Geomagnetic contour matching method and device based on combined spatial constraint and medium

Abstract

The invention discloses a geomagnetic contour matching method and device based on combined spatial constraint and a medium. The method comprises the following steps: acquiring possible matching points and navigation positioning parameters including a reference magnetic field vector, a measurement magnetic field vector and matching point position information; according to the navigation positioning parameters, combined space constraint similarity of possible matching points is determined; and a possible matching point corresponding to the minimum similarity value is used as a candidate point. The constituent elements of the combined space constraint similarity comprise magnetic field difference similarity and continuity similarity. Reducing the search area by taking the candidate point as a center, and carrying out loop iteration until an iteration condition is met; and taking the candidate point obtained by the last iteration as a target matching position. Therefore, when the similarity is calculated, combined spatial constraints in multiple aspects of magnetic field difference and spatial continuity are comprehensively considered, so that candidate points closer to an actual track are determined, the spatial continuity of a matching result is enhanced, and the precision and reliability of geomagnetic matching navigation are improved.

Description

Technical Field

[0001] The present application relates to the field of navigation technology, and in particular, to a geomagnetic contour matching method, device and medium based on combined spatial constraints. Background Art

[0002] The geomagnetic contour matching technology is a technology that uses the unique distribution characteristics of the earth's magnetic field for positioning and navigation. Since the geomagnetic contour matching technology does not need to rely on external radio signals, it can be widely applied to scenarios where satellite signals cannot cover, such as underwater, underground, and urban canyons with high-rise buildings.

[0003] The current geomagnetic contour matching technology mainly realizes accurate position matching by comparing the similarity between the measured geomagnetic data obtained by the sensor in real time and the pre-stored reference geomagnetic data. In the current matching method, only the difference information between the magnetic field measurement value and the reference value is considered during the matching process, and the spatial constraint information between the matching points is not considered. For example, the spatial continuity between the matching points is not considered, resulting in poor continuity of the final matching trajectory, unstable matching results, and low navigation accuracy.

[0004] Therefore, how to enhance the spatial continuity of the matching result, improve the matching accuracy, and thus improve the navigation accuracy is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of this, one aspect of the present application provides a geomagnetic contour matching method based on combined spatial constraints, and the method includes: Performing grid search around the inertial navigation system to obtain a plurality of possible matching points; Obtaining navigation and positioning parameters; wherein, the navigation and positioning parameters include the reference magnetic field vector, measured magnetic field vector and matching point position information of the possible matching points; Determining the combined spatial constraint similarity of the possible matching points according to the navigation and positioning parameters; the constituent elements of the combined spatial constraint similarity include the magnetic field difference similarity for characterizing the magnetic field difference and the continuity similarity for characterizing the spatial position continuity; Taking the possible matching point corresponding to the minimum value of the combined spatial constraint similarity as the candidate point; Taking the candidate point as the center, narrowing the search area, and performing iterative search until the iteration condition is met; and taking the candidate point obtained in the last iteration as the target matching position.

[0006] Optionally, the navigation and positioning parameters further include the inertial navigation position information of the inertial navigation system; the constituent elements further include the inertial navigation trajectory difference similarity for characterizing the difference between the matching trajectory and the inertial navigation trajectory.

[0007] Optionally, determining the combined spatial constraint similarity of the possible matching points according to the navigation and positioning parameters includes: Determining the magnetic field difference similarity according to the reference magnetic field vector and the measured magnetic field vector; Determining the continuity similarity according to the target matching position at the previous moment and the matching point position information; Determining the inertial navigation trajectory difference similarity according to the inertial navigation position information and the matching point position information; Determining the combined spatial constraint similarity based on the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity.

[0008] Optionally, determining the inertial navigation trajectory difference similarity according to the inertial navigation position information and the matching point position information includes: Obtaining the inertial navigation position coordinates at the current moment and the previous moment respectively according to the inertial navigation position information; and determining the inertial navigation displacement increment according to the inertial navigation position coordinates; Determining the matching point displacement increment corresponding to each of the possible matching points according to the target matching position at the previous moment and the matching point position information; Determining the inertial navigation trajectory difference similarity according to the inertial navigation displacement increment and the matching point displacement increment.

[0009] Optionally, determining the combined spatial constraint similarity based on the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity includes: Assigning corresponding weights to the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity respectively; Performing weighted summation on the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity based on the weights to obtain the combined spatial constraint similarity.

[0010] Optionally, the sum of the weights is 1, the weight corresponding to the continuity similarity is greater than the weight corresponding to the magnetic field difference similarity, and the weight corresponding to the magnetic field difference similarity is equal to the weight corresponding to the inertial navigation trajectory difference similarity.

[0011] Optionally, the geomagnetic contour matching method based on combined spatial constraints further includes: Optimizing the target matching position through Kalman filtering to obtain the target navigation position.

