A passive digital tag system based on Beidou and radio frequency identification technology

Abstract

The application provides a passive digital tag system based on Beidou and radio frequency identification technology, which comprises a radio frequency electronic tag, an RFID reader module, a GPRS communication module, an embedded processor and a background server, node information is written in the radio frequency electronic tag in advance, the radio frequency electronic tag stores underground pipe gallery information in a built-in chip to form an information storage database, a GPS-RTK differential positioning algorithm runs in the Beidou positioning module to realize real-time dynamic positioning of the radio frequency electronic tag, and the coordinate information of the radio frequency electronic tag is stored in the database to establish an underground pipe gallery direction electronic map, and a GIS map system is installed in the background server. The application can solve the defects of traditional tags, such as visible information identification, manual reading and small amount of information, solve the problems of traditional identification modes, such as sparse distribution, easy loss and displacement, and solve the problems of traditional identification methods, such as inaccurate positioning of the direction of buried underground pipes and cables and the inability to synchronously record underground pipe and cable information updates.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underground pipeline operation and maintenance management, in particular to a passive digital tag system based on Beidou and radio frequency identification technology. BACKGROUND

[0002] In recent years, in order to meet the requirements of urban construction and environmental beautification, more and more pipeline routes are constructed in the form of underground pipe galleries. The proportion of underground comprehensive pipe galleries in energy transmission and distribution systems is increasing, and the scale is growing rapidly. However, during the service process, they are often damaged by external forces, and faults occur frequently. The type, location and time are difficult to predict, and the safety and reliability of underground pipe galleries are seriously affected. Therefore, it is urgent to protect underground pipelines from external damage. However, the current pipeline channel path indication mainly relies on electronic piles and traditional plastic hanging tag labels erected on the ground for identification. However, these methods have the problems of sparse distribution, displacement, easy blurring and easy loss, and cannot accurately describe the real-time position of the pipeline, so as to ensure the safety of the line. They do not have the function of storing equipment operation and maintenance information, which is contrary to the development direction of energy transportation intelligence. The traditional operation and maintenance technology cannot effectively match the growth rate of energy infrastructure, which puts a lot of pressure on pipeline channel operation and maintenance work. At the same time, the auxiliary equipment of underground pipelines (such as underground cable distribution boxes and ring network cabinets) is at risk of being stolen, so it is of great significance to develop a digital tag to real-time locate the position of underground pipelines and their auxiliary equipment and store and read information. Domestic and foreign research institutions and enterprises have also studied in this regard, but still have the following shortcomings:

[0003] 1. The main problem of radio method is that the identifiable material is single, it cannot identify and analyze multiple underground cables at the same time, the fault tolerance is low, the background signal interference is strong, and the signal cannot penetrate high-conductivity materials.

[0004] 2. The principle of ground penetrating radar technology is to use an antenna to emit high-frequency pulse electromagnetic waves to the detection target. The pulse produces a return wave on the interface. By analyzing the radar waveform, the position and depth of the buried underground cable fault can be analyzed. However, this method cannot distinguish the overlapping situation of multiple underground cables at the same depth, and the equipment cost is high, and the professional skill requirement of technical personnel is high. Only the ground penetrating radar technology is not enough to complete the effective identification of the buried underground cable path. SUMMARY

[0005] The purpose of the present application is to provide a passive digital tag system based on Beidou and radio frequency identification technology, which mainly solves the following problems: solving the defects of traditional tags that can only be identified by visible information, manual reading and small amount of information; solving the problems of sparse distribution, easy loss and displacement of traditional identification methods; solving the problems of inaccurate positioning of buried underground cable direction and inability to record underground cable information updates synchronously.

[0006] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0007] A passive digital tag system based on Beidou and radio frequency identification technology, comprising:

[0008] The radio frequency electronic tag is installed in the monitored node, and the node information is pre-written in the radio frequency electronic tag. The radio frequency electronic tag stores information such as the location of the underground pipe gallery and the operation information of the underground pipe gallery in its built-in chip to constitute an underground pipe gallery information storage database.

[0009] The RFID reader module is used to transmit and receive radio frequency signals corresponding to the radio frequency electronic tag, realize radio frequency electronic tag information acquisition and modification.

[0010] The Beidou positioning module runs the GPS-RTK differential positioning algorithm to realize real-time dynamic positioning of the radio frequency electronic tag, and stores the coordinate information of the radio frequency electronic tag into the database to establish an underground pipe gallery direction electronic map.

