A method for testing the unevenness of a suspended monorail track beam

Abstract

The present invention discloses a method for testing the unevenness of a suspended monorail track beam, a continuous detection method for the track beam based on a GNSS / INS inertial navigation system and a high-speed laser scanner as the main equipment, improves the test system scheme and optimizes and perfects the calculation principle, develops and manufactures a complete detection system for the track beam, and verifies the accuracy and reliability of the proposed test system by comparing the designed line type and the measured line type of the track beam and the results of portable test equipment. The unevenness of the suspended monorail track and the track geometric dimensions obtained by adopting the test system proposed in this paper are of great significance for the design of suspended monorail vehicles and the formulation of track beam design and maintenance standards.

Description

Technical Field

[0001] The present invention relates to the field of rail transit, and particularly to a method for testing the unevenness of a suspended monorail track beam. Background Art

[0002] Suspended monorail traffic is a unique railway transportation system, in which the track beam is lifted above the ground using concrete or steel columns, and the vehicle body is suspended below the track beam using special connecting devices on the bogie. Track unevenness measurement techniques are divided into on-load dynamic detection and off-load static measurement techniques. Dynamic detection techniques include track inspection vehicles, comprehensive track inspection vehicles, and on-vehicle detection equipment. The bogie of a suspended monorail vehicle is located inside the track beam. Due to the limited space of the beam, it is impractical to install specific dynamic detection devices on the bogie. Therefore, dynamic detection techniques may not be applicable to suspended monorail tracks. However, static detection techniques do not consider the influence of vehicle load on the track, and mainly include track geometry measuring instruments based on classical geodetic methods, gauge measurement methods, and chord length measurement methods. At the same time, there are no specific standards for the maintenance of track beams or the detection and acceptable levels of track unevenness. Summary of the Invention

[0003] In view of the above deficiencies in the prior art, the present invention provides a method for testing the unevenness of a suspended monorail track beam.

[0004] To achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0005] A method for testing the unevenness of a suspended monorail track beam, comprising the following steps:

[0006] S1. Construct a detection system including a detection trolley, an inertial navigation system, a 360-degree high-speed laser scanner, a one-dimensional laser sensor, an odometer, and a data acquisition system;

[0007] S2. Use the detection trolley to travel along the track inside the box girder, and use the inertial navigation system and the one-dimensional laser displacement sensor to detect the running attitude of the detection trolley;

[0008] S3. Use the odometer integration to obtain the movement trajectory of the detection trolley, and obtain the long-wave unevenness curve of the track beam; use the high-speed laser scanner to continuously scan the cross-sectional geometric dimensions of the track beam to obtain the short-wave unevenness curves of the running surface and the guiding surface;

[0009] S4. Superimpose the obtained long-wave unevenness curve and short-wave unevenness curve to obtain the final track unevenness test curve.

[0010] Further, the movement trajectory of the detection trolley in S3 is expressed as:

[0011]

[0012] In the formula, is the measured running track of the trolley, is the long-wave irregularity curve in the actual track girder, is the wheelbase of the inspection trolley, is the horizontal displacement of the inspection trolley.

[0013] Furthermore, the long-wave irregularity curve in the track girder in S3 is expressed as:

[0014]

[0015] In the formula, is the long-wave irregularity curve in the actual track girder, is the wheelbase of the inspection trolley, is the amplitude of the long-wave irregularity curve in the actual track girder, is the wavelength of the long-wave irregularity curve in the actual track girder, is the horizontal displacement of the inspection trolley.

[0016] Furthermore, in S3, the short-wave irregularity curves of the running surface and the guiding surface are obtained by converting the test points in the local coordinate system in the trolley track to the absolute coordinate system through the rotation matrix and the translation matrix. The specific method is as follows:

[0017]

[0018] In the formula, is the coordinate of the test point in the absolute coordinate system, is the coordinate of the test point in the local coordinate system, is the translation matrix, and

[0019]

[0020] is the longitudinal distance from the laser scanner to the inertial navigation system;

[0021] are the three-axis components of the transformation matrix, and

[0022]

[0023]

[0024]

[0025] are, in sequence, the roll angle, pitch angle, and yaw angle of the inspection trolley obtained through inertial navigation tests.

[0026] The present invention has the following beneficial effects:

[0027] The present invention installs a 360-degree high-speed laser scanner on a suspended monorail bogie to obtain the internal shape of the track beam. The installation scheme is simple and the amount of collected data is small. The inertial navigation system is used to determine the coordinate system, and combined with the installation of a one-dimensional laser displacement sensor to measure the vertical and lateral displacements of the bogie relative to the track beam, eliminating the influence of the bogie motion posture and tire dynamic deformation on the test results, and obtaining accurate results of track irregularities in the absolute coordinate system. Description of the Drawings

[0028] Figure 1 It is a schematic flow diagram of the method for testing the irregularity of a suspended monorail track beam.