[0012] Another aspect of the present application provides a geomagnetic contour matching device based on combined spatial constraints, and the device includes: A possible matching point acquisition module, which is used to perform grid search around an inertial navigation system to obtain multiple possible matching points; A positioning parameter acquisition module, which is used to acquire navigation positioning parameters; wherein, the navigation positioning parameters include a reference magnetic field vector, a measured magnetic field vector, and matching point position information of the possible matching points; A similarity determination module, which is used to determine the combined space constraint similarity of the possible matching points according to the navigation positioning parameters; the constituent elements of the combined space constraint similarity include a magnetic field difference similarity used to characterize the magnetic field difference and a continuity similarity used to characterize the spatial position continuity; A candidate point acquisition module, which is used to use the possible matching point corresponding to the minimum value of the combined space constraint similarity as a candidate point; A loop control module, which is used to take the candidate point as the center, narrow the search area, and perform loop iterative search until the iteration condition is met; and use the candidate point obtained in the last iteration as the target matching position.

[0013] Another aspect of the present application provides a geomagnetic contour matching device based on combined space constraints, including a memory and a processor. A computer program that can run on the processor is stored on the memory, and when the processor executes the program, the steps of the geomagnetic contour matching method based on combined space constraints are implemented.

[0014] Another aspect of the present application provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the geomagnetic contour matching method based on combined space constraints are implemented.

[0015] The beneficial effects generated by the geomagnetic contour matching method, device, and medium based on combined space constraints provided by the present application are as follows: when calculating the similarity of possible matching points, the combined space constraints in multiple aspects such as magnetic field difference and spatial continuity are comprehensively considered to determine candidate points closer to the actual trajectory, thereby enhancing the spatial continuity of the matching result and improving the accuracy and reliability of geomagnetic matching navigation. Description of the Drawings

[0016] Figure 1 It is a schematic flowchart of a geomagnetic contour matching method based on combined space constraints provided by an embodiment of the present application; Figure 2 It is a schematic principle diagram of a geomagnetic contour matching method based on combined space constraints provided by an embodiment of the present application; Figure 3 It is a schematic flowchart of a geomagnetic contour matching method based on combined space constraints provided by another embodiment of the present application; Figure 4Schematic diagram of a navigation trajectory of a geomagnetic contour matching method based on combined spatial constraints provided by an embodiment of the present application; Figure 5 Error analysis diagram of a geomagnetic contour matching method based on combined spatial constraints provided by an embodiment of the present application; Figure 6 Schematic structural diagram of a geomagnetic contour matching device based on combined spatial constraints provided by an embodiment of the present application; Figure 7 Schematic structural diagram of a geomagnetic contour matching device based on combined spatial constraints provided by another embodiment of the present application.

[0017] The reference numerals are as follows: 40 is a possible matching point acquisition module, 41 is a positioning parameter acquisition module, 42 is a similarity determination module, 43 is a candidate point acquisition module, 44 is a loop control module, 50 is a memory, 51 is a processor, 52 is a display screen, 53 is an input / output interface, 54 is a communication interface, 55 is a power supply, 56 is a communication bus, 501 is a computer program, 502 is an operating system, and 503 is data. Detailed implementation manners

[0018] The terms used in the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "the", and "said" used in the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0019] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0020] Figure 1 Flow schematic diagram of a geomagnetic contour matching method based on combined spatial constraints provided by an embodiment of the present application, as Figure 1 shown, the method includes: S10: Perform grid search around the inertial navigation system to obtain a plurality of possible matching points; In a specific embodiment, when the carrier conducts navigation during movement, a search grid is established centered on the inertial navigation system, and possible matching points are evenly sampled within the initial search radius. Among them, the possible matching points refer to the set of points that may be points on the actual trajectory. At the same time, the geomagnetic field data of the area to be matched is obtained in real time to establish a geomagnetic database.

[0021] When establishing the geomagnetic database, specifically, the geomagnetic field data file is read, which contains the three-component magnetic field data at the longitude and latitude grid points. Further, a magnetic field data interpolator is established to calculate the reference magnetic field vector at any position and record the effective range of the geomagnetic map.

[0022] It should be noted that the carrier in the embodiments of the present application may include, but is not limited to, underwater vehicles, aerial vehicles, vehicles, and robots. When performing the initial grid search, parameters related to the search range need to be obtained, including but not limited to the initial search radius, minimum search radius, maximum search radius, and initial search step.

[0023] For example, in an alternative embodiment, the initial search radius can be set to 1.5 kilometers, the minimum search radius can be set to 1.0 kilometer, the maximum search radius can be set to 5.0 kilometers, and the initial search step can be set to 0.1 kilometer.

[0024] S11: Obtain navigation and positioning parameters; among them, the navigation and positioning parameters include the reference magnetic field vector, measured magnetic field vector, and matching point position information of the possible matching points; After obtaining the possible matching points, the navigation and positioning parameters are obtained through step S11. Specifically, the navigation and positioning parameters include the reference magnetic field vector, measured magnetic field vector, and matching point position information of the possible matching points.

[0025] Among them, the reference magnetic field vector of the possible matching points can be directly obtained from the geomagnetic database, and the measured magnetic field vector can be collected in real time through a geomagnetic sensor. The matching point position information includes the longitude and latitude coordinates of the possible matching points.

[0026] S12: According to the navigation and positioning parameters, determine the combined spatial constraint similarity of the possible matching points; the constituent elements of the combined spatial constraint similarity include the magnetic field difference similarity for characterizing the magnetic field difference and the continuity similarity for characterizing the spatial position continuity; S13: Take the possible matching point corresponding to the minimum value of the combined spatial constraint similarity as the candidate point; Further, in order to determine the best matching point among all possible matching points in the current search matching period, the combined space constraint similarity of each possible matching point is calculated through step S12. In order to improve the geomagnetic matching accuracy and the continuity of the matching position, therefore, in an optional embodiment, when calculating the similarity of possible matching points, the constraint information in multiple aspects such as magnetic field difference and spatial position connection is comprehensively considered.

