Vehicle positioning system and method based on radio frequency identification and visible light communication in tunnel scene

Abstract

The invention provides a vehicle positioning system and method based on radio frequency identification and visible light communication in a tunnel scene. The system comprises an RFID positioning unit, a VLC positioning unit, an information fusion positioning unit, a tunnel light control unit and an information management platform. The initial position information of a vehicle is detected through the RFID positioning unit and the VLC positioning unit, the final position information of the vehicle is calculated by the information fusion positioning unit according to the initial position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and the final position information of the vehicle is transmitted to the tunnel light control unit and the information management platform. Corresponding light control and early warning functions are realized; the system has the characteristics of high-precision positioning and low energy consumption, realizes tunnel full-coverage positioning, ensures continuity and stability of positioning information, and greatly improves the intelligent level of tunnel traffic management.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle positioning, and in particular to a vehicle positioning system and method based on radio frequency identification and visible light communication in a tunnel scenario. Background Art

[0002] In modern urban transportation systems, tunnels are key channels connecting various areas of the city. Their safe and efficient operation is of great significance to relieving traffic pressure and ensuring citizens' travel. However, the internal environment of tunnels is complex, and traditional monitoring methods such as video monitoring and manual inspections are insufficient in terms of real-time, accuracy and cost-effectiveness. Especially in emergency situations, quickly and accurately locating the vehicle is crucial for rescue operations.

[0003] Radio frequency identification (RFID) technology, with its non-contact, high efficiency and remote identification characteristics, provides a new solution for tunnel vehicle positioning. In the special environment of tunnels, RFID systems can be seamlessly integrated with existing traffic management systems to provide real-time data analysis and decision support.

[0004] Visible light communication (VLC) technology is an emerging wireless communication method that uses the visible spectrum for data transmission. It has the advantages of high bandwidth, low latency and environmental friendliness. For positioning applications in tunnels, it can provide a stable communication environment, especially when GPS signals are limited, providing new possibilities for vehicle identification and traffic management.

[0005] The patent application document with publication number CN112821949 A discloses a tunnel vehicle positioning system based on visible light communication and UWB. By using UWB positioning technology and tunnel lights as carriers to achieve optical communication and complete the transmission of data required for positioning, it can achieve vehicle positioning in tunnels without relying on GPS positioning, provide driving assistance information to drivers, and improve the safety of vehicles passing through tunnels. However, under conditions of low visibility or the presence of obstructions, the system may encounter performance degradation problems. At the same time, its installation and maintenance costs are high, and it also has strict requirements on the environmental conditions in the tunnel.

[0006] The patent application document with publication number CN113075676A discloses a method for positioning vehicles in tunnels based on lane line mileage matching. The mileage information of the vehicle in the tunnel is obtained by using the wheel speed meter and laser radar in the tunnel, and the mileage information is matched with the high-precision lane line to complete the precise positioning in the long-distance tunnel environment, thereby completing the precise positioning in the tunnel. Relying on high-precision lane line information and wheel speed meter, the system is limited in application in old or poorly maintained tunnels. At the same time, the performance of laser radar may be impaired in extreme weather. Summary of the invention

[0007] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a vehicle positioning system and method based on radio frequency identification and visible light communication in a tunnel scenario. The preliminary position information of the vehicle is detected by an RFID positioning unit and a VLC positioning unit. The information fusion positioning unit calculates the final position information of the vehicle according to the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and transmits the final position information of the vehicle to the tunnel lighting control unit and the information management platform respectively, so as to realize corresponding lighting control and early warning functions; the system is characterized by high-precision positioning and low energy consumption, realizes full coverage positioning of the tunnel, ensures the continuity and stability of positioning information, and greatly improves the intelligent level of tunnel traffic management.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario, comprising an RFID positioning unit, a VLC positioning unit, an information fusion positioning unit, a tunnel light control unit and an information management platform;

[0010] The RFID positioning unit is used to detect the preliminary position information of the vehicle and transmit the preliminary position information of the vehicle to the information fusion positioning unit;

[0011] The VLC positioning unit is used to detect the preliminary position information of the vehicle and transmit the preliminary position information of the vehicle to the information fusion positioning unit;

[0012] The information fusion positioning unit calculates the final position information of the vehicle based on the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and displays the final position information of the vehicle through the device and transmits it to the tunnel light control unit and the information management platform;

[0013] The tunnel light control unit classifies the traffic congestion status according to the final position information of the vehicle, and implements corresponding light control according to the classification result;

[0014] The information management platform is used to receive, process and analyze the final position information of the vehicle and issue early warning information when necessary.

[0015] Furthermore, the RFID positioning unit includes an RFID electronic tag, an RFID reader and an RFID positioning module;

[0016] The RFID electronic tag includes a microchip and an antenna. The microchip stores a unique ID number of the RFID electronic tag. The RFID electronic tag receives a radio frequency signal from an RFID reader through the antenna, and reflects the signal with its own ID number back to the RFID reader through backscattering, thereby achieving wireless communication with the RFID reader.

[0017] The RFID reader is used to periodically send radio frequency signals; when the RFID reader arrives near a marking point where an RFID electronic tag is installed, the RFID electronic tag receives the radio frequency signal sent by the RFID reader, and uses backscattering technology to reflect the signal with its own ID number (including the tag ID number, signal reception time and signal strength information) back to the RFID reader; after the RFID reader receives the signal reflected by the RFID electronic tag, it transmits the tag ID number, reception time and signal strength information to the RFID positioning module by wireless means;

[0018] The RFID positioning module is used to receive information transmitted by the RFID reader; the RFID positioning module pre-stores the coordinate parameters of all RFID electronic tag installation positions, and the RFID positioning module finds the corresponding coordinate information of the RFID electronic tag according to the ID number of the RFID electronic tag; when the RFID reader transmits the return information of no less than three RFID electronic tags to the RFID positioning module, the RFID positioning module estimates the position of the RFID reader using a two-step weighted least squares method based on the obtained RFID electronic tag coordinates, signal reception time and signal strength information; the position of the RFID reader is the preliminary position of the vehicle.