[0011] The GPRS communication module realizes real-time data communication between multiple electronic tags and between the electronic tag and the background server through the MQTT protocol.

[0012] The embedded processor obtains the location information of the radio frequency electronic tag through the Beidou positioning module or the GPRS communication module, reports to the data receiving processing system through the communication module, receives the location information and device information reported by the monitored node by the data receiving processing system, and processes and displays the data.

[0013] The power management module is used to provide power for the entire passive digital tag system.

[0014] The background server is installed with a GIS map system, and the coordinate information of the radio frequency electronic tag is marked on the GIS map system. The GIS map system and the underground pipe gallery information storage database in the background server are remotely accessed by scanning the radio frequency electronic tag.

[0015] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, wherein the Beidou positioning module comprises a GNSS module, an RTK differential positioning unit, a positioning antenna, a DTU-4G data transparent transmission module, a 4G antenna and an RS232 / TTL protocol conversion module; the positioning antenna is used for receiving satellite signals and transmitting the satellite signals to the GNSS module; the GNSS module is used for acquiring GNSS positioning information, speed information and heading information in real time after receiving the satellite signals, and transmitting the GNSS positioning information, speed information and heading information to the RTK differential positioning unit in a redundant backup transmission mode through a high-speed serial port and an Ethernet; the RTK differential positioning unit is connected with an embedded processor; the embedded processor is connected with the DTU-4G data transparent transmission module through the RS232 / TTL protocol conversion module, and transmits coordinate information to a background server through the 4G antenna.

[0016] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, wherein the following steps are performed in the RTK differential positioning unit:

[0017] The reference station with known coordinates sends carrier phase observation values, the own position and observation error factors and the like to the background server through a 4G network, and the mobile station acquires error factors from the background server in real time through the DTU-4G data transparent transmission module; the mobile station corrects the carrier phase in real time by performing differential solution on the received observation data of the reference station, the real-time error values and the GNSS observation values collected by the mobile station, so that the centimeter-level positioning accuracy value of the mobile station is obtained.

[0018] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, wherein the phase difference between the star stations comprises: a starting integer ambiguity, an integer change value from a starting time to an observation time, and a decimal part of an observation phase; the distance between the star stations is the product of a carrier wavelength and the phase difference between the star stations; the real distance between the star stations, a pseudo-range observation value between the star stations and a pseudo-range correction number are obtained by using known coordinates and satellite ephemeris at the reference station, and the pseudo-range observation value of the user station is modified by using the correction number.

[0019] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, wherein if the satellite tracking does not lose lock in the observation process, the difference between the starting integer numbers is a constant, and the difference between the clock differences of the two receivers, the difference between the noises and the difference between the multipath effects between the two stations are all less than the allowable error of the cm-level dynamic positioning, and the carrier phase measurement difference can also be regarded as a constant in the solving process.

[0020] Therefore, the starting integer number is determined, and the positioning of the mobile station can be realized by simultaneously observing the same four satellites at the reference station and the mobile station, wherein the integer number is calculated by using a related ambiguity algorithm.

[0021] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, when an RFID reader module is used, the propagation time of a signal emitted by an RFID reader to a radio frequency electronic tag and then returned to the RFID reader is obtained, the distance from the radio frequency electronic tag to the RFID reader is obtained from the propagation time, wherein, at least three RFID readers are needed to realize positioning of the radio frequency electronic tag, the distances from the three RFID readers to the radio frequency electronic tag are r1, r2 and r3 respectively, three circles are drawn with each of the RFID readers as the center and the measured distances as the radii, and the intersection of the circles is the position of the electronic tag, and the least square algorithm is used to estimate the position information of the radio frequency electronic tag.

[0022] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, when an RFID reader module is used, the propagation time of a signal emitted by an RFID reader to a radio frequency electronic tag and then returned to the RFID reader is obtained, the distance from the radio frequency electronic tag to the RFID reader is obtained from the propagation time, wherein, at least three RFID readers are needed to realize positioning of the radio frequency electronic tag, the distances from the three RFID readers to the radio frequency electronic tag are r1, r2 and r3 respectively, three circles are drawn with each of the RFID readers as the center and the measured distances as the radii, and the intersection of the circles is the position of the electronic tag, and the least square algorithm is used to estimate the position information of the radio frequency electronic tag.

