A vehicle-mounted device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus

Abstract

The present invention discloses an in-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus, which includes a bus in-vehicle unit, an intelligent in-vehicle terminal, an in-vehicle display screen, and a rear LED display screen. The bus in-vehicle unit includes a data processing unit and a C-V2X communication unit. The C-V2X communication unit receives the basic information of the bus and the roadside information, including the real-time GPS position information of the bus, the driving speed and heading angle of the bus, the intersection map information in the forward direction of the bus, and the traffic light message information of this intersection. After processing these information, the data processing unit sends them to the intelligent in-vehicle terminal; the intelligent in-vehicle terminal sends the received real-time GPS position information of the bus, the driving speed and heading angle of the bus, and the traffic light message information of this intersection to the in-vehicle display screen for processing and display, and sends the traffic light message information of this intersection to the rear LED display screen for processing and display.

Description

Technical Field

[0001] The present invention relates to an in-vehicle device for displaying traffic lights at the intersection ahead, in particular to an in-vehicle device for real-time displaying traffic lights at the intersection ahead on the rear screen of a bus. Background Art

[0002] In recent years, with the rapid development of urban transportation, buses have become one of the indispensable means of transportation in daily travel. However, due to their high body and large volume, the cars following closely behind them cannot obtain the traffic light information of the current intersection, and it is easy to find the phenomenon of running a red light by mistake after following the bus. If waiting for the bus to drive out of the occlusion range before starting, it will seriously affect the traffic flow efficiency at the intersection, especially obvious during the morning and evening rush hours.

[0003] Currently, in-vehicle devices capable of displaying traffic light information at the current intersection have gradually emerged at home and abroad. However, since the traffic light information they display needs to be received, processed, and verified by the server and then forwarded to the in-vehicle device, there will be a large delay in the middle, and it is impossible to accurately provide traffic light information, resulting in traffic safety hazard problems. Summary of the Invention

[0004] Object of the Invention: The technical problem to be solved by the present invention is to provide an in-vehicle device for real-time displaying traffic lights at the intersection ahead on the rear screen of a bus in view of the deficiencies of the prior art.

[0005] To solve the above technical problem, the present invention discloses an in-vehicle device for real-time displaying traffic lights at the intersection ahead on the rear screen of a bus, including: an in-vehicle unit of the bus, an intelligent in-vehicle terminal, an in-vehicle display screen, and a rear LED display screen; wherein, the in-vehicle unit of the bus is installed on the bus and includes: a data processing unit and a C-V2X communication unit. The C-V2X communication unit receives the basic information of the bus and the roadside information, and the above information includes: the real-time GPS position information of the bus, the driving speed and heading angle of the bus, and the traffic light message information of the intersection ahead. The data processing unit processes the above information and then sends it to the intelligent in-vehicle terminal; the intelligent in-vehicle terminal sends the received real-time GPS position information of the bus, the driving speed and heading angle of the bus, and the traffic light message information of the intersection ahead to the in-vehicle display screen for processing and displaying, and at the same time sends the traffic light message information of the intersection ahead to the rear LED display screen for processing and displaying.

[0006] The roadside information comes from roadside devices, that is, the C-V2X communication unit requests roadside information from roadside devices;

[0007] The roadside information includes: the intersection map information of the intersection ahead and the traffic light message information, and the traffic light message information includes the light color and duration.

[0008] The roadside device includes: a communication unit, a traffic light information collection unit, and an intersection map information unit; wherein the intersection map information unit is used to collect the intersection map information of the front intersection, the traffic light information collection unit is used to collect the traffic light message information, and the communication unit is used to perform C-V2X communication with the C-V2X communication unit of the on-vehicle unit of the bus.

