Multi-layer multi-scale grid and dynamic aided positioning method based thereon

Abstract

The application discloses a multi-layer multi-scale grid and a dynamic auxiliary positioning method based on the same, and belongs to the field of wireless positioning. The method comprises the following steps: performing grid division on a target GNSS reference station network coverage area to obtain longitude difference dl, latitude difference db and height difference dh of the target GNSS reference station network coverage area grid; determining a multi-layer multi-scale grid of the target GNSS reference station network coverage area; based on the multi-layer multi-scale grid, a data center receives rough position information sent by a user, searches for a grid point closest to the user as a positioning service grid, and sends information of a virtual observation station of the positioning service grid to the user, so that real-time positioning is completed. The application solves the centimeter-level positioning demand of the service end for a large number of users from the principle of VRS technology, overcomes the problems of low terminal RTK fixing rate and poor accuracy in a complex terrain area, reduces the calculation pressure of the service end, has simple algorithm and strong practicability, and effectively reduces the construction and operation and maintenance cost caused by simply relying on the accumulation of server and other hardware facilities.

Description

Technical Field

[0001] This invention relates to the field of wireless positioning, and more particularly to a multi-layer, multi-scale grid and a dynamic assisted positioning method based thereon. Background Technology

[0002] To achieve GNSS positioning, domestic scholars have conducted relevant research on gridding technology, mainly utilizing regular large-scale planar grids to achieve meter-level differential positioning of pseudorange observations. Based on experience and actual field testing accuracy, planar, static, and uniformly sized regular grids are constructed. However, this regular grid has the following shortcomings:

[0003] 1. This regular grid is a single-layer planar grid, which does not take into account atmospheric delay errors caused by elevation differences, and cannot meet the positioning requirements of the same location at different heights.

[0004] 2. This regular grid is a uniformly sized grid divided based on human experience. It does not scientifically divide the grid for complex terrain and / or complex air environments, and cannot meet the requirements for grid size and number when using RTK positioning. Therefore, when using RTK positioning based on the above regular grid, it is not possible to achieve high-precision positioning in complex terrain and / or complex air environments.

[0005] 3. This rule grid is a static grid, which does not pay attention to the timeliness of grid points. That is, when no user is using the grid, the server still calculates the virtual observation value of the grid, which wastes the server's computing power and increases the server load.

[0006] In summary, existing grid-based VRS technology has the following problems: low RTK fixation rate and poor accuracy in complex terrain areas; and waste of server computing power when the grid is not used, increasing server load. Summary of the Invention

[0007] The purpose of this invention is to provide a multi-layer, multi-scale grid and a dynamic assisted positioning method based thereon, in order to solve the problems of low RTK fixation rate and poor accuracy of existing grid-based VRS technology in complex terrain areas; and the waste of server computing power and increased server load when the grid is not used.

[0008] The first aspect of this invention provides a method for constructing multi-layer, multi-scale meshes, the method comprising:

[0009] S1, based on the longitude difference of a predetermined base grid. Latitude difference The target GNSS reference station network coverage area is divided into several basic grids;

[0010] S2, when neither any basic grid nor any secondary grid after equal division of the basic grid can serve as a grid for providing positioning services, each secondary grid is divided into multiple grid layers at equal intervals to complete the construction of a multi-layer, multi-scale grid covering the target GNSS reference station network coverage area.

[0011] In the above embodiments of the present invention, optionally, S2 further includes: a method for determining whether any one basic grid or any secondary grid after equal division of the basic grid is used as the grid for providing positioning services.

[0012] S201, Select any basic grid, and let the latitude and longitude coordinates of the lower left vertex A of the arbitrary basic grid be... Calculate the maximum elevation within any of the base grids. and minimum elevation ;

[0013] S202, based on the height difference of a pre-determined base grid ,

[0014] judge If any one of the base grids is a grid that provides positioning services, proceed to S204;

[0015] judge If any of the aforementioned basic grids cannot be used as a grid for providing positioning services, proceed to S203;

[0016] S203, each basic grid is divided into multiple secondary grids, and any one of the secondary grids is selected.

