Inertial navigation-based method for transmitting coordinates of planes inside and outside tunnel

Abstract

The invention relates to the technical field of engineering measurement, in particular to a method for transmitting coordinates of planes inside and outside a tunnel based on inertial navigation in a tunnel construction stage. The method includes: early-stage preparation; uninterruptedly collecting data along a closed route; post data processing is carried out, and the initial coordinates of the in-hole points in the CGCS2000 coordinate system are calculated; the distance between point-to-point pairs in the hole is constrained and adjusted, and the measurement precision is improved; and converting coordinates, and calculating to obtain coordinates of the in-hole point tunnel plane engineering coordinate system. According to the invention, inertial navigation is started by one key, data is continuously and automatically acquired, manual instrument erection and reading are not needed, manual intervention is not needed, at least three persons for cooperative operation of wire measurement are reduced to only one person, the manual workload is reduced, and the measurement efficiency is improved; according to the method, high-precision transmission of plane coordinates inside and outside the tunnel is realized in a CPIII-free scene without depending on CPIII control points in the tunnel, so that the applicability is improved; according to the method, through closed path design and dynamic weighted fusion, the problem of tunnel inertial navigation measurement drift in the construction period, which cannot be realized, is fundamentally solved.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering measurement, and in particular to a method for transferring plane coordinates inside and outside a tunnel based on inertial navigation during a tunnel construction phase. Background Art

[0002] During tunnel construction, both external and internal measurements are required to ensure tunnel alignment and provide a planar position reference for internal construction. GNSS technology is often used for external measurements. GNSS field measurements are highly automated, require no line of sight between points, and can be operated in all weather conditions. Due to the narrow and long interior space of tunnels, transferring the planar coordinates of known points outside the tunnel to the interior often involves laying out a traverse or traverse network, and using a total station for ground measurement.

[0003] Chinese patent CN113739770B describes a method for correcting point cloud coordinates for laser scanning during tunnel motion, based on CPIII control points. While this method can efficiently generate a point cloud within a tunnel coordinate system, it requires the use of existing CPIII control points within the tunnel. Without a planar position reference within the tunnel, this method cannot calculate the conversion parameters between the inertial navigation coordinate system and the tunnel coordinate system, nor can it suppress the measurement errors of the gyroscope sensor in the inertial measurement unit that accumulate over time. Consequently, it cannot generate a high-quality point cloud within the tunnel coordinate system, rendering this solution unusable.

[0004] During tunnel construction, external coordinates need to be transferred into the tunnel. However, field measurements with a total station require the cooperation of multiple people, line of sight between points, and measurement of side lengths and angles at each station. This results in a low degree of automation, which affects measurement efficiency. The mobile scanning solution relies on CPIII control points, and no such benchmarks exist inside the tunnel before the external coordinates are transferred into the tunnel. Summary of the Invention

[0005] The present invention provides a method for transferring plane coordinates inside and outside a tunnel based on inertial navigation, which solves the problem in the background art that the method for transferring coordinates inside and outside a tunnel using a total station requires the cooperation of multiple people and has a low degree of automation, and solves the difficulty of reference transfer that does not rely on the CPIII control network.

[0006] The technical solution of the present invention is a method for transferring plane coordinates inside and outside a tunnel based on inertial navigation, comprising the following steps: Step 1, preliminary preparation; Prepare the tunnel's external control points, the control points' coordinates in the CGCS2000 coordinate system and the tunnel's plane engineering coordinate system, the conversion parameters between the CGCS2000 coordinate system and the tunnel's plane engineering coordinate system, paired in-tunnel points, the distance between a pair of in-tunnel points, and a mobile platform equipped with alignment and locking devices; Step 2: continuously collect data along the closed route; From the tunnel outside control point, data is collected along the round trip closed route uninterruptedly, when collecting control point and hole point data, the platform is static after aligning with the control point or hole point, and the data collection time is greater than 30 seconds; when collecting data between the control point or hole point, the moving speed of the platform is less than 1 meter per second; Step 3, post-data processing, calculating the initial coordinates of the hole point in the CGCS2000 coordinate system; The original data collected is respectively forward and backward solved, the forward trajectory and the backward trajectory are obtained, the forward trajectory and the backward trajectory are weighted and fused, after the weighted fusion, the trajectory closure difference is allocated and corrected, and the trajectory after the trajectory closure difference allocation is converted into the CGCS2000 coordinate system; Step 4, hole point pair distance constraint adjustment, improving the measurement accuracy; There are m hole points in the tunnel, which form k=m / 2 point pairs, and the measured distance of each point pair is d j ; the unknown parameter vector X is the coordinates of all hole points, and the observation value vector is the CGCS2000 coordinate system coordinates of the hole points measured by the inertial navigation and the distance between the hole point pairs; the indirect adjustment obtains the CGCS2000 coordinate system coordinates of the hole points; The function model between the unknown parameter vector X and the observation value vector L is established as: L=f(X) When the indirect adjustment is performed, the hole point coordinates X 前 obtained from the forward trajectory are taken as the approximate value of the unknown parameter vector X, and let