[0019] Further, the VLC positioning unit includes a VLC transmitter, a VLC receiver and a VLC positioning module;

[0020] The VLC transmitter is composed of a plurality of LED lighting sources and is used to transmit visible light signals;

[0021] The VLC receiver is used to receive visible light signals from LED lighting sources; the VLC receiver includes a photodiode sensor and an optical signal processing module; the photodiode sensor is used to receive visible light signals, convert the optical signals into electrical signals and transmit them to the optical signal processing module; the optical signal processing module amplifies and filters the received electrical signals, and then uses a demodulation algorithm to convert the amplified and filtered electrical signals into digital signals, and uses mean filtering to calculate the RSSI value corresponding to the received digital signal; finally, the RSSI information is transmitted to the VLC positioning module by wired transmission;

[0022] The VLC positioning module is used to receive the RSSI value of the VLC receiver, establish a conversion relationship model between RSSI and distance, and estimate the distance between the VLC receiver and each VLC transmitter; based on the estimated distances between more than three VLC receivers and each VLC transmitter and the known positions of the VLC transmitters, a two-step weighted least squares algorithm is used to calculate the preliminary position of the vehicle.

[0023] Further, the information fusion positioning unit includes a multi-source information fusion module, a position information display module and a first wireless communication module;

[0024] The multi-source information fusion module is used to receive the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and calculate the final position of the vehicle using the Kalman filter algorithm;

[0025] The position information display module is an on-board electronic display screen that displays the final position information of the vehicle for easy viewing by the driver and management personnel;

[0026] The first wireless communication module is used to receive the vehicle final position information from the multi-source information fusion module and transmit it to the tunnel lighting control unit and information management platform via NB-loT wireless communication.

[0027] Further, the tunnel light control unit includes a congestion assessment module and a light control module;

[0028] The congestion assessment module is used to monitor, analyze and evaluate traffic conditions in real time; the congestion assessment module receives vehicle positioning information transmitted by the first wireless communication module in the information fusion positioning unit, and collects traffic data, including vehicle flow, vehicle speed, vehicle density and driving time; based on the collected real-time traffic data, the traffic status is divided into four states: "unblocked", "mild congestion", "moderate congestion" and "severe congestion";

[0029] The lighting control module sends control instructions to the VLC transmitter through the CAN bus according to the traffic conditions obtained by the congestion assessment module, adjusts the light color of the LED lamp, and realizes intelligent control of the tunnel light;

[0030] Furthermore, the intelligent control strategy of the tunnel lighting is:

[0031] When the traffic condition is "smooth", the light source of the tunnel LED signal light is adjusted to white light; when the traffic condition is "mild congestion", the light source of the tunnel LED signal light is adjusted to green light; when the traffic condition is "moderate congestion", the light source of the tunnel LED signal light is adjusted to yellow light; when the traffic condition is "severe congestion", the light source of the tunnel LED signal light is adjusted to red light.

[0032] Furthermore, the information management platform includes a second wireless communication module and an early warning module;

[0033] The second wireless communication module receives the encapsulated positioning message data from the first wireless communication module of the information fusion positioning unit, and transmits the encapsulated positioning message data to the information management platform through the NB-loT wireless communication protocol, and then sends it to the early warning module through the corresponding API interface;

[0034] The early warning module receives the vehicle position information from the second wireless communication module; if the position of the same vehicle does not change substantially within the range specified by the queuing time index of the congestion standard, it is considered that the vehicle has had an accident in the tunnel, and the early warning module sends early warning information to the staff, reminding them to implement rescue in a timely manner.

[0035] A vehicle positioning method based on radio frequency identification and visible light communication in a tunnel scenario specifically comprises the following steps:

[0036] S1. When a vehicle enters a tunnel, the RFID positioning unit and the VLC positioning unit respectively detect the preliminary location information of the vehicle and transmit it to the information fusion positioning unit;

[0037] S2, after receiving the preliminary vehicle location information transmitted by the RFID positioning unit and the VLC positioning unit in step S1, the multi-source information fusion module of the information fusion positioning unit calculates the final location of the vehicle by multi-source fusion, and visualizes the final location of the vehicle and transmits it to the tunnel light control unit and the information management platform through the first wireless communication module of the information fusion positioning unit;

[0038] S3, based on the vehicle position information transmitted by the first wireless communication module in step S2, controlling the change of the tunnel light:

[0039] After receiving the vehicle positioning information transmitted from the first wireless communication module, the congestion assessment module uses Kalman filtering to fuse and process the data from the first wireless communication module, and uses a linear regression model to analyze the data pre-processed by the Kalman filter, extracting three key features: vehicle spacing, traffic flow change rate, and vehicle speed distribution, to classify the traffic status; the lighting control module sends control instructions to the VLC transmitter through the CAN bus according to the traffic conditions obtained by the congestion assessment module, adjusts the light color of the LED lamp, and realizes intelligent control of the tunnel lighting;

[0040] S4, based on the vehicle position information transmitted by the first wireless communication module in step S2, performing tunnel traffic condition early warning management:

[0041] The second wireless communication module on the information management platform receives the vehicle location information from the first wireless communication module, and transmits the vehicle location information to the early warning module. The early warning module sends early warning information to the staff to remind the staff to implement rescue in time.

[0042] Furthermore, the step S1 is specifically as follows:

[0043] Step S1-1: The RFID positioning unit detects the preliminary location information of the vehicle through the RFID electronic tag, RFID reader and RFID positioning module:

[0044] The RFID reader periodically sends radio frequency signals. When the RFID reader is close to the RFID electronic tag, the RFID electronic tag receives the radio frequency signal sent by the RFID reader and returns a signal with an ID number. After receiving the signal with the ID number, the RFID reader sends the ID number, signal reception time and signal strength information of the RFID electronic tag to the RFID positioning module. The RFID positioning module estimates the preliminary position of the vehicle using a two-step weighted least squares method.