[0009] The intelligent in-vehicle terminal includes: a traffic light information processing unit and a vehicle information processing unit; wherein, the traffic light information processing unit receives the traffic light message information sent by the on-vehicle unit of the bus, packs the data according to the agreed protocol, and sends it to the in-vehicle display screen and the rear LED display screen for display. The vehicle information processing unit receives the basic information of the bus sent by the on-vehicle unit of the bus, packs the data according to the agreed protocol, and sends it to the in-vehicle display screen for display.

[0010] The data processing unit includes: a front intersection discrimination module, a traffic light message processing unit, and a C-V2X protocol stack; wherein, the front intersection discrimination module discriminates the front intersection according to the basic information of the bus and the roadside information, calculates the front intersection number, and through the C-V2X protocol stack and the C-V2X communication unit according to the number, obtains the roadside information of the corresponding number in the roadside device, and hands over the traffic light message information in the obtained roadside information to the traffic light message processing unit. The traffic light message processing unit sends the processed traffic light message information to the intelligent in-vehicle terminal.

[0011] The method for the front intersection discrimination module to discriminate the front intersection includes:

[0012] Step 1, when the bus departs, convert the longitude and latitude position of the bus at the current moment into a GeoHash string, traverse the preset static road network table, and compare bit by bit to select a set number of intersections with the most same digits, that is, the closest distance, to obtain the initially circled intersections.

[0013] Step 2, calculate the straight-line distance from the bus to each initially circled intersection at consecutive moments within a set time interval, and select the intersections with gradually decreasing straight-line distances as alternative intersections. If there are no intersections with decreasing straight-line distances, return to Step 1 and re-traverse the static road network table according to the longitude and latitude position of the bus at the current moment.

[0014] Step 3, calculate the shortest distance between the current position of the bus and the road sections where each alternative intersection is located at consecutive moments within a set time interval. If the shortest distances calculated for the front and rear time intervals differ by no more than the threshold, then determine that this road section is the road section where the bus is traveling; if there are no alternative intersections with the shortest distance difference less than the threshold, return to Step 1 and re-traverse the static road network table according to the longitude and latitude position of the bus at the current moment.

[0015] Step 4: Determine the position of the upcoming intersection by judging the straight-line distance between the bus and the two intersections of the road section where it is traveling, and obtain the upcoming intersection number according to the static road network table;

[0016] Step 5: Save the intersection information passed by the bus as historical intersections in the on-vehicle unit. When the straight-line distance between the current position of the bus and the upcoming intersection is less than the threshold, it is determined that the bus has reached this intersection.

[0017] The set time interval described in Step 2 and Step 3 is 1 second.

[0018] The threshold described in Step 3 and Step 5 is set to 5 meters.

[0019] The in-vehicle display screen at least includes a UI coprocessor and a 16-inch IPS liquid crystal screen.

[0020] The rear LED display screen at least includes a tail screen control card and a 1620*564mm color LED display screen.

[0021] Beneficial effects:

[0022] The present invention innovatively applies C-V2X communication technology to the on-vehicle unit of the bus, incorporates an upcoming intersection discrimination algorithm and a traffic light message processing method, and displays the traffic light information of the upcoming intersection for the following vehicle through an intelligent in-vehicle terminal connected to the rear LED display screen; compared with the prior art, it reduces the links of receiving, processing, and verifying through the server, can accurately provide traffic light information for the following vehicle, and while increasing the intersection passing efficiency, can also reduce the occurrence of traffic accidents. Description of the drawings

[0023] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0024] Figure 1 It is a schematic block diagram of an on-vehicle device for real-time displaying traffic lights of the upcoming intersection at the rear of the bus.

[0025] Figure 2 It is a schematic diagram of communication between the on-vehicle unit of the bus and roadside equipment.

[0026] Figure 3 It is a schematic diagram of determining the upcoming intersection in the case of unknown historical intersections.

