A method for precision measurement of static geometric state of long-span bridge railway track

Abstract

The application discloses a kind of precision measurement methods of large-span bridge railway track static geometric state, the method includes: track measuring trolley is along track and advances to collect track shape data, and send to terminal;Using multiple total stations synchronous tracking and observation track measuring trolley, obtain the three-dimensional coordinate data of track measuring trolley, and send to terminal;Terminal will be the three-dimensional coordinate data of multiple total stations acquisition Space splicing obtains splicing three-dimensional coordinate data, and IMU data with splicing three-dimensional coordinate data are time synchronization;Terminal will be the IMU-odometer data of time synchronization after with splicing three-dimensional coordinate data fusion processing and smoothing processing, obtain track geometric state data.The application proposes new large-span bridge railway track static geometric state fast precision measurement method, can quickly and accurately measure track geometric state, improve the efficiency of measuring large-span bridge railway track static collection state.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engineering surveying, and in particular to a precision measurement method and system for the static geometric state of a long-span bridge railway track. BACKGROUND

[0002] A bridge is an important component of a railway track. In recent years, with the popularization of railways, more and more long-span railway bridges have emerged. With the increase in the length of railway bridges, the difficulty of ensuring the stability and safety of the bridges themselves is also increasing, which also increases the difficulty of track safety maintenance. The static geometric state of a track includes the shape of the track and the three-dimensional position coordinates of the track, etc. The track irregularity parameters can be calculated from the geometric state, which has a major impact on the running safety, speed, smoothness, and component life of the wheel-rail system.

[0003] There are currently several methods for measuring the geometric state of a bridge track, but they are not suitable for measuring the geometric state of a long-span bridge railway track, and have problems such as difficulty in measurement, low efficiency, and susceptibility to environmental influences:

[0004] 1) A camera-based visual sensor is used for long-term observation, and the geometric state of the bridge track is calculated from the photographs. This method has the advantages of simple installation, no need for special targets, and flexible measurement position. However, it requires good lighting conditions and the effective measurement distance is short, making it only suitable for small-span bridges.

[0005] 2) Large-scale detection vehicles are used for dynamic measurement of railway tracks and cannot be used as a means of measuring the static geometric state of a long-span bridge railway track. In addition, large-scale detection vehicles are expensive, have a small number, and require advance planning of inspection time, making it difficult to use them as needed.

[0006] 3) The track inspection trolley has the following disadvantages:

[0007] 1) Low efficiency: when setting up stations, the track inspection trolley needs to be repositioned every 70m or so, and 6-8 CPIII control points need to be observed each time the station is set up. The measurement time for each sleeper is 10 seconds, resulting in a track inspection trolley operating speed of about 150m / h, and only about 300m of track can be measured for the geometric state within a 2h window of time.

[0008] 2) The absolute position accuracy is highly dependent on the CPIII control points, which have high maintenance costs and are difficult to ensure accuracy. Moreover, the CPIII points move with the deformation of the bridge, with a relative point change of up to 6mm.

[0009] 3) Frequent repositioning of the total station instrument produces "overlapping errors", affecting the accuracy of the final results.

[0010] 4) The advantage of the track inspection trolley based on GNSS positioning is that it does not need to frequently change stations, thereby improving the measurement efficiency, and has a relative measurement accuracy of better than 1mm. However, the absolute accuracy of this method is limited by the GNSS positioning accuracy, which is generally in the order of centimeters, and the GNSS signal is easily disturbed or blocked in complex scenes such as bridges, tunnels and valleys.

[0011] Therefore, the prior art is difficult to fully adapt to the rapid and precise measurement of the geometric state of the long-span bridge railway track, and a measurement method with high efficiency, high accuracy and less environmental influence is needed.

[0012] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0013] The main purpose of the present application is to provide a precise measurement method and system for the static geometric state of a long-span bridge railway track, aiming to solve the technical problems of difficult measurement, low measurement efficiency and easy environmental influence of the geometric state of the bridge railway track in the prior art.

[0014] To achieve the above-mentioned purpose, the present application provides a precise measurement method for the static geometric state of a long-span bridge railway track, which comprises the following steps:

[0015] The track measurement trolley collects track shape data along the track and sends it to the terminal. The track measurement trolley is integrated with a high-precision IMU and an odometer. The high-precision IMU is used to collect the acceleration and angular velocity of the track measurement trolley, and the odometer is used to collect the speed of the track measurement trolley. The track shape data includes IMU data and odometer data.

[0016] Multiple total stations are used to synchronously track and observe the track measurement trolley, obtain three-dimensional coordinate data of the track measurement trolley, and send it to the terminal.