[0045] Step S1-2: The VLC positioning unit detects the preliminary position information of the vehicle through the VLC transmitter, VLC receiver and VLC positioning module:

[0046] The VLC transmitter is composed of multiple LED lighting sources, which is used to emit visible light signals; the VLC receiver receives the visible light signal, converts the visible light signal into an electrical signal and transmits it to the optical signal processing module; the optical signal processing module amplifies, filters and demodulates the received electrical signal, obtains the RSSI value and transmits it to the VLC positioning module; after receiving the RSSI value, the VLC positioning module estimates the distance between the vehicle and the VLC transmitter according to the conversion relationship model between RSSI and distance, and uses a two-step weighted least squares algorithm to calculate the preliminary position of the vehicle.

[0047] Furthermore, the step S2 is specifically as follows:

[0048] Step S2-1: The multi-source information fusion module of the information fusion positioning unit uses the Kalman filter algorithm to perform data fusion processing on the preliminary location information of the RFID and VLC to calculate the final location of the vehicle;

[0049] Step S2-2: Displaying the final position information of the vehicle calculated in step S2-1 to the vehicle driver and management personnel through the vehicle electronic display screen;

[0050] Step S2-3: The first wireless communication module receives the final position information of the vehicle processed by the multi-source information fusion module in step S2-1, and transmits it to the tunnel lighting control unit and the information management platform via NB-IoT wireless communication.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] 1. The present invention combines RFID positioning and VLC positioning to achieve full coverage positioning in the tunnel, ensuring that the vehicle can be effectively positioned at any position in the tunnel; at the same time, the continuity and stability of positioning information can be guaranteed regardless of whether it is driving at low speed or high speed.

[0053] 2. The present invention adopts Kalman filtering algorithm to perform data fusion processing on the preliminary location information from RFID and VLC, thereby improving the accuracy and robustness of positioning; even when some tags or transmitters fail, the system can still achieve continuous tracking of the vehicle position through multi-source information fusion, ensuring the uninterrupted positioning service.

[0054] 3. The radio frequency identification (RFID) technology and visible light communication (VLC) technology of the present invention not only achieve high-precision positioning, but also have the characteristics of low energy consumption; visible light communication (VLC) uses existing lighting facilities for communication, avoiding additional energy waste, and (RFID) technology reduces the ineffective loss of energy with its efficient signal processing capability.

[0055] In summary, the present invention proposes a vehicle positioning system based on radio frequency identification and visible light communication, wherein the preliminary position information of the vehicle is detected by an RFID positioning unit and a VLC positioning unit, and the information fusion positioning unit calculates the final position information of the vehicle according to the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and transmits the final position information of the vehicle to the tunnel lighting control unit and the information management platform to realize corresponding lighting control and early warning functions; the system is characterized by high-precision positioning and low energy consumption, realizes full coverage positioning of the tunnel, ensures the continuity and stability of positioning information, and greatly improves the intelligent level of tunnel traffic management. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The figure is an overall structural block diagram of the vehicle positioning system based on radio frequency identification and visible light communication in the tunnel scenario of the present invention.

[0057] Figure 2 The present invention is a flow chart of a vehicle positioning method based on radio frequency identification and visible light communication in a tunnel scenario.

[0058] Figure 3This is the simulation experiment result of the multi-source information fusion module of the moving vehicle of the present invention receiving the information transmitted by three RFID positioning modules.

[0059] Figure 4 This is the simulation experiment result of the multi-source information fusion module of the moving vehicle of the present invention receiving the information transmitted by three VLC positioning modules.

[0060] Figure 5 The vehicle multi-source information fusion module of the present invention uses Kalman filtering to fuse the preliminary positioning information of the RFID positioning module and the preliminary positioning information of the VLC positioning module to estimate the simulation experiment results of the final position information of the vehicle.

[0061] Figure 6 The simulation results of the present invention are as follows: when the vehicle passes through a tunnel at different speeds, different positioning methods are used to estimate the vehicle position; wherein, Figure 6 (a) is the simulation result of estimating the vehicle position using the RFID-based positioning method, the VLC-based positioning method, and the RFID and VLC-based positioning method when the vehicle passes through the tunnel at a speed of 5 m / s; Figure 6 (b) is the simulation result of estimating the vehicle position using the RFID-based positioning method, the VLC-based positioning method, and the RFID and VLC-based positioning method when the vehicle passes through the tunnel at a speed of 10 m / s; Figure 6 (c) is the simulation result of estimating the vehicle position using the RFID-based positioning method, the VLC-based positioning method, and the RFID and VLC-based positioning method when the vehicle passes through the tunnel at a speed of 15 m / s; Figure 6 (d) is the simulation result of estimating the vehicle position using the RFID-based positioning method, the VLC-based positioning method, and the RFID and VLC-based positioning method when the vehicle passes through the tunnel at a speed of 20 m / s; Figure 6 (e) in the figure is the simulation result of estimating the vehicle position when the vehicle passes through the tunnel at a speed of 25m / s using the RFID-based positioning method, the VLC-based positioning method, and the RFID and VLC-based positioning method.

[0062] Figure 7 The present invention shows the root mean square error variation curve of the vehicle position estimated by the RFID-based positioning method, the VLC-based positioning method and the RFID and VLC-based combined positioning method when the vehicle passes through a tunnel at a speed of 10 m / s. DETAILED DESCRIPTION

[0063] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0064] See also Figure 1, a vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario, including an RFID positioning unit, a VLC positioning unit, an information fusion positioning unit, a tunnel light control unit and an information management platform;

[0065] The RFID positioning unit is used to detect the preliminary position information of the vehicle and transmit the preliminary position information of the vehicle to the information fusion positioning unit;

[0066] The RFID positioning unit includes an RFID electronic tag, an RFID reader and an RFID positioning module;

[0067] The RFID electronic tags are installed on the walls of both sides of the tunnel, with one RFID electronic tag installed every 50 meters; the RFID electronic tag includes a microchip and an antenna, the microchip stores a unique ID number of the RFID electronic tag, the RFID electronic tag receives the radio frequency signal from the RFID reader through the antenna, and reflects the signal with its own ID number back to the RFID reader through backscattering, thereby realizing wireless communication with the RFID reader;

[0068] The RFID reader is installed on the vehicle and is used to periodically send radio frequency signals; when the RFID reader arrives near a marking point where an RFID electronic tag is installed, the RFID electronic tag receives the radio frequency signal sent by the RFID reader and uses backscattering technology to reflect the signal with its own ID number (including the tag ID number, signal reception time and signal strength information) back to the RFID reader; after the RFID reader receives the signal reflected by the RFID electronic tag, it transmits the tag ID number, reception time and signal strength information to the RFID positioning module by wireless means;

[0069] The RFID positioning module is installed on the vehicle and is used to receive information transmitted by the RFID reader; the RFID positioning module pre-stores the coordinate parameters of all RFID electronic tag installation positions, and the RFID positioning module finds the corresponding coordinate information of the RFID electronic tag according to the ID number of the RFID electronic tag; when the RFID reader transmits the return information of no less than three RFID electronic tags to the RFID positioning module, the RFID positioning module estimates the position of the RFID reader using a two-step weighted least squares method based on the obtained RFID electronic tag coordinates, signal reception time and signal strength information; the position of the RFID reader is the preliminary position of the vehicle.

