Geophysical field matching navigation suitability pre-analysis and real-time correction method

Abstract

The invention provides a geophysical field matching navigation suitability pre-analysis and real-time correction method. The method comprises the following steps: 1) a pre-analysis stage: estimating a first inertial navigation error according to estimated navigation information and inertial navigation parameters; determining the size of a pre-analysis search window according to the first inertial navigation error; carrying out suitability analysis in the pre-analysis search window, and carrying out track planning and navigation reference according to a suitability analysis result; 2) an actual navigation stage: estimating a second inertial navigation error according to real-time navigation information and inertial navigation parameters; determining the size of a real-time correction search window according to the second inertial navigation error; carrying out suitability analysis in the real-time correction search window; and according to the current suitability analysis result, carrying out real-time matching navigation on the matching point with the suitability meeting the requirement. By using the method, the precision of adaptability analysis and adaptive area selection can be improved, two different requirements of track planning and maneuvering navigation can be met, and the matching efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of navigation, guidance and control technology, and in particular to a geophysical field matching navigation adaptability pre-analysis and real-time correction method. Background Art

[0002] Navigation technology is one of the key technologies for sea, land and air navigation. It directly determines whether the vehicle can navigate safely and accurately reach the designated operating location. It is a key factor in determining the success or failure of the mission.

[0003] Inertial navigation is an autonomous, closed, all-weather navigation system that enables high-precision navigation in a short period of time, making it one of the most important navigation methods. However, due to the influence of its sensor characteristics and navigation algorithms, inertial sensor errors can accumulate during the navigation solution process, causing a continuous decrease in navigation accuracy. Therefore, when using inertial navigation systems for long-term navigation, they must be corrected using other navigation sensors or systems.

[0004] Geophysical field matching navigation can be divided into terrain matching navigation, gravity matching navigation and geomagnetic matching navigation according to different geophysical parameters. The basic principle is to compare the geophysical field background map accurately obtained in advance in the spacecraft with the geophysical field characteristics of the spacecraft's position continuously measured by the sensor to obtain the spacecraft's position.

[0005] Because geophysical field characteristics vary in richness across regions, it's necessary to leverage existing geophysical field data to identify suitable matching areas. Traditional compatibility analysis often fails to consider the impact of inertial navigation error characteristics and navigation state (trajectory, speed, attitude, etc.) on compatibility, resulting in inaccurate selection of the matching area. Furthermore, traditional methods don't modify the compatibility analysis results based on real-time navigation state. When the real-time navigation state differs significantly from the preset state, the original analysis results may become inapplicable. Therefore, traditional methods are not well suited for maneuvering navigation. Summary of the Invention

[0006] In view of this, the present invention provides a geophysical field matching navigation adaptability pre-analysis and real-time correction method, which can improve the accuracy of adaptability analysis and adaptation area selection, while adapting to the two different needs of track planning and maneuvering navigation, and improving matching efficiency.

[0007] In order to solve the above technical problems, the present invention is implemented as follows.

[0008] A geophysical field matching navigation adaptability pre-analysis and real-time correction method, the method comprising:

[0009] Pre-analysis phase: Estimate the first inertial navigation error based on the estimated navigation information and inertial navigation parameters; determine the size of the pre-analysis search window based on the first inertial navigation error; perform adaptability analysis within the pre-analysis search window, and perform track planning and navigation reference based on the adaptability analysis results;

[0010] Actual navigation phase: Estimate the second inertial navigation error based on real-time navigation information and inertial navigation parameters; determine the size of the real-time correction search window based on the second inertial navigation error; perform adaptability analysis within the real-time correction search window; and perform real-time matching navigation at matching points where the adaptability meets the requirements based on the current adaptability analysis results.

[0011] Preferably, in the pre-analysis stage, the first inertial navigation error is estimated based on different estimated navigation information and inertial navigation parameters, and adaptability analysis is performed to obtain different adaptation areas. The adaptation areas used for actual navigation are screened according to mission requirements; and the screened adaptation areas are used for track planning and navigation reference.