[0029] Figure 2 It is a schematic structural diagram of the hanging device suspended on the track beam.

[0030] Figure 3 It is a schematic principle diagram of testing the track alignment using the trajectory method in the embodiment of the present invention.

[0031] Figure 4 It is a schematic diagram of the measured track waveform and the actual track waveform in the embodiment of the present invention.

[0032] Figure 5 It is a schematic diagram of the relationship between the wheelbase of the test trolley and the proportional coefficient of the track linear wavelength in the embodiment of the present invention.

[0033] Figure 6 It is a schematic diagram of the test results of long-wave irregularities in the embodiment of the present invention. Among them, a is the test result of the vertical unevenness of the running surface in the straight section, b is the test comparison result between the beam inspection trolley and the total station, and c is the test comparison result between the beam inspection trolley and the total station.

[0034] Figure 7 It is a schematic diagram of the test results of short-wave irregularities in the embodiment of the present invention. Among them, a is a schematic diagram of the track harmonic irregularity result, and b is the test comparison result of the total station. Detailed Embodiments

[0035] The following describes the detailed embodiments of the present invention to facilitate those skilled in the art to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the detailed embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

[0036] A method for testing the irregularity of a suspended monorail track beam, as Figure 1 shown, includes the following steps:

[0037] S1. Construct a detection system including a detection trolley, an inertial navigation system, a 360-degree high-speed laser scanner, a one-dimensional laser sensor, an odometer, and a data acquisition system;

[0038] The suspended monorail system is a special rail transit system. The bogie runs inside a semi-closed box girder with an opening at the bottom, and the car body is suspended below the track girder through a hanging device, Figure 2 as shown in (a). The track girder is mainly composed of piers and box girders with a length within 20 - 40 m. The box girder is generally a simply supported steel structure beam. In addition to meeting the functions of load-bearing, running, and guiding, it also integrates the functions of power supply, communication, and signal ( Figure 2 as shown in b). The track girder is a multi-functional complex. The track irregularities composed of the geometric dimensions of the internal cross-section of the box girder, the longitudinal linearity of the track girder, the discontinuous connecting finger plates, and the local unevenness, etc., are the excitation sources of the vibration of the monorail vehicle, directly affecting the ride comfort of the vehicle, the structural safety of the vehicle and the track girder, as well as the power supply and communication. Therefore, it is necessary to study a detection system that can accurately, reliably, and efficiently measure all the above indicators.

[0039] The detection trolley plays a mechanical transmission role between the track girder and the non-contact measurement equipment. The running track line of the trolley must be able to accurately reflect the actual geometric shape of the track girder and make an accurate dynamic response (nodding, rolling, lateral translation, etc.) to the irregularity excitation. The response is tested and recorded by the detection system, and the running track of the inspection vehicle, that is, the track irregularity of the track girder, is obtained through the above algorithm. The stability of the inspection trolley during the movement process and the continuous contact with the track girder are the prerequisite conditions for ensuring the measurement accuracy.

[0040] Based on the above test requirements, a set of inspection trolleys specially applied to the test of the suspended monorail box girder track is designed in this embodiment. The main body of the trolley consists of a frame, running wheels, guiding wheels, and various equipment installation interfaces. The frame plays a load-bearing role and requires sufficient stiffness and strength. It is welded by 3-mm square steel. The installation interfaces of the running wheels and guiding wheels are integrally machined to ensure the installation accuracy. The main structure of the frame is connected by bolts and is detachable for convenient transportation; 4 running wheels made of nylon are finely processed to eliminate the non-circularity of each order of the running wheels themselves, and rubber pads with a certain thickness are set on the running wheel mounting seats, which play a role in relieving impact and leveling. The diameter and width of the running wheels are determined according to the size of the track joint to prevent jamming and achieve smooth passing through the joint position; 4 guiding wheels made of nylon and finely processed. Telescopic springs are set inside the guiding wheel mounting seats to achieve the free guiding function and ensure that the guiding wheels always closely adhere to the guiding surface. Displacement sensors are installed on the mounting seats to detect the dynamic displacements of the 4 guiding wheels and obtain the motion posture of the trolley.

