Rail sleeper measurement and counting method based on ultrasonic ranging and system thereof

Abstract

The present application relates to a kind of sleeper measurement counting method based on ultrasonic ranging, comprising S1, set near end action distance SP1 and far end action distance SP2 as determination threshold, near end action distance SP1 is greater than the distance h1 of fastener top surface distance rail top surface, far end action distance SP2 is less than the distance h2 of track bed top surface distance rail top surface;S2, ultrasonic sensor real-time measurement rail detector when driving on rail, dynamic interval h of rail top surface distance fastener top surface and track bed surface, compare dynamic interval h with near end action distance SP1 and far end action distance SP2, if dynamic interval h is less than near end action distance SP1, generate the first state's sleeper detection signal;If dynamic interval h is greater than far end action distance SP2, generate the second state's track bed detection signal;S3, using the sleeper counter of single-chip microcomputer obtains the number of occurrence of sleeper detection signal, obtains sleeper count.The present application is low in power consumption, accurate in counting, suitable for artificial push trolley's railway track detection.

Description

Technical Field

[0001] This invention relates to the field of railway track inspection technology, and in particular to a sleeper measurement and counting method and system based on ultrasonic ranging. Background Technology

[0002] Railways are the lifeblood of the national economy. In recent years, with the rapid development of the national economy and the advancement of technology, rail transit has experienced rapid growth. Ensuring the safety of rail transportation is always the top priority for operation and management departments. Therefore, these departments need to conduct regular inspections of the rails. These inspections include checking track geometry, catenary geometry, and defects. Inspection equipment includes large inspection vehicles and manually pushed inspection trolleys (such as track inspection instruments, ultrasonic flaw detectors, and catenary detectors). All of these inspection devices need to have positioning capabilities to pinpoint the exact location of abnormal data or defects in the rails. This positioning is usually based on the kilometer markers of the track, allowing maintenance personnel to accurately locate defects and address them promptly.

[0003] Currently, the positioning functions of various detection systems mainly employ encoders and GPS positioning systems for mileage counting and location. Due to the encoder mounted on the odometer wheel, slight slippage occurs during the relative movement of the wheel and the rail, leading to significant accumulated mileage errors, potentially reaching the meter level, over long distances. Alternatively, RFID electronic tags are installed at regular intervals along the line to correct mileage positioning errors. GPS positioning is affected by tunnels and mountainous environments; although it can be corrected by combining it with inertial navigation systems, it still produces considerable errors in long tunnels.

[0004] Given that railway sleepers are relatively fixed in position and the distance between each sleeper is the same, image processing technology has been used in recent years to analyze and extract sleeper image features to count sleepers and thus achieve mileage counting. However, this image processing technology involves complex equipment and a large amount of computation, requiring a high-speed computer system, thus demanding high power and making it unsuitable for lightweight, manually pushed inspection trolleys. Patent CN109515471A proposes a non-contact sleeper identification method in a moving state. It uses a laser sensor installed under the crossbeam of a measuring trolley to scan and measure the distance between the track bed and sleepers while the trolley is being pushed, obtaining raw waveform data. This data is then filtered and analyzed to obtain a smooth sleeper waveform image, which is then analyzed to eliminate false detections and missed detections. However, the laser sensor is easily interfered with in strong outdoor fiber optic environments, and may even fail to measure properly. Furthermore, on ballasted tracks, the ballast conditions are complex, with many foreign objects, some of which may be higher than the sleepers, severely affecting the accuracy of the measurement. Patent CN102815319A discloses a non-contact sleeper identification and measurement device and method. It employs a proximity switch installed on a trolley. When the trolley moves on the track, the proximity switch scans the metal fasteners on the sleepers, generating a pulse signal. Processing software then processes the pulse signal to obtain sleeper information. However, the sensing distance of this proximity switch is generally short, and the conditions on railway tracks (especially ballasted tracks) are complex. Foreign objects may collide with the proximity switch, causing damage. Additionally, the presence of numerous metal devices on the track can also cause malfunctions. Summary of the Invention

[0005] Therefore, it is necessary to provide a sleeper measurement and counting method and system based on ultrasonic ranging to address the above problems.