[0023] Serial port configuration of related modules is performed, timer configuration is performed, interrupt serial port configuration is performed, whether the serial port configuration of the first Beidou positioning module is interrupted is judged, if yes, data transmission and reception are performed;

[0024] If not, whether the serial port configuration of the second Beidou positioning module is interrupted is judged, if yes, positioning data and UTC time are obtained, and the screen is refreshed;

[0025] If the serial port configuration of the second Beidou positioning module is not interrupted, whether the serial port configuration of the GPRS communication module is interrupted is judged, if yes, data transmission and reception are performed, and a heartbeat signal is sent to the outside;

[0026] If the serial port configuration of the GPRS communication module is not interrupted, whether the first timing time is reached is judged, if yes, whether the heartbeat counter is greater than 5 is judged, if yes, the line is dropped and reconnected;

[0027] If the second timing time is reached, the information of the radio frequency electronic tag is read, and the read information is uploaded to a background server.

[0028] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, a background server uses a B / S architecture, the port thereof is opened to a public network, a TCP / IP protocol server is created, and the NIO technology is used to improve the concurrent performance of software, the background server website can be accessed through a browser, and then the position condition of a node can be seen; after receiving information, error checking and conversion are performed, the received node ID and longitude and latitude information are saved to an underground pipe gallery information database.

[0029] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, and the RFID reader module comprises an RFID reader, the RFID reader comprises an RFID transmitting circuit, an RFID receiving circuit and an RFID power supply circuit, the RFID transmitting circuit drives a push-pull circuit after the driving signal sent by an embedded processor is shaped by a logic circuit, and then transmits radio signals to the outside through an antenna, the RFID receiving circuit amplifies the received signals through a receiving circuit and a differential amplification circuit, and then transmits the amplified signals to the embedded processor for processing after the signals are amplified by an operational amplifier, and the RFID power supply circuit mainly raises the 5V voltage to the voltage of 24V through a transformer to drive the MOS tube of the RFID transmitting circuit to transmit radio signals.

[0030] The application provides a passive digital tag system based on Beidou and radio frequency identification technology, and when the mobile station is positioned, the known coordinates of the reference station and the three-point circle positioning principle are used to obtain the parameter description of the absolute position of the circular trajectory according to the effective measurement results of the relative positioning of the satellite navigation receiver of the mobile station at multiple points on the preset circular trajectory.

[0031] The satellite navigation receiver of the mobile station moves along the circular trajectory at a preset speed, the ephemeris file and the observation data file are obtained by analyzing the received signals of the satellite navigation receiver of the mobile station, and the available observation data are obtained after the coarse error and cycle slip are inspected.

[0032] The station-to-station inter-satellite carrier phase double-difference ambiguity and the sine value and the cosine value of the relative trajectory circle center yaw angle of the mobile station are used as unknown numbers, the station-to-station inter-satellite pseudo-range double-difference equation and the station-to-station inter-satellite carrier phase double-difference equation between the mobile station and the reference station are established according to the constraint of the circular motion trajectory, and the floating-point ambiguity and the floating-point positioning solution are obtained.

[0033] The floating-point ambiguity is fixed to obtain the integer ambiguity solution, the carrier phase double-difference equation about the relative position vector from the reference station to the mobile station is established according to the integer ambiguity solution.

[0034] The accurate position data of the mobile station are calculated according to the effective fixed solution obtained from the carrier phase double-difference equation and the circular trajectory, and the measurement error of the satellite navigation receiver of the mobile station is calculated according to the observation data of the mobile station, the corresponding accurate position data and the position of the satellite at the corresponding moment.

[0035] Therefore, compared with the prior art, the application is a passive digital tag system with buried underground cable accurate positioning and identification function based on Beidou navigation technology, which realizes long-term operation of the tag by using solar power supply or electric pile power supply, configures a wireless electronic tag reading device system, establishes a virtual digital model of the underground cable line, can realize informationization and digitization of the underground cable, forms a visual system platform, has all-day and real-time monitoring and control capability, can quickly and accurately judge the underground cable path, and can also reduce the technical requirements of manual path identification and improve the timeliness of preventing external force damage, has the advantages of large transmission range, non-line-of-sight, high precision, low system cost and the like, and has high practicality, feasibility and generalization.