[0027] Specifically, calculate the magnetic field difference similarity for characterizing the magnetic field difference between the reference magnetic field vector and the measured magnetic field vector, and at the same time calculate the continuity similarity for characterizing the continuity between the position information of the matching point at the current moment and the target matching position at the previous moment. Further, the combined space constraint similarity can be determined according to the magnetic field difference similarity and the continuity similarity.

[0028] It should be noted that the continuity similarity is used to reflect the position continuity between each currently obtained possible matching point and the target matching position of the final matching result in the previous round (i.e., the final navigation position of the navigation and positioning at the previous moment). Thus, it can be understood that the combined space constraint similarity is used to determine the point among multiple possible matching points that best exhibits both magnetic field difference and spatial position continuity.

[0029] In an optional embodiment, the smaller the combined space constraint similarity, the closer the possible matching point is to the true trajectory. Therefore, the possible matching point corresponding to the minimum value of the combined space constraint similarity in the current search matching is used as the candidate point. It can be understood that the candidate point is the best matching point under the relevant parameter conditions of the current search range.

[0030] S14: Centering on the candidate point, narrow the search area, and perform cyclic iterative search until the iterative condition is met; and use the candidate point obtained in the last iteration as the target matching position.

[0031] Further, centering on the candidate point obtained in step S13, narrow the search area (including but not limited to narrowing the search radius and increasing the search step size), and perform cyclic iterative search, that is, repeatedly execute steps S11 to S13 until the iterative condition is reached. The candidate point obtained in the last iteration is the point closest to the true trajectory at the current moment, denoted as the target matching position.

[0032] In an optional embodiment, after obtaining the target matching position, record the longitude and latitude position information of the target matching position and the corresponding combined space constraint similarity. In addition, in an optional embodiment, in order to improve the matching efficiency, a thread pool is used to perform parallel evaluation of multiple possible matching points, that is, call multi-threaded parallel calculation of the combined space constraint similarity. Among them, set the maximum number of threads to the number of CPU cores of the system to implement a thread-safe data access mechanism.

[0033] It should be noted that in an alternative embodiment, the iteration condition can be a preset number of iterations, that is, the loop search stops after reaching the number of iterations. In addition, it should also be noted that in an alternative embodiment, the current search results and the relevant parameters of the search range are continuously stored and updated to provide a reference for subsequent searches, thereby further improving the matching efficiency and accuracy.

[0034] Therefore, in the geomagnetic contour matching method based on combined space constraints provided by the embodiments of the present application, when calculating the similarity of possible matching points, the combined space constraints in multiple aspects such as magnetic field difference and spatial continuity are comprehensively considered to determine candidate points closer to the actual trajectory, thereby enhancing the spatial continuity of the matching result and improving the accuracy and reliability of geomagnetic matching navigation.

[0035] In order to further improve the geomagnetic contour matching accuracy and ensure that the matching trajectory does not deviate too far from the inertial navigation system trajectory, in an alternative embodiment, the navigation positioning parameters may further include the inertial navigation position information of the inertial navigation system, and the constituent elements of the combined space constraint similarity may further include the inertial navigation trajectory difference similarity used to characterize the difference between the matching trajectory and the inertial navigation trajectory.

[0036] Figure 2 Schematic diagram of the principle of a geomagnetic contour matching method based on combined space constraints provided by the embodiments of the present application, as Figure 2 shown, in a specific embodiment, the constraint condition of the inertial navigation trajectory difference similarity is added to avoid the matching trajectory deviating too far from the inertial navigation trajectory, that is, the difference between the matching trajectory and the inertial navigation trajectory is within an acceptable range.

[0037] In an alternative embodiment, the constituent elements of the combined space constraint similarity include at least two of the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity.

[0038] As Figure 2 shown, in a specific embodiment, the system initialization includes establishing geomagnetic field data. After initialization, a grid search with cyclic iteration is performed around the inertial navigation system, and the navigation positioning parameters are obtained in real time. In each cyclic iteration, the combined space constraint similarity is calculated based on at least two of the magnetic field difference similarity, the inertial navigation trajectory difference similarity, and the continuity similarity according to the obtained navigation positioning parameters.

[0039] In each iteration loop, the minimum value of the combined space constraint similarity is used as the candidate point. When entering the next iteration, with the candidate point of the previous iteration as the center, the search range is narrowed and the search is performed again. This cycle continues until the iteration condition is reached, and the candidate point obtained in the last iteration is used as the target matching position.

[0040] Therefore, the geomagnetic contour matching method based on combined space constraints provided by the embodiments of the present application comprehensively considers the magnetic field difference constraint, the space continuity constraint, and the inertial navigation constraint. While further improving the matching accuracy, it improves the smoothness of the matching trajectory and enhances the anti-interference ability of the system.

