Background
In recent years, the operation mileage and traffic flow of expressways in China are continuously increased, the construction and management of traffic monitoring systems of expressways are greatly improved, and a large number of traffic detection devices such as detection coils, videos and bayonets are used for traffic safety early warning and emergency work of expressways. However, the current traffic monitoring mode mainly depends on macroscopic traffic flow detection, and the operation information of individual vehicles is not fully mastered, so that the pertinence and timeliness of traffic early warning are required to be improved. Under severe weather conditions (e.g., fog, rain, snow), highway traffic accidents occur frequently, in part for reasons including: the driver is unfamiliar with the road condition and is easy to run at overspeed; after the traffic accident, the alarm is not timely, so that the following vehicles cannot timely master the front road condition and traffic early warning information, and further, the more serious secondary traffic accident is caused. Therefore, the method has very important practical significance in early warning of the running speed of the expressway.
At present, the expressway of China mainly adopts a static running vehicle speed guiding mode, and part of expressways adopt a dynamic running vehicle speed guiding mode of a branching section, and the basis is that the change analysis of macroscopic traffic flow (flow, density and speed) is adopted; however, under low flow conditions (e.g., nighttime, sparse roads), macroscopic traffic flow changes are insignificant, resulting in passive, untimely, and delayed emergency treatment of traffic early warning. In recent years, vehicle-road cooperation technology is developed worldwide, and through the vehicle-road cooperation technology, the running information (such as actual running position, speed, acceleration and deceleration, parking condition and the like) of the individual vehicles is obtained, so that the accuracy of traffic information is improved.
The Chinese patent document CN201210379451.1 discloses a highway speed guidance system, which detects parameters such as instant speed, vehicle head distance and the like through a vehicle detector, combines weather and environmental parameters, gives a vehicle acceleration and deceleration suggestion according to the minimum safety distance between vehicles, and issues the suggestion on an LED display screen above a lane. The Chinese patent document CN201410234707.9 discloses a system for controlling the speed of a main line of a highway, which adopts a video detector to detect traffic flow, and optimally gives out a dynamic speed limit value of each lane or an operation instruction for closing the lane by a self-defined fuzzy rule by a traffic guidance control system and outputs the dynamic speed limit value or the operation instruction to LED variable speed limit marks of each lane. The Chinese patent document CN201210427353.0 discloses a highway variable speed limit control system and a control method under a rainy day environment, wherein a ring-shaped coil detector is used for collecting traffic flow, a dynamic bottleneck road section is determined by combining real-time rainfall, and a road section speed limit value is given according to the density and speed relation of the traffic flow and is displayed on a variable speed limit plate.
According to the method, the speed of the macroscopic traffic flow is guided mainly through the analysis of the macroscopic traffic flow of the expressway, and the running speed early warning of the individual vehicles cannot be realized due to the lack of running information of the individual vehicles. The Chinese patent document CN201610643513.3 discloses a system and a method for guiding the safe speed of a highway in a foggy environment facing an intelligent network-connected automobile. According to the method, only the foggy day factor is considered, the triggering condition is single, other severe weather (such as snow and rainfall) is not considered, and the applicability of vehicle speed guidance is limited; in addition, the method omits the early warning of the speed of the individual vehicles running on dangerous road nodes (tunnel exits, curves and accident multiple road sections).
Summary of the invention
The invention aims to overcome the defects and provide a highway running speed active early warning system and method based on vehicle-road cooperation.
The specific steps of the invention are as follows:
the highway operation speed active early warning system based on the cooperation of the vehicle and the road comprises a road side unit for collecting traffic flow information and a weather monitor for collecting weather information, wherein the weather monitor comprises a visibility detector, a rain and snow gauge and a communication module for being communicated with the road side unit, and the road side unit is used for being communicated with a vehicle-mounted unit of the vehicle.
The road side unit comprises a communication module and a data processing module, and is arranged at the position 500-1000 m upstream and downstream of the inlet and outlet of the main line of the expressway, 200-300 m downstream of the tunnel outlet, the middle position of a curve and the middle position of a accident-prone road section.
The vehicle-mounted unit and the road side unit are communicated by adopting a special short-range communication DSRC technology, the road side unit and the weather monitor are communicated by using a 3G or 4G network, the visibility detector is arranged on a foggy road section, and the rain and snow meter is arranged along the expressway.
The road side unit is characterized by further comprising a variable speed indication board which is in communication connection with the road side unit, wherein the variable speed indication board comprises an LED display screen and a warning lamp.
