Background
In an urban intelligent traffic system, devices such as a fixed coil and a geomagnetic traffic detector are widely used for collecting traffic parameters and detecting traffic events. Chinese patent document CN104103171A discloses a method for detecting a double-section traffic incident, which selects two sections of a road, obtains traffic parameters of the two sections, obtains a clock drift rate, obtains a data recovery coefficient, and further improves the detection effect of a double-section traffic incident detection algorithm.
In recent years, the development of vehicle-Road cooperation technology is rapid, and an On Board Unit (OBU) mounted On a vehicle and a Road Side Unit (RSU) arranged On the Road Side are gradually used in the fields of vehicle speed monitoring, Road emergency prompting and early warning, and the like. Chinese patent document CN104064048A discloses an optimum speed processing method for automobile curve running based on an on-board unit and a road side unit, which uses the curve corner, radius, gravity center height of the vehicle, etc. to calculate the optimum running speed of the vehicle, and feeds back the optimum running speed to the on-board unit through the road side unit. Chinese patent document CN104537852A discloses a road accident prompting method based on a vehicle-mounted unit and a road side unit, which judges and prompts the accident of a road traffic accident according to the speed limit condition of the road and the braking frequency threshold of the vehicle.
The equipment such as the fixed coil, the geomagnetic traffic detector and the like can only acquire macroscopic traffic flow parameters but cannot acquire the running information of individual vehicles; in addition, the vehicle-mounted unit can upload the running information of the individual vehicle to the road side unit, but part of macro traffic flow parameters are not easy to acquire. Therefore, a single fixed coil and a geomagnetic traffic detector, or a single vehicle-mounted unit and a road side unit all face the problems that traffic information is incomplete and traffic information collection is easily affected by external factors, which is not beneficial to comprehensively reflecting the running condition of traffic flow and the detection and early warning of traffic events.
Disclosure of Invention
The invention aims to provide a road traffic incident detection and early warning method and a road traffic incident detection and early warning system based on vehicle-road cooperation, aiming at the technical defects in the prior art.
The technical scheme adopted for realizing the purpose of the invention is as follows:
a road traffic incident detection early warning method based on vehicle-road cooperation comprises the following steps,
1) the road side unit arranged at one side of the road is used for collecting the running speed and GPS information of all running vehicles in a preset period, simultaneously, the geomagnetic traffic detector arranged corresponding to the road side unit is used for detecting the sensing speed and road occupancy of the running vehicles,
2) calculating an average vehicle speed and an average occupancy, determining that a traffic event occurs when the average vehicle speed is less than a threshold speed and the average occupancy is greater than the threshold occupancy,
3) calculating the dissipation/accumulation critical speed, determining the section positions of the dissipation area and the accumulation area, and early warning or dredging and shunting the vehicle at the upstream position of the section position of the accumulation area.
The road side unit is arranged at a lane narrowing position, an entrance and exit ramp position, an ascending middle position of an overpass or a traffic jam frequent position, and the geomagnetic traffic detectors are respectively and correspondingly arranged on lanes at preset distances at the upstream and the downstream of the road side unit.
The preset period is 10 minutes to 20 minutes.
The average vehicle speed is the average value of the running vehicle speeds and the sensed vehicle speeds of all vehicles in the preset period, the average occupancy is the average value of the road occupancy of each lane in the preset period, and the threshold speed is 15-22 km/h; the threshold occupancy is 30%.
The method for calculating the dissipation/accumulation critical speed is as follows: finding out the value of the minimum running speed detected by the road side unit in the preset period, and if the value is less than or equal to 10km/h, determining the minimum speed value as 10 km/h; if the minimum running vehicle speed value detected by the road side unit is greater than 10km/h, determining the minimum vehicle speed value according to an actual value; adding 8-12km/h on the basis of the minimum vehicle speed value, and taking the value as the dissipation/accumulation critical speed.
The method for determining the section positions of the dissipation area and the accumulation area comprises the following steps: analyzing running vehicle speed data on the downstream of the road side unit, finding out a vehicle which is closest to the road side unit and has a running vehicle speed greater than or equal to the dissipation/accumulation critical speed, determining GPS (global position system) position information of the vehicle and determining the position of the vehicle as the section position of the dissipation area; analyzing the running vehicle speed data at the upstream of the road side unit, finding out the vehicle which is closest to the road side unit and has the running vehicle speed greater than or equal to the dissipation/accumulation critical speed, determining the GPS position information of the vehicle and determining the position of the vehicle as the section position of the accumulation area.