[0036] The application will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a principle diagram of an embodiment of the passive digital tag system based on Beidou and radio frequency identification technology.

[0038] Figure 2 is a principle diagram of an RFID reader module in the embodiment of the passive digital tag system based on Beidou and radio frequency identification technology.

[0039] Figure 3 is a flow principle diagram of a GPS-RTK differential positioning algorithm in the embodiment of the passive digital tag system based on Beidou and radio frequency identification technology.

[0040] Figure 4 is a flow principle diagram of an interrupt and precise timing for quick response when data is reported in the embodiment of the passive digital tag system based on Beidou and radio frequency identification technology. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme of the application will be described clearly and completely below in conjunction with the drawings in the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0042] The embodiment is a passive digital tag system based on Beidou and radio frequency identification technology (RFID), important nodes of underground pipe galleries are equipped with digital tags, solar power or electric pile power supply is used to realize long-term operation of the tags, Beidou coordinate positioning technology is combined to realize outdoor positioning, GPS-RTK differential positioning technology is used, and the buried depth of the pipe gallery (about 0.7M to 1M) measured during the burying is combined to obtain three-dimensional coordinate information of important nodes of the underground pipe gallery, and a virtual electronic map showing the line direction of the underground pipe gallery is established.

[0043] The underground pipe cable of the embodiment can be a cable, an optical fiber, a communication cable, a pipeline (a gas pipeline, a reclaimed water pipeline and a heating pipeline, etc.), and the like, including but not limited to underground pipelines such as power, communication, broadcast television, water supply, drainage, heat and gas.

[0044] As shown in Figure 1 The present application provides a passive digital tag system based on Beidou and radio frequency identification technology, which comprises:

[0045] The radio frequency electronic tag is installed in the monitored node, and the node information is pre-written in the radio frequency electronic tag. The radio frequency electronic tag stores information such as the location of the underground pipe gallery and the operation information of the underground pipe gallery in the built-in chip to constitute an underground pipe gallery information storage database.

[0046] The RFID reader module is used for transmitting and receiving radio frequency signals corresponding to the radio frequency electronic tag to realize information collection and modification of the radio frequency electronic tag.

[0047] The Beidou positioning module runs the GPS-RTK differential positioning algorithm to realize real-time dynamic positioning of the radio frequency electronic tag, and stores the coordinate information of the radio frequency electronic tag into the database to establish an underground pipe gallery direction electronic map.

[0048] The GPRS communication module realizes real-time data communication between multiple electronic tags and between the electronic tag and the background server through the MQTT protocol, and ensures stable data transmission.

[0049] The embedded processor obtains the position information of the radio frequency electronic tag through the Beidou positioning module or the GPRS communication module, and reports to the data receiving processing system through the communication module. The data receiving processing system receives the position information and device information reported by the monitored node, and processes and displays the data.

[0050] The power management module is used for providing power supply for the whole passive digital tag system. The power module uses a large-capacity and high-power lithium battery for power supply.

[0051] The background server is internally installed with a GIS map system, and the coordinate information of the radio frequency electronic tag is marked on the GIS map system, and the GIS map system and the underground pipe gallery information storage database in the background server are remotely accessed by scanning the radio frequency electronic tag.

[0052] In the embodiment, the Beidou positioning module includes a GNSS module, an RTK differential positioning unit, a positioning antenna, a DTU-4G data transparent transmission module, a 4G antenna, and an RS232 / TTL protocol conversion module. The positioning antenna is used to receive satellite signals and transmit them to the GNSS module. After receiving the satellite signals, the GNSS module analyzes and obtains GNSS positioning information, speed information, and heading information in real time, and sends them to the RTK differential positioning unit through a high-speed serial port and an Ethernet redundant backup transmission mode. The RTK differential positioning unit is connected to the embedded processor, and the embedded processor is connected to the DTU-4G data transparent transmission module through the RS232 / TTL protocol conversion module, and the coordinate information is transmitted to the background server through the 4G antenna.

[0053] As can be seen, the system uses STM32F103RCT6 as the main control chip, obtains the coordinate information of the observation point through the GNSS module and the positioning antenna of Zhongke Microelectronics, processes it through the main control chip, connects it to the DTU4G transparent module through the RS232 / TTL protocol conversion module, and finally transmits the coordinate information to the public network through the 4G antenna.

