A method for transferring planar coordinates inside and outside a tunnel based on inertial navigation

Abstract

This invention relates to the field of engineering surveying technology, specifically to a method for transferring planar coordinates inside and outside tunnels based on inertial navigation during the tunnel construction phase. It includes: preliminary preparation; continuous data acquisition along a closed route; post-construction data processing to calculate the initial coordinates of points within the tunnel in the CGCS2000 coordinate system; distance constraint adjustment between point pairs within the tunnel to improve measurement accuracy; and coordinate transformation to calculate the tunnel planar engineering coordinates of the points within the tunnel. This invention features one-button start-up of the inertial navigation system, continuous and automatic data acquisition, eliminating the need for manual instrument setup and readings, and requiring no manual intervention. It reduces the minimum of three people required for traverse surveying to only one, significantly reducing workload and improving measurement efficiency. This invention achieves high-precision transfer of planar coordinates inside and outside tunnels in scenarios without CPIII control points, improving applicability. Through closed-path design and dynamic weighted fusion, this invention fundamentally solves the problem of drift in inertial navigation measurements during the construction phase, a problem that is otherwise impossible to address.

Description

Technical Field

[0001] This invention relates to the field of engineering surveying technology, specifically to a method for transferring planar coordinates inside and outside a tunnel based on inertial navigation during the tunnel construction phase. Background Technology

[0002] In tunnel construction, to ensure the tunnel alignment and provide a horizontal reference for internal construction, both external and internal tunnel surveying are required to transfer the determined external plane coordinates to the tunnel interior. External tunnel surveying often employs GNSS technology, which offers a high degree of automation, eliminates the need for line-of-sight between points, and allows for all-weather operation. Due to the confined and elongated nature of the tunnel interior, transferring the known plane coordinates of points outside the tunnel to the interior typically involves laying out traverse lines or traverse networks and using a total station for ground surveying.

[0003] The method for correcting the coordinates of a tunnel moving laser scanning point cloud based on CPIII control points, as described in Chinese patent CN113739770B, can efficiently obtain the tunnel in-tunnel point cloud in the tunnel coordinate system, but it requires the use of existing CPIII control points within the tunnel. When there is no planar position reference within the tunnel, this method cannot calculate the transformation parameters between the inertial navigation coordinate system and the tunnel coordinate system, nor can it suppress the measurement errors of the gyroscope sensors in the inertial measurement unit that accumulate over time. Consequently, it cannot obtain a high-quality tunnel in-tunnel point cloud in the tunnel coordinate system, rendering this solution unusable.

[0004] During tunnel construction, it is necessary to transfer external coordinates to the tunnel. However, total station field surveying requires the cooperation of multiple people, requires line-of-sight between points, and measures the side length and angle station by station. The automation level is low, which affects the surveying efficiency. The moving scan scheme relies on CPIII control points, but there are no such reference points in the tunnel before the external coordinates are transferred to the tunnel. Summary of the Invention

[0005] This invention provides a method for transferring planar coordinates inside and outside tunnels based on inertial navigation, which solves the problems of low automation and multiple personnel required for the method of transferring coordinates inside and outside tunnels using a total station in the background art, and solves the problem of reference transfer without relying on the CPIII control network.

[0006] The technical solution of this invention: a method for transferring planar coordinates inside and outside a tunnel based on inertial navigation, comprising the following steps:

[0007] Step 1, Preliminary Preparations;

[0008] Prepare the following: control points outside the tunnel, CGCS2000 coordinate system coordinates of the control points and tunnel plane engineering coordinate system coordinates, CGCS2000 coordinate system and tunnel plane engineering coordinate system conversion parameters, pairs of points inside the tunnel, the distance between a pair of points inside the tunnel, and a moving platform equipped with alignment and locking devices.

[0009] Step 2: Collect data continuously along the closed route;

[0010] Starting from the control point outside the tunnel, data is continuously collected along the round-trip closed route. When collecting data from control points and points inside the tunnel, the platform is aligned with the control point or point inside the tunnel and then stationary for data collection. The data collection time is greater than 30 seconds. When collecting data between control points or points inside the tunnel, the platform moves at a speed of less than 1 meter per second.