[0012] Preferably, in the pre-analysis stage, when determining the pre-analysis search window, for the case where the inertial navigation device is fixed on the carrier, the navigation trajectory is linearized in sections;

[0013] For straight segments, the linear velocity and linear acceleration are ignored, and the inertial navigation error of the straight segment is estimated using the inertial navigation error formula under static base conditions. When entering the next trajectory, the angular motion of the carrier is equivalent to the change in the projection of the gyro constant drift and accelerometer zero bias in the navigation coordinate system. The error equation of the inertial navigation system is equal to the error equation of the previous straight segment plus the error term generated by the change in gyro drift and accelerometer zero bias in the navigation coordinate system input at the trajectory transition point.

[0014] When analyzing the adaptability of a certain point P, the first inertial navigation error is determined according to the error equation of the straight line segment where the point P is located, and then the size of the pre-analysis search window is determined, and the adaptability analysis of the point P is performed using the pre-analysis search window.

[0015] Preferably, in the pre-analysis stage, the segmentation method is:

[0016] Case 1: When the trajectory is straight, keep the original trajectory;

[0017] Case 2: For curved trajectories, the curve is segmented so that the angle between the line connecting the two ends of each curve segment and any tangent of the curve segment is less than or equal to the threshold Agl thres , replace the curve segment with the line between the two endpoints;

[0018] Case 3: In case of broken line trajectory, the turning point is used as the trajectory segmentation point to divide the trajectory into multiple straight lines;

[0019] Case 4: During uniform circular motion, (1) if the angular frequency is greater than 2 times the Schuler frequency ω s , then only the error caused by the projection of the gyro constant drift and the accelerometer zero bias on the straight line where the central axis of the circular motion is located is considered, and the projection of the gyro constant drift and the accelerometer zero bias on the plane where the circular motion is located is ignored; (2) If the angular frequency of the motion is less than or equal to 2 times ω s , handle according to situation 2;

[0020] Case 5: Non-uniform or non-integer circular motion, handle as Case 2.

[0021] Preferably, during the actual navigation phase, when determining the search window, for a case where the inertial navigation device is fixed to the carrier, the navigation trajectory is segmented and linearized;

[0022] For straight segments, the linear velocity and linear acceleration are ignored, and the inertial navigation error of the straight segment is estimated using the inertial navigation error formula under static base conditions. When entering the next trajectory, the angular motion of the carrier is equivalent to the change in the projection of the gyro constant drift and accelerometer zero bias in the navigation coordinate system. The error equation of the inertial navigation system is equal to the error equation of the previous straight segment plus the error term generated by the change in gyro drift and accelerometer zero bias in the navigation coordinate system input at the trajectory transition point.

[0023] When analyzing the adaptability of a certain point P, the second inertial navigation error is determined according to the error equation of the straight line segment where the point P is located, and then the size of the real-time correction search window is determined. The real-time correction search window is used to perform adaptability analysis on the point P.

[0024] Preferably, during the actual navigation phase, the segmentation method is:

[0025] Take the segment time interval T that is much smaller than the Schuler period cor The actual navigation track is segmented; the segmentation time interval T cor The value range is 10-20 minutes. For each segment, the mean value of the gyro constant drift and the mean value of the accelerometer zero bias in the navigation coordinate system are used to replace the gyro constant drift and the accelerometer zero bias in the corresponding direction of the straight line segment. This is equivalent to fixing the attitude on the straight line segment, that is, approximating the curved trajectory into multiple straight line trajectories.

