A GNSS plane control network measurement method for checking closure error of three-side closed loop

Abstract

The application discloses a kind of GNSS plane control network measurement methods of three-side closed loop closure error inspection, including layout plane control network point, obtains the GNSS data of GNSS plane control network point;The three-dimensional coordinate component of each baseline and baseline length, the three-dimensional coordinate component closure error of three-side closed loop and the ring length closure error;Judge whether the three-dimensional closure error data of three-side closed loop is all qualified, if the three-dimensional closure error data of three-side closed loop is not all qualified, then to the unqualified three-side closed loop is carried out the plane closure error inspection of three-side closed loop, judge whether plane closure error data is qualified.The measurement method of the application is suitable for the measurement of two-dimensional plane coordinate data, the closure error inspection of GNSS plane control network three-side closed loop is only carried out the inspection to plane position closure error, greatly reduces the requirement of GNSS plane control network to engineering survey area environment, without considering elevation, both improve work efficiency, and can guarantee that measurement result accuracy meets the specification requirement.

Description

Technical Field

[0001] This invention relates to, specifically, a GNSS plane control network measurement method for verifying the closure error of a three-sided closed loop. Background Technology

[0002] Global Navigation Satellite System (GNSS) is a space-based radio navigation and positioning system that provides users with all-weather, three-dimensional coordinates, velocity, and time information from any location on the Earth's surface or in near-Earth space. Closure error refers to the difference between the measured value of a quantity and its expected value. When several quantities constitute geometric or physical condition equations, errors in the measured values ​​of these quantities prevent them from satisfying the equations, resulting in a certain difference. This difference is called conditional closure error, or simply closure error.

[0003] With the continuous development of GNSS measurement technology and the successful networking of my country's BeiDou Navigation Satellite System, GNSS measurement technology has been widely applied in various fields. A GNSS receiver is a high-tech measuring instrument integrating optics, mechanics, and electronics. GNSS measurement systems can realize real-time automatic data acquisition and processing; they are widely used in measurement fields across various industries.

[0004] Existing GNSS receivers can acquire three-dimensional measurement data, including planar coordinate data and elevation coordinate data, with the planar coordinate data being two-dimensional. When GNSS receivers are networked for measurements, the obtained GNSS data is verified. Existing GNSS verification methods include:

[0005] Asynchronous loop test

[0006] GNSS planar networks typically have multiple network points, and measurements are completed in several groups. The groups are connected by edge or network connections. Measurements within the same group usually require simultaneous power-on and power-off to form a simultaneous measurement group. The resulting baselines are called simultaneous baselines. Since there are no strictly synchronous baselines for simultaneous measurements, the closed loops formed between simultaneous measurement baselines and between measurement baselines from different time periods are called asynchronous loops. The standard stipulates that asynchronous loop closure error verification should be performed. Asynchronous loop verification usually includes verification of the closure error of the three geocentric coordinate components and verification of the loop length closure error. The geocentric coordinate component closure error verification is the main form of three-dimensional closure error verification.

[0007] Therefore, since GNSS data is three-dimensional data, including both two-dimensional planar data and elevation data of control points, the receiver will check the three-dimensional closure error of the three-sided closed loop when verifying the GNSS data after processing the data. The value calculated by the three-dimensional closure error is related to the three parameters in the three-dimensional planar data.

[0008] However, many scenarios in existing technologies do not require 3D data, only 2D planar data. 3D coordinate data is suitable for scenarios that require measuring the elevation of control points, such as mountains, buildings, or other large objects. However, there are still many scenarios in existing technologies that only require obtaining 2D planar data and do not require elevation data. For example, in scenarios where roads, railway tracks, large horizontal objects, or plains are measured within a certain area, there is no need to verify the elevation data. In some projects where elevation is obtained using leveling or electromagnetic wave ranging trigonometric leveling, the GNSS network is only used as a method for obtaining planar coordinates, and elevation data is not required.

[0009] In existing GNSS receivers, after acquiring GNSS data, a three-dimensional closure error check can be performed to determine which groups of data are unqualified and which are qualified. Only when the three-dimensional closure error is qualified can the data measured by the GNSS receiver be considered qualified; only the qualified GNSS data can proceed to the next step of data processing, such as performing two-dimensional constrained adjustment on the GNSS data to obtain the two-dimensional plane coordinates of the GNSS plane control points.

