Gravity measurement filtering method, device and equipment based on gravity field characteristic parameter optimization and medium

Abstract

The invention discloses a gravity measurement filtering method, device and equipment based on gravity field characteristic parameter optimization, and a medium, belongs to the technical field of gravity measurement, and aims to enable gravity measurement original data to be processed by a low-pass filter to retain a changed gravity value. When a carrier enters a gravity field change complex area, the cut-off frequency of the low-pass filter should be properly increased. For the complexity of the gravitational field change, a global gravitational field database can be used for calculation through a series of gravitational field characteristic parameters, and the cut-off frequency of the filter is adjusted according to the calculation result. The method can be suitable for gravity measurement of areas with complex gravitational field changes.

Description

Technical Field

[0001] The present invention belongs to the field of gravity measurement technology, and more specifically, relates to a gravity measurement filtering method, device, equipment and medium based on optimization of gravity field characteristic parameters. Background Art

[0002] Sea and air gravimeters can measure gravity information in a large range and with high efficiency under the condition of a dynamic base. Since the 1980s, with the maturity of satellite navigation technology, inertial device technology, and inertial navigation system technology, sea and air gravimeters have made great contributions in resource exploration, gravity mapping, etc. However, due to the limitation of the measurement mechanism, in order to obtain accurate gravity measurement results through sea and air gravimeters, it is necessary to filter the original measurement data of sea and air gravimeters to remove errors caused by high-frequency noise and motion noise. In engineering applications, low-pass filters (Finite Impulse Response, FIR) are generally used for filtering. However, in actual situations, in some special areas, the gravity field will change rapidly and drastically with the spatial position. In the filtering process, these changing gravity values ​​will also be regarded as noise removal by the low-pass filter, which reduces the accuracy of gravity measurement.

[0003] The basic principle that causes the complex changing gravity values ​​to be treated as noise and removed by the low-pass filter is that the key design parameter of the low-pass filter is the cutoff frequency. Signals above the cutoff frequency in the signal input to the low-pass filter will be removed, and signals below the cutoff frequency will be retained. When the gravity field changes rapidly in the spatial dimension, the gravity values ​​measured by the carrier moving over time will also change rapidly. If the frequency of the gravity value fluctuation is higher than the cutoff frequency, it will be removed by the low-pass filter. Summary of the invention

[0004] In view of the problem that low-pass filters affect the gravity measurement accuracy of sea and air gravimeters in areas with complex gravity field changes, the present invention proposes a method, device, equipment and medium for optimizing the design parameters of gravity measurement filters based on gravity field characteristic parameters, which is suitable for gravity measurement in areas with complex gravity field changes.

[0005] To achieve the above object, according to one aspect of the present invention, a gravity measurement filtering method based on optimization of gravity field characteristic parameters is provided, comprising:

[0006] Based on the gravity database, the gravity field of the gravity measurement area is analyzed, the characteristic parameters of the gravity measurement area are calculated, and multiple characteristic parameters are fused to obtain comprehensive characteristic parameters;

[0007] The degree of change of the gravity field is measured by comprehensive characteristic parameters, and the cutoff frequency of the filter is designed according to the degree of change of the gravity field. The larger the comprehensive characteristic parameter, the more drastic the change of the gravity field, and the larger the corresponding cutoff frequency.

[0008] In some optional implementation schemes, the gravity field of the gravity measurement area is analyzed based on the gravity database, characteristic parameters of the gravity measurement area are calculated, and multiple characteristic parameters are fused to obtain comprehensive characteristic parameters, including:

[0009] The gravity reference map is divided into several gravity measurement areas, and the gravity field standard deviation, gravity field roughness, gravity field slope and gravity field information entropy of each gravity measurement area are calculated;

[0010] The principal component analysis method is used to comprehensively consider the influence of the gravity field standard deviation, gravity field roughness, gravity field slope and gravity field information entropy of each gravity measurement area, and the comprehensive characteristic parameters of the gravity field of each gravity measurement area are obtained.