[0006] A method for measuring and counting railway sleepers based on ultrasonic ranging includes the following steps: S1, set the near-end action distance SP1 and the far-end action distance SP2 as the judgment thresholds, wherein the near-end action distance SP1 is greater than the distance h1 between the top surface of the fastener and the top surface of the rail, and the far-end action distance SP2 is less than the distance h2 between the top surface of the track bed and the top surface of the rail. S2, using an ultrasonic sensor to measure in real time the dynamic distance h between the top surface of the rail and the top surface of the fastener and the ballast surface when the track inspection instrument is traveling on the rail, and comparing the dynamic distance h with the near-end action distance SP1 and the far-end action distance SP2. If the dynamic distance h is less than the near-end action distance SP1, a sleeper detection signal in the first state is generated; if the dynamic distance h is greater than the far-end action distance SP2, a ballast detection signal in the second state is generated. S3, use the sleeper counter of the microcontroller to obtain the number of times the sleeper detection signal based on the fastener appears, and obtain the sleeper count.

[0007] Preferably, S3 further includes S3.1, wherein the microcontroller has a built-in misjudgment counter, the misjudgment counter sets a first threshold L0 between the two sleeper detection signals, and the ultrasonic sensor shields the sleeper detection signal output when it moves within the first threshold L0 range.

[0008] Preferably, S3 further includes S3.2, wherein the microcontroller is equipped with a missed detection counter. When the ultrasonic sensor is allowed to output a sleeper detection signal, if the distance the track inspection instrument pushes on the rail reaches the second threshold L1 set by the missed detection counter of the microcontroller and no sleeper detection signal is detected, then the ultrasonic sensor is forced to output a sleeper detection signal.

[0009] Preferably, the first threshold L0 is 440 mm and the second threshold L1 is 700 mm.

[0010] Preferably, the proximal action distance SP1 is set to 130mm and the distal action distance SP2 is set to 180mm.

[0011] A sleeper measurement and counting system includes a track inspection instrument, and an ultrasonic sensor, a microcontroller, an encoder, and a power supply installed electrically connected to the track inspection instrument. The ultrasonic sensor is used to measure the dynamic distance h between the top surface of the rail and the vertical ground in real time. The microcontroller is configured to count the sleeper detection signal and the track bed detection signal. The encoder is installed on the odometer wheel axle of the track inspection instrument and is used to detect the distance the track inspection instrument pushes on the rail and output a mileage pulse signal. The power supply powers the ultrasonic sensor, the microcontroller, and the encoder.

[0012] The advantages of this invention are as follows: This invention proposes a lightweight sleeper measurement and counting method based on ultrasonic ranging. The principle is to use an ultrasonic sensor to measure the distance from the top surface of the rail to the ballast bed surface and the top surface of the fasteners. Combined with the mileage pulses from the encoder, the method is processed in real time by a low-power embedded chip to achieve accurate counting of the sleepers. Its features include small hardware size, low power consumption, and accurate counting, making it suitable for all-weather, manually pushed railway track inspection. Attached Figure Description

[0013] Figure 1 This is a front view structural diagram of one embodiment of the sleeper measurement and counting system; Figure 2 This is a schematic diagram of a sleeper measurement and counting method based on ultrasonic ranging; Figure 3 This is a schematic diagram illustrating the principle of preventing misjudgment in a sleeper measurement and counting method based on ultrasonic ranging. Figure 4 This is a schematic diagram illustrating the anti-leakage judgment principle of a sleeper measurement and counting method based on ultrasonic ranging; Figure 5 This is a schematic diagram of the circuit module of the sleeper measurement and counting system. Detailed Implementation