[0027] Figure 4 It is a schematic diagram of determining the upcoming intersection in the case of known historical intersections. Specific embodiments

[0028] An on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus, comprising a bus on-vehicle unit, an intelligent on-vehicle terminal, an in-vehicle display screen and a rear LED display screen. The bus on-vehicle unit includes a data processing unit and a C-V2X communication unit. The C-V2X communication unit receives the basic information of the bus and the roadside information, including the real-time GPS position information of the bus, the driving speed and heading angle of the bus, the intersection map information in the forward direction of the bus, and the traffic light message information of the intersection. The data processing unit processes this information and sends it to the intelligent on-vehicle terminal; the intelligent on-vehicle terminal sends the received real-time GPS position information of the bus, the driving speed and heading angle of the bus, and the traffic light message information of the intersection to the in-vehicle display screen for processing and display, and sends the traffic light message information of the intersection to the rear LED display screen for processing and display.

[0029] In the present invention, the data processing unit receives the basic information of the bus and the roadside information through the C-V2X communication unit, including the real-time GPS longitude and latitude position, the driving speed and heading angle of the bus, calculates the intersection number in the forward direction of the bus through these information, and requests the traffic light message information and intersection map information of the corresponding intersection number from the roadside device through the C-V2X communication unit.

[0030] In the present invention, it includes roadside devices. The C-V2X communication unit requests the intersection map information and traffic light message information of the intersection ahead from the roadside device, including the light color and duration.

[0031] In the present invention, the intelligent on-vehicle terminal includes a traffic light information processing unit and a vehicle information processing unit, receives the traffic light message information and the basic information of the bus sent by the bus on-vehicle unit, and sends them to the in-vehicle display screen and the rear LED display screen for display.

[0032] In the present invention, the in-vehicle display screen includes a UI co-processor and a 16-inch IPS liquid crystal screen.

[0033] In the present invention, the rear LED display screen includes a tail screen control card and a 1620*564mm color LED display screen.

[0034] In the present invention, the data processing unit includes an algorithm for discriminating the intersection ahead: when the bus departs, since there is no historical intersection record, the longitude and latitude position of the bus at the current moment is converted into a GeoHash string, and the static road network table is traversed and compared bit by bit. The more identical bits, the closer the distance. Select several intersections with close distances and start further delineation.

[0035] Calculate the straight-line distances from the bus to each defined intersection at consecutive moments with an interval of 1 s. Select the intersections with gradually decreasing straight-line distances as candidate intersections for further screening. If there are no intersections with decreasing straight-line distances, return to the previous step and re-traverse the static road network table according to the latitude and longitude position at the current moment.

[0036] Calculate the shortest distances between the current position of the bus and the sections where each candidate intersection is located at consecutive moments with an interval of 1 s. If the difference in the shortest distances calculated for the front and rear time intervals does not exceed 5 m, determine that this section is the section where the bus is traveling. Lock the position of the front intersection by judging the straight-line distances between the bus and the two intersections of this section, and confirm its intersection number according to the static road network table. If there are no candidate intersections with a shortest distance difference less than 5 m, it is necessary to re-traverse the static road network table for screening according to the current latitude and longitude position.

[0037] In the present invention, the intersection information passed by the bus is saved as historical intersections in the on-vehicle unit of the bus. When the calculated straight-line distance between the current position of the bus and the front intersection is less than 5 m, it is judged that the bus has reached this intersection. The C-V2X communication unit requests intersection map information from the roadside equipment of this intersection, obtains the intersection numbers adjacent to this intersection, and determines the number of the next forward intersection by calculating the difference in the straight-line distances from the adjacent intersections.

[0038] Embodiment:

[0039] As Figure 1 shown, the present invention discloses an on-vehicle device for real-time display of traffic lights of the front intersection on the rear screen of a bus, including an on-vehicle unit of the bus, an intelligent on-vehicle terminal, an in-vehicle display screen, and a rear LED display screen. The on-vehicle unit of the bus includes a data processing unit and a C-V2X communication unit. The C-V2X communication unit receives the basic information of the bus and roadside information. The data processing unit calculates the number of the front intersection through the front intersection discrimination algorithm, and requests intersection map information and traffic light message information from the roadside equipment through the C-V2X communication unit. After processing these information, it is sent to the intelligent on-vehicle terminal, and the intelligent on-vehicle terminal sends the basic information of the bus and the traffic light message information to the in-vehicle display screen and the rear LED display screen for display.