[0011] In some optional implementation schemes, after obtaining the comprehensive characteristic parameters of the gravity field of each gravity measurement area, the method further includes:

[0012] The cutoff frequency of the filter and the comprehensive characteristic parameters of the gravity field of each gravity measurement area are normalized to obtain the normalized cutoff frequency and the normalized comprehensive characteristic parameters of the gravity field of each gravity measurement area.

[0013] In some optional implementation schemes, when the normalized gravity field comprehensive characteristic parameter of the gravimeter in the current gravity measurement area is greater than a set threshold, it is considered that the gravity value of the current gravity field changes more drastically, and the cutoff frequency of the filter is increased;

[0014] When the normalized gravity field comprehensive characteristic parameter of the gravimeter in the current gravity measurement area is less than the set threshold, it is considered that the gravity value of the current gravity field changes relatively slowly, and the cutoff frequency of the filter is reduced.

[0015] In some optional embodiments, According to the normalized gravity field comprehensive characteristic parameters of the current gravity measurement area, gravity field characteristic parameters Calculate the normalized cutoff frequency of the filter Represents the median of the comprehensive characteristic parameters of the normalized gravity field in the measurement area, To set the threshold, f w is the normalized cutoff frequency.

[0016] In some optional embodiments, The median of the comprehensive characteristic parameter is set as the lower limit of the normalized cutoff frequency decrease.

[0017] In some optional embodiments, Get the optimized filter cutoff frequency Among them, F s is the sampling frequency.

[0018] According to another aspect of the present invention, there is provided a gravity measurement filtering device based on optimization of gravity field characteristic parameters, comprising:

[0019] The feature analysis module is used to perform feature analysis on the gravity field of the gravity measurement area based on the gravity database, calculate the feature parameters of the gravity measurement area, and fuse multiple feature parameters to obtain comprehensive feature parameters;

[0020] The cutoff frequency design module is used to measure the degree of change of the gravity field through comprehensive characteristic parameters, and design the cutoff frequency of the filter according to the degree of change of the gravity field. The larger the comprehensive characteristic parameter, the more drastic the change of the gravity field, and the larger the corresponding cutoff frequency.

[0021] According to another aspect of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0022] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of any one of the above methods are implemented.

[0023] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0024] (1) In order to solve the problem that the filter tends to filter out valid gravity measurements as noise in areas with complex gravity value changes, a gravity measurement filter parameter optimization method based on the optimization of gravity field characteristic parameters is proposed. The gravity field characteristic parameters are used to evaluate the gravity field change rate and complexity, and the cutoff frequency is increased in areas with complex gravity field changes. The high-frequency gravity measurement values ​​are fully retained, which can more effectively retain the details of gravity measurements.

[0025] (2) Reduce the cutoff frequency in the area where the gravity field changes slowly, and filter out more high-frequency noise and motion noise. This improves the accuracy of gravity measurement while smoothing the original gravity measurement results. This improves the filtering effect of high-frequency noise and motion noise in the area where the gravity value changes slowly. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of a gravity measurement filtering method based on optimization of gravity field characteristic parameters provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] In the examples of the present invention, "first", "second", etc. are used to distinguish different objects rather than to describe a specific order or sequence.

[0029] In view of the problem that the setting of the filter parameters of the sea and air gravimeter affects the accuracy of gravity measurement, the present invention proposes a method for optimizing the gravity measurement filter parameters based on the characteristic parameters of the gravity field. When performing gravity measurement, the cutoff frequency of the gravity measurement FIR filter is calculated through indicators, and the original gravity measurement data is filtered to filter out high-frequency noise and motion noise. In areas where the gravity field changes complexly, some of the changing gravity measurement values ​​will also be regarded as noise and removed by the filter, resulting in the loss of some details of the gravity measurement value. Therefore, the present invention performs a characteristic analysis on the gravity field of the gravity measurement area based on the gravity database, calculates the characteristic parameters of the area, and fuses multiple characteristic parameters to obtain comprehensive characteristic parameters, and measures the degree of change of the gravity field through the comprehensive characteristic parameters. The cutoff frequency of the filter is optimized and designed using the comprehensive characteristic parameters, the cutoff frequency is increased in areas where the gravity field changes complexly, and more changing gravity measurement values ​​are retained, and the cutoff frequency is reduced in areas where the gravity field changes gently, and more high-frequency noise and motion noise are filtered out. Figure 1 shown.