[0017] judge If any one of the secondary grids is a grid that provides positioning services, proceed to S204;

[0018] judge If any of the sub-grids cannot be used as a location service grid, then the equal-spacing layered processing of any of the sub-grids will be performed.

[0019] S204, the center point of the positioning service grid is used as a virtual reference station, and its three-dimensional coordinates are... ;

[0020] (1).

[0021] In the above embodiments of the present invention, optionally, when the secondary grid is processed into equally spaced layers, the spacing between two adjacent grid layers is the predetermined height difference of the base grid. The secondary mesh is layered at equal intervals, which is implemented according to the following steps:

[0022] With the height difference The target secondary mesh is divided into layers with equal spacing between adjacent mesh layers, resulting in [m, n] mesh layers; where, m represents the layer number of the lowest grid layer after the target secondary grid is divided; n represents the layer number of the highest grid layer after the target secondary grid is divided; the formulas for calculating m and n are formula (2):

[0023] (2)

[0024] The center point of each grid layer of the target secondary grid is set as a virtual reference station, and its three-dimensional coordinates are... For formula (3):

[0025] (3).

[0026] A second aspect of the present invention provides a dynamic assisted positioning method based on a multi-layer, multi-scale grid, the method comprising: dividing the coverage area of ​​a target GNSS reference station network into grids to obtain the longitude difference of the grids within the coverage area of ​​the target GNSS reference station network. Latitude difference and height difference Using the multi-layer, multi-scale grid construction method, a multi-layer, multi-scale grid is determined for the target GNSS reference station network coverage area. Based on the multi-layer, multi-scale grid, the data center receives approximate location information sent by the user, searches for the grid point closest to the user as the grid for providing positioning services, and sends the information of the virtual observation station of the grid providing positioning services to the user, so that the user can complete real-time positioning.

[0027] In the above embodiments of the present invention, optionally, the longitude difference of the grid covering the target GNSS reference station network is... Latitude difference and height difference The calculation is given by formula (4):

[0028] (4)

[0029] in, Ionospheric and tropospheric delay model errors The calculation is given by formula (5);

[0030]

[0031] This indicates the number of reference stations selected from the GNSS reference station network for calculating model errors. This indicates the reference station number representing the selected calculation model error. This represents the value calculated by the double-difference ionospheric and tropospheric delay model for the k-th reference station. This represents the true values ​​of the double-difference ionospheric and tropospheric delays at the k-th reference station;

[0032] The atmospheric delay scaling factor is expressed by the following formula: Ionospheric scaling factor and tropospheric scaling factor The calculation is given by formula (6);

[0033]

[0034] Indicates the selected baseline number. This indicates the number of baselines selected from the baselines that make up the GNSS reference station network. Indicates the length of the r-th baseline; Indicates the double-difference ionospheric delay of the r-th baseline; This represents the double-difference tropospheric delay of the r-th baseline.

[0035] In the above embodiments of the present invention, optionally, at least before the data center receives the approximate location information sent by the user, a dynamic service strategy is further established. The dynamic service strategy includes, but is not limited to: any grid point in the multi-layer, multi-scale grid is not directly activated upon startup; any grid point is the optimal grid point matched by the user; the optimal grid point is instantly woken up and requests data from the data center; the wake-up time is recorded and the grid state of the optimal grid point is marked as activated; if the optimal grid point matched by a new user is in an activated state and continuously broadcasts differential data, then the optimal grid point matched by the new user directly broadcasts differential data to the new user in real time. According to the protocol, when any grid point is in the active state and all users receiving its broadcast differential data are offline, the grid status of that grid point is marked as waiting, and the waiting time is calculated. During the waiting period, the grid point continuously receives differential data sent by the data center. The status of all grid points in the multi-layer multi-scale grid is polled at a preset time. When the grid status of any grid point is waiting and the waiting time exceeds the preset waiting time threshold, the grid status of that grid point is marked as closed, and the receiving of differential data sent by the data center is stopped. The grid point is any grid or any grid layer in the multi-layer multi-scale grid.

[0036] A third aspect of the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the method for constructing the multi-layer, multi-scale mesh.

[0037] A fourth aspect of the present invention provides a computer-readable medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method for constructing the multi-layer, multi-scale grid.