[0011] Step 3: Post-processing data, calculating the initial coordinates of the points inside the tunnel in the CGCS2000 coordinate system;

[0012] The collected raw data are processed in both forward and backward directions to obtain forward and backward trajectories. The forward and backward trajectories are then weighted and fused. After weighted fusion, trajectory closure error allocation and correction are performed. The trajectory after trajectory closure error allocation is then converted into the CGCS2000 coordinate system.

[0013] Step 4: Adjust the distance constraints between points inside the tunnel to improve measurement accuracy;

[0014] There are m points inside the tunnel, forming k = m / 2 point pairs. The measured distance between each point pair is d. j The unknown parameter vector X represents the coordinates of all points inside the tunnel, while the observation vector represents the CGCS2000 coordinates of the points inside the tunnel obtained from inertial navigation measurements and the distance between pairs of points inside the tunnel. The CGCS2000 coordinates of the points inside the tunnel are obtained through indirect adjustment.

[0015] The function model between the unknown parameter vector X and the observed value vector L is established as: L = f(X).

[0016] During indirect adjustment, the coordinates X of the points inside the tunnel obtained from the forward trajectory are taken. 前 Let X be an approximation of the unknown parameter vector X, and let...

[0017] Approximate value X of the unknown parameter vector X 前 Substituting into the function model of indirect adjustment, we have

[0018]

[0019] The error equation for indirect adjustment is:

[0020]

[0021] Where V is the observation correction and A is the coefficient matrix, the result of which is:

[0022]

[0023] In the formula, P is the weight matrix of the observations, and the final result of the indirect adjustment is:

[0024]

[0025] In the above formula, X is the parameter vector obtained after indirect adjustment;

[0026] Step 5: Coordinate transformation, calculate the coordinates of the tunnel plane in the engineering coordinate system of the points inside the tunnel;

[0027] Using the known transformation parameters between the CGCS2000 coordinate system and the tunnel plane engineering coordinate system, the coordinates of the points inside the tunnel in the CGCS2000 coordinate system are converted to the coordinates of the tunnel plane engineering coordinate system; the tunnel plane engineering coordinates of the points inside the tunnel are the final result obtained from the transfer.

[0028] In step 1, no fewer than two control points are set at each entrance outside the tunnel.

[0029] In step 1, the distance between a pair of points inside the cave is no more than 40 meters, and is accurately measured using a rangefinder.

[0030] In step 1, the inertial navigation system is placed on a moving platform. The moving platform is equipped with an alignment device. After the alignment device is aligned with the control point, the center of mass of the platform and the control point are on the same vertical line. The moving platform is equipped with a mechanical locking device, which allows the inertial navigation system to perform static observations after locking.

[0031] The data collected continuously along the round-trip closed path in step 2 includes gyroscope, accelerometer, and raw time data.

[0032] In step 2, after the platform is aligned with the control point outside the tunnel or the point inside the tunnel, the mechanical lock is tightened, and the platform comes to a standstill.

[0033] In step 2, the round-trip closed route starts from the first control point outside the tunnel and collects data from each control point outside the tunnel and each point inside the tunnel until the data collection at the last point inside the tunnel is completed. Then, the data collection proceeds in the reverse order from each point inside the tunnel to each control point outside the tunnel until the data collection is completed at the first control point outside the tunnel. During this process, data collection is uninterrupted.

[0034] In step 3, the forward trajectory and the backward trajectory are denoted as P respectively. 前 and P 后 The weighted fusion method is as follows:

[0035]

[0036] in, As weight;

[0037]

[0038] Where n is the number of data points collected, t1 represents the time of collection of the first data point, and t it represents the collection time of the i-th data point, where i ≤ n. n This indicates the time when the last data was collected.