[0026] Preferably, in the pre-analysis stage and the actual navigation stage, the size of the search window is determined according to the inertial navigation error as follows:

[0027] Based on the inertial navigation error, the fault tolerance space is combined as a search window for adaptability analysis;

[0028] set up is the point to be analyzed, δλ p is the estimated inertial navigation longitude error at point p, is the estimated inertial navigation latitude error at point p; then,

[0029] p point search window S ear The length in the longitude direction is: add 1 minute of redundancy to the absolute value of the inertial navigation longitude error, and round up by the minute;

[0030] p point search window S ear The length in the latitude direction is: round up the absolute value of the inertial navigation latitude error by cents.

[0031] Preferably, the method further comprises: during the actual navigation phase, when the difference between the estimated navigation information corresponding to the current adaptation area and the actual navigation information exceeds a set range, re-performing the adaptability analysis and correcting the adaptation area in real time; the difference includes any one or a combination of speed, time, position, and attitude;

[0032] Re-analyze the suitability as follows:

[0033] The first step is to obtain the segmented results of the actual navigation trajectory from the starting point to the current position;

[0034] In the second step, the current position is used as the starting point and the method of the pre-analysis stage is used to obtain the segmentation result of the trajectory from the current position to the target position;

[0035] In the third step, the two sets of trajectories obtained in the first and second steps are connected in sequence to obtain a complete trajectory set;

[0036] The fourth step is to estimate the inertial navigation error based on the trajectory group and inertial navigation parameters;

[0037] Step 5: Based on the inertial navigation error estimated in step 4, determine the real-time correction search window and obtain the corrected adaptation area.

[0038] Preferably, the geophysical field is a gravity field, and the inertial navigation system is a strapdown inertial navigation system.

[0039] Preferably, the navigation information includes track, speed, time and attitude.

[0040] Beneficial effects:

[0041] (1) The present invention incorporates two phases: pre-analysis and real-time correction. This provides support for both trajectory planning and real-time navigation. The real-time correction scheme is more adaptable to unplanned maneuvers. When the vehicle deviates from the planned trajectory, speed, time, or attitude, resulting in changes in compatibility, the real-time correction of the compatibility is maintained, ensuring that real-time matching is not affected.

[0042] (2) The window for adaptability analysis of the present invention is obtained based on the inertial navigation error rather than a set value. This can avoid interference caused by a search window that is too large, and can also avoid not covering the true position due to a search window that is too small.

[0043] (3) The present invention designs a piecewise linearization scheme for the estimated trajectory, analyzes the characteristics of different types of trajectories and designs a linearization scheme, simplifies the inertial navigation error analysis of the motion state, and enables the inertial navigation error research under static base conditions to be applied to the motion state while ensuring accuracy.

[0044] (4) A piecewise linearization scheme for real-time trajectories is designed. This scheme is not constrained by the trajectory shape, can be calculated in real time, and can better adapt to the maneuvering of the spacecraft.

[0045] (5) Due to the piecewise linearization of the trajectory, the present invention can provide an analytical approximate solution to the strapdown inertial navigation error of an arbitrary shape trajectory, avoiding the huge amount of calculation required by the numerical iteration method, and is fast and more conducive to adaptability analysis.

[0046] (6) Since the window for adaptability analysis is determined based on the divergence of the inertial navigation and a fault tolerance space is set, the present invention can avoid interference caused by inaccurate window scale and analyze adaptability more accurately.

[0047] (7) Since the present invention can analyze the compatibility more accurately, the adaptation region can be selected more efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A flow chart of a geophysical field matching navigation adaptability pre-analysis and real-time correction method provided by the present invention. DETAILED DESCRIPTION

[0049] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0050] Given that underwater gravity matching navigation has high concealment and is an important underwater passive navigation method, and the gravity field information is stable, the embodiments of the present invention are mainly explained using underwater gravity matching navigation. However, it is also applicable to other geophysical field matching navigation methods such as terrain matching navigation and geomagnetic matching navigation, and is also applicable to non-underwater scenarios such as land and aviation.