[0014] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0015] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0017] A sleeper measurement and counting method based on ultrasonic ranging includes the following steps: S1, setting near-end movement distance SP1 and far-end movement distance SP2 as judgment thresholds, wherein the near-end movement distance SP1 is greater than the distance h1 between the top surface of the fastener 11 and the top surface of the rail 10, and the far-end movement distance SP2 is less than the distance h2 between the top surface of the track bed 12 and the top surface of the rail 10. Specifically, this technical solution is applied to a track inspection instrument 20, which is pushed and travels on the rail 10. An ultrasonic sensor 1 is installed at the bottom of the track inspection instrument 20. The near-end movement distance SP1 and far-end movement distance SP2 can be set as judgment thresholds within the ultrasonic sensor 1, or the judgment can be written into the FLASH memory of the microcontroller within the track inspection instrument 20; no specific limitation is made here. Among them, the distance h1 between the top surface of fastener 11 and the top surface of rail 10 and the distance h2 between the top surface of ballast 12 and the top surface of rail 10 are measured values. Distance h1 is a fixed value because rails in China are currently divided into ballasted and ballastless types. The ballast condition of ballasted ballast tracks is complex, so h2 varies considerably and needs to be set according to the track type. For example... Figures 1-2As shown, the three sleepers 13 are evenly distributed on the track bed 12 with a spacing of s. According to the "Design Code for High-Speed ​​Railways" in my country, the spacing of the fasteners 11 nodes on ballastless tracks should not be greater than 650mm. On ballasted tracks, the spacing of the sleepers is generally 600mm, and on station tracks it is generally 695mm.

[0018] S2, using ultrasonic sensor 1, the dynamic distance h between the top surface of rail 10 and the top surface of fastener 11 and the surface of track bed 12 is measured in real time when the track inspection instrument 20 travels on rail 10. This dynamic distance h is compared with the near-end action distance SP1 and the far-end action distance SP2. If the dynamic distance h is less than the near-end action distance SP1, a sleeper detection signal in the first state is generated; if the dynamic distance h is greater than the far-end action distance SP2, a track bed detection signal in the second state is generated. Specifically, the near-end action distance SP1 is used to identify fastener 11. Based on commonly used rail specifications in Chinese railways (50mm rail height 152mm, 60mm rail height 176mm) and the nut height of fastener 11 (approximately 60mm), to ensure stable triggering under different rail types, the near-end action distance SP1 is set to 130mm. This value is greater than the minimum distance h1_min from the top surface of the fastener to the top surface of the rail, ensuring that when the ultrasonic sensor is directly facing the fastener nut, the measured dynamic distance h is necessarily less than SP1. The far-end action distance SP2 is a threshold used to distinguish between the track bed and sleeper areas. According to relevant specifications for ballasted tracks, the minimum distance from the sleeper bearing surface to the ballast is not less than 40mm. Adding the rail height, the minimum distance from the rail surface to the ballast is approximately 192mm (50 rails) or 216mm (60 rails). To ensure reliable identification of the track bed area under various working conditions, the far-end action distance SP2 is set to 180mm. This value is less than the minimum distance h2_min from the top surface of the track bed to the top surface of the rail, ensuring that when the ultrasonic sensor is directly facing the track bed area (without sleeper obstruction), the measured dynamic distance h will necessarily be greater than SP2. Furthermore, if the dynamic distance h < the near-end action distance SP1, the ultrasonic sensor is directly facing the fastener nut. After completing the threshold comparison inside the ultrasonic sensor, a sleeper detection signal in the first state is generated, which is defined as a high level (logic "1") in this embodiment. If the dynamic spacing h > the far-end action distance SP2, and the ultrasonic sensor is facing the track bed area, after completing the threshold comparison inside the ultrasonic sensor, it generates a track bed detection signal in the second state, which is defined as a low level (logic "0") in this embodiment. In other embodiments, a microcontroller can also be used to perform threshold comparison and generate sleeper detection signals and track bed detection signals, which is not specifically limited here.

