A railway power cable line measurement system and method

Abstract

The application discloses a railway power cable line measurement system and method, and belongs to the technical field of railway construction cable measurement. The system comprises an upper data management platform and a measurement trolley terminal, and the measurement trolley terminal communicates with the upper platform. The measurement trolley terminal is composed of a measurement intelligent terminal and an encoder acquisition module, and the measurement intelligent terminal is provided with a Beidou positioning module. The method comprises the following steps: collecting encoder pulses and Beidou positioning data in real time; calculating real-time speed according to the encoder pulses; screening the Beidou data for effectiveness by using the real-time speed; performing Kalman filtering and seven-point moving least square smoothing on the effective data; calculating the encoder length and the Beidou track length; and obtaining the final cable length through weighted fusion. The application realizes the digitization and informatization of railway power cable length measurement by controlling the measurement error within 2% through the fusion of the encoder and the Beidou double source.

Description

Technical Field

[0001] This invention relates to the field of railway construction cable measurement technology, and in particular to a railway power cable line measurement system and method. Background Technology

[0002] Currently, the on-site measurement of power cable laying lengths along railway lines mainly relies on manual operation using roller-type distance measuring instruments, typically mechanical counting distance measuring instruments. These instruments are used by walking along the railway line where power cables need to be laid, with the rollers driving a mechanical gear counting mechanism to count the mileage. After counting, the length of each segment of power cable in the main line is recorded manually. This often leads to omissions, miscounts, and mixed counts, resulting in material waste due to unusable cable cuts during construction. It also frequently causes data errors leading to repeated measurements, wasting manpower and construction time. Furthermore, because general-purpose roller-type distance measuring instruments are often suitable for measuring on flat ground, they are not very applicable to uneven surfaces at construction sites, resulting in significant errors in power cable length measurement. The error of traditional mechanical distance measuring instruments is approximately 5%, while the error of electronic pure encoder distance measuring instruments is approximately 7%.

[0003] Traditional methods of measuring the length of power cable laying have the following limitations due to the limitations of currently available distance measuring instruments:

[0004] 1. Low level of digitalization: Construction workers use mechanical distance measuring instruments, which use rollers to drive gears and then a digital encoder to display the counting value. This requires manual transcription to obtain the length value. While electronic distance measuring instruments exist, they only display the length value on an LCD screen and have a longer counting range than mechanical instruments, resulting in lower on-site usage.

[0005] 2. The level of informatization is low. At present, the construction site mainly relies on manual statistics and manual creation of Excel spreadsheets to record the length data of the construction section within the bus. There is a lack of effective data management, display, comparison and other functions. When comparing measurement data with design data, the comparison work is time-consuming and laborious due to the large amount of data. It is necessary to improve the overall level of informatization.

[0006] 3. Poor measurement accuracy: Due to the limited range of use of general-purpose distance measuring instruments, they are not suitable for uneven roads. When walking on uneven roads, the rollers are also counting as they pass over the potholes. Therefore, the length is often over-recorded on such roads, resulting in a large deviation between the on-site measurement of the power cable laying length and the design data, and the overall measurement accuracy is poor.

[0007] With the increasing demands for digitalization and informatization in high-speed rail construction projects, traditional methods for measuring the length of power cables are becoming increasingly inadequate for on-site applications. Therefore, it is necessary to innovate traditional distance measuring instruments to improve the actual measurement accuracy of power cable laying length and enhance the overall digitalization and informatization level of the process. Summary of the Invention

[0008] The technical problem to be solved by this invention is to overcome the shortcomings of existing methods for measuring the length of railway power cable lines, such as low accuracy, reliance on manual recording, and lack of data management functions. This invention provides a railway power cable line measurement system and method that improves measurement accuracy and achieves automated and information-based management of the measurement process by integrating encoders with BeiDou positioning data.

[0009] The technical solution adopted by this invention to solve its technical problem is as follows: This invention provides a railway power cable line measurement system based on encoder and Beidou positioning, including a host data management platform and a measurement trolley terminal. The measurement trolley terminal is installed on a railway power cable line measurement trolley, and the measurement trolley is equipped with an encoder for collecting pulse signals during the movement of the measurement trolley. The measurement trolley terminal includes a measurement intelligent terminal and an encoder acquisition module.

[0010] The measurement intelligent terminal includes at least a control board, a Beidou positioning module, and a communication module. The Beidou positioning module is connected to the control board, and the measurement intelligent terminal communicates with the upper-level data management platform through the communication module. The encoder acquisition module includes at least a microcontroller, an interface conversion chip, and an encoder pulse interface. The encoder pulse interface is used to connect to the encoder output. The microcontroller's input is connected to the encoder pulse interface to acquire encoder pulse signals, and the microcontroller's output is connected to the interface conversion chip. The interface conversion chip is connected to the measurement intelligent terminal through a data transmission interface.