[0041] Figure 3 FIG. is a schematic flowchart of a geomagnetic contour matching method based on combined space constraints provided by another embodiment of the present application. On the basis of the above embodiments, as an optional embodiment, as Figure 3 shown, according to the navigation and positioning parameters, determine the similarity of the combined space constraints of the possible matching points, including: S30: Determine the magnetic field difference similarity according to the reference magnetic field vector and the measured magnetic field vector; In an optional embodiment, the Euclidean distance between the measured magnetic field vector and the reference magnetic field vector in the geomagnetic field database can be used to measure the magnetic field difference of each possible matching point. In a specific embodiment, each possible matching point can collect a measured magnetic field vector , and a corresponding reference magnetic field vector . Further, calculate the magnetic field difference similarity according to formula (1): (1) Wherein, is the magnetic field difference similarity, is the measured magnetic field vector , is the reference magnetic field vector .

[0042] S31: Determine the continuity similarity according to the target matching position and the matching point position information at the previous moment; As an optional embodiment, the matching point position information includes the matching point coordinates, and the target matching position includes the target position coordinates. Therefore, the continuity similarity can be measured by the Euclidean distance between the target position coordinates at the previous moment and the matching point position coordinates. The specific calculation formula is formula (2): (2) Wherein, is the continuity similarity, is the matching point position coordinate at the current moment, and is the target position coordinate at the previous moment.

[0043] In a specific embodiment, the continuity similarity can be calculated between the position coordinates of each possible matching point and the target position coordinates at the previous moment. The continuity similarity is used to constrain the continuity between two points within the expected range.

[0044] It should be noted that when When it is, it indicates that the current match is the first-round match at the target matching position at the current moment. At this time, the continuity similarity is not calculated.

[0045] S32: Determine the inertial navigation trajectory difference similarity according to the inertial navigation position information and the matching point position information; In an optional embodiment, when calculating the inertial navigation trajectory difference similarity, as Figure 3 shown, the following steps are included: S320: Respectively obtain the inertial navigation position coordinates at the current moment and the previous moment according to the inertial navigation position information; and determine the inertial navigation displacement increment according to the inertial navigation position coordinates; In a specific embodiment, the spatial difference between the matching trajectory and the inertial navigation trajectory is measured by the displacement increment. Specifically, the inertial navigation coordinates at the current moment can be respectively obtained according to the inertial navigation position information , and the inertial navigation position coordinates at the previous moment . Thus, the inertial navigation displacement increment can be obtained.

[0046] S321: Determine the matching point displacement increment corresponding to each possible matching point according to the target matching position and the matching point position information at the previous moment; At the same time, the matching point displacement increment corresponding to each possible matching point can be determined according to the target matching position and the matching point position information at the previous moment. Specifically, calculate the position coordinates of the possible matching point and the target position coordinates of the target matching position at the previous moment difference to determine the matching point displacement increment , that is, .

[0047] S322: Determine the inertial navigation trajectory difference similarity according to the inertial navigation displacement increment and the matching point displacement increment.

[0048] Furthermore, the inertial navigation trajectory difference similarity can be calculated according to formula (3): (3) Wherein, is the inertial navigation trajectory difference similarity, is the matching point displacement increment, is the inertial navigation displacement increment.

[0049] S33: Determine the combined spatial constraint similarity based on the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity.

[0050] In summary, the combined spatial constraint similarity can be determined by the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity. Specifically, in an optional embodiment, , where is the combined spatial constraint similarity.

[0051] Based on the above embodiments, in order to further improve the matching accuracy, the combined spatial constraint similarity is determined based on the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity, including: Assign corresponding weights to the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity respectively; Based on the weights, perform a weighted sum of the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity to obtain the combined spatial constraint similarity.

[0052] It can be understood that in the actual navigation process, the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity have different degrees of influence on the matching result. Therefore, in order to achieve the optimal matching. In an alternative embodiment, corresponding weights are assigned to different constraints. And based on the weights, a weighted sum is performed to obtain the combined spatial constraint similarity. The specific calculation formula is formula (4): (4) where is the weight corresponding to the magnetic field difference similarity, is the weight corresponding to the continuity similarity, is the weight corresponding to the inertial navigation trajectory difference similarity.

[0053] Based on the above embodiments, in order to ensure that the relative contribution degrees of different information sources in the matching and positioning always maintain a reasonable proportional relationship, therefore, the sum of the weights is 1. That is, .

[0054] In order to balance the contributions of each constraint in the matching and considering that the influence degree of spatial continuity on the matching and positioning accuracy is higher, therefore, in an alternative embodiment, the weight corresponding to the continuity similarity can be set to be greater than the weight corresponding to the magnetic field difference similarity, and the weight corresponding to the magnetic field difference similarity is equal to the weight corresponding to the inertial navigation trajectory difference similarity.

[0055] For example, in an alternative embodiment, the weight corresponding to the continuity similarity , the weight corresponding to the magnetic field difference similarity , the weight corresponding to the inertial navigation trajectory difference similarity . As Figure 2 shown, when performing the matching, the system initialization further includes setting the combined spatial constraint parameters, specifically including setting each weight value.

[0056] Of course, in another alternative embodiment, due to the complex and ever-changing navigation environment, in order to improve the adaptability of navigation to complex environments, the weights corresponding to the magnetic field difference similarity , the weights corresponding to the continuity similarity and the weights corresponding to the inertial navigation trajectory difference similarity can be dynamically adjusted according to environmental changes.