[0019] S3, the sleeper counter of the microcontroller 2 is used to obtain the number of occurrences of the sleeper detection signal based on the fastener 11, thus obtaining the sleeper count. Specifically, this embodiment uses an embedded microcontroller 2, and a sleeper counter is maintained inside the microcontroller 2. Each time a complete sleeper detection signal is experienced, the sleeper counter performs an N = N + 1 operation. The final sleeper count value and the corresponding mileage information can be provided to the main control unit of the track inspection system in the form of a square wave signal through the I / O interface, or in the form of a digital message through the RS232 serial port, for data alignment and defect location. The features of this design are small hardware size, low power consumption, and accurate counting, making it suitable for all-weather use of manually pushed trolleys for railway track inspection. To prevent the ultrasonic sensor 1 from colliding with the top of the fastener 11, the ultrasonic sensor 1 is installed inside the crossbeam of the track inspection instrument 20, avoiding damage from collision with the fastener 11 when using proximity switches for measurement. During the displacement of the track inspection instrument 20, the ultrasonic sensor 1 can measure the distance between the top surface of the rail 10 and the surface of the track bed 12 and the top surface of the fastener 11 in real time.

[0020] Specifically, in this embodiment, S3 further includes S3.1, where the microcontroller 2 has a built-in misjudgment counter, which sets a first threshold L0 between two sleeper detection signals. When the ultrasonic sensor 1 shifts within the first threshold L0 range, it shields the sleeper detection signal output. Figures 1-4 As shown, this embodiment is introduced to prevent gravel, ballast, or other protruding foreign objects (whose height may be close to or even exceed that of the sleepers) on the track bed from being mistakenly identified as sleepers. Therefore, this embodiment is used as a misjudgment control logic to eliminate interference from foreign objects in the track bed when outputting the sleeper detection signal. The specific process is as follows: The ultrasonic sensor is initially in the "output allowed" state. When the original sleeper signal changes from low to high (i.e., a sleeper is detected), the sleeper counter N is incremented by 1. Subsequently, the system enters the "misjudgment shielding" state. In the "misjudgment shielding" state, the microcontroller starts a misjudgment counter based on encoder pulses to measure the distance the track inspection instrument 20 pushes on the rail 10. Before this distance reaches the preset first threshold L0 (440mm), regardless of the dynamic spacing h value measured by the ultrasonic sensor, the system will force a low-level output (track bed detection signal), thereby shielding interference signals that may be caused by foreign objects such as ballast. Once the pushing distance reaches L0, the system exits the "false alarm shielding" state, allowing the ultrasonic sensor to re-enter the "output allowed" state and prepare to receive the signal from the next sleeper.

[0021] Specifically, in this embodiment, S3 further includes S3.2, where the microcontroller 2 has a built-in miss detection counter. When the ultrasonic sensor 1 is allowed to output a sleeper detection signal, if the track inspection instrument 20's pushing distance on the rail 10 reaches the second threshold L1 set by the miss detection counter of the microcontroller 2, and no sleeper detection signal is detected, then the ultrasonic sensor 1 is forced to output a sleeper detection signal. For example... Figures 3-4 As shown in this embodiment, the main issue is that if the sleeper detection signal is not recognized due to reasons such as absence, burial, or abnormal sensor signal when the ultrasonic sensor is in the "output allowed" state, it will lead to missed counts. To address this, a missed detection compensation logic is introduced. The specific judgment process is as follows: When the ultrasonic sensor enters the "output allowed" state, another missed detection counter based on encoder pulses inside the microcontroller 2 is simultaneously activated to start measuring the distance the track inspection instrument pushes on the rail. If the ultrasonic sensor detects a valid sleeper detection signal (h < SP1) again before the missed detection counter reaches the preset second threshold L1 (700mm), the missed detection counter is reset and enters the next counting cycle. If the pushing distance reaches L1 and the ultrasonic sensor still does not detect any sleeper detection signal, it is determined that a "missed detection" has occurred. At this time, the ultrasonic sensor forcibly outputs a high-level pulse with a width of K (200 mileage pulses, 40mm) as a virtual sleeper signal, and the sleeper counter is also incremented by 1. After forcibly outputting the signal, the system needs to adjust the subsequent misjudgment shielding distance to compensate for the phase shift caused by the missed detection.