[0038] A fifth aspect of the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the dynamic assisted positioning method based on a multi-layer, multi-scale grid.

[0039] A sixth aspect of the present invention provides a computer-readable medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the dynamic assisted positioning method based on a multi-layer, multi-scale grid.

[0040] This invention addresses the centimeter-level positioning needs of large numbers of users on the server side from the perspective of VRS technology principles. It overcomes the challenges of low RTK fixation rate and poor accuracy in complex terrain areas, reduces server-side computational pressure, features a simple algorithm, strong practicality, and effectively reduces construction and maintenance costs caused by simply relying on server and other hardware infrastructure. Specifically, this invention effectively increases the user limit of existing network RTK services, alleviating the computational pressure on VRS caused by massive numbers of users. Through actual construction of a 4′×4′ basic grid and experimental analysis, out-of-plane coincidence positioning accuracy can reach 1.5cm, and out-of-elevation coincidence positioning accuracy can reach 2cm, meeting the RTK positioning accuracy requirements. When the elevation difference between the user and the grid point exceeds 100m, the absolute maximum value of the U-direction positioning curve exceeds 5cm, indicating a systematic deviation in the U-direction. Based on this invention's technical solution, adding a 2′×2′ grid according to terrain information significantly improves the U-direction positioning accuracy. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a meshing mode according to an embodiment of this application; Indicates the user's location within the GNSS reference station network coverage area; This indicates that a virtual base station has been enabled;

[0042] Figure 2 This is a schematic diagram of the traditional VRS grid-based mode; Indicates the user's location within the GNSS reference station network coverage area; Activated virtual base station; Indicates alternative virtual base stations;

[0043] Figure 3 This is a schematic diagram of the process of constructing a multi-layer, multi-scale mesh in one embodiment of this application;

[0044] Figure 4This is a schematic diagram of the GNSS reference station network coverage area being divided into several basic grids in one embodiment of this application;

[0045] Figure 5 This is a schematic diagram of a basic grid latitude and longitude in one embodiment of this application;

[0046] Figure 6 This is a schematic diagram of a basic grid being divided into four secondary grids in one embodiment of this application;

[0047] Figure 7 This is a schematic diagram of a secondary mesh being divided into multiple mesh layers in one embodiment of this application;

[0048] Figure 8 This is a schematic diagram of a dynamic assisted positioning method based on multi-layer, multi-scale grids in one embodiment of this application;

[0049] Figure 9 is a comparison of the positioning errors of the existing basic grid and the multi-layer multi-scale grid in one embodiment of this application at the same measuring point when the height difference between the user and the grid point is greater than 100m; (a) shows the positioning error of the existing basic grid, and (b) shows the positioning error of the multi-layer multi-scale grid in one embodiment of this application.

[0050] Figure 10 The images show the positioning error sequence diagrams for 12 test points during the morning and afternoon periods, using traditional VRS for RTK positioning and the multi-layer, multi-grid positioning method described in this application; (a) Positioning error sequence diagram for the morning period using traditional VRS for RTK positioning; (b) Positioning error sequence diagram for the morning period using the multi-layer, multi-grid positioning method described in this application; (c) Positioning error sequence diagram for the afternoon period using traditional VRS for RTK positioning; (d) Positioning error sequence diagram for the afternoon period using the multi-layer, multi-grid positioning method described in this application. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0052] The technical solution of the multi-layer, multi-scale grid construction method claimed in this embodiment solves the problems of low RTK fixation rate and poor accuracy in complex terrain areas by dividing each grid into multiple grid layers based on the constructed basic grid, thereby achieving high-precision RTK positioning in complex terrain areas and / or areas with complex air environments.

