Data processing method for horizontal component of dynamic gravity vector measured by strapdown

Abstract

The application discloses a kind of data processing methods of dynamic gravity vector horizontal component measurement of strapdown, belong to dynamic gravity measurement technical field.The application shields the influence of horizontal accelerometer measurement error and horizontal gravity disturbance to horizontal attitude solution using Gyros / GNSS attitude solution method, it is a kind of data processing methods of dynamic gravity vector horizontal component measurement of strapdown, which realizes the closed-loop coupling error decoupling of horizontal gravity disturbance.The low-frequency trend error of horizontal gravity disturbance of effective measuring line is corrected in the application endpoint and slope;Endpoint correction and slope correction need to use the true value of horizontal gravity disturbance of two endpoints of effective measuring line as reference point, and effective measuring line refers to the effective data segment left after discarding the larger result of measuring error at both ends of measuring line.The application solves the problem of unknown measurement target affecting measurement result, makes the complex error coupling situation simple and clear;The low-frequency trend error of horizontal gravity disturbance is corrected using the true value of horizontal gravity disturbance of two endpoints of effective measuring line as reference point, and the absolute measurement of dynamic gravity vector horizontal component of strapdown is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of dynamic gravity measurement. BACKGROUND

[0002] At present, the data processing of the strapdown dynamic gravity scalar measurement by the direct difference method has been relatively mature, and has been widely applied in the field of earth gravity field mapping, but the strapdown dynamic gravity vector measurement by the direct difference method has not been well solved, and the following problems will be faced in the data processing of the horizontal component: the horizontal gravity disturbance causes the gravity disturbance measurement error in the direction as the medium of the attitude error, forms the closed loop coupling error propagation chain of the horizontal gravity disturbance, and causes the problem that the unknown measurement target affects its own measurement result.

[0003] In this error propagation chain, the measurement error is caused by the measurement target itself, the horizontal gravity disturbance is unknown as the target of the strapdown dynamic gravity vector measurement, and the measurement error is caused by the measurement target itself, which directly leads to: the error propagation chain related to the horizontal gravity disturbance forms a coupled closed loop, which greatly increases the difficulty of the data processing of the horizontal component of the strapdown dynamic gravity vector measurement. Therefore, corresponding measures need to be taken to decouple the closed loop error propagation chain related to the horizontal gravity disturbance, solve the problem that the unknown measurement target affects the measurement result, reduce the difficulty of the subsequent data processing, and improve the solving accuracy of the horizontal gravity disturbance. SUMMARY

[0004] The application shields the influence of the horizontal accelerometer measurement error and the horizontal gravity disturbance on the horizontal attitude solution by using the Gyros / GNSS attitude solution method, and is a strapdown dynamic gravity vector horizontal component measurement data processing method which realizes the decoupling of the closed loop coupling error of the horizontal gravity disturbance.

[0005] The application performs endpoint correction and slope correction on the low-frequency trend error of the horizontal gravity disturbance of the effective measurement line; the endpoint correction and the slope correction need to use the true value of the horizontal gravity disturbance of the two endpoints of the effective measurement line as the reference point, the effective measurement line refers to the effective data segment remaining after discarding the measurement error of the two ends of the measurement line; the specific implementation mode of the endpoint correction is to take the true value of the horizontal gravity disturbance of point A1 as the reference, use the difference between points A1 and A2 to obtain the constant deviation and compensate it; the specific implementation mode of the slope correction is to take the true value of the horizontal gravity disturbance of points A1 and B1 as the reference, use the following formula to obtain the slope of the linear growth deviation and compensate it:

[0006]

[0007] Wherein, k represents the slope of linear growth bias, B3 and A2 represent the horizontal gravity disturbance measurement values of two end points of the effective measuring line respectively, B1 and A1 represent the horizontal gravity disturbance true values of the corresponding points respectively, and pos(B)-pos(A) represents the position difference between the positions of two end points B and A of the effective measuring line.