[0007] The approximate value X 前 of the unknown parameter vector X is substituted into the function model of the indirect adjustment, and there is

[0008] The error equation of the indirect adjustment is:

[0009] Wherein, V is the observation value correction number, A is the coefficient matrix, and after calculation, the following is obtained:

[0010] In the formula, P is the weight matrix of the observation value, and the final result of the indirect adjustment is

[0011] X in the above formula is the parameter vector obtained after the indirect adjustment; Step 5, coordinate conversion, calculating the hole point tunnel plane engineering coordinate system coordinates; Using the known conversion parameters of the CGCS2000 coordinate system and the tunnel plane engineering coordinate system, the coordinates of the CGCS2000 coordinate system of the point inside the tunnel are converted into the coordinates of the tunnel plane engineering coordinate system; the tunnel plane engineering coordinates of the point inside the tunnel are the final results obtained by the transfer.

[0012] In step 1, there are no less than 2 control points set at each entrance outside the tunnel.

[0013] The distance between a pair of points in the hole in step 1 is no more than 40 meters and is accurately measured using a rangefinder.

[0014] In step 1, the inertial navigation system is placed on a mobile platform, and the mobile platform is provided 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 plumb line; the mobile platform is equipped with a mechanical locking device, which enables the inertial navigation system to perform stationary observation after locking.

[0015] In step 2, data including gyroscope, accelerometer and time raw data are continuously collected along the round-trip closed route.

[0016] After the platform is aligned with the control point outside the tunnel or the point inside the tunnel in step 2, the mechanical lock is tightened and the platform is stationary.

[0017] The round-trip closed route in step 2 starts from the first control point outside the tunnel, collects data from each control point outside the tunnel and each point inside the tunnel, and completes data collection at the last point inside the tunnel. Then, data is collected from each point inside the tunnel and each control point outside the tunnel in the reverse order until the data collection is completed, and data collection is completed without interruption.

[0018] The forward trajectory and the backward trajectory in step 3 are respectively denoted as P 前 and P 后 , the weighted fusion method is:

[0019] in, is the weight;

[0020] Where n is the number of collected data, t1 represents the collection time of the first data, t i Indicates the collection time of the i-th data, and i≤n, t n Indicates the time when the last data was collected.

[0021] In step 3, the trajectory closure difference is distributed and corrected. First, the trajectory closure difference △P=P n -P1, the closure difference distribution model is:

[0022] The method of the application is inertial navigation one-key starting, continuously and automatically collecting data, without manual instrument erection and reading, and the mobile platform moves at a certain speed between the control points and the in-hole points without manual intervention, so that the minimum required three people for cooperation in the wire surveying are reduced to only one person, the manual workload is reduced, and the surveying efficiency is improved; the application realizes high-precision tunnel in-out plane coordinate transfer under the condition of no CPIII, without relying on in-hole CPIII control points, and improves the applicability; the application solves the problem of unachievable construction period tunnel inertial navigation measurement drift by closed path design and dynamic weighted fusion. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a flowchart of the application; Figure 2 is a layout of tunnel out-control points, in-hole points and data collection routes of an embodiment of the application; Figure 3 is a two-way weighted fusion flowchart of an embodiment of the application. DETAILED DESCRIPTION

[0024] The application will be further described below in combination with the drawings, but the application is not limited to the specific embodiments.