[0039] In step 3, the trajectory closure error allocation and correction first involves calculating the trajectory closure error ΔP = P. n -P1, the closure difference allocation model is:

[0040]

[0041] This invention features a one-button start for inertial navigation, enabling continuous and automatic data acquisition without the need for manual instrument setup and readings. The mobile platform moves at a certain speed between control points and points within the tunnel, requiring no manual intervention. This reduces the minimum of three people needed for traverse surveying to just one, significantly reducing workload and improving measurement efficiency. Furthermore, this invention achieves high-precision transfer of planar coordinates inside and outside the tunnel in scenarios without CPIII control points, enhancing its applicability. Finally, through closed-path design and dynamic weighted fusion, this invention fundamentally solves the problem of drift in inertial navigation measurements during the construction phase, a problem that is otherwise impossible to address. Attached Figure Description

[0042] Figure 1 This is a flowchart illustrating the present invention;

[0043] Figure 2 This is a schematic diagram of the control points outside the tunnel, the points inside the tunnel, and the data acquisition route deployed according to an embodiment of the present invention.

[0044] Figure 3 This is a schematic diagram of the bidirectional weighted fusion process according to an embodiment of the present invention. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the specific embodiments.

[0046] Example

[0047] like Figure 1 This is a flowchart of a method for transferring planar coordinates inside and outside a tunnel based on inertial navigation. It specifically includes the following steps:

[0048] Step 1, Preliminary Preparations;

[0049] (1) Set up two control points, A and B, at the tunnel entrance;

[0050] (2) Determine the CGCS2000 coordinates and the tunnel plane engineering coordinate system coordinates of control points A and B;

[0051] (3) The transformation parameters between the CGCS2000 coordinate system and the tunnel plane engineering coordinate system have been determined in the preliminary survey stage;

[0052] (4) such as Figure 2 As shown, pairs of tunnel points are set on the ground at intervals inside the tunnel, with a total of 4 pairs of tunnel points: P1R and P1L, P2R and P2L, P3R and P3L, and P4R and P4L. The distance between a pair of tunnel points is less than 40 meters, and the distances are d1, d2, d3, and d4 respectively, which are accurately measured in advance using a rangefinder.

[0053] (5) The inertial navigation system is placed on the moving platform. The moving platform is equipped with an alignment device. After the alignment device is aligned with the control point, the center of mass of the platform and the control point are on the same vertical line. The moving platform is equipped with a mechanical locking device. After locking, the inertial navigation system can be used for static observation.

[0054] Step 2: Collect data continuously along the closed route;

[0055] (1) The platform is aligned with control point A outside the tunnel, the mechanical lock is locked, and the inertial navigation system starts to collect raw data from the gyroscope, accelerometer, and time. The data collection time is greater than 30 seconds.

[0056] (2) After the data collection at control point A is completed, open the mechanical lock of the platform and slowly move the platform to control point B outside the tunnel. After aligning with the control point, lock the mechanical lock and collect the data. The data collection time is more than 30 seconds.

[0057] (3) After the data acquisition of control point B outside the tunnel is completed, the mechanical lock of the platform is opened and the platform slowly moves from outside the tunnel to inside the tunnel, traveling along the tunnel centerline; when the platform passes the first point P1R inside the tunnel, the platform is aligned with point P1R inside the tunnel, the mechanical lock is locked, and the data acquisition time is greater than 30 seconds.

[0058] (4) After the data acquisition of the first hole point P1R is completed, open the platform mechanical lock and slowly move the platform to other hole points in turn. After aligning with the hole points, lock the mechanical lock. The data acquisition time is more than 30 seconds.

[0059] (5) After the data collection at the last point P4L inside the tunnel is completed, the platform moves along the opposite route and collects data at the points inside the tunnel and the control points outside the tunnel in reverse order until it returns to the first control point outside the tunnel A to complete the data collection.

[0060] (6) During the data acquisition process, the inertial navigation system is kept powered on from the start of data acquisition at the first control point A outside the tunnel until the data acquisition at the first control point A outside the tunnel is completed. During this period, the inertial navigation system is not powered off and the data acquisition is uninterrupted.