[0008] The application solves the problem of unknown measurement target affecting measurement results, makes the complex error coupling situation simple and clear, uses the horizontal gravity disturbance true values of two end points of the effective measuring line as reference points, corrects the low-frequency trend error of the horizontal gravity disturbance, and realizes the absolute measurement of the horizontal component of the strapdown dynamic gravity vector. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 The method flowchart of the application;

[0010] Figure 2 The schematic diagram of end point correction and slope correction of the application;

[0011] Figure 3 The measuring line track diagram of the vehicle test;

[0012] Figure 4a The direct solving result diagram of the east direction of the traditional method;

[0013] Figure 4b The direct solving result diagram of the north direction of the traditional method;

[0014] Figure 5a The solving result diagram of the east direction of the method proposed by the application;

[0015] Figure 5b The solving result diagram of the north direction of the method proposed by the application. DETAILED DESCRIPTION

[0016] The application comprises two main steps of 'horizontal gravity disturbance closed-loop error propagation chain decoupling' and 'horizontal gravity disturbance low-frequency trend error correction'.

[0017] I. 'Horizontal gravity disturbance closed-loop error propagation chain decoupling'

[0018] Step 1: solving the attitude of the gravity vector instrument by the Gyros / GNSS method;

[0019] Step 2: projecting the measurement results of the three-axis accelerometer of the gravity vector instrument to the local geographic coordinate system by using the above attitude, and obtaining the projection results in the horizontal direction;

[0020] Step 3: performing carrier acceleration correction and Eotvos correction on the horizontal projection results;

[0021] Step 4: Continue low-pass filtering on the above result to obtain the horizontal gravity disturbance closed-loop error propagation chain decoupled gravity vector solution.

[0022] II. "Horizontal gravity disturbance low-frequency trend error correction"

[0023] Step 1: Cut the continuous solution into piecewise independent effective measurement lines.

[0024] Step 2: Perform endpoint correction and slope correction on the horizontal gravity disturbance low-frequency trend error of the effective measurement line. The constant deviation of the horizontal specific force is eliminated by endpoint correction, and the linear growth deviation of the horizontal specific force is eliminated by slope correction.

[0025] Step 3: Obtain the gravity vector solution after horizontal gravity disturbance low-frequency trend error correction.

[0026] Through the above steps, the measurement result of the horizontal component of the strapdown dynamic gravity vector can be calculated.

[0027] Figure 2 This paper mainly explains the "endpoint correction and slope correction" in the "horizontal gravity disturbance low-frequency trend error correction".

[0028] In the figure, from top to bottom, curve A1B1 (dotted line) represents the true value of the horizontal gravity disturbance, curve A2B2 (dashed line) represents the horizontal gravity disturbance solution containing constant deviation, and curve A2B3 (solid line) represents the horizontal gravity disturbance solution containing constant deviation and linear growth deviation.

[0029] Curve A1B1 is the final solution target, which is the true value;

[0030] Curve A2B2 is an intermediate state, which contains constant deviation;

[0031] Curve A2B3 is the direct measurement value, which contains constant deviation and linear growth deviation.

[0032] The constant deviation causes the curve A2B2 to produce a parallel shift based on the curve A1B1, that is, the segment A1-A2 (B1-B2), and the linear growth deviation causes the curve A2B3 to produce a slope shift based on the curve A2B2, that is, the difference θ between the slope angles of baseline 3 and baseline 4.

[0033] According to this feature, reverse correction is performed.

[0034] Endpoint correction: Take the true value of the horizontal gravity disturbance at point A1 as the reference, and subtract the direct measurement value at point A2 from the true value at point A1 to obtain the constant deviation and compensate for it.

[0035] Slope correction: taking the horizontal gravity disturbance true value of A1 and B1 as reference, using the direct measurement value of A2 and B3, the slope of linear growth deviation is calculated by the following formula and compensated:

[0036]

[0037] Wherein, k represents the slope of linear growth deviation, B3 and A2 represent the horizontal gravity disturbance direct measurement value of the two end points of effective measuring line respectively, B1 and A1 represent the horizontal gravity disturbance true value of the corresponding points respectively, and pos(B)-pos(A) represents the position difference between the positions of the two end points B and A of effective measuring line.

[0038] Through the end point correction and slope correction, the constant deviation and linear growth deviation in the direct measurement value (curve A2B3) can be effectively eliminated, and the horizontal gravity disturbance true value (curve A1B1) on the whole effective measuring line can be calculated.