[0011] Furthermore, the control board includes an Android core board and a touchscreen. The communication module is a 4G module. The touchscreen and the Beidou positioning module are electrically connected to the Android core board. The data transmission interface is a USB interface, and the interface conversion chip is a USB interface conversion chip. The USB interface conversion chip is connected to the measurement intelligent terminal via the USB interface, and the 4G module is connected to the Android core board.

[0012] Furthermore, the microcontroller is an STM32F103R8T6, and the USB interface conversion chip is an FT232RL. The TIM1 channel and PA8 and PA9 pins of the STM32F103R8T6 are connected to the A-phase and B-phase signals of the encoder pulse interface, which are used to determine the forward and reverse rotation direction of the roller by the 90° phase difference between the A and B phases; the UART interface of the STM32F103R8T6 is connected to the FT232RL chip.

[0013] Furthermore, the measurement intelligent terminal also includes a power management unit MT6359, which is connected to the Android core board via an SPI interface; a touch screen is connected to the Android core board via a MIPI-DSI interface; and a Beidou positioning module is connected to the Android core board via a UART interface.

[0014] This invention also provides a method for measuring railway power cable lines based on encoders and BeiDou positioning, employing the aforementioned measurement system and including the following steps:

[0015] The system acquires pulse data collected in real time by the encoder during the movement of the measuring trolley, as well as latitude and longitude positioning data collected in real time by the Beidou positioning module.

[0016] The real-time speed of the measuring trolley and the cumulative length measured by the encoder are calculated based on the encoder pulse data.

[0017] The BeiDou positioning data is filtered for validity using the real-time speed, and invalid positioning points are removed.

[0018] The filtered valid BeiDou positioning data are sequentially subjected to Kalman filtering and seven-point moving least squares smoothing to obtain the smoothed BeiDou positioning trajectory.

[0019] The length of the BeiDou positioning trajectory is calculated based on the smoothed BeiDou positioning trajectory.

[0020] The cumulative length measured by the encoder is weighted and fused with the length measured by the Beidou positioning trajectory to obtain the final measured length of the cable line.

[0021] Furthermore, the validity screening includes: calculating the theoretical maximum displacement based on the real-time velocity V, the BeiDou positioning data reading period T, and the judgment coefficient m. If the current BeiDou positioning data corresponds to the walking increment If the displacement is less than the theoretical maximum displacement, it is considered valid; the walking increment Calculate using the following formula: Let the previous point of the current BeiDou positioning data be... The current point is Latitude difference Longitude difference Average latitude ,but , where R is the Earth's radius.

[0022] Furthermore, the filtering is a Kalman filter, and the smoothing process is a seven-point moving least squares smoothing. The Kalman filter is calculated in real time when each valid BeiDou positioning point is generated, and the seven-point moving least squares smoothing is performed on the measurement data sequence after all data acquisition for the current measurement task is completed.

[0023] Furthermore, the weighted fusion is based on Calculation, where This is the fusion coefficient.

[0024] Furthermore, the method also includes a five-segment length acquisition step: the measured length of a cable line is divided into five parts: starting length, bridge height, bridge length, bridge height, and ending length; the start and end encoder pulse values ​​of each part are acquired, and the length of each part is calculated.

[0025] In one specific embodiment, the method includes the following detailed steps:

[0026] Step 1: Read the encoder pulse count value in real time, according to the sampling period. Calculate the real-time speed of the current measuring vehicle. ;

[0027] Step 2: Determine the reading cycle of BeiDou positioning data Check if the destination has been reached. If not, return to step 1; if so, proceed to step 3.

[0028] Step 3: Read the latitude and longitude positioning data of the railway power cable line from the Beidou positioning data. ;

[0029] Step 4: Calculate and determine the valid points of the read BeiDou positioning data, first calculating the incremental BeiDou travel increment. The rules for judgment are as follows: If valid, then invalid; otherwise, then invalid, where m is the determination coefficient; the walking increment Calculate using the following formula: Let the previous point of the current BeiDou positioning data be... The current point is Latitude difference Longitude difference Average latitude ,but , where R is the Earth's radius;

[0030] Step 5: If the value is determined to be invalid, the current BeiDou reading value is discarded and the process returns to Step 1; if the value is determined to be valid, proceed to Step 6.