[0057] Specifically, the weights corresponding to the magnetic field difference similarity can be adjusted by the gradient characteristics generated by the magnetic field. The weights corresponding to the continuity similarity can be adjusted by observing the motion state of the carrier. The weights corresponding to the inertial navigation trajectory difference similarity can be adjusted by the error accumulation time generated by inertial navigation. Therefore, in a specific embodiment, the measured magnetic field vector, carrier motion information, and inertial navigation time information can be obtained to dynamically adjust the weights.

[0058] In an alternative embodiment, the current weight coefficient is adjusted by influencing parameters, including: Determine the magnetic field gradient eigenvalue according to the measured magnetic field vector; and adjust the weight corresponding to the magnetic field difference similarity according to the magnetic field gradient eigenvalue ; the larger the magnetic field gradient eigenvalue, the weight corresponding to the magnetic field difference similarity is larger; Determine the motion state index value reflecting the stability of the carrier motion state according to the carrier motion information; adjust the weight corresponding to the continuity similarity according to the motion state index value ; Determine the error accumulation time of the inertial navigation system according to the inertial navigation time information; and adjust the weight corresponding to the inertial navigation trajectory difference similarity according to the error accumulation time , the larger the error accumulation time, the weight corresponding to the inertial navigation trajectory difference similarity is smaller.

[0059] In an alternative embodiment, when adjusting the weight corresponding to the inertial navigation trajectory difference similarity , the inertial navigation time information obtained in real time includes the current time and the last reset time of the inertial navigation system. Therefore, the error accumulation time can be determined according to the formula . Among them, is the error accumulation time, is the current time, is the last reset time of the inertial navigation system.

[0060] When adjusting the weight corresponding to the inertial navigation trajectory difference similarity according to the error accumulation time , obtain the preset maximum error accumulation time and the weight corresponding to the inertial navigation trajectory difference similarity The maximum weight, and then the weight corresponding to the similarity of the inertial navigation trajectory difference can be obtained Adjustment function formula , where is the maximum weight corresponding to the similarity of the inertial navigation trajectory difference, is the cumulative time of the maximum error

[0061] In an alternative embodiment, the carrier motion information includes the motion speed and heading angle of the carrier; according to the carrier motion information, the motion state index value is determined, including: Through the motion speed, the speed change increment between the current moment and the previous moment is determined, that is, . Where is the motion speed at the current moment, is the motion speed at the previous moment

[0062] Through the heading angle, the heading change increment between the current moment and the previous moment is determined, that is, , where is the heading angle at the current moment, is the heading angle at the previous moment

[0063] Taking the current motion speed of the carrier as the weight of the heading change increment; based on the weight of the heading change increment, the weighted sum of the speed change increment and the heading change increment is calculated to obtain the motion state index value. That is, . Where is the motion state index value, is the speed change increment, is the heading change increment

[0064] Considering that the heading angle has a greater impact on the position change, that is, the heading change has a greater impact on the motion stability. Therefore, in an alternative embodiment, the current motion speed at the current moment is introduced into the heading change increment as the weight. Thus, based on the weight of the heading change increment, the weighted sum of the speed change increment and the heading change increment is calculated, and the motion state index value can be obtained .

[0065] In an alternative embodiment, according to the motion state index value, the weight corresponding to the continuity similarity is adjusted, including: When the motion state index value is greater than the index threshold, obtain the preset weight adjustment rate and the extreme value of the spatial continuity weight; Based on the weight adjustment rate and the motion state index value, adjust the weight corresponding to the continuity similarity within the range of the extreme value of the spatial continuity weight; where the greater the motion state index value, the greater the weight corresponding to the continuity similarity

[0066] Specifically, according to the formula: , the weight corresponding to the continuity similarity is adjusted. Among them, is the minimum value of the spatial continuity weight, is the maximum value of the spatial continuity weight, and constitute the extreme values of the spatial continuity weight, is the weight adjustment rate. By using a weight adjustment function in the form of exponential decay, smooth weight transition can be achieved and mutations can be avoided.

[0067] Start the index threshold for adjusting the weight corresponding to the continuity similarity . In an optional embodiment, it can be set to . In a specific embodiment, when the motion state index value is greater than the index threshold , the weight corresponding to the continuity similarity will be adjusted towards the maximum value of the weight corresponding to the continuity similarity at the weight adjustment rate . That is, the larger the motion state index value , the larger the weight corresponding to the continuity similarity.

[0068] If the motion state index value is not greater than the index threshold , it will decay towards the minimum value of the weight corresponding to the continuity similarity. In fact, the index threshold is used to distinguish between a stable motion state and a violent motion state, triggering different weight adjustment directions.

[0069] In an optional embodiment, according to the measured magnetic field vector, the magnetic field gradient eigenvalue is determined, including: Obtain the preset gradient feature extreme value and magnetic field weight extreme value; Determine the gradient vector between adjacent measured magnetic field vectors; According to the gradient feature extreme value, magnetic field weight extreme value and gradient vector, determine the initial gradient feature; Normalize the initial gradient feature to obtain the magnetic field gradient eigenvalue.

[0070] In a specific embodiment, according to the gradient feature extreme value, magnetic field weight extreme value and gradient vector, the initial gradient feature can be calculated, and the specific formula is .