[0051] The present invention provides a geophysical field matching navigation adaptability pre-analysis and real-time correction method, which uses a strapdown inertial navigation system as the inertial navigation system. It is divided into the following two stages according to mission requirements:

[0052] (1) Adaptability pre-analysis stage

[0053] Step 1: Select the target point and the expected navigation trajectory. The advantage is that the adaptability is analyzed from the perspective of the entire system. The adaptability is not only related to the geophysical field background map, but also to the navigation trajectory, inertial navigation performance, navigation speed, etc., which can be analyzed more accurately.

[0054] Step 2: Segmentally linearize the estimated trajectory.

[0055] This step approximates the trajectory as a piecewise straight line. This has the advantage of allowing the use of the inertial guidance error formula for each segment under static base conditions to estimate the linearized inertial guidance error. This allows the application of inertial guidance error research under static base conditions to motion. Furthermore, by analyzing the characteristics of different trajectory types and designing a linearization scheme, this simplifies the solution of inertial guidance error under motion while maintaining accuracy.

[0056] The specific segmentation method is:

[0057] 1) For straight line trajectories, just keep the original trajectory.

[0058] 2) For the curve trajectory, the curve is segmented so that the angle between the line connecting the two ends of each curve segment and any tangent of the curve segment is less than or equal to the threshold Agl thres , replacing the curve segment with a line between the two endpoints.

[0059] 3) For a broken line trajectory, the turning point is used as the trajectory segmentation point to divide the trajectory into multiple straight lines.

[0060] 4) For uniform circular motion (whole cycle), if the angular frequency is greater than 2 times ω s (Schuler frequency), only the error caused by the projection of the gyro constant drift and the accelerometer zero bias on the straight line where the central axis of the circular motion is located is considered, and the projection of the gyro constant drift and the accelerometer zero bias on the plane where the circular motion is located can be ignored; if the angular frequency of the motion is less than or equal to 2 times ω s , processed according to the curve trajectory.

[0061] 5) For non-uniform or non-integer circular motion trajectories, treat them as curved trajectories.

[0062] Step 3: Based on the estimated navigation information after segmentation and combined with the inertial navigation parameters, estimate the inertial navigation error of each segment.

[0063] The navigation information includes trajectory, speed, time, attitude, etc.

[0064] This step can be implemented using a formula-based method. For each straight line segment, the linear velocity and linear acceleration are ignored, and the inertial navigation error formula under static base conditions is used to estimate the inertial navigation error after the trajectory is segmented and linearized. When entering the next segment of the trajectory, the angular motion of the carrier is equivalent to the change in the projection of the gyro constant drift and the accelerometer zero bias in the navigation coordinate system. At this time, the error equation of the inertial navigation system is equal to the original error equation plus the error term generated by the gyro drift change and the accelerometer zero bias change in the navigation coordinate system input at the trajectory conversion point. Then, when analyzing the adaptability of a certain point P, the inertial navigation error is determined based on the error equation of the straight line segment where point P is located. Its advantage is that it can give an analytical approximate solution to the inertial navigation error of a trajectory of any shape, avoiding the huge amount of calculation required by the numerical iterative method, and is fast.

[0065] Without loss of generality, assume that the total navigation starting point is p start , is the point to be analyzed, λ p is the longitude value of point p, is the latitude value of point p, from p start The time it takes to get to p is t p , the preset segmented tracks are s1, s2, ..., s n (p is located in s n End point), from p start The time to the starting point of each track is t1 (t1 value is zero), t2, ..., t n The longitude error δλ corresponding to point p p and latitude error The error equations are:

[0066] δλ p =A λ (t p -t1)Drif1+A λ (t p -t2)(Drif2-Drif1)+…+A λ (t p -t n )(Drif n -Drif n-1 )

[0067]