[0010] In existing technologies, when measuring two-dimensional plane coordinate data, the three-dimensional coordinate data of the plane control network points is often acquired using a GNSS receiver. Then, the closure error of the three-dimensional coordinate data is checked. After passing the check, the three-dimensional coordinate data is converted to determine the final two-dimensional plane coordinate data. However, the closure error check formula for three-dimensional coordinate data requires the elevation data from the coordinate data to be substituted. Only when the calculated closure error data is acceptable is the data set considered acceptable. However, because the formula includes elevation data, it is easy for the two-dimensional plane data to be acceptable, but the three-dimensional coordinate data to be unacceptable. This significantly increases the requirement for the closure error data of the closed loop during two-dimensional measurement, making it prone to inspection errors. When the closure error data is unacceptable, the measurement needs to be repeated, undoubtedly causing a large amount of unnecessary workload and reducing efficiency. Summary of the Invention

[0011] The purpose of this invention is to provide a GNSS plane control network measurement method for verifying the closure error of a three-sided closed loop.

[0012] To achieve the above objectives, one embodiment of the present invention provides a GNSS plane control network measurement method for verifying the closure error of a three-sided closed loop, characterized by comprising the following steps:

[0013] Step (1) Set up several GNSS plane control points in the engineering survey area, set up GNSS receivers on the GNSS plane control points, and receive the positioning signals of global navigation satellites to obtain GNSS data of the GNSS plane control points;

[0014] Step (2) Solve the GNSS data to obtain the three-dimensional coordinate components of each baseline of the GNSS plane control network, as well as the three-dimensional coordinate component closure error and loop length closure error of the baseline length and the three-sided closed loop.

[0015] Step (3) Determine whether all three-dimensional closure error data of the three-sided closed loop are qualified:

[0016] If all the three-dimensional closure error data of the three-sided closed loop are qualified, proceed to step (4);

[0017] If not all three-dimensional closure error data of the three-sided closed loop are qualified, the unqualified three-sided closed loops shall be subjected to planar closure error testing to determine whether the planar closure error data is qualified. The steps of the planar closure error testing method are as follows:

[0018] Step A: Filter out the baselines with unqualified three-dimensional closure error data in the three-sided closed loop, take the geocentric coordinates of the GNSS plane control network points of the baseline as the starting geocentric coordinates of the baseline, and add the three-dimensional coordinate components of the baseline to obtain the ending geocentric coordinates of the baseline.

[0019] Step B: Convert the geocentric coordinates of the starting and ending points of the baseline to geodetic coordinates of the baseline endpoints. Calculate the geodetic coordinate differences between the baseline endpoints to determine the latitude and longitude differences. Then, calculate the planar position closure error W of the three-sided closed loop using the following formula. S ;

[0020]

[0021]

[0022]

[0023] Among them: W B The difference in horizontal distance (mm) is the sum of the latitude differences between the two endpoints of the baseline of the three-sided closed loop.

[0024] W L The difference in horizontal distance (mm) is the sum of the longitude differences between the two endpoints of the baseline of the three-sided closed loop.

[0025] W S The planar position closure error (mm) of the three-sided closed loop;

[0026] DB iThe latitude difference between the two endpoints of the baseline of the three-sided closed loop is (″);

[0027] DL i The difference in longitude between the two endpoints of the baseline of the three-sided closed loop is (″).

[0028] i is 1, 2, and 3, representing the baseline numbers of the three-sided closed loop, respectively.

[0029] R is the average radius of curvature (mm) of the Earth ellipsoid in the survey area;

[0030] ρ is a constant in radians per second, with a value of 206265″.

