Strapdown dynamic gravity vector horizontal component measurement data processing method

Abstract

The invention discloses a strapdown dynamic gravity vector horizontal component measurement data processing method, and belongs to the technical field of dynamic gravity measurement. According to the strapdown dynamic gravity vector horizontal component measurement data processing method disclosed by the invention, the influence of a horizontal accelerometer measurement error and horizontal gravity disturbance on horizontal attitude calculation is shielded by utilizing a Gyres / GNSS attitude calculation method, and the strapdown dynamic gravity vector horizontal component measurement data processing method realizes horizontal gravity disturbance closed-loop coupling error decoupling. According to the method, endpoint correction and slope correction are carried out on the horizontal gravity disturbance low-frequency trend error of the effective measuring line; end point correction and slope correction need to use horizontal gravity disturbance true values of two end points of an effective measuring line as reference points, and the effective measuring line refers to a remaining effective data segment after a result with a large measuring error at the two ends of the measuring line is abandoned. According to the method, the problem that an unknown measurement target affects a measurement result is solved, and the complex error coupling condition becomes simple and clear; the horizontal gravity disturbance true values of the two end points of the effective measuring line are used as reference points, the low-frequency trend error of the horizontal gravity disturbance is corrected, and absolute measurement of the horizontal component of the strapdown dynamic gravity vector is achieved.

Description

Technical field:

[0001] The invention belongs to the technical field of dynamic gravity measurement. Background technology:

[0002] At present, the "direct difference method" strapdown dynamic gravity scalar measurement data processing has developed to a relatively mature stage and has been widely used in the field of earth gravity field mapping. However, the "direct difference method" strapdown dynamic gravity vector measurement has not been well solved. When processing horizontal component data, it will face the following problems: horizontal gravity disturbance causes gravity disturbance measurement error in this direction through attitude error, forming a closed-loop coupled error propagation chain of horizontal gravity disturbance, resulting in the problem of unknown measurement targets affecting their own measurement results.

[0003] In this error propagation chain, the measurement error is caused by the measurement target itself. As the target of strapdown dynamic gravity vector measurement, horizontal gravity disturbance is unknown, and the measurement to be measured causes its own measurement error, which directly leads to: the error propagation chain related to horizontal gravity disturbance forms a coupled closed loop, which greatly increases the difficulty of processing the measurement data of the horizontal component of the strapdown dynamic gravity vector. Therefore, it is necessary to take corresponding measures to decouple the closed-loop error propagation chain related to horizontal gravity disturbance, solve the problem of unknown measurement targets affecting measurement results, reduce the difficulty of subsequent data processing, and improve the accuracy of solving horizontal gravity disturbance. Summary of the invention:

[0004] The present invention utilizes the Gyros / GNSS attitude solution method to shield the influence of horizontal accelerometer measurement error and horizontal gravity disturbance on horizontal attitude solution, and is a strapdown dynamic gravity vector horizontal component measurement data processing method that realizes the decoupling of horizontal gravity disturbance closed-loop coupling error.

[0005] The present invention performs endpoint correction and slope correction on the low-frequency trend error of the horizontal gravity disturbance of the effective survey line; the endpoint correction and the slope correction need to use the true values ​​of the horizontal gravity disturbance of the two endpoints of the effective survey line as reference points, and the effective survey line refers to the valid data segment remaining after the results with large measurement errors at both ends of the survey line are discarded; the specific implementation method of the endpoint correction is to use the true value of the horizontal gravity disturbance of point A1 as a reference, and use the difference between points A1 and A2 to obtain the constant deviation and compensate for it; the specific implementation method of the slope correction is to use the true values ​​of the horizontal gravity disturbance of points A1 and B1 as a reference, and use the following formula to obtain the slope of the linear growth deviation and compensate for it: Among them, k represents the slope of the linear growth deviation, B3 and A2 represent the measured values ​​of the horizontal gravity disturbance at the two endpoints of the effective survey line, B1 and A1 represent the true values ​​of the horizontal gravity disturbance at the corresponding points, and pos(B)-pos(A) represents the position difference between the B position and the A position of the two endpoints of the effective survey line.