[0071] Among them, is the initial gradient feature, is the gradient vector between adjacent measured magnetic field vectors, and the gradient vector can be expressed as: . represents the Frobenius norm.

[0072] Furthermore, the initial gradient feature is normalized to obtain the magnetic field gradient eigenvalue. Specifically, the initial gradient feature is normalized to the range [0, 1], and the specific formula is: .

[0073] where is the magnetic field gradient eigenvalue, is the minimum value of the gradient feature, is the maximum value of the gradient feature, and constitute the extreme values of the gradient feature. In an alternative embodiment, the minimum value of the gradient feature can be set to 0.1, and the maximum value of the gradient feature can be set to 0.5.

[0074] Furthermore, a weight corresponding to the magnetic field difference similarity can be generated based on the magnetic field gradient eigenvalue adjustment function. Specifically, the specific formula is: .

[0075] where is the minimum value of the magnetic field weight, is the maximum value of the magnetic field weight, and constitute the extreme values of the magnetic field weight.

[0076] In an alternative embodiment, as shown in Figure 2 , in order to further improve the navigation accuracy, the geomagnetic contour matching method based on combined space constraints provided by the present application further includes: Optimizing the target matching position through Kalman filtering to obtain the target navigation position.

[0077] In a specific embodiment, as shown in Figure 2 , the system initialization further includes initializing the Kalman filter. When the grid search loop iteration reaches the iteration condition, the candidate point corresponding to the last iteration is used as the target matching position. At this time, the target matching position is optimized through Kalman filtering to obtain the final target navigation position. Furthermore, the target navigation positions matched at each moment are connected to obtain the matching trajectory.

[0078] When optimizing the target matching position through Kalman filtering, as shown in Figure 2As shown, the system initialization also includes initializing the Kalman filter. Specifically, in an optional embodiment, the dimension of the state vector is set , the dimension of the observation vector is set , and the state transition matrix is initialized :

[0079] The observation matrix is initialized :

[0080] The process noise covariance matrix is configured and the observation noise covariance matrix .

[0081] Furthermore, the state vector is defined as: , which includes the position information and the velocity information . The state transition equation is: , where is the state transition matrix, is the process noise.

[0082] The observation equation is: , where is the observation matrix, is the observation noise. In a specific embodiment, through the recursive mechanism of prediction update, the smoothing optimization of the matching trajectory can be achieved.

[0083] During processing, the state prediction includes predicting the state vector , and the predicted covariance matrix . Among them, is the noise covariance matrix.

[0084] Furthermore, the observation update includes: Calculating the Kalman gain: ; Updating the state estimate: ; Updating the covariance matrix: .

[0085] Among them, is the observation equation, is the Kalman gain, is the observation noise covariance matrix.

[0086] In an optional embodiment, the filtered result sequence is stored to implement the forward-backward smoothing algorithm, thereby outputting the final smoothed trajectory.

[0087] In an alternative embodiment, the navigation system of the carrier can be displayed in real time. Specifically, it includes the real-time display of the geomagnetic isoline map, the display of the drawn real trajectory, inertial navigation trajectory, and matching trajectory, the real-time display of the current position and matching error information, and also includes dynamically updating the display range.

[0088] In another alternative embodiment, the matching results and data are stored and managed in real time. Specifically, the matching results and data are stored in a CSV file, the detailed matching process log is recorded, and the trajectory and error statistical charts are saved.

[0089] As an alternative embodiment, the matching performance can be evaluated. Specifically, it includes accuracy evaluation and real-time analysis. Among them, the accuracy evaluation includes calculating the position matching RMS error, analyzing the trajectory continuity index, and evaluating the algorithm convergence performance. The real-time analysis includes counting the single-point matching time, calculating the system update rate, and evaluating the parallel computing efficiency.

[0090] Figure 4 Schematic diagram of the navigation trajectory of a geomagnetic contour matching method based on combined spatial constraints provided by an embodiment of the present application, as Figure 4 shown, which shows the navigation trajectories under three navigation methods. Among them, the red solid line is the satellite navigation trajectory, the blue dashed line is the inertial navigation trajectory, and the yellow solid line is the geomagnetic navigation trajectory. Correspondingly, the red circle is the current position of satellite navigation, that is, the sampling position of the satellite navigation system. The blue circle is the current position of inertial navigation, that is, the sampling position of the inertial navigation system. The yellow circle is the current position of geomagnetic navigation, that is, the sampling position of the geomagnetic navigation system. The background is a blue contour map showing terrain information, with the abscissa being longitude and the ordinate being latitude, represented in kilometers (km). In an alternative embodiment, Figure 4 the cumulative RMS error (mean square error) is shown, where the cumulative geomagnetic navigation RMS error is 24.37 m and the cumulative inertial navigation RMS error is 3956.43 m.

[0091] Figure 5 Error analysis diagram of a geomagnetic contour matching method based on combined spatial constraints provided by an embodiment of the present application, as Figure 5 shown, the abscissa represents the data point serial number (above 0 - 8000), the left vertical axis represents the geomagnetic matching error (yellow bar chart), and the right vertical axis shows the inertial navigation error (blue dashed line). In an alternative embodiment, the current window geomagnetic navigation RMS error is 10.67 m and the inertial navigation RMS error is 4716.97 m.