[0068] Among them, A λ represents the time-varying coefficient matrix of the inertial navigation longitude error equation under static base conditions, represents the time-varying coefficient matrix of the inertial navigation latitude error equation under static base conditions; Drif1 represents the gyro constant drift and accelerometer zero bias corresponding to trajectory s1; A λ (t p-t1)Drif1 represents the drift of the inertial device of the input system at time t1 (t1 value is zero) under the condition of static base. p Longitude error caused by time; Drif n -Drif n-1 Represented by the trajectory s n-1 Enter trajectory n When , the change in the inertial device drift in the navigation system due to attitude change; A λ (t p -t n )(Drif n -Drif n-1 ) represents the static base condition, t n Moment (i.e., by trajectory s n-1 Enter trajectory n The drift variation of the inertial device under the navigation system (Dri) is input into the system n -Drif n-1 In t p Longitude error caused by time; Indicates the static base condition, t n The drift variation of the inertial device in the navigation system of the time input system Drif n -Drif n-1 In t p The latitude error caused by the moment; the meanings of other terms in the formula can be deduced similarly.

[0069] In practice, the estimation of inertial navigation error can also be achieved by numerical iteration method.

[0070] Step 4: Determine the size of the search window based on the inertial navigation error.

[0071] In this step, the inertial navigation error is combined with the error tolerance space to serve as the search window for the adaptability analysis. This combination can be achieved by adding the inertial navigation error to the error tolerance space and multiplying it by the error tolerance coefficient, or by using a predefined function that determines the relationship between the inertial navigation error and the search window size.

[0072] In this embodiment, the method of inertial navigation error plus fault tolerance space is adopted: considering that the inertial navigation error of the underwater vehicle generally does not exceed 2 minutes at most, and the longitude error diverges over time, and the resolution of the gravity anomaly background map is generally 1 minute or 2 minutes, the longitude error is added with 1 minute redundancy and then rounded up (by minute), and the latitude error is directly rounded up (by minute) as the window scale for adaptability analysis.

[0073] set up is the target point to be analyzed, δλ p is the estimated inertial navigation longitude error at point p, is the estimated inertial navigation latitude error at point p. The window for adaptability analysis is S ear ,have

[0074]

[0075] Among them, ceil is a round-up function. Its advantage is that the window S of the adaptability analysis ear It is determined based on the divergence of inertial navigation and has a tolerance space set to avoid interference caused by inaccurate window scale, allowing for more accurate analysis of adaptability.

[0076] Step 5: In S ear Perform adaptability analysis to obtain the adaptability of point p. The advantages are the same as step 4.

[0077] Step 6: Repeat steps 1 to 5 to obtain the adaptability of multiple points.

[0078] In practice, the first inertial navigation error can be estimated based on different estimated navigation information and inertial navigation parameters, and adaptability analysis can be performed to obtain the adaptability of multiple trajectories. This has the advantage of being able to compare the adaptability not only at different points, but also at the same point, for different trajectories.

[0079] When the adaptability of multiple trajectories is obtained, the adaptation area used for actual navigation can be screened according to mission requirements; and step seven is performed using the screened adaptation area.

[0080] Step 7: Refer to the compatibility analysis results from Step 6 to perform track planning and navigation reference. The advantage is that the compatibility pre-analysis results are only used for track planning and navigation reference, not for real-time matching. If the vehicle deviates from the original trajectory, speed, time, attitude, etc., resulting in changes in compatibility, real-time matching will not be affected.

[0081] (2) Adaptive real-time correction stage

[0082] Step 1: Inertial navigation outputs real-time position, attitude, and velocity information. Its advantage is that the vehicle can navigate freely without following the pre-analyzed trajectory, speed, and attitude.

[0083] Step 2: Take a segment time interval T that is much smaller than the Schuler period cor The gyro drift and accelerometer bias under the navigation system are averaged over a period of 10-20 minutes, replacing the device drift during this period. This effectively fixes the attitude on this straight line segment, approximating the curved trajectory to multiple straight line segments. This approach offers the advantage of a piecewise linearization scheme designed based on the error characteristics of strapdown inertial navigation. This approach is unconstrained by trajectory shape, better adapts to vehicle maneuvers, and allows for real-time calculations.