[0006] The present invention solves the problem of unknown measurement targets affecting measurement results, making complex error coupling situations simple and clear; using the true values ​​of horizontal gravity disturbances at two end points of an effective measurement line as reference points, the low-frequency trend error of the horizontal gravity disturbance is corrected, and the absolute measurement of the horizontal component of the strapdown dynamic gravity vector is realized. Description of the drawings:

[0007] Figure 1 is a flow chart of the method of the present invention; Figure 2 It is a schematic diagram of endpoint correction and slope correction of the present invention; Figure 3 This is the measurement line trajectory diagram of the vehicle-mounted test; Figure 4a This is the result diagram of direct solution to the east direction using the traditional method; Figure 4b This is the result diagram of direct solution to the north direction using the traditional method; Figure 5a This is a diagram of the solution result of the method proposed in the present invention in the east direction; Figure 5b This is a diagram of the solution results for the north direction of the method proposed in the present invention. Specific implementation method:

[0008] The present invention comprises two main steps of "decoupling the closed-loop error propagation chain of horizontal gravity disturbance" and "correcting the low-frequency trend error of horizontal gravity disturbance".

[0009] 1. “Decoupling of the closed-loop error propagation chain of horizontal gravity disturbance” Step 1: Use the Gyros / GNSS method to calculate the attitude of the gravity vector instrument; Step 2: Use the above posture to project the measurement results of the gravity vector instrument's three-axis accelerometer into the local geographic coordinate system to obtain the horizontal projection results; Step 3: Carrier acceleration correction and Ertfos correction are performed on the horizontal projection results; Step 4: Continue to low-pass filter the above results to obtain the gravity vector solution result of the decoupling of the horizontal gravity disturbance closed-loop error propagation chain.

[0010] 2. “Correction of low-frequency trend errors of horizontal gravity disturbances” Step 1: Cut the continuous solution results into separate effective measurement lines; Step 2: Perform endpoint correction and slope correction on the low-frequency trend error of horizontal gravity disturbance of the effective survey line. The constant deviation of horizontal specific force is eliminated by endpoint correction, and the linear growth deviation of horizontal specific force is eliminated by slope correction. Step 3: Obtain the gravity vector solution result after correcting the low-frequency trend error of horizontal gravity disturbance.

[0011] The measurement results of the horizontal component of the strapdown dynamic gravity vector can be solved through the above steps.

[0012] Figure 2 This paper mainly explains the second step "endpoint correction and slope correction" in "correction of low-frequency trend error of horizontal gravity disturbance".

[0013] In the figure, from top to bottom, curve A1B1 (dotted line) represents the true value of horizontal gravity disturbance, curve A2B2 (dashed line) represents the solution result of horizontal gravity disturbance with constant deviation, and curve A2B3 (solid line) represents the solution result of horizontal gravity disturbance with constant deviation and linear growth deviation.

[0014] Curve A1B1 is the final solution target and is the true value; Curve A2B2 is an intermediate state, containing a constant deviation; Curve A2B3 is the direct measurement value, which includes constant deviation and linear growth deviation.

[0015] The constant deviation causes the curve A2B2 to have a parallel offset based on the curve A1B1, that is, the A1-A2 (B1-B2) segment, and the linear growth deviation causes the curve A2B3 to have a slope offset based on the curve A2B2, that is, the difference θ in the slope angles between the baseline 3 and the baseline 4.

[0016] In view of this feature, reverse correction is performed.

[0017] End point correction: Taking the true value of the horizontal gravity disturbance at point A1 as a reference, the direct measurement value at point A2 is subtracted from the true value at point A1 to obtain the constant deviation and compensate for it.

[0018] Slope correction: Taking the true value of horizontal gravity disturbance at points A1 and B1 as reference, using the direct measurement values ​​at points A2 and B3, the slope of the linear growth deviation is calculated and compensated using the following formula: Among them, k represents the slope of the linear growth deviation, B3 and A2 represent the direct measurement values ​​of the horizontal gravity perturbation at the two endpoints of the effective survey line, B1 and A1 represent the true values ​​of the horizontal gravity perturbation at the corresponding points, and pos(B)-pos(A) represents the position difference between the B position and the A position of the two endpoints of the effective survey line.