[0041] The inertial navigation system has a major drawback that the navigation positioning error increases with time, making it difficult to work independently for a long time. There are mainly two ways to solve this problem. One is to improve the accuracy of the inertial navigation system itself, and the other is to adopt integrated navigation technology. Integrated navigation mainly provides navigation accuracy through software technology. In this paper, a combined inertial navigation system of GNSS and INS is selected, which has high accuracy, strong anti-interference ability, and the system can automatically adjust the angle in real time to avoid the problem of angle divergence.

[0042] The inertial navigation system INS is a fully autonomous navigation system that can output high-frequency signals exceeding 200Hz and has high short-term measurement accuracy. In addition to providing position and speed, it can also provide attitude information. However, due to the existence of integration in the algorithm, the errors of the sensors will continuously accumulate, causing the long-term navigation error to increase without limit. In contrast to INS, GNSS has good long-term accuracy, and the navigation error is approximately a few meters. However, its short-term accuracy and output frequency are relatively low. From the above characteristics, INS and GNSS have good complementary characteristics. Integrating the two can obtain a navigation solution with better stability and higher accuracy than a single navigation system. The INS / GNSS integrated navigation system can output high-frequency navigation parameter information (position, speed, attitude) and can have high accuracy during both long-term and short-term navigation processes. Using the optimal estimation method based on Kalman filtering, the positioning and navigation information of GNSS and NIS are fused to estimate the navigation parameter errors in real time from the measurements and correct the inertial navigation parameters, resulting in high-precision and stable test data.

[0043] In this embodiment, a 360-degree high-precision laser scanner produced by Autonics is adopted. The performance indicators are shown in Table 2. The laser ranging range is 0.5 - 15m, the accuracy is 1mm, the scanning angle is 350 degrees, the maximum scanning frequency is 250 revolutions per second. Assuming the vehicle speed is 40km / h, the scanning section spacing is 0.066m, the length of one car body is 10m, and the number of scanning sections reaches 225. When the speed is lower, the number of scanning sections will be more.

[0044] The test accuracy of detecting the running mileage of the inspection trolley directly affects the test result error. A pair of rotational speed encoders is installed on the side of the running wheels of the inspection trolley, and the running distance is calculated by recording the number of rotations of the running wheels. The cumulative error of the mileage measurement value will be caused by both the wheel diameter error of the running wheels and the counting error of the number of rotations, and the cumulative error will increase as the running mileage increases. Therefore, a set of photoelectric sensors is installed at the bottom of the inspection trolley. During the test, reflective strips are pasted on the running surface of the track beam with a length of 20 - 30m for each span. When the trolley passes by, a pulse signal will be received. In this way, the cumulative error of the rotational speed encoder is calibrated and compensated in real time to correct the mileage test error and improve the measurement accuracy.

[0045] S2. Use the inspection trolley to travel along the track inside the box girder, and use the inertial navigation system and a one-dimensional laser displacement sensor to detect the running attitude of the inspection trolley;

[0046] As Figure 3 shown, the geometric cross-sectional dimensions of the box-shaped track girder can be directly obtained by a 360-degree high-speed laser scanner. The most critical part of the entire test project is to accurately, efficiently, and reliably detect the linearity of the track girder in the longitudinal direction. As Figure 3 shown, the track girder alignment is close to the running trajectory of the inspection trolley. The running trajectory of the inspection trolley can be obtained by integrating the attitude angle and running distance of the trolley along the track. The calculation process is as follows:

[0047] Taking the time from step2 to step3 in the OXZ plane as an example, the nodding angle of the trolley obtained through the combined inertial navigation test is , and the moving distance measured by the odometer is ds, then dz can be obtained:

[0048] (1)

[0049] (2)

[0050] Then z t from the starting moment to any moment can be expressed as:

[0051] (3)

[0052] Therefore, the trajectory line of the trolley running can be expressed as: [x t , z t .

[0053] S3. Use the odometer integration to obtain the movement trajectory of the inspection trolley and get the long-wave irregularity curve of the track girder; use the high-speed laser scanner to continuously scan the geometric cross-sectional dimensions of the track girder to obtain the short-wave irregularity curves of the running surface and the guiding surface;

[0054] It can be known from Figure 3 that the running trajectory line of the inspection trolley does not completely coincide with the actual alignment of the track, and there is a deviation in the amplitude between the two, which is related to the fixed distance of the test trolley and the wavelength of the track irregularity. Therefore, it is necessary to correct the deviation value. For the sinusoidal track irregularity, the relationship between the two can be deduced by mathematical methods. Assume that the actual track irregularity is a sine wave z r :

[0055] (4)