[0022] The process of measuring and counting the sleepers is as follows: Figure 3 As shown, the track inspection instrument 20 starts moving from position M0 on the rail. The sleeper counter N is reset to zero, and the enable control is set to "1", allowing sleeper signal output. At this time, the dynamic distance h measured by the ultrasonic sensor is the distance from the top surface of the rail to the ballast, which is greater than the far-end action distance SP2. Therefore, the sleeper detection signal output is "0". When the track inspection instrument continues to move to position M1, the distance h measured by the ultrasonic sensor is less than SP1. At this time, the sleeper detection signal is set to "1". The track inspection instrument continues to move to position M2. At this time, the distance h measured by the ultrasonic sensor is greater than SP2, and the sleeper signal is set to "0". The sleeper counter N = N + 1. At the same time, the enable signal is set to "0", and the misjudgment counter L0 is started. The track inspection instrument continues to move forward. At this time, because the enable signal is set to "0", the output value of the ultrasonic sensor is blocked during this distance before L0 reaches the set value, preventing the output of sleeper misjudgment. When the misjudgment counter L0 reaches the set value, the enable signal is set to "1", and the door is opened to wait for the sleeper signal to arrive. Simultaneously, the missing detection counter L1 is activated. The track inspection instrument continues to advance to position M3. At this point, there are two scenarios: the first scenario ( Figure 3In the normal, no-missed-judgment situation, the ultrasonic sensor detects a distance h less than SP1, and the sleeper signal output is set to "1" until the track inspection instrument is pushed to the M4 position. When the distance h measured by the ultrasonic sensor is greater than SP2, the sleeper signal is set to "0", the sleeper counter N=N+1, and the next measurement and counting cycle begins. The second scenario is a missed detection in the processing procedure ( Figure 4 The measured values ​​at positions M3 and M4 are consistently greater than SP1, and there is no normal sleeper signal output. When the process continues until the value of the missed detection counter L1 is greater than the set value, the missed detection processing program is activated, and a sleeper signal is forcibly inserted and output. The output signal width is K (take 200 mileage pulses), the sleeper counter N=N+1, and the misjudgment counter L0 is restarted. However, L0 at this time should be the normal value (2200) minus the values ​​of T and K, which is 2200-700=1500. The enable signal is then set to "0", and the process enters the next measurement counting cycle.

[0023] like Figure 5As shown, this embodiment provides a sleeper measurement and counting system for implementing the above method, including a track inspection instrument 20, and an ultrasonic sensor 1, a microcontroller 2, an encoder 3, and a power supply 4 electrically connected to the track inspection instrument 20. The ultrasonic sensor 1 is used to measure the dynamic distance h between the top surface of the rail 10 and the vertical ground in real time. The microcontroller 2 is configured to execute the steps of the method described in any one of claims 1 to 5 to count the sleeper detection signal and the track bed detection signal. The encoder 3 is installed at the end of the odometer wheel axle of the track inspection instrument and is used to detect the distance the track inspection instrument 20 pushes on the rail 10 and output a mileage pulse signal. The power supply 4 supplies power to the ultrasonic sensor 1, the microcontroller 2, and the encoder 3. Specifically, the ultrasonic sensor 1 in this design is a transceiver ultrasonic probe with a measurement accuracy of millimeters. It is installed at the bottom of the crossbeam of the track inspection instrument 20, with the detection window facing the center of the rail fastener nut. Encoder 3 is an incremental magnetic encoder, installed on the end of the odometer wheel axle of track inspector 20. The circumference of the odometer wheel is c = 200mm. The encoder outputs N pulses per revolution, where N = 1000. Therefore, each pulse represents a pushing distance of c / N = 0.2mm. Microcontroller 2 is an embedded microcontroller using an ARM Cortex-M series low-power microcontroller. It integrates an ADC for reading ultrasonic sensor signals and a timer / counter peripheral for capturing encoder pulses. The microcontroller internally implements a sleeper counter, a false alarm counter, and a missed alarm counter through software logic. The power module uses a 7.4V / 5000mAh rechargeable lithium battery pack, providing stable voltage to the sensors, microcontroller, and encoder via a DC-DC converter, meeting the low-power requirements of portable testing equipment. Output interfaces include one I / O interface for outputting square wave signals corresponding to each sleeper; and one RS232 serial port for outputting digital messages containing sleeper serial numbers, mileage stamps, and other information. When the system is working, the microcontroller 2 receives pulse signals from the encoder 3 to calculate the pushing distance, and simultaneously receives dynamic spacing h data from the ultrasonic sensor 1. The program embedded in the microcontroller 2 executes steps S1 to S3 as described in Example 1, and finally provides accurate sleeper counting information to the external track detection host through the output interface.