[0061] (7) Slow platform movement refers to a platform movement speed of less than 1 meter per second;

[0062] Step 3: Post-processing data, calculating the initial coordinates of the points inside the tunnel in the CGCS2000 coordinate system;

[0063] (1) Perform forward and backward calculations on the original data respectively. The forward calculation is performed in the order from the first data to the last data to obtain the trajectory P. 前 The backward calculation is performed on the inertial navigation trajectory in the order from the last collected data to the first data, resulting in trajectory P. 后 ;

[0064] (2) P 前 and P 后 Weighted fusion, with the following weights:

[0065]

[0066] Where n is the number of data points collected, t1 represents the time of collection of the first data point, and t i t represents the collection time of the i-th data point, where i ≤ n. n Indicates the time of the last data collection;

[0067] The weighted fusion method is as follows:

[0068]

[0069] By weighted fusion of forward and backward computations and dynamically allocating errors using a time weighting function, the cumulative drift of the inertial navigation system is significantly suppressed, resulting in a 30% improvement in accuracy compared to traditional single-path methods. The bidirectional fusion process is as follows: Figure 3 As shown.

[0070] (3) After weighted fusion, trajectory closure error allocation correction is performed. First, the trajectory closure error is calculated. The closure difference allocation model is as follows:

[0071]

[0072] The closure error ΔP is distributed proportionally over time to achieve a uniform distribution of error and avoid misalignment during segment splicing.

[0073] (4) The trajectory after the trajectory closure error is assigned is converted to the CGCS2000 coordinate system. The trajectory in the CGCS2000 coordinate system is still denoted as P;

[0074] Step 4: Adjust the distance between points inside the tunnel and the coordinate constraints of control points outside the tunnel to improve measurement accuracy;

[0075] (1) There are m=8 points inside the tunnel, forming k=m / 2=4 point pairs. The measured distance of each point pair is d. j ;

[0076] (2) The unknown parameter vector X is the coordinates of all points inside the tunnel, and the observation vector L is the CGCS2000 coordinates of the points inside the tunnel obtained by inertial navigation measurement and the distance between pairs of points inside the tunnel; the CGCS2000 coordinates of the points inside the tunnel are obtained according to the observation time and trajectory P;

[0077] (3) Given the observed value vector L and the unknown parameter vector X, the function model between X and L is established as: L=f(X).

[0078] During indirect adjustment, the coordinates X of the points inside the tunnel obtained from the forward trajectory are taken. 前 Let X be an approximation of the unknown parameter vector X, and let...

[0079]

[0080] Approximate value X of the unknown parameter vector X 前 Substituting into the function model of indirect adjustment, we have

[0081]

[0082] The error equation for indirect adjustment is:

[0083]

[0084] Where V is the observation correction and A is the coefficient matrix. The calculation yields:

[0085]

[0086] In the formula, P is the weight matrix of the observations. The final result of the indirect adjustment is...

[0087]

[0088] In the above formula, X represents the coordinates of the points inside the tunnel after adjustment using the CGCS2000 coordinate system. After distance-constrained adjustment, the accuracy of the coordinates of the points inside the tunnel is improved by more than 30%.

[0089] Step 5: Coordinate transformation, calculate the coordinates of the tunnel plane in the engineering coordinate system of the points inside the tunnel;

[0090] Using known transformation parameters, the coordinates of the points inside the tunnel after adjustment in the CGCS2000 coordinate system are converted to the coordinates in the tunnel plane engineering coordinate system; the tunnel plane engineering coordinates of the points inside the tunnel are the final results obtained from the transfer.