[0056] is the wavelength of the sinusoidal irregularity, in meters. Since the track irregularity amplitude (p is the wheelbase), the measured running trajectory of the trolley zm It can be expressed as:

[0057] (5)

[0058] It can be obtained that

[0059] (6)

[0060] It can be seen that the measured trajectory is also a sine wave. Compared with the actual track alignment, the wavelength is the same, but the amplitude is different. The ratio of the amplitude of the sine wave of the measured trajectory to the amplitude of the actual track alignment :

[0061] (7)

[0062] The range of the proportionality coefficient , The closer to 1, the closer the measured value is to the true value. The proportionality coefficient is related to the wheelbase of the test car and the linear wavelength of the track. Figure 4 and Figure 5 give the relationship between the wheelbase of the test car, the linear wavelength of the track and the proportionality coefficient. It can be seen that the smaller the wheelbase and the larger the wavelength, the closer the proportionality coefficient is to 1. Through the measured waveform and the proportionality coefficient, the measured track waveform can be obtained.

[0063] The above has deduced the relationship between the measured value and the actual value when the track irregularity is a sine wave. In fact, the track irregularity is not a sine wave but a random waveform. At this time, it is necessary to introduce the Fourier transform to convert the random wave into a sine wave, amplify the sine wave, and then invert it into the measured waveform.

[0064] The measured curve x(n) can be obtained through the detection vehicle, and the frequency is F s , and the number of points used is N. Any continuous periodic digital signal can be composed of a set of appropriate sine curves. Therefore, using the discrete Fourier transform, x(n) is decomposed into N sine waves. First, perform the discrete Fourier transform on x(n) to obtain F(k):

[0065] (8)

[0066] F(k) is a set of complex numbers, k = 1, 2,..., N - 1, and F(k) is expressed as:

[0067] (9)

[0068] The amplitudes A k , frequencies f k , and phases of the decomposed sine waves can be expressed as:

[0069] (10)

[0070] The original random wave can be expressed as the linear superposition of N sine waves:

[0071] (11)

[0072] The actual track linearity is:

[0073] (12)

[0074] Due to the "filtering effect" of the wheelbase of the inspection trolley, the line excitations with wavelengths less than twice the wheelbase cannot be obtained through the trace method test. At this time, it is necessary to use a high-precision laser scanner installed on the inspection trolley to test the short-wave line excitations. The laser scanner obtains the coordinates of the surface of surrounding objects in the form of a point cloud by means of pulsed laser ranging when the test trolley is running. The reference coordinate system is the local coordinate system of the scanner system itself. The scanner is fixed at the front end of the test trolley and rolls, nods, and shakes its head together with the trolley. Therefore, it is necessary to convert the test points in the local coordinate system to the absolute coordinate system through the rotation matrix and the translation matrix:

[0075] The transformation matrix R x , R y , R z and the translation matrix T are:

[0076] (15)

[0077] (16)

[0078] (17)

[0079] (18)

[0080] Among them, roll, pitch, yaw are the roll angle, pitch angle, and yaw angle of the trolley obtained through the combined inertial navigation test respectively, and L sc is the longitudinal distance from the laser scanner to the inertial navigation system. The test point P b in the local coordinate system can be converted to P s in the absolute coordinate system:

[0081] (19)

[0082] S4. Superimpose the obtained medium and long wavelength roughness curves and short wavelength roughness curves to obtain the final track roughness test curve.

[0083] The final track roughness curve is expressed as:

[0084]

[0085] In the formula, is the roughness test curve; is the long-wave roughness test curve; are the test point coordinates in the absolute coordinate system, which is the short-wave roughness test curve.

[0086] Experimental verification

[0087] To verify the test accuracy and reliability of the detection system, a total station was used to test the pre-loading of two simply supported beams, and the test results were compared with those of the detection trolley to verify the detection accuracy of the detection trolley for long-wave roughness; a corrugation meter was used to detect the short-wave roughness in a local section, and the results were also compared with those of the trolley to verify the detection accuracy and reliability of the detection trolley for short-wave roughness.

[0088] Verification of long-wave test results

[0089] The suspended monorail track beam is usually composed of simply supported beams with a length of 20 - 35m for each section. To ensure that the simply supported beam is in a straight state when the loaded vehicle passes through it, each simply supported beam is not straight in the free state, but an upward pre-loading is set according to the vehicle weight and the beam section length. The self-weight of the detection system is much smaller than the vehicle weight, so the influence of the self-weight can be ignored. Therefore, the detection trolley can test the pre-loading of the track beam, which is equivalent to the long-wave roughness with a wavelength of 20 - 35m.