[0017] The terminal performs spatial splicing on the three-dimensional coordinate data collected by multiple total stations to obtain spliced three-dimensional coordinate data, and performs time synchronization on the IMU data and the spliced three-dimensional coordinate data.

[0018] The terminal performs fusion processing and smoothing processing on the IMU-odometer data and the spliced three-dimensional coordinate data after time synchronization to obtain track geometric state data.

[0019] Optionally, the precise measurement method for the static geometric state of a long-span bridge railway track, wherein the multiple total stations are used to synchronously track and observe the track measurement trolley, and obtain three-dimensional coordinate data of the track measurement trolley, specifically comprising:

[0020] A plurality of total stations are arranged on the approach bridge deck near the expansion joint, and are set up through the CPIII control points on the approach bridge;

[0021] While the track measurement trolley moves along the bridge track and collects track shape data, the plurality of total stations track and observe the prism on the track measurement trolley to obtain three-dimensional coordinate data of the track measurement trolley.

[0022] Optionally, the precision measurement method of the static geometric state of the long-span bridge railway track, wherein the total station comprises a first total station and a second total station; the first total station and the second total station are arranged at the bridge head and the bridge tail near the expansion joint, respectively;

[0023] The movement process of the track measurement trolley comprises:

[0024] The initial position of the track measurement trolley is on the rail of the bridge main body near the first total station, the prism faces the first total station, and after the data collection instrument is turned on, the track measurement trolley is pushed along the track towards the second total station on the opposite bank;

[0025] At the first mirror turning point, the direction of the prism is changed so that the prism faces the second total station, and the pushing continues in the original direction;

[0026] When the track measurement trolley reaches the expansion joint near the second total station, the direction of the prism is kept unchanged, the driving direction of the track measurement trolley is reversed, and the track measurement trolley is pushed towards the first total station;

[0027] When the track measurement trolley reaches the second mirror turning point, the direction of the prism is changed again so that the prism faces the first total station, and the track measurement trolley continues to be pushed until it returns to the initial position;

[0028] The movement route of the track measurement trolley is divided into three parts through the positions of the first mirror turning point and the second mirror turning point, the process of pushing the track measurement trolley from the initial position expansion joint to the first mirror turning point is named as the first movement process, the process of pushing the track measurement trolley from the first mirror turning point to the second mirror turning point is named as the second movement process, and the process of pushing the track measurement trolley from the second mirror turning point to the initial position expansion joint is named as the third movement process.

[0029] Optionally, the precision measurement method of the static geometric state of the long-span bridge railway track, wherein the three-dimensional coordinate data collected by the plurality of total stations is spliced in space to obtain spliced three-dimensional coordinate data, and the splicing specifically comprises:

[0030] The three-dimensional coordinate data obtained by the plurality of total stations is preprocessed through mileage correction, mileage normalization and determination of corresponding point relationship, the three-dimensional coordinate data after the preprocessing is rotated to obtain rotated track space coordinates;

[0031] Translate the rotated track spatial coordinates by the translation distance to obtain spliced three-dimensional coordinate data.

[0032] Optionally, the method for precision measurement of static geometric state of a long-span bridge railway track, wherein the translation operation is used to minimize the square difference of the elevation residuals of the corresponding points in the overlapping parts of the two point clouds.

[0033] Optionally, the method for precision measurement of static geometric state of a long-span bridge railway track, wherein the time synchronization of the IMU data and the spliced three-dimensional coordinate data specifically comprises:

[0034] The motion speed of the prism is calculated according to the three-dimensional coordinate data and the time stamps observed by the multiple total stations, the time stamps of the prism speed curve are adjusted, the high-precision IMU and the system time stamps of the odometer are slid, the Pearson correlation coefficient between the prism speed and the odometer speed in the same time interval is calculated, the function relationship between the time adjustment amount and the correlation coefficient is obtained, and the time adjustment amount corresponding to the maximum correlation coefficient is taken;

[0035] The time stamps of the multiple total stations are adjusted by a time adjustment amount as a whole to complete the time synchronization of the multiple total stations and the high-precision IMU and the odometer system.

[0036] Optionally, the method for precision measurement of static geometric state of a long-span bridge railway track, wherein the fusion processing and the smoothing processing of the time-synchronized IMU-odometer data and the spliced three-dimensional coordinate data to obtain the track geometric state data specifically comprises:

[0037] The time-synchronized IMU-odometer data and the spliced three-dimensional coordinate data are fused by using Kalman filtering to obtain fused track spatial data.

[0038] The fused track spatial data is smoothed by using the RTS algorithm to obtain the track geometric state data.

[0039] Optionally, the method for precision measurement of static geometric state of a long-span bridge railway track, wherein the track geometric state data comprises track shape and track three-dimensional position coordinates.

[0040] Optionally, the method for precision measurement of static geometric state of a long-span bridge railway track, wherein the total station comprises a TS60 total station with tracking measurement function.

