CN104325978A

CN104325978A - Safety anti-collision early warning method based on vehicular ad-hoc network

Info

Publication number: CN104325978A
Application number: CN201410561883.3A
Authority: CN
Inventors: 黄刘生; 王兴隆; 冷冰; 徐宏力; 郭寒松
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2014-10-21
Filing date: 2014-10-21
Publication date: 2015-02-04

Abstract

The invention discloses a safety anti-collision early warning method based on Internet of Vehicles, comprising the following steps: a vehicle-mounted terminal obtains position information and driving state information of the vehicle, and sends the position information and driving status information of the vehicle when the vehicle brakes. Status information; If the vehicle-mounted terminal monitors the location information and driving status information of the vehicle in front, the vehicle-mounted terminal calculates the actual distance between the two vehicles, the safety distance and the risk factor of the two vehicles; the vehicle-mounted terminal performs early warning processing according to the size of the risk factor, and The driver gives a voice prompt. It is especially suitable for vehicles traveling on expressways, which can improve driving safety and reduce collision accidents on expressways.

Description

A safety anti-collision warning method based on Internet of Vehicles

技术领域technical field

本发明属于汽车安全技术领域，具体涉及一种基于车联网的安全防碰撞预警方法。The invention belongs to the technical field of automobile safety, and in particular relates to a safety anti-collision early warning method based on the Internet of Vehicles.

背景技术Background technique

在车联网(Vehicular Ad-hoc Network,VANET)中，高速移动的车辆通过无线自组织网络的形式实时共享交通路况信息，提高驾驶安全性。In the Vehicular Ad-hoc Network (VANET), high-speed moving vehicles share traffic information in real time through a wireless ad-hoc network to improve driving safety.

近来，高速公路上频繁发生车辆连环相撞事故，给国家和人民带来了巨大的经济损失。如何提高行车安全，降低事故发生率已经成为一个至关重要的问题。在高速公路上，事故通常是由前车紧急制动，而后车来不及反应造成的。这是由于高速公路上车速快、车距远，反应时间短和天气条件(如大雾、暴雨和大雪)的影响，驾驶员往往很难注意到周围车辆的运行状态，最终酿成事故。Recently, serial collisions of vehicles frequently occur on expressways, which have brought huge economic losses to the country and the people. How to improve driving safety and reduce the accident rate has become a crucial issue. On the highway, accidents are usually caused by the car in front braking suddenly, but the car behind has no time to react. This is due to the fast speed, long distance between vehicles, short reaction time and the influence of weather conditions (such as heavy fog, heavy rain and heavy snow) on the expressway. It is often difficult for drivers to notice the running status of surrounding vehicles, which eventually leads to accidents.

发明内容Contents of the invention

本发明目的在于提供一种基于车联网的安全防碰撞预警方法，特别适用于高速公路行驶的车辆，可以提高行车安全，降低高速公路的碰撞事故。The purpose of the present invention is to provide a safety anti-collision early warning method based on the Internet of Vehicles, which is especially suitable for vehicles traveling on expressways, which can improve driving safety and reduce collision accidents on expressways.

为达到上述目的，本发明的技术方案是：一种基于车联网的安全防碰撞预警方法，包括以下步骤:To achieve the above object, the technical solution of the present invention is: a safety anti-collision early warning method based on Internet of Vehicles, comprising the following steps:

(1)车载终端获得本车车辆的位置信息和行驶状态信息，当本车车辆刹车时，发送本车车辆的位置信息和行驶状态信息；(1) The vehicle-mounted terminal obtains the location information and driving status information of the vehicle, and sends the location information and driving status information of the vehicle when the vehicle brakes;

(2)如果车载终端监测到前方车辆的位置信息和行驶状态信息，车载终端计算两车之间的实际距离dis，两车的安全距离sd和危险系数β；(2) If the vehicle-mounted terminal monitors the location information and driving status information of the vehicle in front, the vehicle-mounted terminal calculates the actual distance dis between the two vehicles, the safety distance sd and the risk factor β between the two vehicles;

(3)车载终端根据危险系数大小进行预警处理，并对驾驶员发出语音提示。(3) The vehicle-mounted terminal performs early warning processing according to the size of the risk factor, and issues voice prompts to the driver.

优选的，所述位置信息至少包括经纬度、地面航向角、时间；所述行驶状态信息至少包括行驶方向和加速度。Preferably, the location information includes at least latitude and longitude, ground heading angle, and time; the driving state information includes at least driving direction and acceleration.

优选的，车辆的前后关系通过下列公式得出：Preferably, the front-rear relationship of the vehicle is obtained by the following formula:

$\{\begin{matrix} ((radLon radLon 22 - - radLon radLon 11)) \times \times R R - - tan the tan ((Sur facecour se Sur face course 11 + + 4545)) \times \times ((radLat radLat 22 - - radLat radLat 11)) \times \times R R < < 00 \\ ((radLon radLon 22 - - radLon radLon 11)) \times \times R R - - tan the tan ((Sur facecour se Sur face course 11 - - 4545)) \times \times ((radLat radLat 22 - - radLat radLat 11)) \times \times R R > > 00 \end{matrix}$

其中radLat1和radLat2分别表示两车的纬度，radLon1和radLon2分别表示两车的经度，Surfacecourse1表示本车车辆的地面航向角，R表示地球半径常量。Among them, radLat1 and radLat2 represent the latitude of the two vehicles, radLon1 and radLon2 respectively represent the longitude of the two vehicles, Surfacecourse1 represents the ground heading angle of the vehicle, and R represents the constant radius of the earth.