[0084] Step 3: Estimate the inertial navigation error of each segment based on the real-time navigation information after segmentation and in combination with the inertial navigation parameters.

[0085] The navigation information includes trajectory, speed, time, attitude, etc.

[0086] This step can be implemented using a formula-based method. For each straight line segment, the linear velocity and linear acceleration are ignored, and the inertial navigation error formula under static base conditions is used to estimate the inertial navigation error after the trajectory is segmented and linearized. When entering the next segment of the trajectory, the angular motion of the carrier is equivalent to the change in the projection of the gyro constant drift and the accelerometer zero bias in the navigation coordinate system. At this time, the error equation of the inertial navigation system is equal to the original error equation plus the error term generated by the change in gyro drift and accelerometer zero bias in the navigation coordinate system input at the trajectory conversion point. Its advantage is that it can give an analytical approximate solution to the inertial navigation error of an arbitrary shape trajectory, avoiding the huge amount of calculation required by the numerical iterative method, and is fast.

[0087] The error equation for real-time calibration is the same as that for the pre-analysis phase. The difference is that the trajectory, speed (time), and posture during real-time calibration may differ from those during pre-analysis, and the trajectory segmentation method in step 2 is also different.

[0088] In practice, the estimation of inertial navigation error can also be achieved by numerical iteration method.

[0089] Step 4: Determine the size of the search window based on the inertial navigation error.

[0090] In this step, the inertial navigation error is combined with the error tolerance space to serve as the search window for the adaptability analysis. This combination can be achieved by adding the inertial navigation error to the error tolerance space and multiplying it by the error tolerance coefficient, or by using a predefined function that determines the relationship between the inertial navigation error and the search window size.

[0091] In this embodiment, the method of inertial navigation error plus fault tolerance space is adopted: considering that the inertial navigation error of the underwater vehicle generally does not exceed 2 minutes at most, and the longitude error diverges over time, and the resolution of the gravity anomaly background map is generally 1 minute or 2 minutes, the longitude error is added with 1 minute redundancy and then rounded up (by minute), and the latitude error is directly rounded up (by minute) as the window scale for adaptability analysis.

[0092] set up is the target point to be analyzed, δλ p is the estimated inertial navigation longitude error at point p, is the estimated inertial navigation latitude error at point p. The window for adaptability analysis is S ear ,have

[0093]

[0094] Among them, ceil is a round-up function. Its advantage is that the window S of the adaptability analysis ear It is determined based on the divergence of inertial navigation and has a tolerance space set to avoid interference caused by inaccurate window scale, allowing for more accurate analysis of adaptability.

[0095] Step 5: In S ear Perform adaptability analysis to obtain the adaptability of point p. The advantages are the same as step 4.

[0096] Step 6: Refer to the results of Step 5 and perform real-time matching in areas where the compatibility meets the requirements. The advantage is that real-time matching only needs to consider the compatibility of real-time corrections, and the aircraft can maneuver without worrying about deviations from the original trajectory, speed, time, attitude, etc.

[0097] Step 7. Repeat steps 1 to 6.

[0098] The method further includes: during the actual navigation phase, if the difference between the estimated navigation information corresponding to the current adaptation zone and the actual navigation information exceeds a set range, it is necessary to re-perform adaptability analysis and correct the adaptation zone in real time; the difference includes any one or a combination of speed, time, position, and attitude. The inertial navigation error formula shows that to estimate the inertial navigation positioning error at a certain moment, not only the navigation information at that moment is required, but also navigation information at historical moments. Therefore, when re-performing the adaptability analysis, first, the trajectory segmentation results of the actual navigation from the starting point to the current position are obtained; second, using the current position as the starting point, the method of the pre-analysis phase is used to obtain the trajectory segmentation results from the current position to the target position; third, the above two sets of trajectories are arranged in sequence to obtain a complete trajectory group; fourth, according to the formula, an estimated inertial navigation error is obtained; finally, based on the estimated inertial navigation error, adaptability analysis is performed within the corresponding window to obtain a corrected adaptation zone.