[0041] In addition, to achieve the above object, the application further provides a precision measurement system for static geometric state of a large-span bridge railway track, which is applied to the precision measurement method for static geometric state of the large-span bridge railway track, wherein the precision measurement system for static geometric state of the large-span bridge railway track comprises a track measurement trolley, a plurality of total stations and a terminal; the track measurement trolley is integrated with a high-precision IMU and an odometer; the high-precision IMU is used to collect acceleration and angular velocity of the track measurement trolley; the odometer is used to collect speed of the track measurement trolley; and the track shape data comprises IMU data and odometer data.

[0042] The track measurement trolley collects track shape data along the track and sends the track shape data to the terminal;

[0043] The plurality of total stations synchronously track and observe the track measurement trolley, acquire three-dimensional coordinate data of the track measurement trolley, and send the three-dimensional coordinate data to the terminal;

[0044] The terminal performs spatial splicing on the three-dimensional coordinate data collected by the plurality of total stations to obtain spliced three-dimensional coordinate data, performs time synchronization on the IMU data and the spliced three-dimensional coordinate data, and performs fusion processing and smoothing processing on the time-synchronized IMU-odometer data and the spliced three-dimensional coordinate data to obtain track geometric state data.

[0045] In the application, the track measurement trolley collects track shape data along the track and sends the track shape data to the terminal; the track measurement trolley is integrated with a high-precision IMU and an odometer; the high-precision IMU is used to collect acceleration and angular velocity of the track measurement trolley; the odometer is used to collect speed of the track measurement trolley; the plurality of total stations synchronously track and observe the track measurement trolley, acquire three-dimensional coordinate data of the track measurement trolley, and send the three-dimensional coordinate data to the terminal; the terminal performs spatial splicing on the three-dimensional coordinate data collected by the plurality of total stations to obtain spliced three-dimensional coordinate data, performs time synchronization on the IMU data and the spliced three-dimensional coordinate data, and performs fusion processing and smoothing processing on the time-synchronized IMU-odometer data and the spliced three-dimensional coordinate data to obtain track geometric state data. The application proposes a new rapid precision measurement method for static geometric state of a large-span bridge railway track, which can rapidly and accurately measure track geometric state and improve efficiency of measuring static geometric state of a large-span bridge railway track. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a flowchart of a preferred embodiment of the precision measurement method for static geometric state of a large-span bridge railway track of the application;

[0047] Figure 2 is a flowchart of data acquisition and data calculation in the preferred embodiment of the precision measurement method for static geometric state of a large-span bridge railway track of the application;

[0048] Figure 3 is a field instrument position relation diagram in a preferred embodiment of the precision measurement method of the static geometric state of the long-span bridge railway track of the present application;

[0049] Figure 4 is a measurement route diagram in a preferred embodiment of the precision measurement method of the static geometric state of the long-span bridge railway track of the present application;

[0050] Figure 5 is a space splicing-rotation diagram in a preferred embodiment of the precision measurement method of the static geometric state of the long-span bridge railway track of the present application;

[0051] Figure 6 is a space splicing-translation diagram in a preferred embodiment of the precision measurement method of the static geometric state of the long-span bridge railway track of the present application;

[0052] Figure 7 is a space splicing completion diagram in a preferred embodiment of the precision measurement method of the static geometric state of the long-span bridge railway track of the present application;

[0053] Figure 8 is a time synchronization diagram in a preferred embodiment of the precision measurement method of the static geometric state of the long-span bridge railway track of the present application;

[0054] Figure 9 is a structure diagram of a preferred embodiment of the precision measurement system of the static geometric state of the long-span bridge railway track of the present application. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0056] The precision measurement method of the static geometric state of the long-span bridge railway track of the preferred embodiment of the present application, as shown in Figure 1 and Figure 2 The precision measurement method of the static geometric state of the long-span bridge railway track includes the following steps:

[0057] Step S10, the track measurement trolley collects track shape data along the track and sends it to the terminal, the track measurement trolley is integrated by a high-precision IMU and an odometer, the high-precision IMU is used to collect the acceleration and angular velocity of the track measurement trolley, the odometer is used to collect the speed of the track measurement trolley, and the track shape data includes IMU data (such as the acceleration and angular velocity of the track measurement trolley) and odometer data (such as the speed of the track measurement trolley).

[0058] In the present application, the precision measurement method of the static geometric state of the long-span bridge railway track is applied to a terminal, which includes but is not limited to a computer and a mobile terminal and the like.