[0092] Combined with Figure 4 and Figure 5It can be seen that the inertial navigation system has obvious cumulative errors and drifts significantly over time. In contrast, the geomagnetic navigation system improves the navigation accuracy, with smaller errors and good stability throughout the process.

[0093] Therefore, the geomagnetic contour matching method based on combined space constraints provided by the embodiments of the present application optimizes the matching result by combining a Kalman filter on the basis of comprehensively considering various constraints such as the difference between the magnetic field measurement value and the reference value, spatial continuity constraints, and inertial navigation constraints, further improving the matching accuracy and reliability.

[0094] In the above embodiments, the geomagnetic contour matching method based on combined space constraints is described in detail. The present application also provides an embodiment corresponding to a geomagnetic contour matching device based on combined space constraints.

[0095] Figure 6 It is a schematic structural diagram of a geomagnetic contour matching device based on combined space constraints provided by the embodiments of the present application, as Figure 6 shown. The device includes: A possible matching point acquisition module 40, configured to perform grid search around the inertial navigation system to obtain a plurality of possible matching points; A positioning parameter acquisition module 41, configured to acquire navigation positioning parameters; wherein, the navigation positioning parameters include the reference magnetic field vector, measured magnetic field vector, and matching point position information of the possible matching points; A similarity determination module 42, configured to determine the combined space constraint similarity of the possible matching points according to the navigation positioning parameters; the constituent elements of the combined space constraint similarity include a magnetic field difference similarity for characterizing the magnetic field difference and a continuity similarity for characterizing the spatial position continuity; A candidate point acquisition module 43, configured to use the possible matching point corresponding to the minimum value of the combined space constraint similarity as the candidate point; A loop control module 44, configured to take the candidate point as the center, narrow the search area, and perform loop iterative search until the iteration condition is met; and use the candidate point obtained in the last iteration as the target matching position.

[0096] In addition, the geomagnetic contour matching device based on combined space constraints provided by the embodiments of the present application further includes: A magnetic field difference similarity determination module, configured to determine the magnetic field difference similarity according to the reference magnetic field vector and the measured magnetic field vector; A continuity similarity determination module, configured to determine the continuity similarity according to the target matching position and the matching point position information at the previous moment; An inertial navigation trajectory difference similarity determination module, configured to determine the inertial navigation trajectory difference similarity according to the inertial navigation position information and the matching point position information; The first determination module is configured to determine the combined spatial constraint similarity based on the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity.

[0097] The inertial navigation displacement increment determination module is configured to respectively obtain the inertial navigation position coordinates at the current moment and the previous moment according to the inertial navigation position information; and determine the inertial navigation displacement increment according to the inertial navigation position coordinates. The matching point displacement increment determination module is configured to determine the matching point displacement increment corresponding to each possible matching point according to the target matching position and the matching point position information at the previous moment. The second determination module is configured to determine the inertial navigation trajectory difference similarity according to the inertial navigation displacement increment and the matching point displacement increment.

[0098] The weight assignment module is configured to respectively assign corresponding weights to the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity. The weighted summation module is configured to perform weighted summation on the magnetic field difference similarity, the continuity similarity, and the inertial navigation trajectory difference similarity based on the weights to obtain the combined spatial constraint similarity.

[0099] The optimization module is configured to optimize the target matching position through Kalman filtering to obtain the target navigation position.

[0100] Figure 7 The following is a schematic structural diagram of a geomagnetic contour matching device based on combined spatial constraints provided by another embodiment of the present application. As Figure 7 shown, the geomagnetic contour matching device based on combined spatial constraints includes: a memory 50 for storing a computer program. A processor 51 for implementing the steps of the geomagnetic contour matching method based on combined spatial constraints mentioned in the above embodiment when executing the computer program.

[0101] The geomagnetic contour matching device based on combined spatial constraints provided in this embodiment may include, but is not limited to, a laptop computer or a desktop computer, etc.

[0102] Among them, the processor 51 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 51 may be implemented in at least one hardware form of a digital signal processor (DSP for short), a field-programmable gate array (FPGA for short), and a programmable logic array (PLA for short). The processor 51 may also include a main processor and a coprocessor. The main processor is a processor used to process data in the wake state, also known as the central processing unit (CPU for short); the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 51 may be integrated with a graphics processing unit (GPU for short), and the GPU is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 51 may also include an artificial intelligence (AI for short) processor, and the AI processor is used to process computational operations related to machine learning.

[0103] The memory 50 may include one or more computer-readable storage media, and the computer-readable storage media may be non-transitory. The memory 50 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices and flash storage devices. In this embodiment, the memory 50 is at least used to store the following computer program 501. After the computer program is loaded and executed by the processor 51, it can implement the relevant steps of the geomagnetic contour matching method based on combined space constraints disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 50 may also include an operating system 502 and data 503, etc., and the storage method may be transient storage or permanent storage. Among them, the operating system 502 may include Windows, Unix, Linux, etc. The data 503 may include, but is not limited to, the relevant data involved in the geomagnetic contour matching method based on combined space constraints.

[0104] In some embodiments, the geomagnetic contour matching device based on combined space constraints may further include a display screen 52, an input / output interface 53, a communication interface 54, a power supply 55, and a communication bus 56.