[0025] EMBODIMENT

[0026] As Figure 1 is a tunnel in-out plane coordinate transfer method flowchart based on inertial navigation. Specifically, the steps include: Step 1, preliminary preparation; (1) two control points A and B are set at the tunnel entrance; (2) the CGCS2000 coordinates and the tunnel plane engineering coordinate system coordinates of the control points A and B are determined; (3) the conversion parameters between the CGCS2000 coordinate system and the tunnel plane engineering coordinate system have been determined in the preliminary surveying stage; (4) as shown in Figure 2 , pairs of in-hole points are set on the ground every certain distance in the tunnel, a total of four pairs of in-hole points, P1R and P1L, P2R and P2L, P3R and P3L, and P4R and P4L, the distance between a pair of in-hole points is less than 40 meters, which is accurately determined in advance by using a range finder, and the distances are d1, d2, d3 and d4 respectively; (5) the inertial navigation is placed on the mobile platform, the mobile platform is provided with an alignment device, after the alignment device is aligned with the control points, the platform centroid and the control points are on the same plumb line; the mobile platform is provided with a mechanical locking device, after locking, the inertial navigation can be used for static observation; Step 2, data is collected along the closed route uninterruptedly; (1) The platform is aligned with the control point A outside the tunnel, the mechanical lock is locked, and the inertial navigation starts to collect gyro, accelerometer, and time raw data. The data collection time is longer than 30 seconds; (2) After the data collection of control point A is completed, the platform mechanical lock is opened, and the platform is slowly moved to the control point B outside the tunnel. After aligning with the control point, the mechanical lock is locked and data is collected. The data collection time is longer than 30 seconds; (3) After the data collection of the control point B outside the tunnel is completed, the platform mechanical lock is opened, and the platform slowly moves from outside the tunnel to inside the tunnel, driving along the tunnel axis; when the platform passes the first point P1R inside the tunnel, the platform is aligned with the point P1R inside the tunnel, the mechanical lock is locked, and the data collection time is greater than 30 seconds; (4) After the P1R data collection of the first in-hole point is completed, the platform mechanical lock is opened, and the platform is slowly moved to other in-hole points in turn. After aligning with the in-hole points, the mechanical lock is locked. The data collection time is longer than 30 seconds; (5) After the P4L data collection of the last point 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 the opposite order until it returns to the first control point A outside the tunnel, completing the data collection; (6) During the data collection process, the inertial navigation system will remain powered on from the first control point A outside the tunnel until the data collection is completed at the first control point A outside the tunnel. During this period, the inertial navigation system will not be powered off and data collection will continue. (7) Slow platform movement means the platform moves at a speed of less than 1 meter per second; Step 3: Post-data processing, calculate the initial coordinates of the points in the cave in the CGCS2000 coordinate system; (1) Perform forward and backward solutions on the original data respectively. The forward solution solves the inertial navigation trajectory in the order from the first data collected to the last data, and obtains the trajectory P 前 , the backward solution is performed in the order from the last data collected to the first data to obtain the trajectory P 后 ; (2) P 前 and P 后 Weighted fusion, the weights are:

[0027] Where n is the number of collected data, t1 represents the collection time of the first data, t i Indicates the collection time of the i-th data, and i≤n, t n Indicates the collection time of the last data; The weighted fusion method is:

[0028] The forward solution and the backward solution are fused by weighting, the error is dynamically distributed by time weight function, the cumulative drift of inertial navigation is significantly suppressed, the precision is improved by 30% compared with traditional single path, and the two-way fusion process is as shown in FIG. Figure 3 .

[0029] (3) After weighted fusion, the trajectory closure difference is distributed and corrected, the trajectory closure difference is first calculated , and the closure difference distribution model is:

[0030] The closure difference △P is distributed according to time proportion, error is uniformly distributed, and misplacement of segmented splicing is avoided.

[0031] (4) The trajectory after the trajectory closure difference distribution is converted into CGCS2000 coordinate system, and the trajectory in CGCS2000 coordinate system is still denoted as P; Step 4, hole point point pair distance and tunnel outside control point coordinate constraint adjustment, improve the measurement precision; (1) There are m=8 hole points in the tunnel, which form k=m / 2=4 point pairs, and the measured distance of each point pair is d j ; (2) The unknown parameter vector X is the coordinates of all hole points, the observation value vector L is the CGCS2000 coordinate system coordinates of the hole points and the distance between the hole point pairs obtained by inertial navigation measurement; the CGCS2000 coordinate system coordinates of the hole points are obtained according to the observation time and the trajectory P; (3) There are observation value vector L and unknown parameter vector X, the function model between X and L is established as: L=f(X) In indirect adjustment, the hole point coordinates X 前 obtained by the forward trajectory are taken as the approximate value of the unknown parameter vector X, and let

[0032] The approximate value X 前 of the unknown parameter vector X is substituted into the function model of indirect adjustment, and there is

[0033] The error equation of indirect adjustment is:

[0034] Wherein, V is the observation value correction number, and A is the coefficient matrix. After calculation, the following is obtained:

[0035] In the formula, P is the weight matrix of the observation value. Then the final result of indirect adjustment is

[0036] X in the above formula is the coordinate of the in-hole point after adjustment of the CGCS2000 coordinate system. After distance constraint adjustment, the accuracy of the in-hole point coordinate is improved by more than 30%; Step 5, coordinate conversion, calculate the in-hole point tunnel plane engineering coordinate system coordinate; The known conversion parameters are used to convert the in-hole point CGCS2000 coordinate system coordinate after adjustment into the tunnel plane engineering coordinate system coordinate. The in-hole point tunnel plane engineering coordinate is the final result obtained by transmission.