[0059] Specifically, the track measurement trolley is equipped with an IMU / mileage meter combined measurement system, the precision of the IMU reaches 0.01° / h, and the mileage meter encoder is installed on the track measurement trolley wheel and connected with the system, as shown in the figure, that is, the track measurement trolley integrates a high-precision IMU and a mileage meter, the high-precision IMU is used to collect the acceleration and angular velocity of the track measurement trolley, and the mileage meter is used to collect the speed of the track measurement trolley. Figure 2 The IMU specifically refers to an inertial measurement unit, which is a device that measures the three-axis attitude angle (or angular velocity) and three-axis acceleration of an object, and the mileage meter is a measuring instrument that estimates the change of the pose over time using data from a motion sensor, wherein the wheeled mileage meter tracks the rotation speed of each wheel based on the photoelectric encoder installed on the robot, and then determines the relative position of the robot relative to the starting point through the kinematics model of the robot. In addition, the track measurement trolley is provided with a stand column for arranging a prism, so as to facilitate the total station to obtain the three-dimensional coordinates of the track measurement trolley.

[0060] Step S20, a plurality of total stations are used to synchronously track and observe the track measurement trolley, three-dimensional coordinate data of the track measurement trolley is obtained, and the three-dimensional coordinate data is sent to the terminal.

[0061] The total station (Total station) specifically refers to an electronic total station, which is a high-tech measuring instrument integrating light, machine and electricity, and is a surveying and mapping instrument system integrating horizontal angle, vertical angle, distance (slope distance, horizontal distance) and height difference measurement functions. Because it can complete all the measurement work on the station at one time, it is called a total station, and is widely used in precise engineering measurement or deformation monitoring fields of large ground buildings and underground tunnels.

[0062] The total station in the present application preferably adopts a TS60 total station with tracking measurement function. In the case of using an electronic level, the station setting precision reaches 2 seconds. The continuous tracking point precision of the TS60 is 0.5 seconds in angle and 3mm+1.5ppm in distance. For a 1000m long long-span railway bridge, the point position precision of a single total station tracking observation half of the distance is 3mm+1.5ppm*0.5km=3.75mm, which meets the required precision of the method.

[0063] Before data collection, the track measurement trolley and total station were placed on the bridge deck, as shown in the diagram. Figure 3 As shown. Total stations, such as TS01 (i.e., the first total station) and TS02 (i.e., the second total station), are placed near the expansion joints (bridge expansion joints are devices typically set between the ends of two beams, between the beam end and the abutment, or at the hinged position of the bridge to accommodate bridge deck deformation. The function of bridge expansion joints is to adjust the displacement between the superstructure and the connection between the bridge structure caused by vehicle loads and bridge construction materials. Once the expansion device of a skew bridge is damaged, it will seriously affect the speed, comfort and safety of driving, and even cause traffic accidents. Therefore, all bridge decks must be pre-installed with expansion joints). Stations are set up through the CPIII control points (CPIII means pile control network) on the approach bridge (i.e., TS01 and TS02 are set at the bridgehead and bridge tail near the expansion joints, respectively), thereby avoiding CPIII point position errors caused by the swaying of the main body of the bridge. The track measuring trolley is installed on the track of the main body of the bridge, and the prism of the track measuring trolley needs to ensure line of sight. While the track measuring trolley moves along the track and collects track shape data, the total station tracks and observes the prism to obtain the three-dimensional coordinates of the track measuring trolley.

[0064] The data acquisition process is as follows Figure 4 As shown, Figure 4 Turning point 1 (i.e., the first turning point) and turning point 2 (i.e., the second turning point) refer to the positions where the track surveying trolley is not in direct line of sight to TS01 and TS02 during its advancement. The initial position of the track surveying trolley is on the rails of the main bridge structure near the total station TS01, with the prism facing TS01. After turning on the data acquisition instrument, the track surveying trolley is pushed along the rails towards TS02 on the opposite bank. At turning point 1, the prism's direction is changed to face TS02, and the trolley continues to be pushed in the original direction. When the track surveying trolley reaches the expansion joint near TS02, i.e., the turning point, the prism's direction remains unchanged, and the trolley's direction is reversed, pushing it towards TS01. When the track surveying trolley reaches turning point 2, the prism's direction is changed again to face TS01, and the trolley continues to be pushed until it returns to the initial position.

[0065] like Figure 4 As shown, the positions of the two rotating mirrors (i.e., rotating mirror point 1 and rotating mirror point 2) divide the movement path of the track measuring trolley into three parts. The process of the track measuring trolley from the initial position telescopic joint 1 to rotating mirror point 1 is named Run01 (i.e., the first movement process), the process from rotating mirror point 1 to rotating mirror point 2 is named Run02 (i.e., the second movement process), and the process from rotating mirror point 2 to the initial position telescopic joint 1 is named Run03 (i.e., the third movement process).