[0054] For the visualization, informatization, and digital management and control of underground pipe galleries, the embodiment realizes the fusion of the digital tag system and the GIS geographic information system, integrates the functions of the two systems, and enables the GIS system to display the real-time position information about the underground cables obtained by the Beidou module in the form of an electronic map, and integrate it into the RFID tag information database to create digital labels for underground cables, and realize the visualization, informatization, and digital management and control of underground cable equipment.

[0055] The algorithm part of the embodiment includes a ranging RFID positioning algorithm, a Beidou high-precision positioning-static relative positioning algorithm, and a GPS-RTK differential technology for optimization.

[0056] Since static relative positioning requires long-time stationary observation, it limits the application of this method in dynamic positioning. Therefore, the RTK real-time dynamic positioning technology is used in the Beidou positioning module, so that the following is performed in the RTK differential positioning unit:

[0057] The time and space reference is unified through GPS / BD multi-frequency receiving data, the reference station with known coordinates sends carrier phase observation values, its own position and observation error factors and other data to the background server through the 4G network, the mobile station obtains error factors from the background server in real time through the DTU-4G data transparent transmission module, and the mobile station corrects the carrier phase in real time by performing differential solution on the received observation data of the reference station, real-time error values and the GNSS observation values collected by the mobile station, so that the centimeter-level positioning accuracy value of the mobile station is obtained.

[0058] The specific method is as follows: the phase difference between the star stations includes the initial integer ambiguity, the integer change value from the initial time to the observation time, and the decimal part of the observation phase; the distance between the star stations is the product of the carrier wavelength and the phase difference between the star stations; the real distance between the star stations and the pseudo-range observation value between the star stations can be obtained at the reference station using the known coordinates and satellite ephemeris, and a pseudo-range correction number is calculated.

[0059] If the satellite tracking is not lost during the observation process, the difference between the initial integer numbers is a constant, and the difference between the clock differences of the two receivers, the difference between the noises and the difference between the multipath effects between the two stations are less than the allowable error of cm-level dynamic positioning, and the carrier phase measurement difference can also be regarded as a constant in the solving process.

[0060] Therefore, the initial integer number is determined, and the positioning of the mobile station can be realized by simultaneously observing the same four satellites at the reference station and the mobile station, wherein the integer number is calculated by the related ambiguity algorithm.

[0061] It can be seen that the RTK differential positioning algorithm has a short time consumption and can provide the coordinates of the observation point in real time, effectively improving the identification accuracy of the underground pipe cable, and the flowchart is as shown in Figure 3 .

[0062] The TOA positioning algorithm of the embodiment is based on the TOA circular equation, different positioning equations are constructed through different combinations of the intersection lines between circles, when the RFID reader module is used, the propagation time of the signal transmitted by the RFID reader to the radio frequency electronic tag and then returned to the RFID reader is obtained, and the distance from the radio frequency electronic tag to the RFID reader is obtained from the propagation time, wherein at least three RFID readers are required to realize the positioning of the radio frequency electronic tag, the distances measured from the three RFID readers to the radio frequency electronic tag are r1, r2 and r3, three circles are drawn with each RFID reader as the center and the measured distance as the radius, and the intersection point of the circles is the position of the electronic tag. The least square (LS) algorithm is used to estimate the position information of the radio frequency electronic tag.

[0063] When the position information and the device identification of the digital tag system collected are uploaded to the server through GPRS and Beidou, the server (computer) comprehensively processes the received information. The server program adopts the MVC design mode, and the program runs stably to provide an extensible interface for other users.

[0064] The data reporting software design fully uses the embedded CPU, USART communication interface, fast response interrupt, and accurate timer, etc. Figure 4 As shown in the figure, when the Beidou positioning module and the GPRS communication module are used for radio frequency electronic tag positioning, the following steps are included:

[0065] Serial port configuration of related modules is performed, timer configuration is performed, interrupt serial port configuration is performed, and it is judged whether the serial port configuration of the first Beidou positioning module is interrupted. If yes, data transmission and reception are performed.

[0066] If not, it is judged whether the serial port configuration of the second Beidou positioning module is interrupted. If yes, positioning data and UTC time are obtained, and the screen is refreshed.

[0067] If the serial port configuration of the second Beidou positioning module is not interrupted, it is judged whether the serial port configuration of the GPRS communication module is interrupted. If yes, data transmission and reception are performed, and a heartbeat signal is sent externally.