The control method of the expressway operation speed active early warning system based on the vehicle-road cooperation is characterized by comprising the following steps of,
1) The weather monitor collects weather information and classifies weather respectively, wherein the weather information comprises rainfall, snowfall and visibility; dividing each type of weather information into a plurality of weather grades, wherein each weather grade corresponds to a corresponding weather limiting speed, and the weather limiting speed corresponding to the higher weather grade is smaller;
2) Determining a weather limit vehicle speed according to weather conditions, and determining the weather limit vehicle speed according to the weather conditions of the highest level when a plurality of weather conditions exist;
3) The recommended vehicle speed is set according to the weather-defined vehicle speed and is directly notified to the on-vehicle unit.
And 3) comparing the weather-limited vehicle speed with the smooth vehicle speed, taking a smaller value as a recommended vehicle speed and informing the vehicle-mounted unit, wherein the actual running vehicle speed of the road section is acquired in a period, when the absolute value of the difference value between the running vehicle speed of the road section and the running vehicle speed of an upstream or downstream road section in the period is greater than or equal to a difference threshold value, the smooth vehicle speed in the next period is calculated according to the running vehicle speed of the upstream or downstream road section, and when the absolute value of the difference value between the running vehicle speed of the road section and the running vehicle speed of the upstream or downstream road section is less than the difference threshold value, the smooth vehicle speed is equal to the running vehicle speed.
The method for calculating the smoothing speed is that,Wherein V (xi-1, t) is the running speed of the upstream road section, V (xi+1, t) is the running speed of the downstream road section,/>As the weight coefficient, when the speed of the downstream road section is greater than or equal to the speed of the upstream road section, the speed of the upstream road section is equal to or greater than the speed of the upstream road sectionThe value range is 0.6-1.0, and when the speed of the downstream road section is smaller than that of the upstream road section, the speed of the upstream road section is greater than that of the downstream road sectionThe value range is 0-0.4.
And when at least two pieces of weather information are located at the highest weather grade, executing the weather limiting speed after upgrading the highest weather grade by one step.
Meteorological information corresponding to severe weather is divided into four grades of 1,2,3 and 4, and meteorological limiting speeds corresponding to different grades of weather are respectively 80km/h, 60km/h, 40km/h and 20km/h and are driven away from an expressway.
For the main line section, extracting 85% bit vehicle speeds collected by the head end and tail end road side units of the section, and then averaging to serve as the running vehicle speed of the section; for tunnel exits, curves and accident multiple road sections, taking the 85% position vehicle speed collected by a road side unit as the running vehicle speed, and sending an early warning of 'front driving too fast and cautiously driving' to an upstream vehicle if the running vehicle speed is greater than or equal to the set 85% position vehicle speed in one detection period; in one detection period, when road side units at the places detect more than 2 vehicles, the maximum braking deceleration is more than or equal to 7.0 m/s2, and the parking time of the vehicles is more than or equal to 2 minutes, traffic accidents are judged, and a front danger is sent to upstream vehicles to ask for early warning of deceleration driving.
The invention has the following effects:
By using the visibility detector, the rain and snow gauge, the road side unit and the vehicle-mounted unit, weather information, real-time traffic flow information and running information of individual vehicles can be obtained, the running speed of the road is dynamically optimized by dividing the weather into sections and branching the road sections, the speed difference of adjacent sections of the expressway is reduced, and the traffic efficiency is improved; and (3) carrying out running speed early warning on tunnel exits, curves and accident multiple road sections, and improving the traffic safety level.
Detailed Description
The invention will be further described with reference to specific examples and drawings.
The invention discloses an active early warning system for expressway operation speed based on vehicle-road cooperation, which comprises a road side unit for collecting traffic flow information and a weather monitor for collecting weather information, wherein the weather monitor comprises a visibility detector, a rain and snow gauge and a communication module for communicating and connecting with the road side unit, and the road side unit is used for communicating with a vehicle-mounted unit of a vehicle.
The active early warning system for the expressway operation speed collects weather information, real-time traffic flow information and operation information of individual vehicles, analyzes the weather information, obtains the weather limited speed of expressway sections, early warns operation vehicles of tunnel exits, curves and accident multiple sections, and sends an operation speed recommended value and early warning information to a vehicle-mounted unit for reference of vehicle drivers.
The expressway operation speed active early warning system based on the vehicle-road cooperation carries out information interaction through wireless communication, wherein a road side unit and a vehicle-mounted unit interact through a special short-range communication DSRC technology, and a meteorological monitor and the road side unit interact through a 3G or 4G technology. The weather monitor consists of a visibility detector and a rain and snow gauge, and can detect visibility, rainfall and snowfall. The traffic information acquisition system consists of a road side unit and a vehicle-mounted unit, wherein the vehicle-mounted unit of the vehicle acquires the speed, braking deceleration, parking time and vehicle position of the vehicle and sends the vehicle speed, braking deceleration and parking time indexes of the vehicle to the road side unit through the wireless communication module, and the road side unit acquires the flow, the speed, the vehicle braking deceleration and the vehicle parking time indexes of the section where the road side unit is positioned.