[0030] Furthermore, assuming that the size of the gravity database is a p×q grid, the gravity reference map is divided into several m×n grid areas, the current actual gravity measurement area corresponds to one of the m×n grid areas, and G represents the gravity value at the grid point in the gravity database.

[0031] Among them, the measurement of gravity field characteristic parameters can be achieved by the following methods:

[0032] (1) Standard deviation

[0033] Gravity field standard deviation σ G It indicates the range of gravity value deviation from the average gravity value. It is a parameter that reflects the intensity of regional gravity field fluctuation. The calculation formula is as follows:

[0034]

[0035] Among them, G(i,j) represents the gravity value at the grid point coordinates (i,j).

[0036] (2) Roughness

[0037] Roughness G It reflects the average smoothness and local fluctuation of the regional gravity field. The greater the roughness, the more severe the local fluctuation of gravity. The calculation formula is as follows:

[0038]

[0039] Among them, r λ and r φ are the roughness in longitude and latitude, r G is the overall roughness.

[0040] (3) Slope

[0041] Slope S G reflects the rate of change of the gravity field, while the slope standard deviation σ S It reflects the fluctuation of the slope change rate, and the calculation formula is as follows:

[0042]

[0043] Among them, S λ and S φ are the slopes in longitude and latitude respectively; S G is the gravity field slope; is the average slope, σ S is the standard deviation of the slope.

[0044] (4) Information entropy

[0045] Gravitational field information entropy H G It reflects the amount of information contained in the gravity field of the area. The more drastic the change in gravity value, the richer the information, the smaller the calculated entropy value, and the more conducive to matching. The calculation formula is as follows:

[0046]

[0047] Among them, H G represents the gravity anomaly entropy; p ij represents the local difference probability; D(i,j) represents the gravity anomaly difference value.

[0048] (5) Fusion of gravity field characteristic parameters

[0049] Each characteristic parameter of the gravity field reflects the changing characteristics of the gravity field to varying degrees. The principal component analysis (PCA) method is used to comprehensively consider the influence of each characteristic parameter to obtain the comprehensive characteristic parameters of the gravity field, and then the filtering parameters are optimized based on the comprehensive characteristic parameters.

[0050] (a) The basic idea of ​​principal component analysis

[0051] Because each variable has some connection with each other and reflects the relevant information of the research problem to varying degrees, after the characteristic data statistics are completed, the information reflected by the obtained statistical data must overlap to a certain extent. Therefore, what principal component analysis needs to do is to try to transform these related variables into another different new coordinate system through linear transformation, so that the new variables obtained in this coordinate system are all linearly uncorrelated, so as to achieve the purpose of summarizing the main aspects of a lot of information with these latest variables and retaining the most important information in the data to the maximum extent.

[0052] (b) Implementation of the principal component analysis algorithm

[0053] Calculate the standardized sample feature parameter matrix X:

[0054]

[0055] Among them, X represents the observed k variable indicators x1, x2,…, x k The characteristic parameter information matrix of t grids; x ij represents the jth feature parameter x j The calculation result of the ith grid is obtained by calculating the characteristic parameter indexes used in the present invention: standard deviation of gravity field, roughness, slope, information entropy, so k=4, t=m·n.

[0056] Calculate the correlation matrix R of the standardized matrix:

[0057]

[0058] Calculate the eigenvalues ​​and eigenvectors of the correlation matrix R, calculate the eigenvalues ​​of the correlation matrix R, and arrange the obtained eigenvalues ​​from large to small λ1, λ2, …, λ k , and obtain the corresponding eigenvectors l1, l2, ..., l k , calculate the contribution rate α through the eigenvalue:

[0059]

[0060] Determine the number of principal components β according to the contribution rate:

[0061]

[0062] Wherein, min represents the set principal component contribution rate threshold, which can generally be set to 85%, 90% or 99%.