[0053] Reference Figure 3Example 1: The technical solution of this example is a method for constructing multi-layer, multi-scale meshes, the method comprising:

[0054] S101, based on the longitude difference of a predetermined base grid. Latitude difference The target GNSS reference station network coverage area is divided into several basic grids, numbered G11~Gm, such as... Figure 4 As shown;

[0055] S102, select any basic grid G11, and let the latitude and longitude coordinates of the lower left vertex A of the basic grid G11 be... The maximum elevation within the base grid was calculated using the DEM model. and minimum elevation ,like Figure 5 As shown;

[0056] S103, based on a predetermined height difference ,

[0057] judge If so, then the basic grid G11 is the grid that provides positioning services, proceed to S106;

[0058] judge If the basic grid G11 cannot be a grid that provides positioning services, proceed to S104;

[0059] S104, the basic grid G11 is divided into 4 secondary grids, numbered G11-1 to G11-4, as follows: Figure 6 As shown. Select any secondary mesh G11-1,

[0060] judge Then the secondary grid G11-1 becomes the grid that provides positioning services, and proceeds to S106;

[0061] judge If so, the secondary grid G11-1 cannot be a grid that provides positioning services, and proceed to S105;

[0062] S105, with a predetermined height difference of the base grid The secondary grid G11-1 is divided into equal-spaced layers to maintain the spacing between adjacent grid layers, resulting in [m, n] grid layers; where, ; m represents the layer number of the lowest grid layer after the secondary grid G11-1 is layered; n represents the layer number of the highest grid layer after the secondary grid G11-1 is layered; the formulas for calculating m and n are formula (1):

[0063] (1)

[0064] The center point O of each grid layer of the secondary grid G11-1 is a virtual reference station, and its three-dimensional coordinates are as follows: Enter S107;

[0065] (2)

[0066] S106, the center point O of the positioning service grid is used as a virtual reference station, and its three-dimensional coordinates are... Enter S107;

[0067] (3)

[0068] S107, return to S102, until all basic grids are divided, completing the construction of a multi-layer, multi-scale grid covering the target GNSS reference station network area.

[0069] This application claims a technical solution based on a multi-layer, multi-scale grid construction method. This method constructs a multi-layer, multi-scale grid over a target area, and then performs RTK positioning based on this grid. It improves the original 1:1 customized model to an n:1 standardized model, meaning that instead of one virtual reference station per user, n users share one virtual reference station. Within the same grid area, n users only use their nearest neighbor grid point as the virtual reference station. Figure 1 As shown, after receiving a rough location from the user, the data center does not generate a virtual observation value based on it. Instead, it matches the nearest grid point and sends the virtual observation information of the nearest grid point to the user, who then uses this information for high-precision positioning. This reduces the computational burden on the server side, the algorithm is simple, highly practical, and effectively reduces the construction and maintenance costs caused by simply relying on the accumulation of hardware facilities such as servers.

[0070] Example 2

[0071] One embodiment of this technical solution is a dynamic assisted positioning method based on multi-layer, multi-scale grids, the method comprising:

[0072] S201. Grid Division Scale Calculation—Divide the target GNSS reference station network coverage area into grids to obtain the longitude difference of the grid within the target GNSS reference station network coverage area. Latitude difference and height difference .

[0073] VRS technology uses gridded points as virtual reference stations to achieve conventional RTK positioning with users. Inter-station differential eliminates clock errors, and the positioning error is the atmospheric delay error after differential. Its magnitude directly determines the ease and accuracy of positioning. That is, the closer the atmospheric delay error fitted by the grid point observation value through the GNSS reference station network is to the user's atmospheric delay error, the better the positioning accuracy.

[0074] Atmospheric delay error after differentiation It consists of two parts: first, the model error of the user atmospheric delay fitted to the GNSS reference station network. First, the fitting point is at the grid point rather than the user's location, meaning the unfitted atmospheric delay differential residual is caused by the location difference. , means as follows: .

[0075] Since the grid points and user points are located close to each other, the spatial distribution of atmospheric delay can be considered as... It is linearly proportional to the baseline length, therefore It is expressed as follows: . The atmospheric delay scaling factor, i.e., the change in atmospheric delay per unit length, is divided into... and That is, the ionospheric and tropospheric delay scaling factors; The baseline length between the user and the grid points.

[0076] In this embodiment, while ensuring that the user's RTK positioning accuracy is not compromised, based on The basic grid specifications are determined; therefore, the longitude difference of the grid in the coverage area of ​​the target GNSS reference station network is... Latitude difference and height difference The calculation is given by formula (4):

[0077] (4)

[0078] In equation (4), For ionospheric and tropospheric delay model errors, The calculation is performed by selecting a small number of base stations in the known base network as known quantities, and the calculation formula is Equation (5).