[0031] Step 6: Refresh the comparison point data based on valid BeiDou positioning data;

[0032] Step 7: Record the current valid location point data;

[0033] Step 8: Perform Kalman filtering on the recorded BeiDou positioning data;

[0034] Step 9: Write the filtered BeiDou positioning point data into the BeiDou positioning data queue for storage;

[0035] Step 10: Determine if the current measurement task has ended. If not, return to Step 2 and continue the loop; if it has ended, proceed to Step 11.

[0036] Step 11: Calculate the encoder length based on the cumulative encoder pulse count. ,in, This is the total number of pulses within the long period; This refers to the number of pulses per revolution of the encoder. This is the circumference of the encoder's measuring wheel;

[0037] Step 12: Based on the filtered trajectory points in the BeiDou positioning data queue, smoothing is performed using a seven-point minimum smoothing algorithm, and then the distances between adjacent points are accumulated to calculate the length of the BeiDou positioning trajectory. For the filtered trajectory point sequence : ;in, This represents the total number of points in the trajectory point sequence.

[0038] Step 13: Perform a weighted calculation on the encoder length and the BeiDou positioning trajectory length to obtain the final measured length value. ,in This is the fusion coefficient.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. This invention integrates real-time pulse ranging with BeiDou positioning ranging. Abnormal jump points in BeiDou positioning are eliminated through velocity correlation effectiveness screening. The result is then processed through two stages of filtering: Kalman filtering and seven-point moving least squares smoothing. Finally, a weighted fusion is performed to obtain the final length. Actual testing on a bumpy high-speed railway subgrade road section of approximately 2km was conducted with 100 measurements. The results were compared with the actual cable laying length after construction. The maximum comprehensive measurement error can be controlled within 2%, far exceeding the approximately 5% accuracy of traditional mechanical rangefinders and the approximately 7% accuracy of pure encoder ranging.

[0041] 2. Existing fusion solutions often require the addition of an inertial navigation unit (IMU), but the IMU will produce significant errors on dirt roads or bumpy gravel sections at railway construction sites. This invention achieves high-precision measurement through a pure software algorithm of effective point selection, two-stage filtering, and weighted fusion, without the need for additional hardware, reducing system cost and complexity, and is more adaptable to the harsh road conditions at railway construction sites.

[0042] 3. The measurement trolley terminal automatically collects, stores, and uploads data. The upper-level data management platform provides functions such as Beidou trajectory display, automatic comparison of measurement data with design documents, and deviation alarms, replacing traditional manual transcription and manual statistics using Excel, which greatly improves the efficiency and accuracy of data management.

[0043] 4. This invention is designed for the typical process of railway power cable laying. It has a five-segment length acquisition function, which includes the starting point, the bridge, the bridge section, the bridge section, and the end point. Operators can mark the segments by using a dedicated button on the touch screen. The system automatically records the start and end pulse values ​​of each segment and calculates the length separately, which simplifies on-site operation and reduces the risk of misoperation.

[0044] 5. The measurement intelligent terminal and encoder acquisition module adopt a separate dual-unit structure and can be connected by a USB interface. The encoder acquisition module can be replaced or upgraded independently, and the same measurement intelligent terminal can be adapted to different types of roller encoders, facilitating on-site maintenance. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall structure of a railway power cable line measurement system based on encoder and Beidou positioning in an embodiment of the present invention.

[0046] Figure 2 This is a schematic diagram of the hardware structure of the measurement vehicle terminal in an embodiment of the present invention.

[0047] Figure 3 This is a schematic diagram of the functional structure of the measurement system software in an embodiment of the present invention.

[0048] Figure 4 This is a flowchart illustrating the railway power cable line measurement method based on encoder and BeiDou positioning in an embodiment of the present invention. Detailed Implementation

[0049] The invention will now be described in further detail with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary and not intended to limit the scope or application of the invention.

[0050] like Figure 1 As shown in the figure, the railway power cable line measurement system based on encoder and Beidou positioning provided in this embodiment of the invention includes two parts: a host data management platform and a measurement trolley terminal. The measurement trolley terminal and the host data management platform interact with each other via a 4G network using the MQTT protocol.

[0051] The upper-level data management platform is installed in the project site office and includes a server computer, a database, a backend data management program, and a frontend management platform web application. The server computer deploys the database, the backend data management program, and the frontend management platform web application. The server computer receives data uploaded by the measurement vehicle terminal via a 4G network and stores it in the database. The backend data management program is responsible for logical calculations such as data packetization and parsing, file comparison, and alarm determination. The frontend management platform accesses the database to display, compare, and trigger alarms.