[0091] Traditional traverse surveying requires manual setup of a total station at the station for readings, and manual installation of prisms at the foresight and backsight points for aiming. At least three people are needed for this work, and manual relocation of the station is required after each measurement is completed. In contrast, using inertial navigation for the transfer of planar coordinates inside and outside the tunnel requires only one person and takes significantly less time.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for transferring planar coordinates inside and outside a tunnel based on inertial navigation, characterized in that: Includes the following steps: Step 1, Preliminary Preparations; Prepare the following: control points outside the tunnel, CGCS2000 coordinate system coordinates of the control points and tunnel plane engineering coordinate system coordinates, CGCS2000 coordinate system and tunnel plane engineering coordinate system conversion parameters, pairs of points inside the tunnel, the distance between a pair of points inside the tunnel, and a moving platform equipped with alignment and locking devices. Step 2: Collect data continuously along the closed route; Starting from the control point outside the tunnel, data is continuously collected along the round-trip closed route. When collecting data from control points and points inside the tunnel, the platform is aligned with the control point or point inside the tunnel and then stationary for data collection. The data collection time is greater than 30 seconds. When collecting data between control points or points inside the tunnel, the platform moves at a speed of less than 1 meter per second. Step 3: Post-processing data, calculating the initial coordinates of the points inside the tunnel in the CGCS2000 coordinate system; The collected raw data are processed in both forward and backward directions to obtain forward and backward trajectories. The forward and backward trajectories are then weighted and fused. After weighted fusion, trajectory closure error allocation and correction are performed. The trajectory after trajectory closure error allocation is then converted into the CGCS2000 coordinate system. Step 4: Adjust the distance constraints between points inside the tunnel to improve measurement accuracy; There are m points inside the tunnel, forming k = m / 2 point pairs. The measured distance between each point pair is d. j The unknown parameter vector X represents the coordinates of all points inside the tunnel, while the observation vector represents the CGCS2000 coordinates of the points inside the tunnel obtained from inertial navigation measurements and the distance between pairs of points inside the tunnel. The CGCS2000 coordinates of the points inside the tunnel are obtained through indirect adjustment. Step 5: Coordinate transformation, calculate the coordinates of the tunnel plane in the engineering coordinate system of the points inside the tunnel; Using the known transformation parameters between the CGCS2000 coordinate system and the tunnel plane engineering coordinate system, the coordinates of the points inside the tunnel in the CGCS2000 coordinate system are converted to the coordinates of the tunnel plane engineering coordinate system; the tunnel plane engineering coordinates of the points inside the tunnel are the final result obtained from the transfer.

2. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 1, no fewer than two control points are set at each entrance outside the tunnel.

3. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 1, the distance between a pair of points inside the cave is no more than 40 meters, and is accurately measured using a rangefinder.

4. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 1, the inertial navigation system is placed on a moving platform. The moving platform is equipped with an alignment device. After the alignment device is aligned with the control point, the center of mass of the platform and the control point are on the same vertical line. The moving platform is equipped with a mechanical locking device, which allows the inertial navigation system to perform static observations after locking.

5. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: The data collected continuously along the round-trip closed path in step 2 includes gyroscope, accelerometer, and raw time data.

6. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 2, after the platform is aligned with the control point outside the tunnel or the point inside the tunnel, the mechanical lock is tightened, and the platform comes to a standstill.

7. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 2, the round-trip closed route starts from the first control point outside the tunnel and collects data from each control point outside the tunnel and each point inside the tunnel until the data collection at the last point inside the tunnel is completed. Then, the data collection proceeds in the reverse order from each point inside the tunnel to each control point outside the tunnel until the data collection is completed at the first control point outside the tunnel. During this process, data collection is uninterrupted.

8. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 3, the forward trajectory and the backward trajectory are denoted as P respectively. 前 and P 后 The weighted fusion method is as follows: in, As weight; Where n is the number of data points collected, t1 represents the time of collection of the first data point, and t i t represents the collection time of the i-th data point, where i ≤ n. n This indicates the time when the last data was collected.

9. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 3, the trajectory closure error allocation and correction first involves calculating the trajectory closure error ΔP = P. n -P1, the closure difference allocation model is: .

10. The method for transferring planar coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 4, the coordinates of the points inside the cave in the CGCS2000 coordinate system are obtained through indirect adjustment, specifically as follows: The function model between the unknown parameter vector X and the observed value vector L is established as follows: L=f(X) During indirect adjustment, the coordinates X of the points inside the tunnel obtained from the forward trajectory are taken. 前 Let X be an approximation of the unknown parameter vector X, and let... ； Approximate value X of the unknown parameter vector X 前 Substituting into the function model of indirect adjustment, we have ； The error equation for indirect adjustment is: ； Where V is the observation correction and A is the coefficient matrix, the result of which is: ； In the formula, P is the weight matrix of the observations, and the final result of the indirect adjustment is: ； In the above formula, X is the parameter vector obtained after indirect adjustment.

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