[0079]

[0080] This indicates the number of reference stations selected from the GNSS reference station network for calculating model errors. This indicates the reference station number representing the selected calculation model error. This represents the value calculated by the double-difference ionospheric and tropospheric delay model for the k-th reference station. This represents the true values ​​of the double-difference ionospheric and tropospheric delays at the k-th reference station;

[0081] In equation (4), The atmospheric delay scaling factor is expressed by the following formula: Ionospheric scaling factor and tropospheric scaling factor The calculation is given by formula (6);

[0082]

[0083] Indicates the selected baseline number. This indicates the number of baselines selected from the baselines that make up the GNSS reference station network. Indicates the length of the r-th baseline; Indicates the double-difference ionospheric delay of the r-th baseline; This represents the double-difference tropospheric delay of the r-th baseline.

[0084] S202, Multi-layer, Multi-scale Mesh Construction

[0085] Using the multi-layer, multi-scale grid construction method described in Example 1, a multi-layer, multi-scale grid is established for the target GNSS reference station network coverage area.

[0086] S203, based on the multi-layer, multi-scale grid described in S202, the data center receives approximate location information sent by the user, searches for the grid point closest to the user as the grid providing positioning services, and sends the information of the virtual observation station of this positioning service grid to the user, enabling the user to complete real-time positioning. Specifically:

[0087] S2031, Based on the aforementioned multi-layer, multi-scale grid, monitor whether a user request has been received.

[0088] If so, match the grid point closest to the user and proceed to S302;

[0089] If not, continue listening;

[0090] S2032, Determine the state of the grid point.

[0091] If it is in either the startup state or the waiting state, the grid point broadcasts differential data to the user;

[0092] If it is in the off state, the grid point will be instantly woken up and data will be requested from the data center. The system will enter S303, and the time will be recorded and marked as the start state.

[0093] S2033, the grid point will broadcast the data received from the data center to the user, and the user will complete real-time monitoring.

[0094] In this S203 step, at least before the data center receives the approximate location information sent by the user, a dynamic service policy is established, as referred to... Figure 8 The dynamic service strategy includes, but is not limited to:

[0095] (1) Any grid point in the multi-layer multi-scale grid is not directly activated when it starts. The grid point is the optimal grid point matched by the user. The optimal grid point is woken up instantly and requests data from the data center. The wake-up time is recorded and the grid state of the optimal grid point is marked as started.

[0096] (2) If the grid status of the optimal grid point matched by the new user is in the start state and the differential data is continuously broadcast, then the optimal grid point matched by the new user will directly broadcast the differential data to the new user in real time.

[0097] (3) When any grid point is in the start state and all users receiving its broadcast differential data are offline, the grid status of any grid point is marked as waiting and the waiting time is calculated. During the waiting process, any grid point continuously receives differential data sent by the data center.

[0098] (4) The state of all grid points in the multi-layer multi-scale grid is trained in a preset time. When the grid state of any grid point is waiting and the waiting time exceeds the preset waiting time threshold, the grid state of any grid point is marked as closed and the differential data sent by the data center is stopped.

[0099] Here, the grid point can be any grid or any grid layer in the multi-layer, multi-scale grid.

[0100] Figure 9 This is a comparison chart showing the positioning error of an existing basic grid and a multi-layer, multi-scale grid in one embodiment of this application at the same measuring point when the height difference between the user and the grid point is greater than 100m; (a) shows the positioning error chart of the existing basic grid, and (b) shows the positioning error chart of the multi-layer, multi-scale grid in one embodiment of this application. Figure 9 As can be seen from the comparison of positioning errors of the existing basic grid and the multi-layer multi-scale grid in this example at the same measuring point when the height difference between the user and the grid point is greater than 100m, it shows that: as the height difference between the user and the grid point is greater than 100m, the absolute value of the positioning curve in the U direction exceeds 5cm, and a systematic deviation occurs in the U direction. Based on the technical solution of this invention, after adding 2′×2′ grids according to the terrain information, the positioning accuracy in the U direction is significantly improved.