The vehicle is early-warned or the diversion flow is set at the upstream of the section position of the accumulation area by 150-200m meters; if the cross section position upstream of the accumulation area has an entrance ramp within the range of 500-800m meters, the entrance ramp is set at the position of 150-200 meters upstream of the entrance ramp.
A detection and early-warning system for realizing the road traffic incident detection and early-warning method comprises an on-board unit which is in communication connection with a vehicle ECU (electronic control Unit), a plurality of road side units which are arranged at intervals on the road side and can be in communication with the on-board unit, and geomagnetic traffic detectors which are arranged corresponding to the road side units.
The road side unit is arranged at a lane narrowing position, an entrance and exit ramp position, an ascending middle position of the overpass or a traffic jam frequent position, and geomagnetic traffic detectors are correspondingly arranged on lanes at preset distances at the upstream and downstream of the road side unit respectively.
The vehicle-mounted unit is in communication connection with the vehicle ECU through a CAN bus.
Compared with the prior art, the invention has the beneficial effects that:
by jointly using the vehicle-mounted unit, the road side unit and the geomagnetic traffic detector of the vehicle, macroscopic traffic flow parameters can be obtained, and the operation information of individual vehicles can also be obtained, so that the information source of traffic event detection is enriched, and the reliability and accuracy of the traffic event detection are improved; in addition, the position of issuing the early warning information is reasonably determined on the basis of the section of the accumulation area, so that the traffic early warning effect is favorably improved, and the traffic jam is further relieved.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1-4, the detection and early warning system for implementing the detection and early warning method of road traffic events according to the present invention includes an on-board unit communicatively connected to a vehicle ECU, a plurality of roadside units disposed at intervals on the roadside and capable of communicating with the on-board unit, and a geomagnetic traffic detector disposed corresponding to the roadside units. The road side unit is arranged at a lane narrowing position, an entrance and exit ramp position, an ascending middle position of an overpass or a traffic jam frequent position, and geomagnetic traffic detectors are correspondingly arranged on lanes at preset distances at the upstream and the downstream of the road side unit respectively. The vehicle-mounted unit is in communication connection with the vehicle ECU through a CAN bus module, and meanwhile, the vehicle end also comprises a vehicle-mounted unit in communication connection with the vehicle-mounted unit, the vehicle-mounted unit is in communication with a communication module, specifically, in order to realize the communication between the roadside unit and the vehicle, as shown in figure 3, the vehicle-mounted unit obtains the vehicle speed and GPS position information of the vehicle through the vehicle CAN bus module and the GPS module, and the vehicle speed and GPS position information are sent to a read-write control module of the roadside unit through the communication module by using a special short-range communication technology; when traffic early warning is required, the read-write control module of the road side unit transmits traffic early warning information to the vehicle-mounted unit through the communication module by using a special short-range communication technology for the driver to refer to.
The invention realizes the collection of the running speed and the GPS information by utilizing the communication between the road side units and the vehicle, realizes the full coverage of the road, especially an express way or an expressway or the full coverage of partial key areas by the plurality of road side units arranged at intervals, is convenient for information collection and early warning information distribution, and judges the road traffic incident by combining the average speed and the average road occupancy rate and accurately by combining the adoption of a geomagnetic traffic detector.
As one specific example, first, a plurality of roadside units are installed at a place where traffic congestion is often recognized by a traffic management department, then, 2 geomagnetic traffic detectors 3, 4 are installed at a position 100 meters upstream of one of the cores, such as the roadside unit at the middle, and 2 geomagnetic traffic detectors 1, 2 are installed at a position 100 meters downstream of the roadside unit. Wherein, earth magnetic traffic detectors 1, 3 are installed on a lane, and earth magnetic traffic detectors 2, 4 are installed on a lane.
The vehicle runs on the road, the vehicle-mounted unit obtains the speed and the GPS position information of the vehicle through the vehicle CAN bus module and the GPS module, and the vehicle speed and the GPS position information are sent to the road side unit through the communication module by using a special short-range communication technology; the geomagnetic traffic detector collects lane occupancy and vehicle speed information, which is similar to the prior art and will not be described herein.
