A gravity measurement filtering method, device, equipment and medium based on optimization of gravity field characteristic parameters

Abstract

The present invention discloses a gravity measurement filtering method, apparatus, device, and medium based on optimization of gravity field characteristic parameters, belonging to the field of gravity measurement technology. To ensure that the raw gravity measurement data can retain the changing gravity value after being processed by a low-pass filter, the cutoff frequency of the low-pass filter should be appropriately increased when the carrier enters an area with complex gravity field changes. The complexity of the gravity field changes can be calculated using a series of gravity field characteristic parameters using a global gravity field database, and the filter cutoff frequency is adjusted based on the calculated results. The present invention can be applied to gravity measurements in areas with complex gravity 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] Marine and airborne gravimeters can measure gravity information over a large area with high efficiency under dynamic base conditions. Since the 1980s, with the maturity of satellite navigation technology, inertial device technology, and inertial navigation system technology, marine and airborne gravimeters have made significant contributions to resource exploration and gravity mapping. However, due to the limitations of the measurement mechanism, obtaining accurate gravity measurements using marine and airborne gravimeters requires filtering the raw data 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 this filtering. However, in real-world situations, the gravity field in some special areas can vary rapidly and dramatically with spatial position. During the filtering process, these varying gravity values ​​are also treated as noise by the low-pass filter, reducing the accuracy of gravity measurements.

[0003] The basic principle that causes the complex changes in gravity values ​​to be treated as noise and removed by low-pass filters 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 response to 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 the multiple characteristic parameters are fused to obtain the 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 parameters are, the more drastic the change of the gravity field is, and the corresponding cutoff frequency is larger.

[0008] In some optional implementation schemes, 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:

[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, the 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 parameters, 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. 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) Aiming at the problem that the filter tends to filter out effective 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, so as to fully retain the gravity measurement values ​​with high frequency changes, and can more effectively retain the details of gravity measurements.

[0025] (2) Reduce the cutoff frequency in areas where the gravity field changes slowly, filtering out more high-frequency noise and motion noise. This improves the accuracy of gravity measurements while smoothing the raw gravity measurement results. This improves the filtering effect of high-frequency noise and motion noise in areas where gravity values ​​change 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 objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining 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 may 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 response to the problem that the setting of sea and air gravimeter filter parameters affects the accuracy of gravity measurement, the present invention proposes a gravity measurement filter parameter optimization method based on gravity field characteristic parameters. 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 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 by using 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 to retain more changing gravity measurement values, and the cutoff frequency is reduced in areas where the gravity field changes gently to filter out more high-frequency noise and motion noise. 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 through 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 reflecting the intensity of regional gravity field fluctuation. The calculation formula is as follows:

[0034]

[0035] Where G(i,j) represents the gravity value at the grid point coordinate (i,j).

[0036] (2) Roughness

[0037] Roughness r 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 respectively, r G is the overall roughness.

[0040] (3) Slope

[0041] Slope S G reflects the rate of change of the gravity field, and 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 the longitude and latitude directions 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 region. 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. Using the principal component analysis (PCA) method, the influence of each characteristic parameter is comprehensively considered 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 certain connections 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 are all linearly uncorrelated in this coordinate system, so as to achieve the purpose of using these latest variables to summarize the main aspects of a lot of information and retain 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 characteristic parameter x j The characteristic parameter indicators used in the present invention are: gravity field standard deviation, 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] Here, 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 characteristic 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 by:

[0067] The raw sensor signal usually contains a large amount of high-frequency noise and external disturbance noise. In engineering applications, the raw results of gravity measurement are generally filtered using a low-pass filter. Currently, the finite impulse response filter (FIR filter) is mainly used to achieve gravity measurement. The FIR filter can be equivalent to a difference 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 gravimeter spatial resolution d (also known as half-wavelength resolution) 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 settings 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 designed filter s The dimension of is Hz, and the comprehensive characteristic parameter T of gravity field is dimensionless statistical data. In order to facilitate the cutoff frequency f 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, that is, 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 are 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 gravity field characteristic parameters in the following ways:

[0080] When the gravimeter is in the current measurement area, the normalized gravity field comprehensive characteristic parameters Greater than the set threshold It can be considered that the gravity value of the current gravity field changes more dramatically, and the detailed information of the gravity field is more. In order to retain more detailed features of the measured gravity value, the cutoff frequency of the filter can be increased so that the small changes in the original measured gravity value can be retained. When the normalized gravity field comprehensive characteristic parameter of the current measurement area of ​​the gravimeter is 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 lowered 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 based on the characteristic parameter T of the gravity field is:

[0081]

[0082] in, Indicates the median of the normalized gravity field comprehensive characteristic parameters in the measurement area and the screening threshold of the gravity field comprehensive characteristic parameters In order to prevent the normalized cutoff frequency from being infinitely reduced, which would cause 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. Then the optimized filter cutoff frequency is calculated:

[0083]

[0084] This paper proposes a gravity measurement filtering method based on the optimization of gravity field characteristic parameters. This method integrates these characteristic parameters into the calculation of gravity measurement filter parameters, taking into account the rate of change and complexity of the gravity field. This method improves gravity measurement accuracy. By adaptively adjusting the cutoff frequency of the gravity measurement FIR filter based on these comprehensive characteristic parameters, the method provides smooth and accurate filtering results for gravity measurements.

[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 parameters, 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 having a computer program stored thereon, wherein the computer program implements the steps of any of the above methods when executed by a processor.

[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, or 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 merely 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 scope of protection 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 the multiple characteristic parameters are fused to obtain the 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. The method of performing feature analysis on the gravity field of the gravity measurement area based on the gravity database, calculating the 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.

2. The method according to claim 1, 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.

3. The method according to claim 2, 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.

4. The method according to claim 3, characterized in that Depend on According to the normalized gravity field comprehensive characteristic parameters of the current gravity measurement area, the 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, is the normalized cutoff frequency.

5. The method according to claim 4, characterized in that , set the median of the comprehensive characteristic parameters as the lower limit of the normalized cutoff frequency decrease.

6. The method according to claim 4 or 5, characterized in that Depend on Get the optimized filter cutoff frequency ,in, is the sampling frequency.

7. A gravity measurement filter device based on optimization of gravity field characteristic parameters, characterized in that: include: The feature analysis module is used to divide the gravity reference map into several gravity measurement areas and calculate the gravity field standard deviation, gravity field roughness, gravity field slope and gravity field information entropy of each gravity measurement area; The principal component analysis method is used to comprehensively consider the influence of gravity field standard deviation, gravity field roughness, gravity field slope and gravity field information entropy in each gravity measurement area, and the comprehensive characteristic parameters of gravity field in each gravity measurement area are obtained. 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 parameters, the more drastic the change of the gravity field, and the larger the corresponding cutoff frequency.

8. 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 6 when executing the computer program.

9. A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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