[0070] The VLC positioning unit is used to detect the preliminary position information of the vehicle and transmit the preliminary position information of the vehicle to the information fusion positioning unit;

[0071] The VLC positioning unit includes a VLC transmitter, a VLC receiver and a VLC positioning module;

[0072] The VLC transmitter is installed on the top of the tunnel, with one VLC transmitter arranged every 10 meters; the VLC transmitter is composed of multiple LED lighting sources for transmitting visible light signals;

[0073] The VLC receiver is installed on the vehicle and is used to receive visible light signals from LED lighting sources; the VLC receiver includes a photodiode sensor and an optical signal processing module; the photodiode sensor is used to receive visible light signals, convert the optical signals into electrical signals and transmit them to the optical signal processing module; the optical signal processing module amplifies and filters the received electrical signals, and then uses a demodulation algorithm to convert the amplified and filtered electrical signals into digital signals, and uses mean filtering to calculate the RSSI value corresponding to the received digital signal; finally, the RSSI information is transmitted to the VLC positioning module by wired transmission;

[0074] The VLC positioning module is installed on the vehicle and is used to receive the RSSI value of the VLC receiver, establish a conversion relationship model between RSSI and distance, and estimate the distance between the VLC receiver and each VLC transmitter; based on the estimated distances between the three VLC receivers and each VLC transmitter and the known positions of the VLC transmitters, a two-step weighted least squares algorithm is used to calculate the preliminary position of the vehicle.

[0075] The information fusion positioning unit calculates the final position information of the vehicle based on the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and displays the final position information of the vehicle through the device and transmits it to the tunnel light control unit and the information management platform;

[0076] The information fusion positioning unit includes a multi-source information fusion module, a position information display module and a first wireless communication module;

[0077] The multi-source information fusion module is arranged inside the vehicle, and is used to receive the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and calculate the final position of the vehicle using the Kalman filter algorithm;

[0078] The position information display module is an on-board electronic display screen arranged inside the vehicle, which displays the final position information of the vehicle for the convenience of the driver and the management personnel to view;

[0079] The first wireless communication module is arranged inside the vehicle, and is used to receive the vehicle final position information from the multi-source information fusion module, and transmit it to the tunnel lighting control unit and the information management platform via NB-loT wireless communication.

[0080] The tunnel light control unit classifies the traffic congestion status according to the final position information of the vehicle, and implements corresponding light control according to the classification result;

[0081] The tunnel light control unit is arranged at the top of the tunnel and includes a congestion assessment module and a light control module;

[0082] The congestion assessment module is used to monitor, analyze and evaluate traffic conditions in real time; the congestion assessment module receives vehicle positioning information transmitted by the first wireless communication module in the information fusion positioning unit, and collects traffic data, including vehicle flow, vehicle speed, vehicle density and driving time; based on the collected real-time traffic data, the traffic status is divided into four states: "unblocked", "mild congestion", "moderate congestion" and "severe congestion";

[0083] The lighting control module sends control instructions to the VLC transmitter through the CAN bus according to the traffic conditions obtained by the congestion assessment module, adjusts the light color of the LED lamp, and realizes intelligent control of the tunnel light;

[0084] The intelligent control strategy of the tunnel lighting is:

[0085] When the traffic condition is "smooth", the light source of the tunnel LED signal light is adjusted to white light; when the traffic condition is "mild congestion", the light source of the tunnel LED signal light is adjusted to green light; when the traffic condition is "moderate congestion", the light source of the tunnel LED signal light is adjusted to yellow light; when the traffic condition is "severe congestion", the light source of the tunnel LED signal light is adjusted to red light.

[0086] The information management platform is used to receive, process and analyze the final position information of the vehicle and issue early warning information when necessary.

[0087] The information management platform includes a second wireless communication module and an early warning module;

[0088] The second wireless communication module receives the encapsulated positioning message data from the first wireless communication module of the information fusion positioning unit, and transmits the encapsulated positioning message data to the information management platform through the NB-loT wireless communication protocol, and then sends it to the early warning module through the corresponding API interface;

[0089] The early warning module receives the vehicle position information from the second wireless communication module; if the position of the same vehicle does not change substantially within the range specified by the queuing time index of the congestion standard, it is considered that the vehicle has had an accident in the tunnel, and the early warning module sends early warning information to the staff, reminding them to implement rescue in a timely manner.

[0090] like Figure 2As shown, a vehicle positioning method based on radio frequency identification and visible light communication in a tunnel scenario specifically includes the following steps:

[0091] S1. When a vehicle enters a tunnel, the RFID positioning unit and the VLC positioning unit respectively detect the preliminary location information of the vehicle and transmit it to the information fusion positioning unit;

[0092] The step S1 is specifically as follows:

[0093] Step S1-1: The RFID positioning unit detects the preliminary location information of the vehicle through the RFID electronic tag, RFID reader and RFID positioning module:

[0094] The RFID reader periodically sends radio frequency signals; when the RFID reader on the vehicle approaches an RFID electronic tag installed on the tunnel wall, the RFID electronic tag receives the radio frequency signal sent by the RFID reader and reflects the signal with its own ID number (including the tag ID number, signal reception time and signal strength information) back to the RFID reader through backscattering; the RFID reader sends the ID number, signal reception time and signal strength information to the RFID positioning module, and the RFID positioning module can find the corresponding coordinate information of the RFID electronic tag according to the ID number of the RFID electronic tag; when the RFID reader transmits the return information of the three RFID electronic tags to the RFID positioning module, the RFID positioning module uses the two-step weighted least squares method to estimate the position of the RFID reader according to the coordinates, signal reception time and signal strength information of the RFID electronic tags; the position of the RFID reader is the preliminary position of the vehicle.