[0052] The measurement trolley terminal is used for on-site line measurement, collecting encoder data and BeiDou positioning data, and packaging, managing, and uploading the data. The upper-level data management platform is used to receive the data uploaded by the measurement trolley terminal, perform data management, analysis, comparison, alarm processing, as well as filtering, smoothing, and trajectory display of BeiDou positioning data.

[0053] The measuring vehicle terminal, comprising the measuring intelligent terminal and the encoder acquisition module, is a single unit mounted on the push rod of the roller rangefinder via a fixed bracket, moving with the roller rangefinder during use. The measuring intelligent terminal is powered by a power bank, while the encoder acquisition module is powered by two 1.5V dry batteries. In this embodiment, the measuring intelligent terminal is powered by a 12000mAh power bank, allowing for 10 hours of continuous operation. The encoder quadrature pulses can be derived from existing rangefinder products on the market, or a dedicated roller rangefinder device can be designed and manufactured.

[0054] Compared with traditional high-precision BeiDou ranging solutions, this invention does not require a high-precision BeiDou receiver, significantly reducing costs, while the overall error can be controlled within 2%, combining advantages in both accuracy and cost.

[0055] like Figure 2 As shown, the measurement vehicle terminal includes two independent housing units: a measurement intelligent terminal and an encoder acquisition module, which are connected via a USB interface.

[0056] The measurement intelligent terminal includes: MT6789 Android core board, 8-inch touch screen, 4G module, Beidou positioning module, power management unit, speaker output unit, USB2.0 module and user control unit.

[0057] The MT6789 Android core board serves as the main control unit, running the Android operating system, processing data, and controlling peripherals. An 8-inch touchscreen, the human-machine interface unit, is electrically connected to the MT6789 core board via a MIPI-DSI interface, enabling display and touch operation. The 4G module, including a 4G antenna and peripheral circuitry, connects to the MT6789 Android core board, providing 4G mobile communication services. The BeiDou positioning module, including a BeiDou antenna and peripheral circuitry, is electrically connected to the MT6789 Android core board, providing BeiDou satellite positioning functionality. The power management unit, including the MT6359 power management chip and RTC module, is electrically connected to the MT6789 Android core board via an SPI interface, providing power management, voltage regulation, and real-time clock functions for the terminal. The USB 2.0 module includes a USB 2.0 interface, one end connected to the MT6789 Android core board, and the other end can connect to an external USB flash drive or an encoder acquisition module. The speaker output unit is the audio output module, connected to the MT6789 Android core board, enabling audio playback and prompt functions. The user control unit, which includes power and screen-off control buttons, connects to the MT6789 Android core board to control the terminal's power on / off, screen off, and wake-up. The measurement smart terminal receives external 5V power through its USB Type-C interface, which is then converted by the power management unit MT6359 into the voltage required by each module before supplying power.

[0058] The encoder acquisition module includes an STM32F103R8T6 microcontroller, a USB interface conversion chip, and an encoder pulse interface. In this embodiment, the USB interface conversion chip is an FT232RL chip.

[0059] The encoder pulse interface is a 4-wire system defined as: 3.3V, A phase, B phase, and GND. It connects to the output of the roller encoder, which outputs quadrature pulse signals. The STM32F103R8T6 microcontroller's TIM1 channel and PA8 and PA9 pins are connected to the A and B phase signals of the encoder pulse interface, respectively, to acquire and process the encoder pulse signals. The 90° phase difference between the A and B phases determines the forward and reverse rotation direction of the roller, and the acquired data is then uploaded to the MT6789 Android core board via serial port. The STM32F103R8T6 microcontroller's UART interface is connected to the corresponding pins of the FT232RL chip. In the STM32F103R8T6's UART interface, TX connects to PA2, and RX connects to PA3. The FT232RL chip connects to the USB 2.0 interface of the measurement intelligent terminal via a USB interface.

[0060] like Figure 3As shown, the upper-level data management platform is used for data visualization, data comparison and alarm, and data file management. The intelligent terminal APP of the measuring vehicle is used for the collection and processing of length and Beidou positioning data, data packaging and transmission, fusion processing of Beidou trajectory data and encoder, and calculation of the cable laying length value that meets the measurement expectations.