[0040] The above-mentioned data processing unit uses the NXP IMX8MN application processor, which contains four ARM Cortex-A53 cores with a main frequency of 1.6 GHz, is configured with 2G of memory and 8G of flash memory, runs the Linux operating system, and the included C-V2X software protocol stack can communicate with other C-V2X devices; it contains a front intersection discrimination algorithm that receives real-time GPS longitude and latitude positions, the driving speed and heading angle of the bus through the C-V2X communication unit, calculates the intersection number in the forward direction of the bus, and requests traffic light message information and intersection map information from the roadside device corresponding to the intersection number through the C-V2X communication unit, and sends the basic information of the bus and the traffic light message information to the intelligent in-vehicle terminal.

[0041] The above-mentioned C-V2X communication unit uses the Datang GaoHong DMD3A module, which is based on the 3GPP Release 14 protocol, supports C-V2X PC5 direct communication, uses the globally unified ITS 5.9 GHz frequency band to communicate with roadside devices to receive traffic light message information and intersection map information; the Datang GaoHong DMD3A module can obtain GPS position information and clock information through the GNSS module.

[0042] The above-mentioned intelligent in-vehicle terminal uses the NXP LPC1768 microcontroller with an operating frequency of up to 100 MHz, runs the Linux operating system, includes a traffic light information processing unit and a vehicle information processing unit, receives the traffic light message information and the basic information of the bus sent by the on-vehicle unit of the bus, and sends them to the in-vehicle display screen and the rear LED display screen for display.

[0043] The above-mentioned in-vehicle display screen includes a UI coprocessor and a 16-inch IPS liquid crystal screen. The UI coprocessor uses an Intel Celeron J1800 with a main frequency of 2.41 GHz, receives formatted data through the network port, runs the IPS liquid crystal screen driver program for display, and mainly displays the basic information of the bus and the traffic light message information.

[0044] The above-mentioned rear LED display screen includes a tail screen control card and a 1620*564mm color LED display screen. The tail screen control card uses the NXP IMX6Q high-performance processor, which contains four ARM Cortex-A9 cores with a frequency of up to 1.2 GHz, is configured with 2G of memory and 8G of flash memory, runs the Linux operating system, receives formatted data through the 485 serial port, processes it, and controls the LED screen for display, mainly displaying the traffic light message information.

[0045] The historical intersection refers to the intersection that the bus has just driven to and left.

[0046] The road section where the alternative intersection is located refers to the road between the alternative intersection and its adjacent intersections.

[0047] The above-mentioned forward intersection discrimination algorithm relies on static road network data. By judging the distance from the section where the alternative intersection is located, the current section is locked, and then the position of the forward intersection is judged.

[0048] When the bus departs, since there is no historical intersection record, the longitude and latitude position of the bus at the current moment is converted into a GeoHash string, and the static road network table is traversed and compared bit by bit. The more digits are the same, the closer the distance is. Select several intersections with close distances and start further delineation.