Specifically, road side units are installed at 500-1000 m upstream and downstream of a main line entrance of a highway, 200-300 m downstream of a tunnel exit, at the middle position of a curve and at the middle position of a accident-prone road section; the middle position of the main line section of the expressway is provided with a visibility detector and a rain and snow gauge, and the equipment layout of the section and the tunnel outlet is shown in the figure; the visibility detector detects a visibility index, and the rain and snow gauge detects rainfall intensity and a snow fall index; the vehicle-mounted unit of the vehicle collects the speed, braking deceleration, parking time and vehicle position of the vehicle and sends the speed, braking deceleration, parking time and vehicle position to the communication module of the road side unit through the wireless communication module, and the road side unit collects the flow, speed, vehicle braking deceleration and vehicle parking time indexes of the section where the road side unit is located.
The data processing module of the road side unit is responsible for calculating the running speed of the road section/node. For the main line section, extracting 85% bit vehicle speeds collected by the head end and tail end road side units of the section, and then averaging to serve as the running vehicle speed of the section; and regarding the tunnel exit, the curve and the accident multiple road sections, taking the 85% vehicle speed collected by the road side unit as the running vehicle speed.
The visibility detector acquires visibility information, the rain and snow gauge acquires rainfall and snowfall information, and bad weather is classified into four grades of 1, 2,3 and 4, and weather limiting speeds corresponding to different grades of weather are respectively 80km/h, 60km/h, 40km/h and 20km/h and are driven away from the expressway; when two indexes of visibility, rainfall and snowfall simultaneously meet a certain early warning level, the early warning level of the running vehicle speed is increased by one step; the vehicle speed operation early warning information is prompted through the vehicle-mounted unit. When no bad weather exists, the meteorological limiting speed is the normal highway section speed limit value. If the speed limit value of the straight road section is 120km/h generally, the speed limit of the curve road section is 80-100km/h, the speed limit of the tunnel is 60-80km/h, the weather limiting vehicle speed can be directly transmitted to the vehicle-mounted unit through the communication module of the road side unit, and meanwhile, each speed limit value can also be directly transmitted to the speed limit prompt board arranged on the road side, such as a variable speed indication board, and the variable speed indication board comprises an LED display screen and a warning lamp. Speed warning and notification is performed through numbers and visual colors.
In order to improve the overall vehicle speed control little, the meteorological limiting vehicle speed is sent to the road side unit, and then is sent to the vehicle-mounted unit after being processed, and if the meteorological limiting vehicle speed is compared with the smooth vehicle speed, the meteorological limiting vehicle speed is sent to the vehicle-mounted unit by taking a small value.
Specifically, when the absolute value of the difference between the running vehicle speeds of the road section and the upstream or downstream road section is smaller than the difference threshold, the road section is considered to run stably, the smooth vehicle speed is the running vehicle speed, when the absolute value of the difference between the running vehicle speeds of the road section and the upstream or downstream road section is larger than or equal to the difference threshold, for example, 20km/h, the data processing module calculates the smooth vehicle speed of the next period of the road section as the speed difference between the smooth road sections: Wherein V (xi-1, t) is the running speed of the upstream road section, V (xi+1, t) is the running speed of the downstream road section,/>As the weight coefficient, when the speed of the downstream road section is greater than or equal to the speed of the upstream road section, the speed of the upstream road section is equal to or greater than the speed of the upstream road sectionThe value range is 0.6-1.0, and when the speed of the downstream road section is smaller than that of the upstream road section, the speed of the upstream road section is greater than that of the downstream road sectionThe value range is 0-0.4. And when the next period starts, the data processing module sends smaller values of the weather limited speed and the smooth speed to the road side unit through the wireless communication module, and the road side unit sends the smaller values to the vehicle-mounted unit through the wireless communication module for a vehicle driver to refer to, so that the running speed of the vehicle is guided, and the road section running speed guiding flow is shown in fig. 4.
Meanwhile, the system also gives an early warning to the running vehicle speed of the tunnel outlet, the curve and the accident-prone road section. In a detection period, if the 85% of the vehicle speed detected by the road side units at the places is greater than or equal to a set speed limit value, the road side units are sent to the vehicle-mounted units of the upstream vehicles through the wireless communication module, and early warning of 'driving ahead too fast and driving cautiously' is sent; in a detection period, when road side units at the places detect more than 2 vehicles, the maximum braking deceleration is more than or equal to 7.0 m/s2, and the parking time of the vehicles is more than or equal to 2 minutes, the road side units judge that traffic accidents occur, send the traffic accidents to the vehicle-mounted units of upstream vehicles through the wireless communication module, send forward danger to the upstream vehicles and ask for early warning of deceleration driving. The early warning flow of the speed of the tunnel exit, the curve and the accident-prone road section is shown in figure 5.