[0095] like Figure 3 The figure shows the positioning results of the RFID positioning method. The horizontal axis in the figure represents the X-axis position, the vertical axis represents the Y-axis position, and the vertical axis represents the Z-axis position. The "red dots" in the figure represent the location information of the three RFID electronic tags, the "blue +" represents the actual location of the vehicle, and the "green square" represents the preliminary location information of the vehicle based on the RFID positioning method.

[0096] In the RFID positioning simulation experiment for vehicle positioning, it is assumed that the actual position of the vehicle in the tunnel is (8,180,2) (unit: meter). When the RFID positioning module on the vehicle obtains the position information and received signal strength information of the RFID electronic tag, it is assumed that information from three RFID electronic tags is received. The three RFID electronic tags are all arranged on the right side of the tunnel wall (the RFID positioning module and the RFID reader are both in the vehicle). The position coordinates of the three RFID electronic tags are A (0, 50, 2), B (0, 100, 2), and C (0, 150, 2) (unit: meter). In the experiment, the distance between the unknown node (i.e., the vehicle) and the three RFID electronic tags is estimated based on the signal strength information received by the RFID reader. The position of the unknown node can be estimated by using the two-step weighted least squares method. The result is (8, 180.9, 2) (unit: meter). This position information is regarded as the preliminary position information of the vehicle and compared with the actual position of the vehicle.

[0097] Step S1-2: The VLC positioning unit detects the preliminary position information of the vehicle through the VLC transmitter, VLC receiver and VLC positioning module:

[0098] The VLC transmitter consists of an LED lighting source on the top of the tunnel wall, which is used to emit visible light signals; the VLC receiver on the top of the vehicle receives the visible light signal, converts the visible light signal into an electrical signal and transmits it to the optical signal processing module; the optical signal processing module amplifies, filters and demodulates the received electrical signal, obtains the RSSI value and transmits it to the VLC positioning module; after receiving the RSSI value, the VLC positioning module estimates the distance between the vehicle and the VLC transmitter based on the conversion relationship model between RSSI and distance, and uses a two-step weighted least squares algorithm to calculate the preliminary position of the vehicle.

[0099] like Figure 4 As shown in the figure, the positioning results of the VLC positioning method are shown. The horizontal axis in the figure represents the X-axis position, the vertical axis represents the Y-axis position, and the vertical axis represents the Z-axis position. The "blue triangle" in the figure represents the position information of the three LED lighting sources, the "blue +" represents the actual position of the vehicle, and the "yellow ×" represents the preliminary position information of the vehicle obtained based on the VLC positioning method.

[0100] In the VLC positioning simulation experiment for vehicle positioning, it is assumed that the actual position of the vehicle in the tunnel is (8,180,2) (unit: meter). When the VLC positioning module on the vehicle obtains the position information and received signal strength information of the VLC transmitter, it is assumed that information from three VLC transmitters is received. The three VLC transmitters correspond to three LED lighting sources arranged on the top of the tunnel. The position coordinates of the three LED lighting sources are A (5,70,5), B (5,120,5) and C (5,170,5) (unit: meter). In the experiment, the distance between the unknown node (i.e., the vehicle) and the three LED lighting sources is estimated based on the signal strength information received by the VLC receiver. The position of the unknown node can be estimated by using the two-step weighted least squares method. The result is (8,179.2,2) (unit: meter). This position information is regarded as the preliminary position information of the vehicle and compared with the actual position of the vehicle.

[0101] S2, after receiving the preliminary vehicle location information transmitted by the RFID positioning unit and the VLC positioning unit in step S1, the multi-source information fusion module of the information fusion positioning unit calculates the final location of the vehicle by multi-source fusion, and visualizes the final location of the vehicle and transmits it to the tunnel light control unit and the information management platform through the first wireless communication module of the information fusion positioning unit;

[0102] The step S2 is specifically as follows:

[0103] Step S2-1: The multi-source information fusion module of the information fusion positioning unit uses the Kalman filter algorithm to perform data fusion processing on the preliminary location information of the RFID and VLC to calculate the final location of the vehicle;

[0104] Step S2-2: Displaying the final position information of the vehicle calculated in step S2-1 to the vehicle driver and management personnel through the vehicle electronic display screen;

[0105] Step S2-3: The first wireless communication module receives the final position information of the vehicle processed by the multi-source information fusion module in step S2-1, and transmits it to the tunnel lighting control unit and the information management platform via NB-IoT wireless communication.

[0106] like Figure 5As shown in the figure, the positioning results of the multi-source information fusion method are shown. The horizontal axis in the figure represents the X-axis position, the vertical axis represents the Y-axis position, and the vertical axis represents the Z-axis position. The "red dot" in the figure represents the position information of the three RFID electronic tags, the "blue +" represents the actual position of the vehicle, the "green square" represents the preliminary position information of the vehicle based on the RFID positioning method, the "blue triangle" represents the position information of the three LED lighting sources, the "yellow ×" represents the preliminary position information of the vehicle based on the VLC positioning method, and the "black pentagon" represents the final position information of the vehicle based on the joint positioning method of RFID and VLC.

[0107] In the RFID and VLC joint positioning simulation experiment for vehicle positioning, it is assumed that the actual position of the vehicle in the tunnel is (8,180,2) (unit: meter). After the multi-source information fusion module on the vehicle obtains the preliminary position information of RFID and VLC, it is assumed that information from three RFID electronic tags and three VLC transmitters are received. The three RFID electronic tags are arranged on the right side of the tunnel wall, and the position coordinates of the three RFID electronic tags are A (0, 50, 2), B (0, 100, 2), and C (0, 150, 2) (unit: meter); the three VLC transmitters correspond to three LED lighting sources arranged on the top of the tunnel, and the position coordinates of the three LED lighting sources are D (5, 70, 5), E (5, 120, 5), and F (5, 170, 5) (unit: meter). In the experiment, the distance between the unknown node (i.e., the vehicle) and the two RFID readers and the two LED lighting sources is estimated based on the signal strength information received by the RFID reader and the VLC receiver. By applying the Kalman filter, the final position of the unknown node can be estimated, and the result is (8,180.2,2) (unit: meter), which is regarded as the final position information of the vehicle.

