domain; calculate the estimated value of the change of the measured value of the depth information at any time relative to the measured value at the initial time , , Indicates time Depth information; If the first The latitude information within the interval is If the latitude information is outside the range, it is determined to be a wild value and replaced by ; Splice the latitude information of all intervals together in chronological order, perform Kalman filtering, and obtain the measured value of the latitude information ,in ; Using spline interpolation, Extend to ; Calculate the estimated value of the change of the measured value of the latitude information at any time relative to the measured value at the initial time , , Indicates time Latitude information; If the first Northeast Tiansu information in the interval is If the information is not included, the Northeast Skyspeed information is determined to be a wild value and replaced by ; Splice the Northeast Skyspeed information of all intervals together in chronological order, perform Kalman filtering, and obtain the measured value of the Northeast Skyspeed information ,in ; Using spline interpolation, Extend to ; Calculate the estimated value of the change of the measured value of the Northeast Skyspeed information at any time relative to the measured value at the initial time , , Indicates time Northeast Skyspeed Information.

7. A method for eliminating errors in external information of underwater gravity measurement as claimed in claim 6, characterized in that: The process of constructing a set of stochastic differential equations based on the standard deviation of white noise and the estimated value of the variation, solving the set of stochastic differential equations, and obtaining the external information of underwater gravity measurement that eliminates external errors is as follows: System of stochastic differential equations: in, represents the external information of underwater gravity measurement with external errors eliminated, represents the estimated value of the change, , ; It means that the mean is 0 and the standard deviation is , and Gaussian white noise random process; The numerical format for constructing the stochastic differential equation system using the Euler-Mauryama method is: in, , For the general The time interval of the equally spaced grid; for At the moment The numerical solution at Indicates time The estimated change in is a Gaussian white noise random process at time With the moment The difference between the values; make The value of gradually approaches 0 from 1, and the numerical format is used to solve the system of stochastic differential equations until , () represents the expected function, Indicates time The external information of underwater gravity measurement that eliminates external errors, then is the solution of the stochastic differential equation system, In each The expected value of the number is calculated to obtain the external information of underwater gravity measurement that eliminates external errors.

8. A system for eliminating errors in external information of underwater gravity measurement, characterized in that: The method for eliminating the error of external information of underwater gravity measurement according to any one of claims 1 to 7 comprises: a data acquisition module, a white noise calculation module, a variation estimation calculation module and an external information calculation module, wherein the data acquisition module is respectively connected to the white noise calculation module and the variation estimation calculation module, and the external information calculation module is respectively connected to the white noise calculation module and the variation estimation calculation module. Data acquisition module, used to obtain external information of underwater gravity measurement; A white noise calculation module, used to calculate the white noise standard deviation value according to the external information of underwater gravity measurement; The change amount estimation calculation module is used to strip the measured wild value of the underwater gravity measurement external information, then perform Kalman filtering, and then calculate the change amount estimation of the measurement value of the underwater gravity measurement external information at any time relative to the measurement value at the initial time; The external information calculation module is used to construct a group of random differential equations according to the white noise standard deviation value and the estimated value of the variation, solve the group of random differential equations, and obtain the external information of underwater gravity measurement that eliminates the external error.

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