[0101] The statistical analysis of the positioning accuracy of the test points under the two positioning methods is shown in Table 1. It can be seen that the positioning accuracy based on multi-layer and multi-grid in this application is comparable to that of traditional VRS RTK positioning. The user's out-of-plane coincidence positioning accuracy can reach within 1.5cm, and the out-of-elevation coincidence positioning accuracy can reach within 2cm.

[0102] Table 1. Accuracy of RTK positioning using traditional VRS and positioning based on multi-layer, multi-grid technology in this application.

[0103]

[0104] Figure 10 The positioning accuracy of the dynamic assisted positioning method based on multi-layer multi-scale grids in this application is comparable to the stability of RTK positioning using traditional VRS. The positioning error sequence diagrams of 12 test points using traditional VRS RTK positioning and the multi-layer multi-scale grid positioning method in this application are shown in the morning and afternoon time periods: (a) Positioning error sequence diagram of the morning time period using traditional VRS RTK positioning; (b) Positioning error sequence diagram of the morning time period using multi-layer multi-scale grid positioning method in this application; (c) Positioning error sequence diagram of the afternoon time period using traditional VRS RTK positioning; (d) Positioning error sequence diagram of the afternoon time period using multi-layer multi-scale grid positioning method in this application.

[0105] By adopting the above-disclosed technical solution of this invention, the following beneficial effects are achieved: The technical solution of this invention addresses the centimeter-level positioning needs of large numbers of users on the server side from the perspective of VRS technology principles, overcoming the problems of low RTK fixation rate and poor accuracy in complex terrain areas, reducing the computational pressure on the server side, and featuring a simple algorithm with strong practicality. It effectively reduces the construction and maintenance costs caused by simply relying on hardware infrastructure such as servers. The technical solution of this invention effectively increases the user limit of existing network RTK services, alleviating the VRS computational pressure brought by massive numbers of users. Through actual construction of a 4′×4′ basic grid and experimental analysis, the out-of-plane coincidence positioning accuracy can reach 1.5cm, and the out-of-elevation coincidence positioning accuracy can reach 2cm, meeting the RTK positioning accuracy requirements. When the elevation difference between the user and the grid point exceeds 100m, the absolute maximum value of the U-direction positioning curve exceeds 5cm, indicating a systematic deviation in the U-direction. Based on the technical solution of this invention, after adding a 2′×2′ grid according to terrain information, the U-direction positioning accuracy is significantly improved.

[0106] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for constructing multi-layer, multi-scale meshes, characterized in that, The method includes: S1, based on the longitude difference of a predetermined base grid. Latitude difference The target GNSS reference station network coverage area is divided into several basic grids; S2, when neither any basic grid nor any secondary grid after equal division of the basic grid can serve as a grid for providing positioning services, each secondary grid is divided into multiple grid layers at equal intervals to complete the construction of a multi-layer, multi-scale grid covering the target GNSS reference station network area; S2 also includes: a method for determining whether any basic grid or any secondary grid after equal division of the basic grid is used as the grid for providing positioning services: S201, Select any basic grid, and let the latitude and longitude coordinates of the lower left vertex A of the arbitrary basic grid be... Calculate the maximum elevation within any of the base grids. and minimum elevation ; S202, based on the height difference of a pre-determined base grid , judge If any one of the base grids is a grid that provides positioning services, proceed to S204; judge If any of the aforementioned basic grids cannot be used as a grid for providing positioning services, proceed to S203; S203, each basic grid is divided into multiple secondary grids. Select any one secondary grid and calculate its maximum elevation. and minimum elevation , judge If any one of the secondary grids is a grid that provides positioning services, proceed to S204; judge If any of the sub-grids cannot be used as a location service grid, then the equal-spacing layered processing of any of the sub-grids will be performed. S204, the center point of the positioning service grid is used as a virtual reference station, and its three-dimensional coordinates are... ; When processing secondary grids into equally spaced layers, the spacing between two adjacent grid layers is the predetermined height difference of the base grid. ; The secondary mesh is layered at equal intervals, which is implemented according to the following steps: With the height difference The target secondary mesh is divided into layers with equal spacing between adjacent mesh layers, resulting in [m, n] mesh layers; where, m represents the layer number of the lowest grid layer after the target secondary grid is divided; n represents the layer number of the highest grid layer after the target secondary grid is divided; the formulas for calculating m and n are formula (2): （2） The center point of each grid layer of the target secondary grid is set as a virtual reference station, and its three-dimensional coordinates are... : （3）。 2. A dynamic assisted positioning method based on multi-layer, multi-scale grids, characterized in that, The method includes: The target GNSS reference station network coverage area is divided into grids to obtain the longitude difference of the grid within the target GNSS reference station network coverage area. Latitude difference and height difference ; Using the multi-layer, multi-scale grid construction method as described in claim 1, the multi-layer, multi-scale grid of the target GNSS reference station network coverage area is determined; Based on the multi-layer, multi-scale grid, the data center receives approximate location information from the user, searches for the grid point closest to the user as the grid for providing positioning services, and sends the information of the virtual observation station of the grid providing positioning services to the user, so that the user can complete real-time positioning.