[0105] Those skilled in the art can understand that Figure 7 the structure shown in

[0106] The geomagnetic contour matching device based on combined space constraint provided by an embodiment of the present application includes a memory and a processor. When the processor executes the program stored in the memory, it can implement the geomagnetic contour matching method based on combined space constraint in the above embodiment.

[0107] It should be noted that although the operations are depicted in a specific order in the drawings, this should not be construed as requiring the operations to be performed in the specific order shown or sequentially, or requiring all of the illustrated operations to be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. In addition, the separation of the various system modules and components in the above embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Claims

1. A geomagnetic contour matching method based on combined spatial constraints, characterized in that: The method comprises: Perform a grid search around the inertial navigation system to obtain multiple possible matching points; Acquire navigation positioning parameters; wherein the navigation positioning parameters include the reference magnetic field vector, the measured magnetic field vector and the matching point position information of the possible matching point; Determine the combined spatial constraint similarity of the possible matching points according to the navigation positioning parameters; the constituent elements of the combined spatial constraint similarity include magnetic field difference similarity for characterizing magnetic field difference and continuity similarity for characterizing spatial position continuity; Taking the possible matching point corresponding to the minimum value of the combined spatial constraint similarity as a candidate point; With the candidate point as the center, the search area is narrowed and a cyclic iterative search is performed until the iteration condition is met; and the candidate point obtained in the last iteration is used as the target matching position.

2. The geomagnetic contour matching method based on combined spatial constraints according to claim 1, characterized in that: The navigation positioning parameters also include the inertial navigation position information of the inertial navigation system; the constituent elements also include the inertial navigation trajectory difference similarity used to characterize the difference between the matching trajectory and the inertial navigation trajectory.

3. The geomagnetic contour matching method based on combined spatial constraints as claimed in claim 2, characterized in that: The determining, according to the navigation positioning parameters, the combined spatial constraint similarity of the possible matching points comprises: Determining the magnetic field difference similarity according to the reference magnetic field vector and the measured magnetic field vector; Determining the continuity similarity according to the target matching position at the last moment and the matching point position information; Determining the inertial navigation trajectory difference similarity according to the inertial navigation position information and the matching point position information; The combined spatial constraint similarity is determined based on the magnetic field difference similarity, the continuity similarity and the inertial navigation trajectory difference similarity.

4. The geomagnetic contour matching method based on combined spatial constraints as claimed in claim 3, characterized in that: The determining the inertial navigation trajectory difference similarity according to the inertial navigation position information and the matching point position information includes: According to the inertial navigation position information, respectively obtaining the inertial navigation position coordinates at the current moment and the previous moment; and determining the inertial navigation displacement increment according to the inertial navigation position coordinates; Determine the matching point displacement increment corresponding to each of the possible matching points according to the target matching position at the previous moment and the matching point position information; The inertial navigation trajectory difference similarity is determined according to the inertial navigation displacement increment and the matching point displacement increment.

5. The geomagnetic contour matching method based on combined spatial constraints as claimed in claim 3, characterized in that: The determining the combined spatial constraint similarity based on the magnetic field difference similarity, the continuity similarity and the inertial navigation trajectory difference similarity includes: Assigning corresponding weights to the magnetic field difference similarity, the continuity similarity and the inertial navigation trajectory difference similarity respectively; Based on the weight, the magnetic field difference similarity, the continuity similarity and the inertial navigation trajectory difference similarity are weightedly summed to obtain the combined spatial constraint similarity.

6. The geomagnetic contour matching method based on combined spatial constraints according to claim 5, characterized in that: The sum of the weights is 1, the weight corresponding to the continuity similarity is greater than the weight corresponding to the magnetic field difference similarity, and the weight corresponding to the magnetic field difference similarity is equal to the weight corresponding to the inertial navigation trajectory difference similarity.

7. The geomagnetic contour matching method based on combined spatial constraints according to claim 1, characterized in that: The method further comprises: The target matching position is optimized by Kalman filtering to obtain the target navigation position.

8. A geomagnetic profile matching device based on combined spatial constraints, characterized in that: The device comprises: A possible matching point acquisition module is used to perform a grid search around the inertial navigation system to obtain multiple possible matching points; A positioning parameter acquisition module, used to acquire navigation positioning parameters; wherein the navigation positioning parameters include the reference magnetic field vector, the measured magnetic field vector and the matching point position information of the possible matching point; A similarity determination module, used to determine the combined spatial constraint similarity of the possible matching points according to the navigation positioning parameters; the constituent elements of the combined spatial constraint similarity include magnetic field difference similarity for characterizing magnetic field difference and continuity similarity for characterizing spatial position continuity; A candidate point acquisition module, used to take the possible matching point corresponding to the minimum similarity value of the combined spatial constraint as a candidate point; The loop control module is used to narrow the search area with the candidate point as the center and perform loop iterative search until the iteration condition is met; and the candidate point obtained in the last iteration is used as the target matching position.

9. A geomagnetic contour matching device based on combined spatial constraints, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, characterized in that: When the processor executes the program, the steps of the geomagnetic contour matching method based on combined spatial constraints as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the geomagnetic contour matching method based on combined spatial constraints as described in any one of claims 1 to 7 are implemented.

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