[0066] Step S30, the terminal performs spatial splicing on the three-dimensional coordinate data collected by the multiple total stations to obtain spliced three-dimensional coordinate data, and performs time synchronization on the IMU data and the spliced three-dimensional coordinate data.

[0067] The railway track of a bridge is generally a straight line in the horizontal plane and presents a fluctuating shape in the elevation direction. Therefore, the track is taken as the X axis, the mileage is taken as the X coordinate, the elevation direction is taken as the Z axis, and a coordinate system is established perpendicular to the track direction as the Y axis. The shape of a series of three-dimensional point clouds (the meaning of the three-dimensional point clouds is a series of points with three-dimensional coordinates obtained by the total station measurement) obtained by the total station is a curve extending along the mileage direction of the track. The mileage of the curve is corrected and normalized, so as to unify the mileages of the measurement points of the multiple total stations. Therefore, it is considered that the mileages, i.e., the X coordinates, of the data of the multiple total stations do not need to be adjusted, the errors in the Y axis and Z axis directions are adjusted based on the X axis as the reference, and the spatial splicing of the total station data is completed. The part of the point cloud curve of the total station in which the mileages are overlapped is taken as the to-be-registered region, and the points with the same mileage are taken as the corresponding points.

[0068] After the above-mentioned mileage correction, mileage normalization, and determination of the corresponding point relationship (for the curves obtained by the TS01 and TS02 measurement, two corresponding points with the same mileage in the two curves need to be determined, and this process is referred to as the corresponding point relationship confirmation), and the like, the spatial splicing of the total station data is performed. Taking the mileage-elevation plane coordinate system, i.e., the X-Z plane, as an example, the spatial splicing contains two steps. The first step is rotation. As shown in the formula (1), the point cloud data of the reference total station are selected, and the target point cloud is rotated counterclockwise by an angle θ along the center point C0 (M0, H0) of the total station, where M0 and H0 represent the coordinate values of the center point C0 of the total station, so that the mileage of the two point cloud curves is the same, i.e., the elevation residual (i.e., the distance in the point cloud splicing) of the corresponding points of the point clouds is minimized, and the formula is as follows: Figure 5

[0069]

[0070]

[0071]

[0072]

[0073] wherein, and are the mileage coordinate and the elevation coordinate of the point t k in the rotated point cloud T, k is the mileage coordinate of the point t k in the point cloud T before rotation, is the elevation coordinate of the point t k in the point cloud T before rotation,​ is the elevation coordinate of point t in the rotated point cloud R k k is the elevation residual between the corresponding points after rotation and its mean value, k represents the number of point clouds, and Var(ΔH k ) is the variance of the elevation residual.

[0074] The value of θ is obtained by solving the above equation, and then the target point cloud curve is rotated according to the value of θ.

[0075] As shown in Figure 6 , after the rotation operation, the target point cloud that has been rotated in the last step is translated up and down in the elevation direction by a distance τ, and the purpose is to minimize the square difference f(τ) of the elevation residual of the corresponding points in the mileage overlap part of the two point clouds, and the formula is:

[0076]

[0077]

[0078] After the above rotation and translation, the target point cloud curve and the reference point cloud curve are in the best matching state, as shown in Figure 7 . The curves of the two in the mileage overlap area coincide, and are in the same coordinate system of the reference point cloud curve, thereby completing the total station data space splicing in the X-Z plane. The total station data space splicing process in the mileage-orthogonal direction to the track direction two-dimensional plane, i.e., the X-Y plane, is similar to the X-Z plane, but does not need to be rotated, and only needs to translate the target point cloud curve in the Y-axis direction.

[0079] Generally, the IMU / mileage meter system on the track measurement trolley is turned on for measurement throughout the whole process, and the time stamp is continuous and complete, while each total station only observes part of the route, and its time stamp only accounts for part of the total measurement time, and may also be discontinuous. Therefore, the IMU / mileage meter system is selected as the reference benchmark, and the time stamp of each total station is adjusted for synchronization.

[0080] The time synchronization method is to first calculate the prism movement speed according to the three-dimensional coordinates and time stamp of the points observed by the total station, then adjust the time stamp of the prism speed curve, slide on the IMU / mileage meter system time stamp, as shown on the left side of Figure 8 , and calculate the Pearson correlation coefficient between the prism speed and the mileage meter speed in the same time interval, so as to obtain the function relationship between the time adjustment amount t lag and the correlation coefficient r. Finally, the time adjustment amount t max corresponding to the maximum correlation coefficient r best is taken, as shown on the right side of Figure 8 . The calculation method of the Pearson correlation coefficient is:​​

[0081]

[0082] wherein V TS , V Od is the speed calculated by the total station and the speed of the odometer, is the standard deviation of the two, and respectively represent the average value of the speed calculated by the total station and the speed of the odometer, and E represents the calculation of the expected value.