[0108] S3, based on the vehicle position information transmitted by the first wireless communication module in step S2, controlling the change of the tunnel light:

[0109] After receiving the vehicle positioning information transmitted from the first wireless communication module, the congestion assessment module uses Kalman filtering to fuse and process the data from the first wireless communication module, and uses a linear regression model to analyze the data pre-processed by the Kalman filter, extracting three key features: vehicle spacing, traffic flow change rate, and vehicle speed distribution, to classify the traffic status; the lighting control module sends control instructions to the VLC transmitter on the top of the tunnel through the CAN bus according to the traffic conditions obtained by the congestion assessment module, adjusts the light color of the LED lamp, and realizes intelligent control of the tunnel lighting;

[0110] S4, based on the vehicle position information transmitted by the first wireless communication module in step S2, performing tunnel traffic condition early warning management:

[0111] The second wireless communication module on the information management platform receives the vehicle location information from the first wireless communication module, and transmits the vehicle location information to the early warning module. The early warning module sends early warning information to the staff to remind the staff to implement rescue in time.

[0112] The application effect of the present invention is described in detail below in conjunction with simulation experiments.

[0113] The simulation experiment considered different traffic flows and tunnel environmental conditions to evaluate the effectiveness of RFID, VLC, and the combined localization method of the two. The simulation was performed in a digital tunnel model designed according to the dimensions and characteristics of the actual tunnel. In the simulation, vehicles moved at different speeds and flow patterns to simulate peak and off-peak traffic conditions. The parameter settings of the RFID and VLC systems were based on the performance indicators of the actual equipment.

[0114] In the simulation experiment of the present invention, a tunnel environment is simulated, and RFID electronic tags and VLC transmitters are deployed therein. The RFID electronic tags are installed on the walls of both sides of the tunnel, and one RFID electronic tag is installed every 50 meters. The VLC transmitter is installed on the top of the tunnel, and one VLC transmitter is arranged every 10 meters. In the simulation, vehicles travel in the tunnel at speeds of 5m / s, 10m / s, 15m / s, 20m / s, and 25m / s, respectively, to simulate different traffic flows.

[0115] See Table 1, which lists in detail the root mean square error (RMSE) values ​​of each positioning method at different speeds.

[0116]

[0117] According to Table 1 above, when the vehicle is traveling in the tunnel at a speed of 10m / s, the RMSE of vehicle positioning is 0.9946 meters when the RFID-based positioning method is used; the RMSE of vehicle positioning is 0.6623 meters when the VLC positioning method is used; and the RMSE of positioning is only 0.3154 meters when the RFID and VLC-based vehicle positioning method is used. The simulation results show that the vehicle positioning accuracy when the RFID and VLC-based vehicle positioning method is used is better than that when only RFID or VLC is used. At the same time, it can be seen from the simulation results that the vehicle positioning system based on RFID and VLC shows higher vehicle positioning accuracy regardless of low speed or high speed conditions.

[0118] Figure 6(a)-(e) show the vehicle position simulation results obtained by using RFID-based positioning method, VLC-based positioning method, and RFID and VLC combined positioning method when the vehicle passes through the tunnel at speeds of 5m / s, 10m / s, 15m / s, 20m / s, and 25m / s respectively.

[0119] from Figure 6 It can be seen from the positioning curves provided by (a) and (b) that, under the same vehicle speed conditions, the deviation between the positioning curves of the RFID-based positioning method and the VLC-based positioning method and the actual position of the vehicle is relatively large, while the deviation between the positioning curve of the positioning method based on the combination of RFID and VLC and the actual position of the vehicle is relatively small. Specifically, Figure 6 (a) shows the positioning results when the vehicle passes through the tunnel at a speed of 5m / s. The RMSE value of the RFID-based positioning method is 0.9342 meters, the RMSE value of the VLC-based positioning method is 0.6132 meters, and the RMSE value of the RFID-VLC combined positioning method is only 0.2488 meters; Figure 6 (b) shows the positioning results when the vehicle passes through the tunnel at a speed of 10m / s. At this time, the RMSE value of the RFID-based positioning method is 0.9946 meters, the RMSE value of the VLC-based positioning method is 0.6623 meters, and the RMSE value of the RFID and VLC-based positioning method is reduced to 0.3154 meters.

[0120] Further observation Figure 6 From the performance of (c), (d) and (e) at higher speeds, we can see that as the vehicle speed increases, the RMSE values ​​of the RFID-based positioning method and the VLC-based positioning method change greatly. For example, at a speed of 15m / s, the RMSE value of the RFID-based positioning method increases to 1.0145 meters, the RMSE value of the VLC-based positioning method increases to 0.7245 meters, and the RMSE value of the RFID-VLC combined positioning method remains at around 0.3895 meters. At speeds of 20m / s and 25m / s, this trend continues, showing that the RFID-VLC combined positioning method can maintain high positioning accuracy at different speeds.

[0121] This simulation is done by Figure 6 The positioning curves provided in (a) and (b) are combined with the RFID positioning method and the VLC positioning method to simulate the root mean square error (RMSE) curves of the RFID positioning method, the VLC positioning method, and the RFID and VLC joint positioning method when the vehicle passes through the tunnel at a speed of 10m / s. Figure 7 shown.

[0122] observe Figure 7 From the root mean square error (RMSE) change curves of the three positioning methods, it can be found that when the vehicle passes through the tunnel at a speed of 10m / s, the value of the root mean square error change curve based on the RFID positioning method is in the range of 0.7-1.2, the value of the root mean square error change curve based on the VLC positioning method is in the range of 0.6-0.8, and the value of the root mean square error change curve based on the RFID and VLC joint positioning method is in the range of 0.2-0.6. Compared with RFID positioning and VLC positioning, the RFID and VLC joint positioning method can maintain a higher positioning accuracy.