[0024] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A sleeper measurement and counting method based on ultrasonic ranging, characterized in that: Includes the following steps, S1, set the near-end action distance SP1 and the far-end action distance SP2 as the judgment thresholds, wherein the near-end action distance SP1 is greater than the distance h1 between the top surface of the fastener and the top surface of the rail, and the far-end action distance SP2 is less than the distance h2 between the top surface of the track bed and the top surface of the rail. S2, using an ultrasonic sensor to measure in real time the dynamic distance h between the top surface of the rail and the top surface of the fastener and the ballast surface when the track inspection instrument is traveling on the rail, and comparing the dynamic distance h with the near-end action distance SP1 and the far-end action distance SP2. If the dynamic distance h is less than the near-end action distance SP1, a sleeper detection signal in the first state is generated; if the dynamic distance h is greater than the far-end action distance SP2, a ballast detection signal in the second state is generated. S3, use the sleeper counter of the microcontroller to obtain the number of times the sleeper detection signal based on the fastener appears, and obtain the sleeper count.

2. The sleeper measurement and counting method based on ultrasonic ranging as described in claim 1, characterized in that: S3 further includes S3.1, wherein the microcontroller is equipped with a misjudgment counter, the misjudgment counter sets a first threshold L0 between two sleeper detection signals, and the ultrasonic sensor shields the sleeper detection signal output when it moves within the first threshold L0 range.

3. The sleeper measurement and counting method based on ultrasonic ranging as described in claim 2, characterized in that: S3 further includes S3.2, wherein the microcontroller is equipped with a missed detection counter. When the ultrasonic sensor is allowed to output a sleeper detection signal, if the distance the track inspection instrument pushes on the rail reaches the second threshold L1 set by the missed detection counter of the microcontroller and no sleeper detection signal is detected, then the ultrasonic sensor is forced to output a sleeper detection signal.

4. The sleeper measurement and counting method based on ultrasonic ranging as described in claim 3, characterized in that: The first threshold L0 is 440 mm, and the second threshold L1 is 700 mm.

5. The sleeper measurement and counting method based on ultrasonic ranging as described in claim 1, characterized in that: The proximal action distance SP1 is set to 130mm, and the distal action distance SP2 is set to 180mm.

6. A sleeper measurement and counting system for implementing the method of any one of claims 1 to 5, characterized in that; The system includes a track inspection instrument, an ultrasonic sensor, a microcontroller, an encoder, and a power supply, all electrically connected to the track inspection instrument. The ultrasonic sensor is used to measure the dynamic distance h between the top surface of the rail and the vertical ground in real time. The microcontroller is configured to count the sleeper detection signals and the track bed detection signals. The encoder is installed on the odometer wheel axle of the track inspection instrument and is used to detect the distance the track inspection instrument pushes on the rail and output mileage pulse signals. The power supply provides power to the ultrasonic sensor, the microcontroller, and the encoder.

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