[0031] Step C: Calculate the planar position closure error limit W of the three-sided closed loop based on the number of GNSS receivers and the relative mean square error accuracy requirements of the weakest adjacent point side lengths specified in the GNSS network measurement level. S限 :

[0032]

[0033] Among them: W S限 The limit value (mm) for the planar position closure error of the three-sided closed loop;

[0034] n is the number of receivers;

[0035] Di is the planar distance (mm) of a certain edge in the closed loop;

[0036] p represents the relative mean square error of the side length of the weakest adjacent point specified in the measurement grade;

[0037] Step D: Determine the planar position closure error W of the three-sided closed loop. S Limit value W for planar position closure S限 The magnitude relationship, if the planar position closure error W S Not greater than the limit value W of the planar position closure error S限 If the planar closure error test is passed, proceed to step (4); if the planar position closure error W S Greater than the limit value W for planar position closure error S限 If the plane closure error test fails, the measurement result is deemed unqualified.

[0038] Step (4) Obtain GNSS data of GNSS plane control points, perform two-dimensional constraint adjustment on the GNSS data, and obtain the two-dimensional plane coordinates of GNSS plane control points.

[0039] The preferred method of this invention is as follows: the geocentric coordinates of the GNSS plane control points in step A are the geocentric coordinates of the GNSS plane control points obtained by three-dimensional unconstrained adjustment.

[0040] The preferred method of this invention is as follows: the number of plane control points is at least 3, and the number of GNSS receivers is at least 3.

[0041] In summary, the present invention has the following advantages:

[0042] The measurement method of this invention is applicable to the measurement of two-dimensional plane coordinate data. The closure error test of the three-sided closed loop of the GNSS plane control network only tests the plane position closure error, which greatly reduces the requirements of the GNSS plane control network on the engineering measurement area environment. Without considering the elevation, it not only improves the work efficiency, but also ensures that the accuracy of the measurement results meets the specifications. Attached Figure Description

[0043] Figure 1 This is a schematic diagram illustrating the layout of the planar control network points of the present invention to form a closed triangular loop baseline. Detailed Implementation

[0044] This invention provides a GNSS plane control network measurement method for verifying the closure error of a three-sided closed loop, comprising the following steps:

[0045] Step (1) Set up several GNSS plane control points in the engineering survey area, set up GNSS receivers on the GNSS plane control points, and receive the positioning signals of global navigation satellites to obtain GNSS data of the GNSS plane control points;

[0046] Step (2) resolves the GNSS data to obtain the three-dimensional coordinate components of each baseline of the GNSS plane control network, the baseline length, the three-dimensional coordinate component closure error of the three-sided closed loop, and the loop length closure error. Each end of a baseline belongs to two control network points; two points determine one baseline, meaning every two plane control network points can determine one baseline, and every three plane control network points can form a three-sided closed loop. For example... Figure 1 Each line in the network can be considered a baseline, and the triangle formed by the three baselines is a three-sided closed loop. Furthermore, the GNSS receiver can determine the three-dimensional coordinate components between any two plane control points, i.e., the difference in three-dimensional coordinates.

[0047] Step (3) Determine whether all three-dimensional closure error data of the three-sided closed loop are qualified:

[0048] Currently, the data requirements for the three-dimensional closure error Ws are: in n represents the number of closed loop edges. The value of the 3D closure error is related to all three parameters of the 3D coordinates. If a set of data meets the requirements of the 3D closure error, it will definitely meet the requirements of the planar closure error coordinate data, but the reverse is not necessarily true. Therefore, using the value of the 3D closure error to determine the required accuracy of a 2D scene in the existing technology may lead to errors in the recognition of some data.

[0049] If all the three-dimensional closure error data of the three-sided closed loop are qualified, then proceed to step (4), and the obtained three-dimensional coordinate data can be directly converted into two-dimensional planar coordinate data.

[0050] If not all three-dimensional closure error data of the three-sided closed loop are qualified, the unqualified three-sided closed loops shall be subjected to planar closure error testing to determine whether the planar closure error data is qualified. The steps of the planar closure error testing method are as follows:

[0051] Step A: Filter out the baselines with unqualified three-dimensional closure error data in the three-sided closed loop. These unqualified data groups correspond to the baselines. Take the geocentric coordinates of the GNSS plane control network points of the baseline as the starting geocentric coordinates of the baseline, and add the three-dimensional coordinate components of the baseline to obtain the ending geocentric coordinates of the baseline.