[0123] From the above data analysis, it can be concluded that: no matter at low speed or high speed, the RFID and VLC joint positioning method provides the lowest RMSE value, that is, the highest positioning accuracy. This shows that by integrating the two technologies of RFID and VLC, the positioning accuracy of vehicles in tunnel scenarios can be significantly improved. And as the vehicle speed increases, the root mean square error (RMSE) values ​​of the positioning curves of the RFID-based positioning method and the VLC-based positioning method change greatly, while the root mean square error (RMSE) value of the positioning curve of the positioning method based on the joint positioning method of RFID and VLC changes relatively little, and does not change much with the increase of speed. This shows that the RFID and VLC joint positioning method can maintain a high positioning accuracy at different speeds and has good speed adaptability and robustness.

[0124] In summary, compared with the existing technology:

[0125] The present invention combines RFID positioning and VLC positioning to achieve full coverage positioning in the tunnel, ensuring that the vehicle can be effectively positioned at any position in the tunnel; at the same time, the continuity and stability of positioning information can be guaranteed regardless of whether it is driving at low speed or high speed.

[0126] The present invention adopts Kalman filtering algorithm to perform data fusion processing on the preliminary location information from RFID and VLC, thereby improving the accuracy and robustness of positioning; even when some tags or transmitters fail, the system can still achieve continuous tracking of the vehicle position through multi-source information fusion, ensuring the uninterrupted positioning service.

[0127] The radio frequency identification (RFID) technology and visible light communication (VLC) technology of the present invention not only achieve high-precision positioning, but also have the characteristics of low energy consumption; visible light communication (VLC) uses existing lighting facilities for communication, avoiding additional energy waste, and (RFID) technology reduces ineffective energy loss with its efficient signal processing capability.

[0128] In summary, the present invention proposes a vehicle positioning system based on radio frequency identification and visible light communication, wherein the preliminary position information of the vehicle is detected by an RFID positioning unit and a VLC positioning unit, and the information fusion positioning unit calculates the final position information of the vehicle according to the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and transmits the final position information of the vehicle to the tunnel lighting control unit and the information management platform to realize corresponding lighting control and early warning functions; the system is characterized by high-precision positioning and low energy consumption, realizes full coverage positioning of the tunnel, ensures the continuity and stability of positioning information, and greatly improves the intelligent level of tunnel traffic management.

[0129] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario, characterized in that: Including RFID positioning unit, VLC positioning unit, information fusion positioning unit, tunnel lighting control unit and information management platform; The RFID positioning unit is used to detect the preliminary position information of the vehicle and transmit the preliminary position information of the vehicle to the information fusion positioning unit; The VLC positioning unit is used to detect the preliminary position information of the vehicle and transmit the preliminary position information of the vehicle to the information fusion positioning unit; The information fusion positioning unit calculates the final position information of the vehicle based on the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and displays the final position information of the vehicle through the device and transmits it to the tunnel light control unit and the information management platform; The tunnel light control unit classifies the traffic congestion status according to the final position information of the vehicle, and implements corresponding light control according to the classification result; The information management platform is used to receive, process and analyze the final position information of the vehicle and issue early warning information when necessary.

2. According to claim 1, a vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario is characterized by: The RFID positioning unit includes an RFID electronic tag, an RFID reader and an RFID positioning module; The RFID electronic tag includes a microchip and an antenna. The microchip stores a unique ID number of the RFID electronic tag. The RFID electronic tag receives a radio frequency signal from an RFID reader through the antenna, and reflects the signal with its own ID number back to the RFID reader through backscattering, thereby achieving wireless communication with the RFID reader. The RFID reader is used to periodically send radio frequency signals; when the RFID reader arrives near a marking point where an RFID electronic tag is installed, the RFID electronic tag receives the radio frequency signal sent by the RFID reader, and uses backscattering technology to reflect the signal with its own ID number (including the tag ID number, signal reception time and signal strength information) back to the RFID reader; after the RFID reader receives the signal reflected by the RFID electronic tag, it transmits the tag ID number, reception time and signal strength information to the RFID positioning module by wireless means; The RFID positioning module is used to receive information transmitted by the RFID reader; the RFID positioning module pre-stores the coordinate parameters of all RFID electronic tag installation positions, and the RFID positioning module finds the corresponding coordinate information of the RFID electronic tag according to the ID number of the RFID electronic tag; when the RFID reader transmits the return information of no less than three RFID electronic tags to the RFID positioning module, the RFID positioning module estimates the position of the RFID reader using a two-step weighted least squares method based on the obtained RFID electronic tag coordinates, signal reception time and signal strength information; the position of the RFID reader is the preliminary position of the vehicle.

3. According to the vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario according to claim 1, it is characterized by: The VLC positioning unit includes a VLC transmitter, a VLC receiver and a VLC positioning module; The VLC transmitter is composed of a plurality of LED lighting sources and is used to transmit visible light signals; The VLC receiver is used to receive visible light signals from an LED lighting source; the VLC receiver includes a photodiode sensor and an optical signal processing module; the photodiode sensor is used to receive visible light signals, convert the optical signals into electrical signals, and transmit them to the optical signal processing module; The optical signal processing module amplifies and filters the received electrical signal, then uses a demodulation algorithm to convert the amplified and filtered electrical signal into a digital signal, and uses mean filtering to calculate the RSSI value corresponding to the received digital signal; finally, the RSSI information is transmitted to the VLC positioning module by wired transmission; The VLC positioning module is used to receive the RSSI value of the VLC receiver, establish a conversion relationship model between RSSI and distance, and estimate the distance between the VLC receiver and each VLC transmitter; based on the estimated distances between more than three VLC receivers and each VLC transmitter and the known positions of the VLC transmitters, a two-step weighted least squares algorithm is used to calculate the preliminary position of the vehicle.