[0099] When determining the search window, the present invention can use a platform inertial navigation system instead of a strapdown inertial navigation system. The direction of the inertial device of the platform inertial navigation system is approximately unchanged, and the error characteristics are similar to those of the strapdown inertial navigation system during straight-line navigation, so segmentation is not required.

[0100] The above specific embodiments merely illustrate the design principles of the present invention. The shapes and names of the components described herein may vary and are not limiting. Therefore, those skilled in the art may modify or substitute equivalents for the technical solutions described in the above embodiments. Such modifications and substitutions, without departing from the inventive spirit and technical solutions of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A geophysical field matching navigation adaptability pre-analysis and real-time correction method, characterized in that: The method includes: Pre-analysis stage: estimate the first inertial navigation error based on the estimated navigation information and inertial navigation parameters; determine the size of the pre-analysis search window based on the first inertial navigation error; perform adaptability analysis within the pre-analysis search window, and perform track planning and navigation reference based on the adaptability analysis results; Actual navigation phase: Estimate the second inertial navigation error based on real-time navigation information and inertial navigation parameters; determine the size of the real-time correction search window based on the second inertial navigation error; perform adaptability analysis within the real-time correction search window; based on the current adaptability analysis results, perform real-time matching navigation at the matching point where the adaptability meets the requirements.

2. A geophysical field matching navigation adaptability pre-analysis and real-time correction method as claimed in claim 1, characterized in that: In the pre-analysis stage, the first inertial navigation error is estimated based on different estimated navigation information and inertial navigation parameters, and adaptability analysis is performed to obtain different adaptation areas. The adaptation area used for actual navigation is selected according to mission requirements; the selected adaptation area is used for track planning and navigation reference.

3. A geophysical field matching navigation adaptability pre-analysis and real-time correction method as claimed in claim 1, characterized in that: In the pre-analysis stage, when determining the pre-analysis search window, for the case where the inertial navigation device is fixed on the carrier, the navigation trajectory is linearized in sections; For the straight line segment, the linear velocity and linear acceleration are ignored, and the inertial navigation error of the straight line segment is estimated using the inertial navigation error formula under the static base condition; when entering the next trajectory, the angular motion of the carrier is equivalent to the change of the projection of the gyro constant drift and the accelerometer zero bias in the navigation coordinate system, then the error equation of the inertial navigation system is equal to the error equation of the previous straight line segment plus the error term generated by the gyro drift change and the accelerometer zero bias change in the navigation coordinate system input at the trajectory conversion point; When analyzing the adaptability of a certain point P, the first inertial navigation error is determined according to the error equation of the straight line segment where the point P is located, and then the size of the pre-analysis search window is determined, and the adaptability analysis of the point P is performed using the pre-analysis search window.

4. A geophysical field matching navigation adaptability pre-analysis and real-time correction method as claimed in claim 3, characterized in that: In the pre-analysis stage, the segmentation method is: Case 1: When the trajectory is straight, keep the original trajectory; Case 2: When the curve trajectory is a curve, the curve is segmented so that the angle between the line connecting the two ends of each curve segment and any tangent line of the curve segment is less than or equal to the threshold Agl thres , replace the curve segment with the line between the two endpoints; Case 3: In case of broken line trajectory, the turning point is used as the trajectory segmentation point to divide the trajectory into multiple straight lines; Case 4: In case of uniform circular motion over a whole cycle, (1) if the angular frequency of the motion is greater than 2 times the Schuler frequency ω s , then only the error caused by the projection of the gyro constant drift and the accelerometer zero bias on the straight line where the central axis of the circular motion is located is considered, and the projection of the gyro constant drift and the accelerometer zero bias on the plane where the circular motion is located is ignored; (2) If the angular frequency of the motion is less than or equal to 2 times ω s , handle according to situation 2; Case 5: Non-uniform or non-integer circular motion, handle as in Case 2.