[0052] Step B: Convert the geocentric coordinates of the starting and ending points of the baseline to geodetic coordinates of the baseline endpoints. Calculate the geodetic coordinate differences between the baseline endpoints to determine the latitude and longitude differences. Then, calculate the planar position closure error W of the three-sided closed loop using the following formula. S ;

[0053]

[0054]

[0055]

[0056] Among them: W B The difference in horizontal distance (mm) is the sum of the latitude differences between the two endpoints of the baseline of the three-sided closed loop.

[0057] W L The difference in horizontal distance (mm) is the sum of the longitude differences between the two endpoints of the baseline of the three-sided closed loop.

[0058] W S The planar position closure error (mm) of the three-sided closed loop;

[0059] DB i The latitude difference between the two endpoints of the baseline of the three-sided closed loop is (″);

[0060] DL i The difference in longitude between the two endpoints of the baseline of the three-sided closed loop is (″).

[0061] i is 1, 2, and 3, representing the baseline numbers of the three-sided closed loop, respectively.

[0062] R is the average radius of curvature (mm) of the Earth ellipsoid in the survey area;

[0063] ρ is a constant in radians per second, with a value of 206265″.

[0064] Step C: Calculate the planar position closure error limit W of the three-sided closed loop based on the number of GNSS receivers and the relative mean square error accuracy requirements of the weakest adjacent point side lengths specified in the GNSS network measurement level. S限 :

[0065]

[0066] Among them: W S限 The limit value (mm) for the planar position closure error of the three-sided closed loop;

[0067] n is the number of receivers;

[0068] Di is the planar distance (mm) of a certain edge in the closed loop;

[0069] p represents the relative mean square error of the side length of the weakest adjacent point specified in the measurement grade.

[0070] For example, Table 4.2.1 of the "Specification for Surveying and Mapping of Hydropower Projects" (NB / T 35029-2014) stipulates that the relative mean square error of the side length of the weakest adjacent point in a second-order GNSS network should not be greater than 1 / 150,000. If this stipulation is taken as the compliance level, then the P value is 1 / 150,000.

[0071] Step D: Determine the planar position closure error W of the three-sided closed loop. S Limit value W for planar position closure S限 The magnitude relationship, if the planar position closure error W S Not greater than the limit value W of the planar position closure error S限 If the planar closure error test is passed, proceed to step (4); if the planar position closure error W S Greater than the limit value W for planar position closure error S限 If the plane closure error test fails, the measurement result is deemed unqualified.

[0072] When the measurement results are deemed unqualified, it is necessary to select new personnel or time to conduct a remeasurement.

[0073] Step (4) Obtain GNSS data of GNSS plane control points, perform two-dimensional constraint adjustment on the GNSS data, and obtain the two-dimensional plane coordinates of GNSS plane control points.

[0074] Preferably, in step A of this invention, the geocentric coordinates of the GNSS plane control points are obtained through three-dimensional unconstrained adjustment. The number of plane control points is at least three, and the number of GNSS receivers is at least three.

[0075] Steps (1), (2), and (4) of this invention are existing technologies. In existing technologies, after obtaining GNSS data using a GNSS receiver, and after all data passes the three-dimensional closure error test, the collected data is converted to obtain the required two-dimensional plane coordinates. The main difference between this invention and existing technologies lies in how to determine whether each set of data meets the requirements of two-dimensional plane coordinates. Since the two-dimensional plane coordinates test does not require elevation parameters, the non-compliant data identified through the three-dimensional closure error test is re-verified. If the verified data meets the qualified conclusion obtained from the plane closure error test method of this invention, it can be determined that although the set of data does not meet the detection requirements of the three-dimensional closure error test method, it meets the measurement requirements of the plane closure error, and the set of data can be directly identified as normal qualified data. After being identified as qualified data, the two-dimensional data undergoes plane conversion, and the accuracy of the converted two-dimensional plane data will meet the specifications.

[0076] Example 1:

[0077] Step (1) Reference Figure 1 Six plane control points were set up within the engineering survey area, and six GNSS receivers were installed at the plane control points. Two time periods were measured according to the second-order static GNSS network in the "Specifications for Hydropower Engineering Surveying" NB / T 35029-2014; GNSS data of the GNSS plane control points were obtained.