3. The dynamic assisted positioning method based on multi-layer, multi-scale grids according to claim 2, characterized in that, Longitude difference of the grid covering the target GNSS reference station network Latitude difference and height difference The calculation is given by formula (4): （4） In equation (4), ∈ M For the ionospheric and tropospheric delay model errors, ∈ v This represents the atmospheric delay error after differentiation. in, Ionospheric and tropospheric delay model errors The calculation is given by formula (5); ， This indicates the number of reference stations selected from the GNSS reference station network for calculating model errors. This indicates the reference station number representing the selected calculation model error. This represents the value calculated by the double-difference ionospheric and tropospheric delay model for the k-th reference station. This represents the true values ​​of the double-difference ionospheric and tropospheric delays at the k-th reference station; The atmospheric delay scaling factor is expressed by the following formula: Ionospheric scaling factor and tropospheric scaling factor The calculation is given by formula (6); ， Indicates the selected baseline number. This indicates the number of baselines selected from the baselines that make up the GNSS reference station network. Indicates the length of the r-th baseline; Indicates the double-difference ionospheric delay of the r-th baseline; This represents the double-difference tropospheric delay of the r-th baseline.

4. The dynamic assisted positioning method based on multi-layer, multi-scale grids according to claim 2, characterized in that, At least before the data center receives the approximate location information sent by the user, a dynamic service policy is established, which includes, but is not limited to: When any grid point in the multi-layer, multi-scale grid is started, it is not directly activated. The grid point is the optimal grid point matched by the user. The optimal grid point is instantly woken up and requests data from the data center. The wake-up time is recorded and the grid state of the optimal grid point is marked as started. If the optimal grid point matched by a new user is in the active state and continuously broadcasts differential data, then the optimal grid point matched by the new user will directly broadcast differential data to the new user in real time. When any grid point is in the startup state and all users receiving its broadcast differential data are offline, the grid status of that grid point is marked as waiting, and the waiting time is calculated. During the waiting process, that grid point continues to receive differential data sent by the data center. The status of all grid points in the multi-layer, multi-scale grid is polled at a preset time. When the grid status of any grid point is waiting and the waiting time exceeds a preset waiting time threshold, the grid status of that grid point is marked as closed, and the reception of differential data sent by the data center is stopped. The grid point can be any grid or any grid layer in the multi-layer, multi-scale grid.

5. An electronic device, characterized in that, include: One or more processors; A memory for storing one or more programs that, when executed by one or more processors, cause the one or more processors to implement the method for constructing multi-layer, multi-scale meshes as described in claim 1.

6. A computer-readable medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method for constructing multi-layer, multi-scale meshes as described in claim 1.

7. An electronic device, characterized in that, include: One or more processors; A memory for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to implement the dynamic assisted positioning method based on a multi-layer, multi-scale grid as described in any one of claims 2-4.

8. A computer-readable medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the dynamic assisted positioning method based on a multi-layer, multi-scale grid as described in any one of claims 2-4.

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