Further details are provided below by way of specific examples.
In the first step, the data processing module of the road side unit is responsible for calculating the running speed of the road section/node. And for the main line section, extracting the 85% bit vehicle speed collected by the head end and tail end road side units of the section, and then averaging to serve as the running vehicle speed of the section. For example, the speed of 85% bits collected by a road side unit at the head end of a certain road section is 100km/h, and the speed of 85% bits collected by a road side unit at the tail end is 90km/h, and the running speed of the road section is 95km/h; for tunnel exits, curves and accident-prone sections, the 85% bit vehicle speed collected by the road side units is used as the running vehicle speed, for example, the 85% bit vehicle speed is 80km/h.
And secondly, grading and early warning of bad weather. Dividing severe weather into four grades of 1,2, 3 and 4 according to visibility, rainfall and snowfall information, wherein weather limiting speeds corresponding to different grades of weather are respectively 80km/h, 60km/h, 40km/h and 20km/h, and the weather limiting speeds are driven off the expressway. The classification and early warning of bad weather are shown in the following table.
When two indexes of visibility, rainfall and snowfall simultaneously meet a certain early warning level, the early warning level of the running vehicle speed is improved by one step. For example, the visibility of a certain road section is 200m < L < 500m, about 300m, and meanwhile, the early warning level is improved from 1 level to 2 levels, and the corresponding weather limiting speed is recommended to be reduced from 80km/h < 60km/h, for example, the weather limiting speed is 60km/h.
And thirdly, calculating the smooth vehicle speed of the road section for balancing the vehicle flow of each road section on the premise of giving the weather limited vehicle speed. When the absolute value of the running vehicle speed difference between the road section and the upstream or downstream road section is larger than or equal to a difference threshold value, such as 20km/h, the data processing module calculates the smooth vehicle speed of the next period of the road section for the speed difference between the smooth road sections:
Wherein V (xi-1, t) is the running speed of the upstream road section, V (xi+1, t) is the running speed of the downstream road section,/>Is a weight coefficient. Assuming that the running speed of the road section is 55km/h, the running speeds of the upstream and downstream road sections are 35km/h and 85km/h, respectively, the absolute value of the difference between the running speeds of the road section and the upstream road section is 20km/h, and the absolute value of the difference between the running speeds of the road section and the downstream road section is 30km/h. To smooth the speed difference of different road sections,/>And if the value is 0.6, calculating a vehicle speed suggested value of the road section as follows: v Smoothing(xi, t+Δt) = (1-0.6) ×35+0.6× 85=65 km/h, the vehicle-mounted unit is notified that the weather-defined vehicle speed and the smoothed vehicle speed take small values, i.e., the notified vehicle speed is 60km/h.
And fourthly, simultaneously, the invention also gives an early warning to the running speed of the tunnel outlet, the curve and the accident-prone road section. In one detection period, the road side units at the sites detect 85% bit vehicle speed (such as 80km/h in the first step), and if the detected speed is greater than or equal to a set speed limit value, such as 70km/h, the risk of overspeed operation exists. In one detection period, when the road side units at the places detect more than 2 vehicles, the maximum braking deceleration is more than or equal to 7.0 m/s2, and the parking time of the vehicles is more than or equal to 2 minutes, for example, the maximum braking deceleration of 3 vehicles is 7.0 m/s2, 7.3 m/s2 and 7.5 m/s2, and the parking time of the vehicles is 4 minutes, 3 minutes and 2 minutes respectively, the risk of occurrence of a rear-end collision accident is judged. The above situation requires an early warning. The information release system sends the early warning information of the expressway running speed to the vehicle-mounted unit.
In summary, the invention firstly judges the weather limit speed according to the weather condition, the speed is the maximum allowable speed, the road side unit sends the vehicle-mounted unit of the road section vehicle through the wireless communication module, and the early warning information such as bad weather and speed limit of 60km/h is sent. When the next period starts, the data processing module acquires and calculates a smooth vehicle speed or a 85% vehicle speed through the wireless communication module, and the road side unit sends small values of each speed limit to the vehicle-mounted unit through the wireless communication module so as to be used for a vehicle driver to refer to, and the running speed of the vehicle is guided.
In addition, when the risk of overspeed operation exists at the positions of tunnel exits, curves and accident multiple road sections, the road side units are sent to the vehicle-mounted units of upstream vehicles through the wireless communication modules, and early warning of 'driving ahead is too fast and driving cautiously' is sent; when the traffic accident risk exists, the road side unit sends the traffic accident risk to the vehicle-mounted unit of the upstream vehicle through the wireless communication module, and sends a front danger to the upstream vehicle to request early warning of deceleration driving.
It is to be understood that the above examples are presented by way of illustration only and not limitation. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it intended that all embodiments be exhaustive, but obvious variations or modifications that come within the scope of the invention are desired.