[0019] Through endpoint correction and slope correction, the constant deviation and linear growth deviation in the direct measurement value (curve A2B3) can be effectively eliminated, and the true value of the horizontal gravity disturbance on the entire effective measuring line can be solved (curve A1B1).

[0020] Experimental results A vehicle-mounted strapdown gravity vector measurement test was conducted using a certain type of gravity measurement system to verify the actual use effect of the method of the present invention.

[0021] The test line trajectory of this test is as follows: Figure 3 As shown in the figure, the length of a single measuring line from the starting point to the end point is about 30km. The measuring vehicle makes two round trip measurements between the starting point and the end point, and obtains data of 4 repeated measuring lines. During the measurement process, the vehicle speed is maintained at about 40km / h.

[0022] Compare Figure 4a , 4b and Figure 5a , 5b It can be found that the traditional method δg E and δg N The solution results of the method proposed in this invention are relatively scattered. Although the peaks and troughs of the details are similar, the overall trend of change is not the same. E and δg N The same trend of change appeared, and the internal consistency was very high, which shows that the new method has solved the effective horizontal gravity disturbance results.

[0023] In summary, the present invention provides a strapdown dynamic gravity vector horizontal component measurement data processing method. The main implementation mode of the method is: first, the posture of the gravity vector instrument is solved using the Gyros / GNSS method, and the measurement results of the gravity vector instrument's three-axis accelerometer are projected to the local geographic coordinate system using the posture. After the horizontal projection result is subjected to carrier acceleration correction, Ertfos correction and low-pass filtering, the gravity vector solution result of the horizontal gravity disturbance closed-loop error propagation chain decoupling is obtained; then, the effective survey line is intercepted, and the high linear fitting accuracy of the Gyros / GNSS horizontal attitude error is used to perform endpoint correction and slope correction on the low-frequency trend error of the horizontal gravity disturbance, and the constant deviation and linear growth deviation are eliminated respectively. The method provided by the present invention can effectively solve the closed-loop coupling problem of the unknown target to be measured causing the measurement error itself to affect the measurement result, and realize the absolute measurement of the strapdown dynamic gravity vector horizontal component.

[0024] In brief, the present invention is accomplished by the following steps: S1: Decoupling of closed-loop error propagation chain of horizontal gravity disturbance. First, the attitude of the gravity vector instrument is solved using the Gyros / GNSS method. The measurement results of the three-axis accelerometer of the gravity vector instrument are projected into the local geographic coordinate system using this attitude. After the horizontal projection results are corrected for carrier acceleration, Euterpe correction and low-pass filtering, the gravity vector solution results with decoupling of the closed-loop error propagation chain of horizontal gravity disturbance are obtained.

[0025] S2: Correction of low-frequency trend error of horizontal gravity disturbance. Intercept the effective survey line, and use the high linear fitting accuracy of Gyros / GNSS horizontal attitude error to perform endpoint correction and slope correction on the low-frequency trend error of horizontal gravity disturbance of the effective survey line, eliminate the constant deviation and linear growth deviation of horizontal specific force respectively, and obtain the gravity vector solution result after the correction of low-frequency trend error of horizontal gravity disturbance.

Claims

1. A strapdown dynamic gravity vector horizontal component measurement data processing method, characterized in that: Endpoint correction and slope correction are performed on the low-frequency trend error of horizontal gravity disturbance of the effective survey line. Endpoint correction and slope correction need to use the true value of horizontal gravity disturbance at the two endpoints of the effective survey line as reference points. The effective survey line refers to the valid data segment remaining after discarding the results with large measurement errors at both ends of the survey line. The specific implementation method of endpoint correction is to use the true value of the horizontal gravity disturbance at point A1 as a reference, and use the difference between points A1 and A2 to obtain the constant deviation and compensate for it; the specific implementation method of slope correction is to use the true value of the horizontal gravity disturbance at points A1 and B1 as a reference, and use the following formula to obtain the slope of the linear growth deviation and compensate for it: Among them, k represents the slope of the linear growth deviation, B3 and A2 represent the measured values ​​of the horizontal gravity disturbance at the two endpoints of the effective survey line, B1 and A1 represent the true values ​​of the horizontal gravity disturbance at the corresponding points, and pos(B)-pos(A) represents the position difference between the B position and the A position of the two endpoints of the effective survey line.

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