[0083] The total station timestamp is adjusted by an amount t best , so as to complete the time synchronization of the total station and the IMU / odometer system.

[0084] In step S40, the terminal fuses and smooths the IMU-odometer data after time synchronization with the spliced three-dimensional coordinate data to obtain the track geometric state data.

[0085] Specifically, the IMU-odometer data after time synchronization is fused with the spliced three-dimensional coordinate data using Kalman filtering to obtain fused track spatial data; and the fused track spatial data is smoothed using an RTS algorithm to obtain the track geometric state data.

[0086] wherein the system state model, the error model and the observation model of the Kalman filtering are represented as:

[0087]

[0088]

[0089]

[0090] wherein X and P are the system state vector and the covariance matrix thereof at the previous time, is the system state matrix and the covariance matrix thereof at this time, A and H are the state transition matrix and the observation matrix, is the observation vector at this time, w and v are process noise and observation noise, both of which are subject to normal distribution with mean 0 and covariance Q and R, N(0, Q) represents normal distribution with covariance Q, N(0, R) represents normal distribution with covariance R, A T represents the transpose of the state transition matrix.

[0091] According to the actual situation, the system state matrix x and the observation matrix Z are designed, wherein X contains various errors of the IMU / odometer system, and Z is the observation error of the prism.

[0092] X = [δφ δv δr δbg δb a δk d ];

[0093]

[0094] where δφ, δv, δr, δb g , δb a , δk d are the attitude angle error vector, velocity error vector, position error vector, random walk error vector, acceleration error vector, odometry scale factor error, δr p represents the observation error of the prism, are the predicted position coordinates and measured position coordinates of the prism control point, r INS is the predicted IMU position, is the attitude transformation matrix, is the position vector of the prism relative to the IMU center, r TS is the prism position coordinate obtained by total station measurement, ε TS is the total station measurement noise.

[0095] The Kalman gain matrix K is calculated from the system state matrix and its covariance matrix at the previous time, so as to obtain the system state and covariance at this time. Through continuous forward iteration, the system state of the entire track route can be calculated.

[0096] K=APA T H T (HAPA T H T +R) -1 ;

[0097]

[0098]

[0099] where I represents the unit matrix;

[0100] The RTS (Rauch-Tung-Striebel) algorithm is used for backward filtering of the data for smoothing processing. The RTS algorithm principle is similar to the Kalman filtering, but the calculation direction is opposite. The RTS smoothing algorithm calculates the smoothing gain matrix G through the state and covariance X, P at the next time, and calculates the smoothed state and covariance at this time that is:

[0101] G=PA T (APA T +Q) -1 ;

[0102]

[0103]

[0104] The δr in the above obtained vector X is the three-dimensional coordinate error of the track point, and adding the original amount of the three-dimensional coordinates of the track point can obtain the optimal three-dimensional coordinate estimation of the track point, so that the static geometric state of the measured track can be obtained through the three-dimensional coordinates of the track point.

[0105] The overall flow of the precision measurement method of the static geometric state of the long-span bridge railway track of the application is divided into two parts of data acquisition and data solving. In the data acquisition process, the track measurement trolley collects track linear related data, wherein the inertial measurement unit (IMU) collects the acceleration and angular velocity of the track measurement trolley, the odometer collects the speed of the trolley, and the total station instrument observes the three-dimensional coordinates of the track measurement trolley. In the data solving process, firstly, the data of multiple total station instruments need to be spatially spliced, then the time of multiple total station instruments and IMU / odometer is synchronized, and finally the data fusion and smoothing of numerous sensors are carried out, that is, the data fusion method based on Kalman filtering and RTS smoothing filtering, so as to finally obtain the track geometric state parameters.

[0106] The method of the application uses the track measurement trolley integrated with high-precision IMU and odometer to collect track shape data along the track, and uses multiple total station instruments to synchronously track and observe the track measurement trolley to obtain its three-dimensional coordinate data. Then, the spatial splicing and time synchronization of the data of multiple sensors are carried out, and after fusion and smoothing, the track geometric state data can be obtained.

[0107] The advantages of the method are as follows: 1. The track measurement trolley can collect track geometric state data with high precision and high frequency; 2. Multiple total station instruments track and observe the track measurement trolley in sections, realize all-weather observation, and can absolutely position the track measurement trolley throughout the track; 3. After spatial splicing and time synchronization of the data by using the algorithm, the track geometric state is obtained by fusing the data of multiple sensors, and the track geometric state is obtained by using the algorithm, so as to effectively suppress the divergence error of the IMU.

[0108] Field tests show that the measurement method based on IMU / odometer assisted by multiple total station instruments has obvious advantages in precision and efficiency, and can measure the geometric state of a 1000m long bridge railway track with millimeter level precision within 1 hour. It is an effective new measurement scheme and has good practical significance.