[0061] The upper-level data management platform, as upper-level software, includes modules such as BeiDou trajectory display, measurement data display, design document comparison, alarm display, user management, smart terminal management, measurement data editing, comparison alarm settings, design document import, result file export, MQTT data parsing, and database management. The system includes several modules: a BeiDou trajectory display module, which displays the measurement trajectory of the surveying vehicle on a map after data parsing based on BeiDou positioning data uploaded by the vehicle terminal; a measurement data display module, which divides the segment length data uploaded by the vehicle terminal into five parts—starting point length, bridge height, bridge length, bridge height, and ending point length—and visualizes these five segments using curves; a design file comparison module, which automatically compares the actual measurement data with the imported design files, identifies deviations, and performs comparisons on each of the five segments while displaying them on the curves; an alarm display module, which centrally displays and alerts users to alarms such as deviation exceeding thresholds and equipment malfunctions during the comparison of actual measurement data with the imported design files; a user management module, which has two permissions—highest-level administrator and operator—to manage platform user accounts, permissions, parameters, and operation logs; and a smart terminal management module, which enables multi-terminal management. The platform includes: an online status monitoring, configuration distribution, and remote management module for the intelligent terminal of the surveying vehicle; a measurement data editing module that supports manual correction, annotation, and supplementation of stored measurement data; a comparison alarm setting module that allows for customizable deviation thresholds, triggering an alarm when the deviation between actual measurement data and design data exceeds the threshold; a design file import module that imports preset route design files by reading Excel spreadsheets for comparison with actual measurement data; a result file export module that exports measurement results, comparison reports, and trajectory data as standard Excel format files; an MQTT data parsing module that receives and parses MQTT data packets uploaded by the intelligent terminal of the surveying vehicle, extracting length measurement data and BeiDou positioning data; and a database management module that stores all business data, including user information, terminal information, measurement data, design files, and alarm records, providing data support for all functional modules of the platform.

[0062] The measurement trolley's intelligent terminal APP, as the lower-level software, is deployed on the Android system of the measurement intelligent terminal. It includes modules such as five-segment length acquisition, bus line management, MQTT data upload, length file packaging and management, Beidou file packaging and management, encoder pulse acquisition, Beidou positioning data acquisition, and Beidou positioning data smoothing.

[0063] The bus line management module obtains bus information from the upper-level data management platform. This information includes the unit project, cable specifications, loop type, and loop name, and is used to manage data ownership during the measurement process. The MQTT data upload module uploads the processed length data and BeiDou positioning data files to the upper-level data management platform via the MQTT protocol. The length file packaging and management module packages and stores the collected length measurement data according to a preset format. The BeiDou file packaging and management module packages and stores the BeiDou positioning data according to a preset format. The encoder pulse acquisition module acquires the pulse signals output by the encoder to achieve length data acquisition and calculation. The BeiDou positioning data acquisition module acquires the raw positioning data output by the BeiDou positioning module. The BeiDou positioning data smoothing module fuses with the encoder data, performing filtering, smoothing, and filtering on the acquired BeiDou positioning data to improve the continuity and accuracy of the positioning trajectory.

[0064] The specific operation for collecting five length segments is as follows: Bus information refers to the name and information of the entire railway line, while segment information refers to the name and information of a specific segment within the bus. A segment is divided into five parts: start point, on-bridge section, on-bridge section, off-bridge section, and end point. During measurement, the operator selects five virtual buttons on the touchscreen, labeled "Start Point," "On-Bridge Section," "On-Bridge Section," "Off-Bridge Section," and "End Point." First, select the bus information and segment information, then click "Start" to begin the measurement task for that segment. After starting the measurement, clicking any button begins the length measurement of the corresponding section. Clicking another button saves the current section's length record and begins the measurement of a new section. Clicking the "End" button ends the segment measurement. Measurement data is stored in CSV file format on the measurement smart terminal's FLASH memory, recording five independent start and end pulse values ​​and calculating the length information for storage. During 4G upload, the saved CSV file is read, and the data is split into frames and uploaded to the upper-level data management platform.

[0065] Typical operating procedure example: The operator moves the roller encoder along the railway power cable path, starts the measurement smart terminal APP, selects the bus information and section information, and clicks "Start" to begin measurement. The operator sequentially clicks the "Start Point," "On Bridge," "On Bridge," "Off Bridge," and "End Point" buttons to mark segments, and the system automatically records the start and end pulse values ​​for each segment. After measurement, clicking "End" calculates the length of each segment and stores the data as a CSV file, which is then uploaded to the upper-level data management platform via a 4G module using the MQTT protocol. Upon receiving the data, the upper-level platform displays the BeiDou trajectory and measurement data, automatically compares it with the design documents, and issues a red alarm when the deviation exceeds the threshold.

[0066] In the upper-level data management platform, the specific logic for comparing design documents is as follows: The design document is an Excel spreadsheet containing information such as bus name, segment name, segment notes, up / down route, start point, upper bridge, bridge on, lower bridge, end point, and magnification factor. During comparison, a deviation threshold for each part is set via a web interface, typically set to 20 meters. The five parts of the measured length data are compared with the corresponding parts of the design document, and any deviation exceeding the threshold is marked in red with an alarm.

