Abstract: Based on the requirements of railway track data acquisition site, an intelligent railway track data acquisition system is designed. The hardware structure and software design of the acquisition system are described in detail, and the solutions to key problems and difficulties are explained in detail . Keywords: railway data; PC/104 bus; sensors Under the influence of locomotive and rolling stock dynamics and natural erosion, railway lines not only undergo elastic deformation but also permanent deformation. Permanent deformation can be divided into two categories : one is the change in geometric position, such as track creep, malfunction, and gauge widening or narrowing; the other is the wear of various parts of the track, such as rail wear. The existence of permanent deformation not only affects the high-speed and smooth operation of trains, but also, when this deformation accumulates and exceeds a certain limit, it will greatly reduce the strength and stability of the track, seriously threatening traffic safety. Whether the various data of the track meet the requirements is related to the safety of train operation. Performing accurate measurement, maintenance, and repair of railway lines to improve their quality is an important task for railway track maintenance workers. Currently, the measurement of important track data on railway sites is all done manually. Track maintenance workers use simple tools such as rulers, tape measures, and ropes, employing methods like string lines to measure these important parameters (including gauge, level, triangular grooves, curve superelevation, elevation difference, and track alignment); the measurement data is read by the surveyor's eyes. This measurement method is not only inaccurate but also consumes a large amount of manpower and resources, and requires extensive and tedious calculations. From the above description of the current situation on railway sites, it can be seen that the workload of railway track maintenance workers is extremely heavy, and this measurement method has many potential errors, which are highly dependent on the surveyor's condition; different surveyors may obtain different measurement results for the same section. To address the challenges of high workload and difficulty in ensuring accuracy at railway sites, this project designs an automatic measurement system. Through necessary sensors and controllers, the system collects, processes, and calculates data. With just a few button presses, workers can automatically detect railway track data. Furthermore, the data can be transferred to a PC for further processing. This allows for the creation of a track inspection logbook based on measured track parameters, data retrieval, and the generation of various tables such as over-limit location logbooks and summary tables, facilitating the maintenance of track equipment integrity and quality consistency. The PC also provides a graphical view of track parameters at any point. This intelligent railway track data acquisition system significantly reduces worker workload and shortens inspection time, while also ensuring more complete and accurate data collection, maximizing the fulfillment of railway site requirements. 1. System Structure The intelligent railway track coefficient acquisition system consists of two parts: a GD-1 type intelligent railway track data acquisition instrument for on-site data collection and a PC-based railway track data processing system. The GD-1 type intelligent railway track data acquisition instrument is shown in Figure 1. This system uses the AR-B1320 model, a PC/104 CPU module, which features an 80386SX-40 MHz CPU, a PC/104 expansion bus, two RS-232/RS-485 serial ports, and a programmable watchdog timer, with an additional 64 MDOC expansion slot. The PC/104 bus is the bus standard used in ultra-small PC microcomputers. These ultra-small PC microcomputers are small in size and compact in structure, making them popular in various industrial control and communication control applications. They can be embedded in products with high requirements for size and power consumption, such as medical instruments, laboratory instruments, communication equipment, commercial terminals, military electronic equipment, and robots; therefore, PC/104 microcomputers are often called embedded PCs. This type of microcomputer has two bus connectors, P1 with 64 pins and P2 with 40 pins, totaling 104 pins, hence the name PC/104. It does not use a slide rail or bus motherboard; the modules are stacked together. Aside from their miniaturized structure, the bus and the entire system are fully compatible with the ISA standard in both hardware and software. Essentially, they are miniaturized XT, AT, 386, and 486 models developed to better meet the requirements of industrial control or miniaturized equipment. The main characteristics of embedded PCs using the PC/104 bus are: the use of ultra-small modules, including the CPU module; all functional modules are designed according to the PC/104 standard, with a module size of 90.2mm × 95.9mm, much smaller than typical PC motherboards; a self-stacking bus structure, eliminating the baseboard and slots, utilizing stackable bus connectors on the modules