[0068] If the serial port configuration of the GPRS communication module is not interrupted, it is judged whether the first timing time is reached. If yes, it is judged whether the heartbeat counter is greater than 5. If yes, the line is dropped and reconnected.

[0069] If the second timing time is reached, the information of the radio frequency electronic tag is read, and the read information is uploaded to the background server.

[0070] In the embodiment, the background server uses the B / S architecture, the port thereof is opened to the public network, a TCP / IP protocol server is created, and the NIO technology is used to improve the concurrent performance of the software. The background server website can be accessed through a browser, and then the position of the node can be seen. After receiving the information, the node ID and the latitude and longitude information received are saved to the underground pipe gallery information database after error checking and conversion.

[0071] As shown in the figure, Figure 2As shown, the RFID reader module includes an RFID reader, middleware, and an application system, the RFID reader includes an RFID transmitting circuit, an RFID receiving circuit, and an RFID power supply circuit, the RFID transmitting circuit receives a driving signal sent by an embedded processor, shapes the driving signal through a logic circuit, drives a push-pull circuit, and transmits a radio signal to the outside through an antenna, the RFID receiving circuit amplifies a received signal through a receiving circuit and a differential amplification circuit, and then transmits the amplified signal to the embedded processor for processing through an operational amplifier, and the RFID power supply circuit mainly raises a 5V voltage to a positive and negative 24V voltage through a transformer to drive a MOS tube of the RFID transmitting circuit to transmit a radio signal.

[0072] In the embodiment, the static relative positioning generally adopts carrier phase observations as basic observations to accurately measure baselines of various lengths, and steps of the static relative positioning mainly include: establishment of a double-difference carrier phase observation equation, adjustment of the double-difference observation equation, solution of a least square method for a floating point ambiguity, fixing of an integer ambiguity by using a LAMBDA algorithm, solution of a baseline, and completion of positioning calculation.

[0073] Specifically, when positioning the mobile station, based on known coordinates of the reference station and a three-point circle positioning principle, parameters of absolute positions of the circular trajectory are obtained according to effective measurement results of the mobile station satellite navigation receiver in the preset circular trajectory;

[0074] The mobile station satellite navigation receiver moves along the circular trajectory at a preset speed, and ephemeris files and observation data files are parsed from received signals of the mobile station satellite navigation receiver, and available observation data are obtained after gross error and cycle slip inspection;

[0075] Taking double-difference ambiguity of inter-station inter-satellite carrier phase and sine and cosine values of a relative trajectory center drift angle of the mobile station as unknowns, and according to a constraint of the circular motion trajectory, an inter-station inter-satellite pseudo-range double-difference equation and an inter-station inter-satellite carrier phase double-difference equation between the mobile station and the reference station are established, and a floating point ambiguity and a floating point positioning solution are obtained;

[0076] The floating point ambiguity is fixed to obtain an integer ambiguity solution, and a carrier phase double-difference equation about a relative position vector from the reference station to the mobile station is established according to the integer ambiguity solution;

[0077] According to the effective fixed solution and the circular trajectory obtained by the carrier phase double difference equation, the accurate position data of the mobile station is calculated, and according to the observation data of the mobile station, the corresponding accurate position data and the corresponding satellite position at the moment, the measurement error of the satellite navigation receiver of the mobile station is calculated. It can be seen that the above-mentioned algorithm improves the success rate and accuracy of the ambiguity float solution, optimizes the float solution covariance matrix to make it easier to be correctly fixed; the circular motion trajectory constraint makes the positioning error also measurable, and a part of the time when the effective fixed solution is missing can be calculated by the interpolation method, so that the error measurement result is more comprehensive and reliable.

[0078] In summary, the embodiment is a passive digital tag system with buried underground cable accurate positioning and identification function based on Beidou navigation technology, which realizes long-term operation of the tag by using solar power supply or electric pile power supply, configures a wireless electronic tag reading device system, establishes a virtual digital model of the underground cable line, can realize informationization and digitization of the underground cable, and forms a visual system platform, so that it has all-day and real-time supervision and monitoring capability, can quickly and accurately judge the underground cable path, and can also reduce the technical requirements of manual path identification and improve the timeliness of external force damage prevention, has the advantages of large transmission range, non-line-of-sight, high precision, low system cost, etc., and has high practicality, feasibility and generalizability.