[0067] like Figure 4 As shown, the railway power cable line measurement method based on encoder and Beidou positioning in this embodiment includes the following detailed steps:

[0068] Step 1: Read the encoder pulse count value in real time, according to the sampling period. Calculate the real-time speed of the current measuring vehicle. .

[0069] Let the number of pulses per revolution of the encoder be... The circumference of the measuring wheel is , The difference in the number of pulses between the two samples. The relationship between the number of pulses and the displacement is as follows: The formula for calculating real-time speed is: In this embodiment, , , The 100ms sampling period is determined based on the following: a human walking speed is 0.8~1.1m / s, the roller encoder's roller rotates 1000mm per revolution, with 120 pulses per revolution, resulting in a resolution of approximately 8.33mm. When a human walking speed is 1m / s, the walking increment within a 100ms sampling period is approximately 100mm, and the overall length error is on the order of meters. Since the walking increment within the sampling period is less than the overall length error, the sampling requirements are met, and the sampling cost is minimized.

[0070] Step 2: Determine the BeiDou positioning data reading cycle Has the speed been reached? If not, return to step 1 to continue reading the encoder value and calculating the real-time speed; if reached, proceed to step 3. In this embodiment, The basis for determining the BeiDou reading cycle of 200ms is as follows: the overall length error is on the order of meters, and the travel distance in 200ms is about 200mm. Discretizing the position information into discrete points of about 200mm helps to filter effective BeiDou points and meet the requirements of the data volume.

[0071] Step 3: Read the latitude and longitude positioning data output by the Beidou module .

[0072] Step 4: Calculate and determine valid points from the read BeiDou positioning data. First, calculate the incremental BeiDou navigation increment. The rules for judgment are as follows: If valid, then invalid; the walking increment Calculate using the following formula: Let the previous point of the current BeiDou positioning data be... The current point is Latitude difference Longitude difference Average latitude ,but Where R is the Earth's radius, R≈6371000m. The determination coefficient m=1.2. The value of m=1.2 is based on: the range of the next BeiDou point generated is estimated according to the encoder's walking speed, and the maximum error in the walking speed calculation is 5%; the acceptable error range for BeiDou positioning is 15%, therefore m=1.2 is chosen. BeiDou data exceeding this range is considered to have a large deviation and is discarded.

[0073] Step 5: If the value is determined to be invalid, the current BeiDou reading value is removed and the process returns to Step 1; if the value is determined to be valid, proceed to Step 6.

[0074] Step 6: Refresh the comparison point data based on valid BeiDou positioning data.

[0075] Step 7: Record the current valid location point data.

[0076] Step 8: Perform Kalman filtering on the recorded BeiDou positioning data. The Kalman filter is calculated in real time when each valid BeiDou positioning point is generated, and the filtered point value at that time is obtained and stored in the measurement data sequence.

[0077] The Kalman filter configuration is as follows:

[0078] 1) Define k as the current BeiDou sampling frame number, and the BeiDou positioning data reading cycle. Construct a four-dimensional state vector ,in Let k be the planar coordinates of point k relative to the starting point. Speed ​​is measured on the horizontal and vertical axes.

[0079] 2) State transition equation: State transition matrix , It is noise during the walking process, and its covariance matrix is .

[0080] 3) Observation equation: Observation vector The observation matrix represents the transformed planar coordinate observations. , For BeiDou measurement noise, the covariance matrix is: .

[0081] 4) Process noise covariance ,in As the acceleration noise reference, the value is taken as follows. Measure noise covariance ,in .

[0082] Step 9: Write the filtered BeiDou positioning point data into the BeiDou positioning data queue for storage.

[0083] Step 10: Determine if the current measurement task has ended. If not, return to Step 2 and continue the loop; if ended, proceed to Step 11. The measurement task ends when the "End" button on the touchscreen is clicked, generating an end signal.

[0084] Step 11: Calculate the encoder length based on the cumulative encoder pulse count. .in This is the total number of pulses within the long period.

[0085] Step 12: Based on the filtered trajectory points in the BeiDou positioning data queue, smoothing is performed using a seven-point moving least squares smoothing algorithm, with a smoothing weight array. Then, the distances between adjacent points are accumulated to calculate the length of the BeiDou positioning trajectory. For the filtered trajectory point sequence The calculation formula is: , where n is the total number of points in the trajectory point sequence.