[0090] Figure 6 (a) shows the test results of the vertical unevenness of the running surface of a 220m long straight section (9 spans) of the track beam. It can be seen from the figure that the vertical unevenness is composed of 9 obvious long waves and countless short waves superimposed. The 9 long waves correspond to the pre-loading of 9 sections of simply supported beams respectively. To verify the detection accuracy of the long-wave roughness of the system we proposed, the 7th and 8th sections of simply supported beams were re-measured using a total station (the 8th beam is in the turnout area). Using the distance measurement function of the total station, the line geometry along the longitudinal direction of the simply supported beam can be measured. The comparison of the test results of the two simply supported beams by the detection trolley and the total station is shown in Figure 6 (b) and 6(c). It can be seen from the figure that the two line geometries are basically in agreement. The main difference is that the total station cannot measure the short-wave roughness of the line. The above results verify the test accuracy of the detection system for the long-wave roughness of the line.

[0091] Verification of short-wave test results

[0092] As Figure 7As shown in Fig. a, in the test results, it is found that there are regular harmonic irregularities with a wavelength of 0.7 - 0.8 m in the 3rd and 4th segments of the straight track beam. The average amplitude is about 1.2 mm, and the maximum value reaches 1.5 mm. There are no regular harmonic irregularities in other segments of the track beam. Comparing the data of two round trips, the results are consistent and occur at the same positions.

[0093] To verify the reliability of the test results, a total station was used to conduct a static re - measurement on the 3rd and 4th segments of the track beam. The wave grinding instrument has a test range of 1.0 m and a test accuracy of 0.1 μm. The results of the static re - measurement are shown in Figure 7 Fig. b. There are indeed short - wave irregularities with a wavelength of 0.7 - 0.8 m in the track beam, and the amplitude is also about 1.5 mm. It can be seen that this set of detection systems can accurately detect the short - wave irregularities of the track beam.

[0094] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general - purpose computer, a special - purpose computer, an embedded processor, or other programmable data - processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data - processing devices generate means for realizing the functions specified in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0095] These computer program instructions can also be stored in a computer - readable memory that can direct a computer or other programmable data - processing device to work in a specific manner, so that the instructions stored in the computer - readable memory generate a manufactured article including instruction means, and the instruction means realizes the functions specified in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data - processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer - implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0097] In the present invention, specific embodiments are used to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

[0098] Those of ordinary skill in the art will realize that the embodiments described herein are for helping the reader understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations that do not depart from the essence of the present invention according to these technical revelations disclosed by the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. A method for testing the unevenness of a suspended monorail track beam, characterized in that: The steps include: S1. Build a detection system including a detection vehicle, an inertial navigation system, a 360-degree high-speed laser scanner, a one-dimensional laser sensor, an odometer, and a data acquisition system; S2, using the detection trolley to move along the track in the box beam, and using the inertial navigation system and the one-dimensional laser displacement sensor to detect the running posture of the detection trolley; S3, using the odometer integral to obtain the motion trajectory of the detection vehicle, and obtain the long-wave irregularity curve in the track beam; using a high-speed laser scanner to continuously scan the cross-sectional geometric dimensions of the track beam, and obtain the short-wave irregularity curves of the running surface and the guide surface; S4. The obtained long-wave irregularity curve and short-wave irregularity curve are superimposed to obtain the final track irregularity test curve, wherein the long-wave irregularity curve in the track beam is expressed as: In the formula, It is the long wave irregular curve in the track beam. To detect the wheelbase of the trolley, is the amplitude of the long wave irregularity curve in the actual track beam, is the wavelength of the long wave irregularity curve in the actual track beam, To detect the horizontal displacement of the car; The shortwave irregular curve is specifically expressed as: In the formula, is the coordinate of the test point in the absolute coordinate system, is the coordinate of the test point in the local coordinate system, is the translation matrix, and is the longitudinal distance from the laser scanner to the inertial navigation system; are the three-axis components of the transformation matrix, and They are respectively the roll angle, nod angle and shake angle of the detection vehicle obtained through the inertial navigation test; The final track unevenness test curve is expressed as: In the formula, Test curve for final track irregularity; It is the long wave irregular curve in the track beam; is the coordinate of the test point in the absolute coordinate system, that is, the shortwave uneven curve.

2. A method for testing unevenness of a suspended monorail track beam according to claim 1, characterized in that: The motion trajectory of the vehicle detected in S3 is expressed as: In the formula, To measure the running trajectory of the car, is the long wave irregularity curve in the actual track beam, To detect the wheelbase of the trolley, To detect the horizontal displacement of the car.

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