[0037] In traditional traverse survey, a total station is manually set up at the station and readings are taken, and a prism is manually set up at the foresight point and the back sight point for aiming. At least 3 people are needed to work together. After the completion of one station survey, the station needs to be manually moved. Based on inertial navigation, only one person is needed to complete the work, and the time is shorter.

[0038] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for transferring plane coordinates inside and outside a tunnel based on inertial navigation, characterized by: The following steps are involved: Step 1, preliminary preparation; Prepare the tunnel's external control points, the control points' coordinates in the CGCS2000 coordinate system and the tunnel's plane engineering coordinate system, the conversion parameters between the CGCS2000 coordinate system and the tunnel's plane engineering coordinate system, paired in-tunnel points, the distance between a pair of in-tunnel points, and a mobile platform equipped with alignment and locking devices; Step 2: continuously collect data along the closed route; Starting from the control point outside the tunnel, data is collected continuously along the round-trip closed route. When collecting data at control points and points inside the tunnel, the platform is aligned with the control point or point inside the tunnel and then stationary for collection. The data collection time is greater than 30 seconds. When collecting data between control points or points inside the tunnel, the platform movement speed is less than 1 meter per second. Step 3: Post-data processing, calculating the initial coordinates of the points in the cave in the CGCS2000 coordinate system; The collected raw data are solved forward and backward respectively to obtain the forward trajectory and the backward trajectory. The forward trajectory and the backward trajectory are weighted fused. After the weighted fusion, the trajectory closure difference distribution correction is performed. The trajectory after the trajectory closure difference distribution is converted to the CGCS2000 coordinate system. Step 4: Distance constraint adjustment between point pairs in the tunnel to improve measurement accuracy; There are m points in the tunnel, forming k=m / 2 point pairs, and the measured distance between each point pair is d j The unknown parameter vector X is the coordinate of all points in the cave, and the observation value vector is the CGCS2000 coordinate system coordinate of the points in the cave obtained by inertial navigation measurement and the distance between the points in the cave. The CGCS2000 coordinate system coordinates of the points in the cave are obtained by indirect adjustment. Step 5: coordinate conversion, calculate the coordinates of the tunnel plane engineering coordinate system of the point in the tunnel; Using the known conversion parameters of the CGCS2000 coordinate system and the tunnel plane engineering coordinate system, the coordinates of the CGCS2000 coordinate system of the point inside the tunnel are converted into the coordinates of the tunnel plane engineering coordinate system; the tunnel plane engineering coordinates of the point inside the tunnel are the final results obtained by the transfer.

2. The method for transferring coordinates of inner and outer planes of a tunnel based on inertial navigation according to claim 1, characterized in that: In step 1, there are no less than 2 control points set at each entrance outside the tunnel.

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

4. The method for transferring coordinates of inner and outer planes of a tunnel based on inertial navigation according to claim 1, characterized in that: In step 1, the inertial navigation system is placed on a mobile platform, and the mobile platform is provided 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 plumb line; the mobile platform is equipped with a mechanical locking device, which enables the inertial navigation system to perform stationary observation after locking.

5. The method for transferring coordinates of inner and outer planes of a tunnel based on inertial navigation according to claim 1, characterized in that: In step 2, data including gyroscope, accelerometer and time raw data are continuously collected along the round-trip closed route.

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

7. The method for transferring plane coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: The round-trip closed route in step 2 starts from the first control point outside the tunnel, collects data from each control point outside the tunnel and each point inside the tunnel, and completes data collection at the last point inside the tunnel. Then, data is collected from each point inside the tunnel and each control point outside the tunnel in the reverse order until the data collection is completed, and data collection is completed without interruption.

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

9. The method for transferring plane coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: In step 3, the trajectory closure difference is distributed and corrected. First, the trajectory closure difference △P=P n -P1, the closure difference distribution model is: .

10. The method for transferring plane coordinates inside and outside a tunnel based on inertial navigation according to claim 1, characterized in that: The indirect adjustment in step 4 obtains the coordinates of the points in the tunnel in the CGCS2000 coordinate system, specifically: The function model between the unknown parameter vector X and the observation value vector L is established as: L=f(X) In indirect adjustment, the coordinates of the points in the tunnel obtained by the forward trajectory are X 前 Let be the approximate value of the unknown parameter vector X, ； The approximate value X of the unknown parameter vector X 前 Substituting into the function model of indirect adjustment, we have ； The error equation of indirect adjustment is: ； Among them, V is the observation correction number, A is the coefficient matrix, and after calculation, we get: ； Where P is the weight matrix of the observation value, the final result of the indirect adjustment is ； X in the above formula is the parameter vector obtained after indirect adjustment.

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