[0063] Linear transformation of characteristic data and evaluation of gravity measurement area:

[0064]

[0065] Among them, l j represents the jth eigenvector, X i Represents the i-th row element of the feature parameter data matrix, that is, X i =[x i1 x i2 …x ik ], T i represents the comprehensive evaluation index of the i-th gravity measurement area, that is, the comprehensive characteristic parameter, T i The larger the value, the more complex the gravity field changes and the more information there is. j is the j-th eigenvalue of the correlation matrix R.

[0066] Furthermore, the gravity measurement filtering method design can be achieved in the following ways:

[0067] The original sensor signal usually contains a large amount of high-frequency noise and external disturbance noise. In engineering applications, the original results of gravity measurement are generally filtered using a low-pass filter. At present, the finite impulse response filter (FIR filter) is mainly used to realize gravity measurement. The FIR filter can be equivalent to a differential equation form that is easy to encode and implement:

[0068]

[0069] Where: a k ,b k is the filter coefficient; M and N together constitute the filter order; x is the input gravity measurement sequence; y is the output gravity filter sequence.

[0070] In the actual design of the FIR filter, it is necessary to combine the spatial resolution d (or half-wavelength resolution) of the gravimeter to calculate the cutoff frequency of the FIR filter:

[0071]

[0072] Where: v is the horizontal movement speed of the carrier; f s is the filter cutoff frequency corresponding to an attenuation gain of -3dB.

[0073] Furthermore, the optimization of the gravity measurement filter parameter setting based on the gravity field characteristic parameters can be achieved in the following ways:

[0074] Since the cutoff frequency f is the parameter of the filter design s The dimension of is Hz, and the comprehensive characteristic parameter T of the gravity field is dimensionless statistical data. In order to facilitate the cutoff frequency f through the comprehensive characteristic parameter T s Adjustment is performed, and then the two parameters are normalized and dimensionless. Normalized cutoff frequency f w for:

[0075]

[0076] Among them, F s is the sampling frequency, i.e., the sampling frequency of the gravity measurement sequence x input to the filter. The normalized gravity field comprehensive characteristic parameters of the i-th gravity measurement area for:

[0077]

[0078] Among them, T min represents the smallest comprehensive characteristic parameter in the gravity database; T max Represents the largest comprehensive characteristic parameter in the gravity database. Normalized gravity field characteristic parameter The value range is [0,1].

[0079] Furthermore, the filter cutoff frequency can be optimized based on the characteristic parameters of the gravity field by the following methods:

[0080] When the gravimeter is in the normalized gravity field comprehensive characteristic parameters of the current measurement area Greater than the set threshold It can be considered that the gravity value of the current gravity field changes more dramatically, and there is more detailed information in the gravity field. In order to retain more detailed features of the measured gravity values, the cutoff frequency of the filter can be increased so that the slight changes in the original measured gravity values ​​can be retained. Less than the set threshold It can be considered that the gravity value of the current gravity field changes relatively slowly, and the cutoff frequency of the filter can be reduced to more thoroughly remove the high-frequency noise and external disturbance noise in the original measured gravity value. The normalized cutoff frequency of the filter calculated according to the characteristic parameter T of the gravity field is:

[0081]

[0082] in, Indicates the median of the normalized comprehensive characteristic parameters of the gravity field in the measurement area and the screening threshold of the comprehensive characteristic parameters of the gravity field In order to prevent the normalized cutoff frequency from being infinitely reduced, causing the filter to filter out all the fluctuation data, the median of the comprehensive characteristic parameter is set as the lower limit of the normalized cutoff frequency decrease. Then the optimized filter cutoff frequency is calculated:

[0083]

[0084] The present invention proposes a gravity measurement filtering method based on the optimization of gravity field characteristic parameters. According to the change rate and complexity of the gravity field, the gravity field characteristic parameters are integrated into the calculation of the parameters of the gravity measurement filter to improve the accuracy of gravity measurement. By adaptively adjusting the cutoff frequency of the gravity measurement FIR filter based on the comprehensive characteristic parameters, a smooth and accurate filtering result is provided for gravity measurement.