[0079] Further, the intelligent location service terminal is fused with the electronic tag of RFID and the positioning module of Beidou, the GPS-RTK carrier phase difference positioning technology is used for calculation, the carrier phase is corrected in real time to obtain centimeter-level positioning accuracy, the Beidou high-precision positioning-static relative positioning technology is used to improve the solution accuracy of the integer ambiguity, and the influence of observation noise is eliminated, so that the indoor positioning and outdoor positioning are fused, and the accurate positioning of the tag position is realized.

[0080] Further, the middleware and the application software constitute the whole application system, and the application system can provide a business logic processing interface for the digital tag, and realizes the interaction between the man-machine or system and the digital tag according to the equipment information read by the reader-writer.

[0081] The technical features of the above embodiments can be combined arbitrarily, and in order to make the description concise, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0082] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the protection scope of the present application, and any non-essential changes and replacements made by those skilled in the art on the basis of the present application shall fall within the scope of the present application.

Claims

1. A passive digital tag system based on Beidou and radio frequency identification technology, characterized in that: include: Radio frequency electronic tags are installed in monitored nodes. Node information is pre-written in the radio frequency electronic tags. The radio frequency electronic tags store underground pipeline corridor locations and underground pipeline corridor operation information through their built-in chips to form an underground pipeline corridor information storage database. RFID reader / writer module, used to transmit and receive radio frequency signals corresponding to radio frequency electronic tags, to realize radio frequency electronic tag information collection and modification; Beidou positioning module, which runs a GPS-RTK differential positioning algorithm to achieve real-time dynamic positioning of radio frequency electronic tags, and stores the coordinate information of radio frequency electronic tags in the database to establish an electronic map of the underground pipeline corridor; GPRS communication module, which realizes real-time data communication between multiple electronic tags and between electronic tags and background servers through MQTT protocol; Embedded processor: The embedded processor obtains the location information of the radio frequency electronic tag through the Beidou positioning module or GPRS communication module, and reports it to the data receiving and processing system through the communication module. The data receiving and processing system receives the location information and device information reported by the monitored node, and processes and displays the data; Power management module, used to provide power for the entire passive digital tag system; Backend server: A GIS map system is installed in the backend server. The coordinate information of the RFID tag is marked on the GIS map system. The GIS map system and the underground pipeline corridor information storage database in the backend server can be remotely accessed by scanning the RFID tag. Among them, when using the Beidou positioning module and GPRS communication module for radio frequency electronic tag positioning, it includes: Configure the serial ports of related modules, configure the timer, interrupt the serial port configuration, and determine whether the serial port configuration of the first Beidou positioning module is interrupted. If so, send and receive data; If not, determine whether the serial port configuration of the second Beidou positioning module triggers an interrupt. If so, locate the data and obtain the UTC time, and refresh the screen; If the serial port configuration of the second Beidou positioning module has not triggered an interrupt, it is determined whether the serial port configuration of the GPRS communication module is interrupted. If so, data is sent and received, and a heartbeat signal is sent to the outside. If the serial port configuration of the GPRS communication module has not triggered an interrupt, it is determined whether the first timing time is reached. If so, it is determined whether the heartbeat counter is greater than 5. If so, the line is disconnected and reconnected; If the second timing time is reached, the information of the radio frequency electronic tag is read and the read information is uploaded to the background server.

2. The system according to claim 1, wherein: The Beidou positioning module includes a GNSS module, an RTK differential positioning unit, a positioning antenna, a DTU-4G data transparent transmission module, a 4G antenna, and an RS232 / TTL protocol conversion module. The positioning antenna is used to receive satellite signals and transmit them to the GNSS module. After receiving the satellite signals, the GNSS module parses and obtains GNSS positioning information, speed information, and heading information in real time, and sends them to the RTK differential positioning unit via a high-speed serial port and Ethernet in a redundant backup transmission mode; the RTK differential positioning unit is connected to the embedded processor, which is connected to the DTU-4G data transparent transmission module via the RS232 / TTL protocol conversion module and transmits the coordinate information to the background server via the 4G antenna.

3. The system according to claim 2, characterized in that: Execute in the RTK differential positioning unit: The base station with known coordinates sends the carrier phase observation value, its own position and observation error factor data to the background server through the 4G network. At the same time, the mobile station obtains the error factor in real time from the background server through the DTU-4G data transparent transmission module. The mobile station will perform differential calculation on the observation data and real-time error value received from the base station and the GNSS observation value collected by itself, and correct the carrier phase in real time to obtain the centimeter-level positioning accuracy value of the mobile station.