[0078] Step (2) uses professional software to solve the GNSS data, obtaining the three-dimensional coordinate components and baseline length of each baseline of the GNSS plane control network, the three-dimensional coordinate component closure error and loop length closure error of the three-sided closed loop. Based on the GNSS measurement data, 120 three-sided closed loops were formed from the qualified baselines directly calculated. Among them, 11 loops were found to be unqualified according to the asynchronous loop inspection specified in the standard. The inspection data of the unqualified asynchronous three-sided loops are shown in Table 1.

[0079] Table 1. Non-conforming Tri-sided Asynchronous Loop Inspection Data

[0080]

[0081]

[0082] It is evident that not all three-dimensional closure error data of the three-sided closed loop are up to standard, therefore it is necessary to determine whether the unqualified three-sided loop data meets the two-dimensional requirements.

[0083] To determine whether the planar closure error data is acceptable, the inspection method for planar closure error is as follows:

[0084] Step A: Filter out the baselines with unqualified three-dimensional closure error data in the three-sided closed loop, take the geocentric coordinates of the GNSS plane control network points of the baseline as the starting geocentric coordinates of the baseline, and add the three-dimensional coordinate components of the baseline to obtain the ending geocentric coordinates of the baseline.

[0085] Step B: Convert the geocentric coordinates of the starting and ending points of the baseline to geodetic coordinates of the baseline endpoints. Calculate the geodetic coordinate differences between the baseline endpoints to determine the latitude and longitude differences. Then, calculate the planar position closure error W of the three-sided closed loop using the following formula. S ;

[0086] Step C: Calculate the planar position closure error limit W of the three-sided closed loop based on the number of GNSS receivers and the relative mean square error accuracy requirements of the weakest adjacent point side lengths specified in the GNSS network measurement level. S限 :

[0087] (4) The geocentric coordinate components in Table 1 are the three-dimensional coordinate components. Combined with the geocentric coordinates of the plane control network points collected by the GNSS receiver, the geocentric coordinates of the two endpoints of each baseline are calculated. The geocentric coordinates of the plane control network points in the unconstrained adjustment results are shown in Table 2.

[0088] Table 2 Geocentric coordinates of unconstrained adjustment of GNSS plane control network

[0089]

[0090] Based on the data in Table 2 and the geocentric coordinate components in Table 1, the geocentric coordinates of the endpoints of the three-sided asynchronous loop baseline can be obtained. The geocentric coordinates of the starting point and ending point of the baseline are the geocentric coordinates of the two endpoints of the baseline, as detailed in Table 3.

[0091] Table 3 Geocentric coordinates of the baseline endpoints of the GNSS plane control network

[0092]

[0093]

[0094] (5) Based on the geocentric coordinates in Table 3, convert the geocentric coordinates of the starting point and ending point of the baseline into the geodetic coordinates of the baseline endpoints, as shown in Table 4. Calculate the difference in geodetic coordinates between the baseline endpoints and determine the difference in latitude and longitude between the baseline endpoints.

[0095] Table 4 Geodetic coordinates of the endpoints of the three-sided asynchronous loop baseline of the GNSS plane control network.

[0096]

[0097]

[0098] (6) Calculate the planar position closure error W of the three-sided closed loop. S

[0099] Table 5 Geodetic coordinates and closure error of GNSS plane control network endpoints.

[0100]

[0101]

[0102] As shown in Table 5, the planar position closure errors of all three-sided closed loops are qualified, so two-dimensional constraint adjustment is performed. In this embodiment, two-dimensional constraint adjustment is performed using KZ05 and KZ02 as fixed points, and the adjustment results are shown in Table 6.

[0103] Table 6. Results of Two-Dimensional Constrained Adjustment

[0104]

[0105] Table 4.2.1 of the "Specification for Surveying and Mapping of Hydropower Engineering" (NB / T 35029-2014) stipulates that the relative mean square error of the weakest adjacent point side length in a second-order GNSS network should not exceed 1 / 150000. However, after verification according to the method of this invention, the relative mean square error of the weakest side of the baseline in the adjustment result of Example 1 of this invention is 1 / 229947, which is far better than the requirement of the specification. Moreover, the positional mean square error of the weakest point KZ06 in this network is 1.28mm, which is fully suitable for the network construction survey of a specialized first-order control network. Table 11.1.2 of NB / T 35029-2014 stipulates that the plane mean square error of the weakest point in a specialized first-order control network is 1.5mm.