[0039] Experimental effect

[0040] The vehicle-borne strapdown gravity vector measurement test is carried out by using a certain type of gravity measurement system, and the practical use effect of the method is verified.

[0041] The measuring line trajectory of this test is shown in Figure 3 , in which the length of a single measuring line from the starting point to the ending point is about 30km, the measuring vehicle measures twice between the starting point and the ending point, and 4 repeated measuring line data are obtained, and the vehicle speed is kept at about 40km / h during the measuring process.

[0042] Comparison Figure 4a , 4b and Figure 5a , 5b It can be found that the calculation results of the traditional method δg E and δg N are relatively dispersed, although the details of the peak and valley are similar, but the overall trend changes are not consistent, while the calculation results of the method proposed by the application δg E and δg N appear the same change trend, and the internal consistency is very high, which shows that the new method calculates the effective horizontal gravity disturbance result.

[0043] In summary, the application provides a strapdown dynamic gravity vector horizontal component measurement data processing method. The main implementation mode of the method is as follows: first, the attitude of the gravity vector instrument is solved by using the Gyros / GNSS method, the measurement results of the three-axis accelerometer of the gravity vector instrument are projected to the local geographic coordinate system by using the attitude, after the horizontal projection results are corrected by the carrier acceleration, the Eotvos correction and the low-pass filtering, the gravity vector solving results of the horizontal gravity disturbance closed loop error propagation chain decoupling are obtained; then, the effective measuring line is intercepted, the end point correction and the slope correction of the horizontal gravity disturbance low frequency trend error are performed by using the characteristics of the high linear fitting accuracy of the Gyros / GNSS horizontal attitude error, and the constant deviation and the linear growth deviation are eliminated respectively. By using the method provided by the application, the closed loop coupling problem that the measurement error of the unknown target to be measured affects the measurement results can be effectively solved, and the absolute measurement of the strapdown dynamic gravity vector horizontal component is realized.

[0044] Briefly, the application is completed by the following steps:

[0045] S1: horizontal gravity disturbance closed loop error propagation chain decoupling. First, the attitude of the gravity vector instrument is solved by using the Gyros / GNSS method, the measurement results of the three-axis accelerometer of the gravity vector instrument are projected to the local geographic coordinate system by using the attitude, after the horizontal projection results are corrected by the carrier acceleration, the Eotvos correction and the low-pass filtering, the gravity vector solving results of the horizontal gravity disturbance closed loop error propagation chain decoupling are obtained.

[0046] S2: horizontal gravity disturbance low frequency trend error correction. The effective measuring line is intercepted, the end point correction and the slope correction of the horizontal gravity disturbance low frequency trend error of the effective measuring line are performed by using the characteristics of the high linear fitting accuracy of the Gyros / GNSS horizontal attitude error, and the constant deviation and the linear growth deviation of the horizontal specific force are eliminated respectively, so that the gravity vector solving results after the horizontal gravity disturbance low frequency trend error correction are obtained.

Claims

1. A method of processing data from a strapdown dynamic gravity vector horizontal component measurement, the method comprising: The low-frequency trend error of the horizontal gravity disturbance of the effective measuring line is corrected by end point correction and slope correction; the end point correction and slope correction need to use the true value of the horizontal gravity disturbance of the two end points of the effective measuring line as the reference point, and the effective measuring line refers to the effective data segment left after discarding the results with larger measurement error at both ends of the measuring line; ​ The specific implementation mode of the end point correction is to take the true value of the horizontal gravity disturbance of point A1 as the reference, use the difference between points A1 and A2 to obtain the constant deviation and compensate it; the specific implementation mode of the slope correction is to take the true value of the horizontal gravity disturbance of points A1 and B1 as the reference, use the following formula to obtain the slope of the linear growth deviation and compensate it: Wherein, k represents the slope of the linear growth deviation, B3 and A2 respectively represent the horizontal gravity disturbance measurement values of the two end points of the effective measuring line, B1 and A1 respectively represent the true value of the horizontal gravity disturbance of the corresponding points, and pos(B)-pos(A) represents the position difference between the positions of the two end points B and A of the effective measuring line.

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