to connect them together, resulting in compact and flexible assembly; low bus drive current (6mA) and low power consumption (1-2W). To meet miniaturization requirements, each module uses VLSI devices, gate arrays, ASIC chips, and large-capacity solid-state drives. The PEM-AIO modular medium-speed analog input module, combined with the IBM PC-compatible PC/104 CPU module system, forms a high-performance data acquisition and control system. The PEM-AIO module features: 8/16 single-ended analog input channels, a 12-bit 20-microsecond or 10-microsecond A/D converter, 24 channels of programmable digital I/O based on the TTL/CMOS 8255 chip, and three independent 16-bit, 8MHz timers/counters (or 5MHz). Other equipment includes six differential transformer displacement sensors with linearity <0.05% and a range of ±20mm; a photoelectric encoder; a 5×4 non-encoded keyboard; and an LCD display. [align=center]Figure 1 Block Diagram of the Intelligent Railway Track Data Acquisition Instrument[/align] The intelligent railway track data acquisition instrument can automatically acquire track data at adjustable intervals of 0.01 meters to 0.99 meters. Railway track data includes distance, gauge, level (superelevation), and triangular pits, and can switch between straight and curved tracks. It not only records all measurement data to a DOC file but also records information such as the surveyor's number, track type, up/down direction, and measurement time. It features a display function, allowing for simultaneous measurement and data display, enabling track maintenance personnel to immediately acquire measurement data on-site. Track gauge, level, and other data have specific range requirements; if these limits are exceeded, the instrument will alarm. During the testing process, real-time monitoring of power supply, time and date, and remaining disk space is possible. Special points can be marked, and testing can be paused. During measurement, previously measured data can be queried for comparison with the current measurement; queries can also be performed on the aforementioned marked points. The railway track measuring instrument transfers the actual measured data from the field to a PC via an RS/232 serial port, where the data is processed by the PC's railway track data processing system. 2. Software Design The railway track data intelligent acquisition system software consists of two main parts. The first part is the software for the GD-1 type railway track data intelligent acquisition instrument, implemented using the powerful tool of PC/104—the C language; the other part is the ground information processing software, implemented using Microsoft's visual programming language VB6.0 and the ACCESS database. The GD-1 railway track data intelligent acquisition instrument software consists of a data measurement module, a keyboard and display program module, a RS-232 communication module, other auxiliary modules, and an anti-interference program module. The challenge here lies in handling the programmable interval timer 8253. The 8253 operates in mode 0 (counting end interrupt mode). The common method is to write an initial value after the count ends, and the count continues as the initial value is continuously written. However, this method only writes the initial value when an external pulse is present. We cannot guarantee that the external photoelectric encoder will provide a pulse precisely when the software program is writing the initial value. Therefore, this method of continuously writing the initial value is not feasible. The method used here is to initially write the initial value to start the counter; then, the value in the counter is continuously read, and it is determined whether the difference between this value and the initial value is greater than or equal to the count value. If it is, the current value is treated as the initial value, necessary processing is performed, and counting continues. The difference between this value and the initial value is then checked again to see if it is greater than or equal to the count value. This process is repeated, thus avoiding errors caused by the initial value not being written. The calculation method differs when the count value crosses the threshold from 0 to 0xFFFF. The ground information processing software mainly has data processing and graphics functions. Specifically, it can receive data from the acquisition system (via RS-232 serial communication line); create or open databases to store received data; input standard values ​​through human-computer interaction and perform corresponding data processing based on the standard values; generate a series of track data information tables such as inspection record books, summary tables of over-limit locations, and statistical tables of over-limit locations; and perform graphical processing on the collected track data to depict track status graphics. Operators can drag the mouse to view all data values ​​at any point on the track, making track status information more readily apparent. 