[0085] The present invention also provides a gravity measurement filtering device based on optimization of gravity field characteristic parameters, comprising:

[0086] The feature analysis module is used to perform feature analysis on the gravity field of the gravity measurement area based on the gravity database, calculate the feature parameters of the gravity measurement area, and fuse multiple feature parameters to obtain comprehensive feature parameters;

[0087] The cutoff frequency design module is used to measure the degree of change of the gravity field through comprehensive characteristic parameters, and design the cutoff frequency of the filter according to the degree of change of the gravity field. The larger the comprehensive characteristic parameter, the more drastic the change of the gravity field, and the larger the corresponding cutoff frequency.

[0088] The specific implementation of each module can refer to the description of the above method embodiment, and the embodiment of the present invention will not be repeated.

[0089] The present invention also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0090] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0091] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0092] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A gravity measurement filtering method based on optimization of gravity field characteristic parameters, characterized in that: include: Based on the gravity database, the gravity field of the gravity measurement area is analyzed, the characteristic parameters of the gravity measurement area are calculated, and multiple characteristic parameters are fused to obtain comprehensive characteristic parameters; The degree of change of the gravity field is measured by comprehensive characteristic parameters, and the cutoff frequency of the filter is designed according to the degree of change of the gravity field. The larger the comprehensive characteristic parameter, the more drastic the change of the gravity field, and the larger the corresponding cutoff frequency.

2. The method according to claim 1, characterized in that The method of performing feature analysis on the gravity field of the gravity measurement area based on the gravity database, calculating feature parameters of the gravity measurement area, and fusing multiple feature parameters to obtain comprehensive feature parameters includes: The gravity reference map is divided into several gravity measurement areas, and the gravity field standard deviation, gravity field roughness, gravity field slope and gravity field information entropy of each gravity measurement area are calculated; The principal component analysis method is used to comprehensively consider the influence of the gravity field standard deviation, gravity field roughness, gravity field slope and gravity field information entropy of each gravity measurement area, and the comprehensive characteristic parameters of the gravity field of each gravity measurement area are obtained.

3. The method according to claim 2, characterized in that After obtaining the comprehensive characteristic parameters of the gravity field of each gravity measurement area, the method further includes: The cutoff frequency of the filter and the comprehensive characteristic parameters of the gravity field of each gravity measurement area are normalized to obtain the normalized cutoff frequency and the normalized comprehensive characteristic parameters of the gravity field of each gravity measurement area.

4. The method according to claim 3, characterized in that When the normalized gravity field comprehensive characteristic parameter of the gravimeter in the current gravity measurement area is greater than the set threshold, it is considered that the gravity value of the current gravity field changes more drastically, and the cutoff frequency of the filter is increased; When the normalized gravity field comprehensive characteristic parameter of the gravimeter in the current gravity measurement area is less than the set threshold, it is considered that the gravity value of the current gravity field changes relatively slowly, and the cutoff frequency of the filter is reduced.

5. The method according to claim 4, characterized in that Depend on According to the normalized gravity field comprehensive characteristic parameters of the current gravity measurement area, gravity field characteristic parameters Calculate the normalized cutoff frequency of the filter Represents the median of the comprehensive characteristic parameters of the normalized gravity field in the measurement area, To set the threshold, f w is the normalized cutoff frequency.

6. The method according to claim 5, characterized in that The median of the comprehensive characteristic parameter is set as the lower limit of the normalized cutoff frequency decrease.

7. The method according to claim 5 or 6, characterized in that: Depend on Get the optimized filter cutoff frequency Among them, F s is the sampling frequency.

8. A gravity measurement filter device based on optimization of gravity field characteristic parameters, characterized in that: include: The feature analysis module is used to perform feature analysis on the gravity field of the gravity measurement area based on the gravity database, calculate the feature parameters of the gravity measurement area, and fuse multiple feature parameters to obtain comprehensive feature parameters; The cutoff frequency design module is used to measure the degree of change of the gravity field through comprehensive characteristic parameters, and design the cutoff frequency of the filter according to the degree of change of the gravity field. The larger the comprehensive characteristic parameter, the more drastic the change of the gravity field, and the larger the corresponding cutoff frequency.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method according to any one of claims 1 to 7.

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