[0049] Calculate the straight-line distance from the bus to each delineated intersection at consecutive moments with an interval of 1s. Select the intersection with a gradually decreasing straight-line distance as an alternative intersection for further screening. If there is no intersection with a decreasing straight-line distance, return to the previous step and traverse the static road network table again according to the longitude and latitude position at the current moment. The straight-line distance d from the bus to each delineated intersection is calculated by Formula 1 using the current longitude value X1, current latitude value Y1 of the bus, and the longitude value X2 and latitude value Y2 of the delineated intersection:

[0050]

[0051] Calculate the shortest distance Ln from the current position of the bus to the section where each alternative intersection is located at consecutive moments with an interval of 1s. Then the shortest distance difference ΔL can be calculated by Formula 2:

[0052] ΔL = |L n -L n-1 | (Formula 2)

[0053] If the shortest distance difference ΔL calculated for the front and back time intervals does not exceed 5m, it is determined that this section is the section where the bus is traveling. The straight-line distance between the bus and the two intersections of this section is judged by Formula 1 to lock the position of the forward intersection, and its intersection number is confirmed according to the static road network table; if there is no alternative intersection with a shortest distance difference ΔL less than 5m, it is necessary to traverse the static road network table again according to the current longitude and latitude position for screening.

[0054] The intersection information passed by the bus is saved as historical intersection information in the on-vehicle unit of the bus. When the straight-line distance between the current position of the bus and the forward intersection calculated by Formula 1 is less than 5m, it is judged that the bus has reached this intersection. The C-V2X communication unit will request the intersection map information from the roadside equipment of this intersection, obtain the intersection numbers adjacent to this intersection, and then calculate the straight-line distance between the current longitude and latitude position of the bus and these adjacent intersections by Formula 1, and calculate the difference change Δd between the front and back adjacent time intervals by Formula 3:

[0055] Δd = |d n -d n-1 | (Formula 3)

[0056] The intersection with the largest difference Δd between adjacent time intervals is the next intersection for the bus to proceed to, and its intersection number is confirmed based on the static road network table.

[0057] The vehicle-mounted device is installed in the bus in a rear-mounted manner, and the rear LED display screen needs to replace the original rear screen of the bus, such as Figure 2 As shown in the figure, a roadside device will be installed at each intersection, which will be directly connected to the traffic light at the intersection to obtain traffic light message information. When the bus-mounted unit calculates the number of the intersection ahead, it will request traffic light message information and intersection map information from the roadside device with the corresponding number, and send the traffic light message information and basic bus information to the in-vehicle display and the rear LED display for display through the intelligent vehicle terminal. The application of the C-V2X communication unit ensures the low latency of the device, so that the rear LED display is fully synchronized with the traffic light information at the intersection, and can provide real-time traffic light information to the following vehicles.

[0058] like Figure 3 As shown in the figure, B1, B2, B3, and B4 are the locations of the bus every second during its driving process when it just starts. First, the longitude and latitude of B1 are converted into a GeoHash string, and the three intersections R1, R2, and R3 are circled after traversing the static road network table and comparing them bit by bit.

[0059] Formula 1 can be used to calculate the straight-line distances d1, d2, and d3 between the bus at positions B1, B2, and B3 and the three intersections R1, R2, and R3:

[0060]

[0061] The calculation shows that when the bus travels from position B1 to position B3, the straight-line distances d1 and d2 decrease, while d3 increases, which means that the bus is approaching the intersections R1 and R2. At this time, these two intersections are selected as candidate intersections for the next step of screening. If there is no gradually decreasing distance in the calculated straight-line distance, it is necessary to convert the current latitude and longitude position of the bus into a GeoHash string and re-traverse the static road network for screening.

[0062] like Figure 3 As shown, the two alternative intersections R1 and R2 involve r 10 、r 12 、r 14 、r 23 、r 25 、r 26 There are six sections in total, and the section in the middle of the alternative intersection is preferred. 12 , calculate the current location of the bus and the road section r 12 The shortest distance Ln, then the shortest distance difference ΔL can be calculated by formula 2:

[0063] ΔL = |L n - L n-1 | (Formula 2)

[0064] The shortest distance difference ΔL calculated from the time intervals before and after does not exceed 5 m, and the road section r 12 is determined to be the road section where the bus is traveling. By using Formula 1 to judge the straight-line distances between the bus and the two intersections (R1, R2) of this road section, it is found that the bus is approaching R2 while moving away from R1. Thus, R2 is determined to be the intersection in front of the bus, and its intersection number is confirmed according to the static road network table. If there is no alternative intersection with the shortest distance difference ΔL less than 5 m, then first select the remaining r 10 , r 14 , r 23 , r 25 , r 26 five road sections to continue the calculation; if it still does not meet the condition that the shortest distance difference ΔL is less than 5 m, then it is necessary to convert the current longitude and latitude position of the bus into a GeoHash string and re-traverse the static road network for screening.