Assuming that the time is 7:00-8:00 early peak and the traffic information acquisition cycle is 10 minutes, in the traffic information acquisition cycle, m vehicles pass through the road side unit, the running vehicle speed and the GPS position information are sent to the road side unit, and the running vehicle speed acquired by the road side unit is recorded as: v. of1,RSU,v2,RSU,…,vm,RSUThe average speed of the geomagnetic traffic detectors 1, 2, 3, and 4 is recorded as: v. of1,DC,v2,DC,v3,DC,v4,DCThe average occupancy rate acquired by the geomagnetic traffic detectors 1, 2, 3, and 4 is recorded as: occupanacy1,DC,Occupancy2,DC,Occupancy3,DC,Occupancy4,DC. The average vehicle speed is recorded as: (v)1,DC+v2,DC+v3,DC+v4,DC)/4+(v1,RSU+v2,RSU+...+vm,RSU) /m) ÷ 2; average Occupancy was reported as (Occupanacy)1,DC+Occupancy2,DC+Occupancy3,DC+Occupancy4,DC)/4. It is assumed that the calculated average vehicle speed is 18km/h and the average occupancy is 35% within a traffic information collection period of 10 minutes.
Since the average occupancy is greater than or equal to 30% and the average vehicle speed is less than 15-22km/h, such as 20km/h,and judging that a traffic incident occurs. Finding out the minimum running speed value detected by the road side unit in a traffic information acquisition cycle, and recording the minimum running speed value as min { v }1,RSU,v2,RSU,...,vm,RSUDetermining the minimum vehicle speed value as 10km/h if the value is less than or equal to 10 km/h; if min { v1,RSU,v2,RSU,...,vm,RSUAnd if the speed is larger than 10km/h, determining the minimum vehicle speed according to an actual value. Then, 8-12km/h, such as 8km/h, is added on the basis of the minimum vehicle speed value, and the value is taken as the dissipation/accumulation critical speed. Suppose min { v1,RSU,v2,RSU,...,vm,RSUWith a value of 13km/h, the dissipation/accumulation critical speed is determined to be 21 km/h.
Analyzing the running vehicle speed data at the downstream of the road side unit based on the vehicle speed data detected by other road side units distributed on one side of the road, finding out the vehicle which is closest to the road side unit and has the running vehicle speed of more than or equal to 21km/h, determining the GPS position information of the vehicle, and determining the section where the vehicle is located as the section position of the dissipation area, such as A1 shown in FIG. 2; and analyzing the running vehicle speed data at the upstream of the road side unit on the basis of the running vehicle speed data detected by the road side unit, finding out the vehicle which is closest to the road side unit and has the running vehicle speed of more than or equal to 21km/h, determining the GPS position information of the vehicle, and determining the section where the vehicle is located as the section position of the accumulation area, such as A2 shown in FIG. 2. The area from a1 to a2 is referred to as a traffic event impact zone.
Then, determining an early warning information release position according to the traffic incident influence area, and setting a traffic early warning information release position S1 at a position 150-200 meters upstream of the section position of the accumulation area, as shown in FIG. 2, performing early warning at the position to effectively remind a driver to reduce the speed of the vehicle and prevent secondary accidents, wherein the early warning mode can be broadcasting through a road side unit at the position, and the like; meanwhile, if there is an entrance ramp in the range of 500-800 meters upstream of the section position of the accumulation area, the warning reminding position is set at the position of 150-200 meters upstream of the entrance ramp, as shown in the position S2 in fig. 2, and the warning information issuing form can be broadcast, vehicle-mounted short message or notice board. Namely, the traffic early warning is carried out on the vehicles which are at the upstream of the traffic early warning information release positions S1 and S2 and have the same running direction as the traffic flow direction of the vehicle at the side.
The invention jointly uses the vehicle-mounted unit, the road side unit and the geomagnetic traffic detector, and judges whether a traffic incident occurs or not by taking the average speed and the average occupancy as indexes; calculating the dissipation/accumulation critical speed, determining the positions of the sections of the dissipation area and the accumulation area, and arranging traffic early warning equipment at the upstream position of the accumulation area to early warn vehicles.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.