3. Key Issues and Difficulties Railway workers and some researchers have been making unremitting efforts to find a convenient and accurate way to measure railway track data. Currently, the only instrument used for automatic track data measurement is the "track inspection vehicle." China has a total of 30 track inspection vehicles: 17 GJ-3 type, 6 XGJ-1 type, and 7 GJ-4 type. Track inspection vehicles are not only few in number but also extremely large, making each inspection a very difficult task. Because track inspection vehicles perform dynamic measurements, their accuracy is affected at high speeds. According to engineers on site, there is a significant error (around ±5mm) between the data obtained from track inspection vehicles and the data measured manually by on-site workers. Therefore, engineers only use them to observe track trends, while the actual track data is still obtained through manual measurement. Due to these inconveniences of track inspection vehicles, many people have been developing automatic track data detection devices, but achieving ultra-high level accuracy is very difficult. The main method for track inspection vehicles to measure ultra-high level is to use gyroscopes and inclinometers to detect the roll angle of the vehicle. While gyroscopes are very accurate in measuring angles, they are relatively expensive. Therefore, although a considerable amount of time and personnel have been involved in developing an intelligent track data acquisition system, they have all given up halfway through, directly because ultra-high level measurement is difficult and using gyroscopes is too costly. When measuring horizontal (superelevation) levels, this system considered and compared many methods, such as measuring the pressure difference using the inclination of a mercury column. However, this method was abandoned because the pressure difference is very large, and it is generally difficult to find a suitable pressure sensor. Ultimately, a method using a weight to pull a displacement sensor was selected. The advantages of this method are high accuracy in static measurements and low cost. However, it also has disadvantages: the weight is prone to swinging during dynamic movement, leading to balance issues. To solve this problem, in addition to appropriately increasing the damping within the allowable error range, the instrument also employs a compensatory measurement strategy. This involves using an indicator light at each measurement point to alert the operator. When the red light illuminates, the operator stops pushing the instrument, and the instrument automatically waits for a period of time (a few seconds) until the weight is stationary. Only then does the software perform the horizontal (superelevation) measurement. After the measurement, another indicator light (green light) reminds the operator to continue pushing the instrument. This measurement method avoids errors caused by the weight's swinging motion, and in practical application, it has not significantly affected work efficiency. Feedback from on-site workers indicates that this design method is well-suited to human physiological responses. After pushing the instrument along the rails for a period of time, people are inclined to stop and rest, and the design of this instrument perfectly meets this need. 4. Conclusion The intelligent railway track data acquisition system was developed for the Jinan Railway Bureau's Engineering Section. The system's hardware and software designs have been successfully debugged. Extensive testing on a railway line in Jinan shows that the measurement effect on track data is excellent, with a measurement accuracy significantly higher than previous manual measurements by workers, reaching ±0.01 mm. It also greatly reduces the workload of railway workers. Practical application by on-site workers has received unanimous praise. Below are some examples of manual measurement data collected on a straight section of the railway (see Table 1) and the measurement data from this system (see Table 2). The superiority of this system can be seen from the comparison. Table 1: Manual Measurement Data Table 2: Measurement Data from this System From an economic perspective, this intelligent railway track data acquisition system will bring convenience to the measurement work of railway engineering workers, making measurements more accurate. Based on an annual production of 20 sets, the estimated annual output value is approximately 1 million yuan. The innovation of this paper lies in designing an intelligent railway track data acquisition system to improve the current situation where railway line measurement and maintenance are all done manually. This system can automatically measure railway track data (including gauge, level, triangular emplacements, curve superelevation, elevation difference, and track alignment). Data measured on-site can be transferred to a PC via an RS/232 serial port. The data is then processed by the PC's railway track data processing system, resulting in fast processing and long-term data storage. This system is economical, reliable, and has significant application value. References: [1] Railway Curve Maintenance [M]. China Railway Publishing House, 1985. [2] Shen Guoxiang. Railway Track [M]. China Railway Publishing House, 1996. [3] Tan Haoqiang. C Programming Tutorial [M]. 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