[0065] As Figure 4 shown, when the straight-line distance between the current longitude and latitude position of the bus and intersection R2 calculated by Formula 1 is less than 5 m, it is judged that the bus has reached intersection R2 at this time. The C-V2X communication unit will request the map information of intersection R2 from the roadside device of intersection R2, and parse to obtain the three intersections R3, R5, and R6 adjacent to intersection R2. Then, the straight-line distances d3, d5, and d6 between the current longitude and latitude position of the bus and these three intersections are calculated by Formula 1, and the difference change Δd between the adjacent time intervals before and after is calculated by Formula 3:

[0066] Δd = |d n - d n-1 | (Formula 3)

[0067] Among them, the intersection with the largest difference change Δd between the adjacent time intervals before and after is the next intersection where the bus will move forward. In the figure, it is intersection R6, and its intersection number is confirmed according to the static road network table.

[0068] The on-vehicle device is installed in the bus in a retrofit manner, and the rear LED display screen at the rear of the vehicle needs to replace the original rear screen of the bus, as Figure 2As shown in the figure, a roadside device will be installed at each intersection, which is directly connected to the signal machine at that intersection to obtain traffic light message information. When the on-vehicle unit of the bus calculates the number of the intersection ahead, it requests traffic light message information and intersection map information from the roadside device corresponding to the number, and sends the traffic light message information and the basic information of the bus to the in-vehicle display screen and the rear LED display screen through the intelligent on-vehicle terminal for display. The application of the C-V2X communication unit ensures the low latency of the device, making the rear LED display screen fully synchronized with the traffic light information at the intersection, and enabling real-time traffic light information to be provided for the following vehicle.

[0069] In specific implementation, the present application provides a computer storage medium and a corresponding data processing unit. Among them, the computer storage medium can store a computer program, and when the computer program is executed by the data processing unit, it can run the inventive content of an on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus and some or all of the steps in each embodiment. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0070] Those skilled in the art can clearly understand that the technical solutions in the embodiments of the present invention can be implemented by means of a computer program and its corresponding general hardware platform. Based on such an understanding, the essence of the technical solutions in the embodiments of the present invention, or the part that contributes to the prior art, can be embodied in the form of a computer program, that is, a software product. The computer program software product can be stored in the storage medium, including several instructions for causing a device (which can be a personal computer, a server, a single-chip microcomputer, a MUU, or a network device, etc.) containing a data processing unit to execute the methods described in each embodiment or some parts of the embodiments of the present invention.

[0071] The present invention provides an idea and method for an on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus. There are many methods and ways to specifically implement this technical solution. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by the prior art.