[0109] Further, as Figure 9The application also provides a precision measurement system for the static geometric state of a long-span bridge railway track, which is applied to the precision measurement method for the static geometric state of the long-span bridge railway track, wherein the precision measurement system for the static geometric state of the long-span bridge railway track comprises a track measurement trolley, multiple total stations and a terminal; the track measurement trolley is integrated with a high-precision IMU and an odometer; the high-precision IMU is used to collect the acceleration and angular velocity of the track measurement trolley; the odometer is used to collect the speed of the track measurement trolley; the track shape data comprises IMU data and odometer data;

[0110] The track measurement trolley sends the track shape data collected along the track to the terminal;

[0111] The multiple total stations synchronously track and observe the track measurement trolley, acquire the three-dimensional coordinate data of the track measurement trolley, and send the three-dimensional coordinate data to the terminal;

[0112] The terminal performs spatial splicing on the three-dimensional coordinate data collected by the multiple total stations to obtain spliced three-dimensional coordinate data, performs time synchronization on the IMU data and the spliced three-dimensional coordinate data, and performs fusion processing and smoothing processing on the time-synchronized IMU-odometer data and the spliced three-dimensional coordinate data to obtain track geometric state data.

[0113] In summary, the application provides a precision measurement method and system for the static geometric state of a long-span bridge railway track, which comprises the following steps: a track measurement trolley collects track shape data along the track and sends the track shape data to a terminal; the track measurement trolley is integrated with a high-precision IMU and an odometer; the high-precision IMU is used to collect the acceleration and angular velocity of the track measurement trolley; the odometer is used to collect the speed of the track measurement trolley; multiple total stations are used to synchronously track and observe the track measurement trolley, acquire the three-dimensional coordinate data of the track measurement trolley, and send the three-dimensional coordinate data to the terminal; the terminal performs spatial splicing on the three-dimensional coordinate data collected by the multiple total stations to obtain spliced three-dimensional coordinate data, and performs time synchronization on the IMU data and the spliced three-dimensional coordinate data; the terminal performs fusion processing and smoothing processing on the time-synchronized IMU-odometer data and the spliced three-dimensional coordinate data to obtain track geometric state data. The application provides a new rapid precision measurement method for the static geometric state of a long-span bridge railway track, which can rapidly and accurately measure the track geometric state and improve the efficiency of measuring the static geometric state of a long-span bridge railway track.

Claims

1. A precise measurement method for the static geometric state of railway tracks on long-span bridges, characterized in that, The precise measurement method for the static geometric state of railway tracks on long-span bridges includes: The track measuring trolley moves along the track to collect track shape data and sends it to the terminal. The track measuring trolley integrates a high-precision IMU and an odometer. The high-precision IMU is used to collect the acceleration and angular velocity of the track measuring trolley, and the odometer is used to collect the velocity of the track measuring trolley. The track shape data includes IMU data and odometer data. Multiple total stations are used to simultaneously track and observe the track measuring trolley, acquire the trolley's three-dimensional coordinate data, and send it to the terminal; The terminal spatially stitches together the three-dimensional coordinate data collected by multiple total stations to obtain stitched three-dimensional coordinate data, and synchronizes the IMU data with the stitched three-dimensional coordinate data in time; The terminal fuses and smooths the time-synchronized IMU-odometer data with the stitched 3D coordinate data to obtain the track geometry data. The process of spatially stitching together three-dimensional coordinate data collected by multiple total stations to obtain stitched three-dimensional coordinate data specifically includes: Preprocessing is performed on the three-dimensional coordinate data acquired by multiple total stations, including mileage correction, mileage normalization, and determination of corresponding point relationships. Acquire total station point cloud data and counterclockwise rotation angle, and perform counterclockwise rotation operation on the preprocessed three-dimensional coordinate data based on the total station point cloud data and the counterclockwise rotation angle to obtain the rotated track space coordinates; The rotated orbital space coordinates are translated according to the translation distance to obtain the stitched three-dimensional coordinate data. After the rotation operation, the previously rotated target point cloud is translated vertically along the elevation direction by a distance of [distance to be filled in]. The goal is to find the squared difference f(elevation) of the elevation residuals of points corresponding to the overlapping parts of two point cloud mileages. The minimum value is found by the formula: ； ； in, It is a rotated point cloud Points in elevation coordinates Indicates the point cloud before rotation Points in elevation coordinates Indicates the translation distance. It is a rotating point cloud. The point in Elevation coordinates Indicates the number of point clouds. This represents the difference of squares.