[0086] Considering the computing power of the measurement smart terminal and the over-smoothing problem that cubic spline smoothing can cause in long-distance data, the calculated curve length is more than 10% greater than the actual measured value. The 5-point smoothing algorithm has individual sharp data that affect the overall length value. The 7-point smoothing algorithm has strong robustness in terms of path shape preservation and computational efficiency.

[0087] Kalman filtering is calculated in real time when each valid point is generated, and the filtered point value is stored in the measurement data sequence. After all the measurement data in the segment is completed, the seven-point moving least squares smoothing algorithm is used to smooth the entire data sequence.

[0088] Step 13: Perform a weighted calculation on the encoder length and the BeiDou positioning trajectory length to obtain the final measured length value. , where the fusion coefficient .

[0089] Based on a high degree of trust in the encoder measurements using the rollers, actual test data shows that the encoder's measured length generally deviates from the actual length by 3% to 5%. After data smoothing and discrete point linear fitting, the calculated length from BeiDou data is often smaller than the actual length, with errors reaching 10% to 15%. Based on long-term comparisons of measured data and actual cable length values... A range of 0.89 to 0.92 is suitable. To ensure that the measured length data has a slight margin compared to the actual cable length, 0.91 is chosen in this invention.

[0090] The measurement accuracy of this invention was verified through field testing. The test conditions were as follows: on a bumpy road surface of a high-speed railway subgrade, a test section of approximately 2 km was selected, and 100 measurements were performed. The measurement results were then compared with the actual cable length laid out after construction. The test results show that the maximum comprehensive measurement error can be controlled within 2%, which is far superior to the approximately 5% accuracy of traditional mechanical distance measuring instruments and the approximately 7% accuracy of pure encoder distance measurement.

[0091] This invention integrates BeiDou trajectory data with an encoder, and the algorithm does not rely on an inertial navigation unit (IMU). Inertial navigation units determine the attitude and motion of a moving vehicle through velocity and angular velocity. (However, on dirt roads or bumpy sections with stones at railway construction sites, IMUs can cause significant errors, making them unsuitable for the application scenarios of this invention.) This invention upgrades existing construction methods through digitalization and informatization. Actual measurements show that the error of a pure encoder is approximately 5%, while the overall error is reduced to less than 2% after incorporating BeiDou positioning data.

[0092] The measurement intelligent terminal uses a soft timer to count in milliseconds. The encoder pulse data and BeiDou positioning data are synchronized within this timer to generate a time period. When acquiring BeiDou data, the encoder count value is also acquired simultaneously.

[0093] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A railway power cable line measurement system based on encoder and Beidou positioning, characterized in that, include: The system includes a host data management platform and a measuring trolley terminal. The measuring trolley terminal is installed on a railway power cable line measuring trolley, and the measuring trolley is equipped with an encoder for collecting pulse signals during the movement of the measuring trolley. The measurement vehicle terminal includes a measurement intelligent terminal and an encoder acquisition module; The measurement intelligent terminal includes at least a control board, a Beidou positioning module, and a communication module. The Beidou positioning module is connected to the control board, and the measurement intelligent terminal communicates with the upper-level data management platform through the communication module. The encoder acquisition module includes at least a microcontroller, an interface conversion chip, and an encoder pulse interface; The encoder pulse interface is used to connect to the output end of the encoder. The input end of the microcontroller is connected to the encoder pulse interface to acquire encoder pulse signals. The output end of the microcontroller is connected to the interface conversion chip. The interface conversion chip is connected to the measurement intelligent terminal through a data transmission interface.

2. The railway power cable line measurement system based on encoder and Beidou positioning as described in claim 1, characterized in that: The control board includes an Android core board and a touch screen. The communication module is a 4G module. The touch screen is electrically connected to the Android core board, and the Beidou positioning module is electrically connected to the Android core board. The data transmission interface is a USB interface, and the interface conversion chip is a USB interface conversion chip. The USB interface conversion chip is connected to the measurement smart terminal through the USB interface, and the 4G module is connected to the Android core board.

3. The railway power cable line measurement system based on encoder and Beidou positioning as described in claim 2, characterized in that: The microcontroller is an STM32F103R8T6, and the USB interface conversion chip is an FT232RL. The TIM1 channel and PA8 and PA9 pins of the STM32F103R8T6 are connected to the A-phase and B-phase signals of the encoder pulse interface, which are used to determine the forward and reverse rotation direction of the roller by the 90° phase difference between the A and B phases. The UART interface of the STM32F103R8T6 is connected to the FT232RL chip.

4. The railway power cable line measurement system based on encoder and Beidou positioning as described in claim 2, characterized in that: The measurement intelligent terminal also includes a power management unit MT6359, which is connected to the Android core board via an SPI interface; the touch screen is connected to the Android core board via a MIPI-DSI interface; and the Beidou positioning module is connected to the Android core board via a UART interface.