Claims

1. An on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus, characterized in that, Including: A bus on-vehicle unit, an intelligent vehicle terminal, an in-vehicle display screen, and a rear LED display screen; among them, the bus on-vehicle unit is installed on the bus and includes: a data processing unit and a C-V2X communication unit. The C-V2X communication unit receives the basic information of the bus and the roadside information. The above information includes: the real-time GPS position information of the bus, the driving speed and heading angle of the bus, and the traffic light message information of the front intersection. The data processing unit processes the above information and sends it to the intelligent vehicle terminal; the intelligent vehicle terminal sends the received real-time GPS position information of the bus, the driving speed and heading angle of the bus, and the traffic light message information of the front intersection to the in-vehicle display screen for processing and display, and at the same time sends the traffic light message information of the front intersection to the rear LED display screen for processing and display; Among them, the data processing unit includes: a front intersection discrimination module, a traffic light message processing unit, and a C-V2X protocol stack; among them, the front intersection discrimination module discriminates the front intersection according to the basic information of the bus and the roadside information, calculates the front intersection number, and through the C-V2X protocol stack and the C-V2X communication unit according to the number, obtains the roadside information corresponding to the number in the roadside device, and hands the traffic light message information in the obtained roadside information to the traffic light message processing unit. The traffic light message processing unit sends the processed traffic light message information to the intelligent vehicle terminal; The method for the front intersection discrimination module to discriminate the front intersection includes: Step 1, when the bus departs, convert the longitude and latitude position of the bus at the current moment into a GeoHash string, traverse the preset static road network table, and compare bit by bit to select a set number of intersections with the most identical digits, that is, the closest distance, to obtain the initially circled intersections; Step 2, calculate the straight-line distance from the bus to each initially circled intersection at consecutive moments within a set time interval, and select the intersections with gradually decreasing straight-line distances as alternative intersections. If there are no intersections with decreasing straight-line distances, return to Step 1 and re-traverse the static road network table according to the longitude and latitude position of the bus at the current moment; Step 3, calculate the shortest distance between the current position of the bus and the road sections where each alternative intersection is located at consecutive moments within a set time interval. If the shortest distances calculated for the front and rear time intervals differ by no more than a threshold, it is determined that this road section is the road section where the bus is driving; if there are no alternative intersections with a shortest distance difference less than the threshold, return to Step 1 and re-traverse the static road network table according to the longitude and latitude position of the bus at the current moment; Step 4, determine the position of the front intersection by judging the straight-line distance between the bus and the two intersections of the driving road section, and obtain the front intersection number according to the static road network table; Step 5, save the intersection information passed by the bus as historical intersections in the bus on-vehicle unit. When the straight-line distance between the current position of the bus and the front intersection is less than the threshold, it is determined that the bus has reached this intersection.

2. The on-vehicle device for real-time display of traffic lights at the front intersection on the rear screen of a bus according to claim 1, characterized in that, The roadside information comes from roadside devices, that is, the C-V2X communication unit requests roadside information from roadside devices; The roadside information includes: intersection map information of the upcoming intersection and traffic light message information, where the traffic light message information includes the light color and duration.

3. The on-vehicle device for real-time display of traffic lights at the front intersection on the rear screen of a bus according to claim 2, wherein, The roadside device includes: a communication unit, a traffic light information collection unit, and an intersection map information unit; among them, the intersection map information unit is used to collect the intersection map information of the upcoming intersection, the traffic light information collection unit is used to collect the traffic light message information, and the communication unit is used to perform C-V2X communication with the C-V2X communication unit of the on-vehicle unit of the bus.

4. The on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus according to claim 1, characterized in that, The intelligent in-vehicle terminal includes: a traffic light information processing unit and a vehicle information processing unit; among them, the traffic light information processing unit receives the traffic light message information sent by the on-vehicle unit of the bus, packs the data according to the agreed protocol, and sends it to the in-vehicle display screen and the rear LED display screen for display. The vehicle information processing unit receives the basic information of the bus sent by the on-vehicle unit of the bus, packs the data according to the agreed protocol, and sends it to the in-vehicle display screen for display.

5. The on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus according to claim 4, wherein, The set time interval described in steps 2 and 3 is 1 second.

6. The on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus according to claim 5, characterized in that, The threshold value described in steps 3 and 5 is set to 5 meters.

7. The on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus according to claim 1, wherein The in-vehicle display screen at least includes a UI coprocessor and a 16-inch IPS liquid crystal screen.

8. The on-vehicle device for real-time display of traffic lights at the intersection ahead on the rear screen of a bus according to claim 1, characterized in that, The rear LED display screen at least includes a tail screen control card and a 1620*564mm color LED display screen.

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