[0106] As can be seen from Example 1, the method of the present invention can appropriately reduce the environmental requirements for GNSS plane control network measurement, greatly improve the work efficiency, and avoid invalid rework caused by low accuracy of geodetic height measurement due to building and vegetation obstruction, which would result in the three-dimensional verification of the three-sided closed loop failing to meet the accuracy requirements of the corresponding specification level.

[0107] Although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A GNSS plane control network measurement method for verifying the closure error of a three-sided closed loop, characterized in that, Includes the following steps: Step (1) Set up several GNSS plane control points in the engineering survey area, set up GNSS receivers on the GNSS plane control points, and receive the positioning signals of global navigation satellites to obtain GNSS data of the GNSS plane control points; Step (2) Solve the GNSS data to obtain the three-dimensional coordinate components of each baseline of the GNSS plane control network, as well as the three-dimensional coordinate component closure error and loop length closure error of the baseline length and the three-sided closed loop. Step (3) Determine whether all three-dimensional closure error data of the three-sided closed loop are qualified. The three-dimensional closure error data includes the closure error of the three-dimensional coordinate components and the closure error of the loop length: If all the three-dimensional closure error data of the three-sided closed loop are qualified, then proceed to step (4). If not all three-dimensional closure error data of the three-sided closed loop are qualified, the unqualified three-sided closed loops shall be subjected to planar closure error testing to determine whether the planar closure error data is qualified. The steps of the planar closure error testing method are as follows: Step A: Filter out the baselines with unqualified three-dimensional closure error data in the three-sided closed loop, take the geocentric coordinates of the GNSS plane control network points of the baseline as the starting geocentric coordinates of the baseline, and add the three-dimensional coordinate components of the baseline to obtain the ending geocentric coordinates of the baseline. Step B: Convert the geocentric coordinates of the baseline's starting and ending points into geodetic coordinates of the baseline endpoints. Calculate the geodetic coordinate differences between the baseline endpoints to determine the latitude and longitude differences. Then, calculate the planar position closure error of the three-sided closed loop using the following formula. ; ； ； ； in: The sum of the latitude differences between the two endpoints of the baseline of the three-sided closed loop corresponds to the horizontal distance difference, in mm; The sum of the longitude differences between the two endpoints of the baseline of the three-sided closed loop corresponds to the difference in horizontal distance, in mm. The planar positional closure difference of the three-sided closed loop is expressed in mm. The latitude difference between the two endpoints of the baseline of the three-sided closed loop is expressed in "″". The difference in longitude between the two endpoints of the baseline of the three-sided closed loop is expressed in "″". R is the average radius of curvature of the Earth ellipsoid in the survey area, in mm; 1, 2, and 3 represent the baseline numbers of the three-sided closed loop, respectively; ； Step C: Calculate the planar position closure error limit of the three-sided closed loop based on the number of GNSS receivers and the relative mean square error accuracy requirements of the weakest adjacent point side lengths specified in the GNSS network measurement level. : ； in: The limit value for the planar position closure error of the three-sided closed loop is given in mm. Number of receivers; This represents the planar distance of a certain edge in the closed loop, in mm; p represents the relative mean square error of the side length of the weakest adjacent point specified in the measurement grade; Step D: Determine the planar position closure error of the three-sided closed loop. Limit of closure difference with planar position The magnitude relationship, if the planar position closure error Not greater than the limit of planar position closure error If the planar closure error test is passed, proceed to step (4); if the planar position closure error... Greater than the limit of planar position closure error If the plane closure error test fails, the measurement result is deemed unqualified. Step (4) Obtain GNSS data of GNSS plane control points, perform two-dimensional constraint adjustment on the GNSS data, and obtain the two-dimensional plane coordinates of GNSS plane control points.

2. The GNSS plane control network measurement method for verifying the closure error of a three-sided closed loop as described in claim 1, characterized in that: The geocentric coordinates of the GNSS plane control points in step A are obtained from the three-dimensional unconstrained adjustment.

3. The GNSS plane control network measurement method for verifying the closure error of a three-sided closed loop as described in claim 1, characterized in that: The number of plane control points shall be at least 3, and the number of GNSS receivers shall be at least 3.

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