5. A method for measuring railway power cable lines based on encoders and BeiDou positioning, characterized in that, The measurement system as described in any one of claims 1-4 includes the following steps: The system acquires pulse data collected in real time by the encoder during the movement of the measuring trolley, as well as latitude and longitude positioning data collected in real time by the Beidou positioning module. The real-time speed of the measuring trolley and the cumulative length measured by the encoder are calculated based on the encoder pulse data. The BeiDou positioning data is filtered for validity using the real-time speed, and invalid positioning points are removed. The filtered valid BeiDou positioning data are sequentially subjected to Kalman filtering and seven-point moving least squares smoothing to obtain the smoothed BeiDou positioning trajectory. The length of the BeiDou positioning trajectory is calculated based on the smoothed BeiDou positioning trajectory. The cumulative length measured by the encoder is weighted and fused with the length measured by the Beidou positioning trajectory to obtain the final measured length of the cable line.

6. The railway power cable line measurement method based on encoder and Beidou positioning as described in claim 5, characterized in that: The validity screening includes: calculating the theoretical maximum displacement based on the real-time velocity V, the BeiDou positioning data reading period T, and the judgment coefficient m. If the current BeiDou positioning data corresponds to the walking increment If the displacement is less than the theoretical maximum displacement, it is considered valid; the walking increment Calculate using the following formula: Let the previous point of the current BeiDou positioning data be... The current point is Latitude difference Longitude difference average latitude ,but , where R is the Earth's radius.

7. The railway power cable line measurement method based on encoder and Beidou positioning as described in claim 5, characterized in that: The filtering is Kalman filtering, and the smoothing process is seven-point moving least squares smoothing. The Kalman filtering is calculated in real time when each valid BeiDou positioning point is generated. After all data acquisition for the current measurement task is completed, the seven-point moving least squares smoothing is then performed on the measurement data sequence.

8. The railway power cable line measurement method based on encoder and Beidou positioning as described in claim 5, characterized in that: The weighted fusion is according to Calculation, where This is the fusion coefficient.

9. The railway power cable line measurement method based on encoder and Beidou positioning as described in claim 5, characterized in that: It also includes five length acquisition steps: the measured length of a cable line is divided into five parts: starting length, bridge height, bridge length, bridge height, and ending length. The start and end encoder pulse values ​​of each part are collected, and the length of each part is calculated.

10. The railway power cable line measurement method based on encoder and Beidou positioning as described in claim 5, characterized in that, Specifically, the following steps are included: Step 1: Read the encoder pulse count value in real time, according to the sampling period. Calculate the real-time speed of the current measuring vehicle. ; Step 2: Determine the reading cycle of BeiDou positioning data Check if the destination has been reached. If not, return to step 1; if so, proceed to step 3. Step 3: Read the latitude and longitude positioning data of the railway power cable line from the Beidou positioning data. ; Step 4: Calculate and determine the valid points of the read BeiDou positioning data, first calculating the incremental BeiDou travel increment. The rules for judgment are as follows: If valid, then invalid; otherwise, then invalid, where m is the determination coefficient; the walking increment Calculate using the following formula: Let the previous point of the current BeiDou positioning data be... The current point is Latitude difference Longitude difference average latitude ,but , where R is the Earth's radius; Step 5: If the value is determined to be invalid, the current BeiDou reading value is discarded and the process returns to Step 1; if the value is determined to be valid, proceed to Step 6. Step 6: Refresh the comparison point data based on valid BeiDou positioning data; Step 7: Record the current valid location point data; Step 8: Perform Kalman filtering on the recorded BeiDou positioning data; Step 9: Write the filtered BeiDou positioning point data into the BeiDou positioning data queue for storage; Step 10: Determine if the current measurement task has ended. If not, return to Step 2 and continue the loop; if it has ended, proceed to Step 11. Step 11: Calculate the encoder length based on the cumulative encoder pulse count. ,in, This is the total number of pulses within the long period; This refers to the number of pulses per revolution of the encoder. This is the circumference of the encoder's measuring wheel; Step 12: Based on the filtered trajectory points in the BeiDou positioning data queue, smoothing is performed using a seven-point minimum smoothing algorithm, and then the distances between adjacent points are accumulated to calculate the length of the BeiDou positioning trajectory. For the filtered trajectory point sequence : ;in, This represents the total number of points in the trajectory point sequence. Step 13: Perform a weighted calculation on the encoder length and the BeiDou positioning trajectory length to obtain the final measured length value. ,in This is the fusion coefficient.

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