5. The method for pre-analysis and real-time correction of geophysical field matching navigation adaptability according to claim 1, characterized in that: In the actual navigation phase, when determining the search window, the navigation trajectory is segmented and linearized when the inertial navigation device is fixed on the carrier; For the straight line segment, the linear velocity and linear acceleration are ignored, and the inertial navigation error of the straight line segment is estimated using the inertial navigation error formula under the static base condition; when entering the next trajectory, the angular motion of the carrier is equivalent to the change of the projection of the gyro constant drift and the accelerometer zero bias in the navigation coordinate system, then the error equation of the inertial navigation system is equal to the error equation of the previous straight line segment plus the error term generated by the gyro drift change and the accelerometer zero bias change in the navigation coordinate system input at the trajectory conversion point; When analyzing the adaptability of a certain point P, the second inertial navigation error is determined according to the error equation of the straight line segment where the point P is located, and then the size of the real-time correction search window is determined, and the adaptability analysis of the point P is performed using the real-time correction search window.

6. A geophysical field matching navigation adaptability pre-analysis and real-time correction method as claimed in claim 5, characterized in that: In the actual navigation phase, the segmentation method is as follows: Take the segment time interval T which is much smaller than the Schuler period cor The actual navigation track is segmented; the segmentation time interval T cor The value range is 10-20 minutes; For each segment, the mean gyro constant drift and accelerometer zero bias in the navigation coordinate system are used to replace the gyro constant drift and accelerometer zero bias in the corresponding direction of the straight line segment, which is equivalent to fixing the attitude on the straight line segment, that is, approximating the curved trajectory into multiple straight line trajectories.

7. A geophysical field matching navigation adaptability pre-analysis and real-time correction method as claimed in claim 1, characterized in that: In the pre-analysis stage and the actual navigation stage, the size of the search window is determined according to the inertial navigation error: Based on the inertial navigation error, the error tolerance space is combined as a search window for adaptability analysis; set up is the point to be analyzed, δλ p is the estimated inertial navigation longitude error at point p, is the estimated inertial navigation latitude error at point p; then, p point search window S ear The length in the longitude direction is: add 1 point of redundancy to the absolute value of the inertial navigation longitude error, and then round up by points; p point search window S ear The length in the latitude direction is: round up the absolute value of the inertial navigation latitude error by cents.

8. A geophysical field matching navigation adaptability pre-analysis and real-time correction method as claimed in claim 1, characterized in that: The method further comprises: in the actual navigation stage, when the difference between the estimated navigation information corresponding to the current adaptation area and the actual navigation information exceeds a set range, re-performing adaptability analysis and correcting the adaptation area in real time; the difference includes any one or a combination of speed, time, position, and attitude; Re-analyze the suitability as follows: The first step is to obtain the segmented results of the actual navigation trajectory from the starting point to the current position; In the second step, the current position is taken as the starting point, and the method of the pre-analysis stage is used to obtain the segmentation result of the trajectory from the current position to the target position; The third step is to connect the two sets of trajectories obtained in the first and second steps in sequence to obtain a complete trajectory set; The fourth step is to estimate the inertial navigation error based on the trajectory group and inertial navigation parameters; Step 5: Based on the inertial navigation error estimated in step 4, determine the real-time correction search window and obtain the corrected adaptation area.

9. A geophysical field matching navigation adaptability pre-analysis and real-time correction method as claimed in any one of claims 1 to 8, characterized in that: The geophysical field is a gravity field, and the inertial navigation system is a strapdown inertial navigation system.

10. The geophysical field matching navigation adaptability pre-analysis and real-time correction method according to claim 1, characterized in that: The navigation information includes track, speed, time and attitude.

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