4. A vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario according to claim 1, 2 or 3, characterized in that: The information fusion positioning unit includes a multi-source information fusion module, a position information display module and a first wireless communication module; The multi-source information fusion module is used to receive the preliminary position information of the vehicle detected by the RFID positioning unit and the VLC positioning unit, and calculate the final position of the vehicle using the Kalman filter algorithm; The position information display module is an on-board electronic display screen that displays the final position information of the vehicle for easy viewing by the driver and management personnel; The first wireless communication module is used to receive the vehicle final position information from the multi-source information fusion module and transmit it to the tunnel lighting control unit and information management platform via NB-loT wireless communication.

5. The vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario according to claim 4, characterized in that: The tunnel light control unit includes a congestion assessment module and a light control module; The congestion assessment module is used to monitor, analyze and evaluate traffic conditions in real time; the congestion assessment module receives vehicle positioning information transmitted by the first wireless communication module in the information fusion positioning unit, and collects traffic data, including vehicle flow, vehicle speed, vehicle density and driving time; based on the collected real-time traffic data, the traffic status is divided into four states: "unblocked", "mild congestion", "moderate congestion" and "severe congestion"; The lighting control module sends control instructions to the VLC transmitter through the CAN bus according to the traffic conditions obtained by the congestion assessment module, adjusts the light color of the LED lamp, and realizes intelligent control of the tunnel light.

6. The vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario according to claim 5, characterized in that: The intelligent control strategy of the tunnel lighting is: When the traffic condition is "smooth", the light source of the tunnel LED signal light is adjusted to white light; when the traffic condition is "mild congestion", the light source of the tunnel LED signal light is adjusted to green light; when the traffic condition is "moderate congestion", the light source of the tunnel LED signal light is adjusted to yellow light; when the traffic condition is "severe congestion", the light source of the tunnel LED signal light is adjusted to red light.

7. A vehicle positioning system based on radio frequency identification and visible light communication in a tunnel scenario according to claim 1 or 5, characterized in that: The information management platform includes a second wireless communication module and an early warning module; The second wireless communication module receives the encapsulated positioning message data from the first wireless communication module of the information fusion positioning unit, and transmits the encapsulated positioning message data to the information management platform through the NB-loT wireless communication protocol, and then sends it to the early warning module through the corresponding API interface; The warning module receives the vehicle position information from the second wireless communication module; If the position of the same vehicle remains basically unchanged within the range of the queue time index of the congestion standard, then it is considered that the vehicle has had an accident in the tunnel. At the same time, the early warning module sends an early warning message to the staff, reminding them to carry out rescue in a timely manner.

8. A vehicle positioning method based on radio frequency identification and visible light communication in a tunnel scenario, characterized in that: The specific steps include: S1. When a vehicle enters a tunnel, the RFID positioning unit and the VLC positioning unit respectively detect the preliminary location information of the vehicle and transmit it to the information fusion positioning unit; S2, after receiving the preliminary vehicle location information transmitted by the RFID positioning unit and the VLC positioning unit in step S1, the multi-source information fusion module of the information fusion positioning unit calculates the final location of the vehicle by multi-source fusion, and visualizes the final location of the vehicle and transmits it to the tunnel light control unit and the information management platform through the first wireless communication module of the information fusion positioning unit; S3, based on the vehicle position information transmitted by the first wireless communication module in step S2, controlling the change of the tunnel light: After receiving the vehicle positioning information transmitted from the first wireless communication module, the congestion assessment module uses Kalman filtering to fuse and process the data from the first wireless communication module, and uses a linear regression model to analyze the data pre-processed by the Kalman filter, extracting three key features: vehicle spacing, traffic flow change rate, and vehicle speed distribution, to classify the traffic status; the lighting control module sends control instructions to the VLC transmitter through the CAN bus according to the traffic conditions obtained by the congestion assessment module, adjusts the light color of the LED lamp, and realizes intelligent control of the tunnel lighting; S4, based on the vehicle position information transmitted by the first wireless communication module in step S2, performing tunnel traffic condition early warning management: The second wireless communication module on the information management platform receives the vehicle location information from the first wireless communication module, and transmits the vehicle location information to the early warning module. The early warning module sends early warning information to the staff to remind the staff to implement rescue in time.

9. The vehicle positioning method based on radio frequency identification and visible light communication in a tunnel scenario according to claim 8, characterized in that: The step S1 is specifically as follows: Step S1-1: The RFID positioning unit detects the preliminary location information of the vehicle through the RFID electronic tag, RFID reader and RFID positioning module: The RFID reader periodically sends radio frequency signals. When the RFID reader is close to the RFID electronic tag, the RFID electronic tag receives the radio frequency signal sent by the RFID reader and returns a signal with an ID number. After receiving the signal with the ID number, the RFID reader sends the ID number, signal reception time and signal strength information of the RFID electronic tag to the RFID positioning module. The RFID positioning module estimates the preliminary position of the vehicle using a two-step weighted least squares method. Step S1-2: The VLC positioning unit detects the preliminary position information of the vehicle through the VLC transmitter, VLC receiver and VLC positioning module: The VLC transmitter is composed of multiple LED lighting sources for emitting visible light signals; the VLC receiver receives the visible light signals and converts them into electrical signals for transmission to the optical signal processing module; The optical signal processing module amplifies, filters and demodulates the received electrical signal to obtain the RSSI value and transmits it to the VLC positioning module; after receiving the RSSI value, the VLC positioning module estimates the distance between the vehicle and the VLC transmitter based on the conversion relationship model between RSSI and distance, and uses a two-step weighted least squares algorithm to calculate the preliminary position of the vehicle.

10. A vehicle positioning method based on radio frequency identification and visible light communication in a tunnel scenario according to claim 8 or 9, characterized in that: The step S2 is specifically as follows: Step S2-1: The multi-source information fusion module of the information fusion positioning unit uses the Kalman filter algorithm to perform data fusion processing on the preliminary location information of the RFID and VLC to calculate the final location of the vehicle; Step S2-2: Displaying the final position information of the vehicle calculated in step S2-1 to the vehicle driver and management personnel through the vehicle electronic display screen; Step S2-3: The first wireless communication module receives the final position information of the vehicle processed by the multi-source information fusion module in step S2-1, and transmits it to the tunnel lighting control unit and the information management platform via NB-IoT wireless communication.

Images