2. The method for precise measurement of the static geometric state of railway tracks for long-span bridges according to claim 1, characterized in that, The method of using multiple total stations to simultaneously track and observe the track surveying trolley to obtain its three-dimensional coordinate data specifically includes: Multiple total stations were set up on the approach bridge deck near the expansion joint, and the stations were set up through the CPIII control point on the approach bridge. While the track measuring trolley moves along the bridge track and collects track shape data, multiple total stations track and observe the prisms on the track measuring trolley to obtain the trolley's three-dimensional coordinate data.

3. The method for precise measurement of the static geometric state of railway tracks for long-span bridges according to claim 2, characterized in that, The total station includes a first total station and a second total station; the first total station and the second total station are respectively located at the bridgehead and the bridge tail near the expansion joint; The motion process of the track measuring trolley includes: The initial position of the track measuring trolley is on the rail of the main bridge structure near the first total station, with the prism facing the first total station. After turning on the data acquisition instrument, the track measuring trolley is pushed along the track towards the second total station on the opposite bank. At the first turning point, change the direction of the prism so that it faces the second total station, and continue pushing in the original direction; When the track surveying trolley reaches the expansion joint near the second total station, keep the prism direction unchanged, turn the track surveying trolley in the correct direction, and push it toward the first total station. When the track surveying trolley reaches the second rotating mirror point, the direction of the prism is changed again so that the prism faces the first total station, and the track surveying trolley is continued to be pushed until it returns to the initial position. The movement path of the track measuring trolley is divided into three parts based on the positions of the first and second rotating mirror points. The process of the track measuring trolley from the initial position telescopic joint to the first rotating mirror point is named the first motion process, the process from the first rotating mirror point to the second rotating mirror point is named the second motion process, and the process from the second rotating mirror point to the initial position telescopic joint is named the third motion process.

4. The method for precise measurement of the static geometric state of railway tracks for long-span bridges according to claim 1, characterized in that, The translation operation is used to minimize the squared difference of the elevation residuals of corresponding points in the overlapping parts of the two point cloud mileages.

5. The method for precise measurement of the static geometric state of railway tracks for long-span bridges according to claim 1, characterized in that, The process of synchronizing IMU data with stitched 3D coordinate data in time specifically includes: The motion velocity of the prism is calculated based on the three-dimensional coordinate data and timestamps observed by multiple total stations. The timestamps of the prism velocity curve are adjusted, and the curve is slid across the system timestamps of the high-precision IMU and the odometer. The Pearson correlation coefficient between the prism velocity and the odometer velocity within the same time interval is calculated. The functional relationship between the time adjustment and the correlation coefficient is obtained, and the time adjustment corresponding to the maximum correlation coefficient is taken. The timestamps of multiple total stations are adjusted by a single time adjustment amount to achieve system time synchronization between the multiple total stations, the high-precision IMU, and the odometer.

6. The method for precise measurement of the static geometric state of railway tracks for long-span bridges according to claim 5, characterized in that, The process of fusing and smoothing the time-synchronized IMU-odometer data with the stitched 3D coordinate data to obtain orbital geometric state data specifically includes: Kalman filtering is used to fuse the time-synchronized IMU-odometer data with the stitched 3D coordinate data to obtain the fused orbital space data; The RTS algorithm is used to smooth the fused orbital spatial data to obtain orbital geometric state data.

7. The method for precise measurement of the static geometric state of railway tracks for long-span bridges according to claim 6, characterized in that, The track geometry data includes the track shape and the track's three-dimensional position coordinates.

8. The method for precise measurement of the static geometric state of railway tracks for long-span bridges according to any one of claims 1-7, characterized in that, The total station includes the TS60 total station with tracking measurement function.

9. A precision measurement system for the static geometric state of railway tracks on long-span bridges, applied to the precision measurement method for the static geometric state of railway tracks on long-span bridges as described in any one of claims 1-8, characterized in that, The precision measurement system for the static geometry of railway tracks on long-span bridges includes: a track measuring trolley, multiple total stations, and terminals; the track measuring trolley integrates a high-precision IMU and an odometer, the high-precision IMU is used to collect the acceleration and angular velocity of the track measuring trolley, the odometer is used to collect the velocity of the track measuring trolley, and the track shape data includes IMU data and odometer data; The track measuring trolley moves along the track to collect track shape data and then sends it to the terminal. Multiple total stations simultaneously track and observe the track measuring trolley, acquire the three-dimensional coordinate data of the track measuring trolley, and send it to the terminal; The terminal spatially stitches together the three-dimensional coordinate data collected by multiple total stations to obtain stitched three-dimensional coordinate data. It then synchronizes the IMU data with the stitched three-dimensional coordinate data in time, and performs fusion and smoothing processing on the time-synchronized IMU-odometer data and the stitched three-dimensional coordinate data to obtain track geometry data.

Images