4. The system according to claim 3, wherein: The phase difference between satellite stations includes: the initial whole-week ambiguity, the whole-week change from the starting time to the observation time, and the fractional part of the observed phase; at the base station, the true distance between satellite stations and the pseudo-range observation value between satellite stations can be obtained using the known coordinates and satellite ephemeris, and the pseudo-range correction number can be calculated, and this correction number is used to modify the pseudo-range observation value of the user station.

5. The system according to claim 4, characterized in that: If satellite tracking does not lose lock during the observation process, the difference in the initial full cycle number is a constant, and the difference in the clock errors of the two receivers, the difference in noise, and the difference in the multipath effect between the two stations between adjacent epochs are all less than the allowable error of cm-level dynamic positioning, the carrier phase measurement difference is considered a constant in the solution process; After the starting integer number is determined, the mobile station can be positioned by observing the same four satellites at the base station and the mobile station at the same time. The starting integer number is calculated by the correlation ambiguity algorithm.

6. The system according to claim 1, wherein: The RFID reader / writer module includes an RFID reader, which includes an RFID transmitting circuit, an RFID receiving circuit, and an RFID power supply circuit. The RFID transmitting circuit receives the driving signal sent by the embedded processor, drives the push-pull circuit after shaping by the logic circuit, and sends a radio signal outward through the antenna. The RFID receiving circuit amplifies the received signal through the receiving circuit and the differential amplifier circuit, and then amplifies the signal through the operational amplifier and transmits it to the embedded processor for processing. The RFID power supply circuit mainly converts the 5V voltage to a positive or negative 24V voltage through a transformer, driving the MOS tube of the RFID transmitting circuit to transmit the radio signal.

7. The system according to claim 1, wherein: The backend server uses a B / S architecture, with its port open to the public network. It creates a TCP / IP protocol server and uses NIO technology to improve the concurrent performance of the software. The location of the node can be viewed by accessing the backend server URL through a browser. After receiving the information, the received node ID and longitude and latitude information will be saved in the underground pipeline corridor information database after error correction and conversion.

8. The system according to claim 6, characterized in that: When using an RFID reader / writer module, the propagation time of the signal emitted by the RFID reader to the radio frequency electronic tag and then back to the RFID reader is obtained. The distance from the radio frequency electronic tag to the RFID reader is obtained from the propagation time. At least three RFID readers are required to locate the radio frequency electronic tag. The distances measured by the three RFID readers to the radio frequency electronic tag are r1, r2, and r3 respectively. Three circles are drawn with each RFID reader as the center and the measured distance as the radius. The intersection of the circles is the electronic tag position, and the least squares algorithm is used to estimate the radio frequency electronic tag position information.

9. The system according to claim 5, characterized in that: When positioning a mobile station, based on the known coordinates of the base station and the principle of three-point circle determination, the parameter description of the absolute position of the circular trajectory is obtained according to the effective measurement results of the mobile station satellite navigation receiver's multi-point static relative positioning on the preset circular trajectory; The mobile station satellite navigation receiver moves along a circular trajectory at a preset speed, and the ephemeris file and observation data file are parsed from the received signal of the mobile station satellite navigation receiver. After the gross error and cycle slip test, the usable observation data are obtained; The inter-station and inter-satellite carrier phase double-difference ambiguities and the sine and cosine values ​​of the yaw angle of the mobile station relative to the center of the trajectory are unknown. Based on the circular motion trajectory constraints, the inter-station and inter-satellite pseudorange double-difference equations and the inter-station and inter-satellite carrier phase double-difference equations between the mobile station and the reference station are established, and the floating-point ambiguities and floating-point positioning solutions are obtained by solving them. The floating point ambiguity is fixed to obtain an integer ambiguity solution, and a carrier phase double difference equation about the relative position vector from the reference station to the mobile station is established based on the integer ambiguity solution; The accurate position data of the mobile station is calculated based on the effective fixed solution and circular trajectory obtained from the carrier phase double-difference equation. The measurement error of the mobile station satellite navigation receiver is calculated based on the observation data of the mobile station, the corresponding accurate position data and the satellite position at the corresponding time.

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