优选的，所述两车实际距离dis根据车辆的经纬度坐标计算，计算公式为：Preferably, the actual distance dis between the two vehicles is calculated according to the latitude and longitude coordinates of the vehicles, and the calculation formula is:

$dis dis = = 22 \times \times arcsin arcsin ((\sqrt{{sin sin}^{22} ((\frac{radLat radLat 11 - - radLat radLat 22}{22})) + + cos cos ((radLat radLat 11)) \times \times cos cos ((radLat radLat 22)) \times \times {sin sin}^{22} ((\frac{radLon radLon 11 - - radLon radLon 22}{22}))})) \times \times R R$

其中，radLat1和radLat2分别表示两车的纬度，radLon1和radLon2分别表示两车的经度，R表示地球半径常量。Among them, radLat1 and radLat2 represent the latitude of the two vehicles respectively, radLon1 and radLon2 represent the longitude of the two vehicles respectively, and R represents the earth radius constant.

优选的，所述两车的安全距离sd的计算公式为：Preferably, the formula for calculating the safety distance sd of the two vehicles is:

sd＝T*|v₁-v₂|；sd=T*| _v1 - _v2 |;

其中v₁是本车车速，v₂是前车车速，T为反应时间。Among them, v ₁ is the speed of the vehicle, v ₂ is the speed of the front vehicle, and T is the reaction time.

优选的，所述车速v根据经纬度坐标计算，计算公式为：Preferably, the vehicle speed v is calculated according to latitude and longitude coordinates, and the calculation formula is:

$v v = = \frac{22 * * R R * * arcsin arcsin ((\sqrt{{sin sin}^{22} ((\frac{radLat radLat 11 - - radLat radLat 22}{22})) + + cos cos ((radLat radLat 11)) \times \times cos cos ((radLat radLat 22)) \times \times {sin sin}^{22} ((\frac{radLon radLon 11 - - radLon radLon 22}{22}))}))}{{t t}_{22} - - {t t}_{11}}$

其中，t₂和t₁分别表示当前时间和上一次时间，radLat1和radLat2分别表示上一位置的纬度和当前位置的纬度，radLon1和radLon2分别表示上一位置的经度和当前位置的经度，R表示地球半径常量。Among them, t ₂ and t ₁ represent the current time and the last time respectively, radLat1 and radLat2 represent the latitude of the previous position and the latitude of the current position respectively, radLon1 and radLon2 represent the longitude of the previous position and the longitude of the current position respectively, and R represents Earth radius constant.

优选的，所述危险系数β计算公式为：Preferably, the formula for calculating the risk factor β is:

$β β = = \frac{sd sd - - dis dis}{dis dis} . .$

本发明还提供了一种基于车联网的安全防碰撞预警系统，包括采集车辆的加速度信息以及判断车辆是否刹车的加速度模块；采集车辆位置信息以及判断本车与刹车车辆的距离的GPS模块；用于通信和信息处理的无线通信模块；用于报警提示的语音模块。The present invention also provides a safety anti-collision early warning system based on the Internet of Vehicles, including an acceleration module for collecting vehicle acceleration information and judging whether the vehicle is braking; a GPS module for collecting vehicle position information and judging the distance between the vehicle and the braking vehicle; Wireless communication module for communication and information processing; voice module for alarm prompt.

相对于现有技术中的方案，本发明的优点是：Compared with the scheme in the prior art, the advantages of the present invention are:

1.本方法利用车联网实时通信技术来获取相关信息，能够不断获取邻车最新的GPS数据，并且计算出其车速，使得误差较小；1. This method uses the Internet of Vehicles real-time communication technology to obtain relevant information, can continuously obtain the latest GPS data of neighboring vehicles, and calculate its speed, making the error smaller;

2.本方法利用无线模块进行数据处理，减少了系统的体积，便于在高速公路环境下部署；2. This method uses the wireless module for data processing, which reduces the volume of the system and facilitates deployment in the highway environment;

3.本方法将邻车的预警信息保存在优先级队列中，并选择危险系数最大的信息进行处理，给予驾驶员报警，实用性较高；3. This method saves the early warning information of adjacent vehicles in the priority queue, and selects the information with the largest risk factor for processing, and gives the driver an alarm, which has high practicability;

4.本方法的适用范围较大，在浓雾、暴雪等恶劣天气在都能可靠使用。4. The scope of application of this method is relatively large, and it can be used reliably in bad weather such as dense fog and snowstorm.

附图说明Description of drawings

下面结合附图及实施例对本发明作进一步描述：The present invention will be further described below in conjunction with accompanying drawing and embodiment:

图1为本发明应用场景示意图；Fig. 1 is a schematic diagram of the application scene of the present invention;

图2为本发明基于车联网的安全防碰撞预警方法的流程图；Fig. 2 is the flowchart of the safety anti-collision warning method based on Internet of Vehicles in the present invention;

图3为本发明基于车联网的安全防碰撞预警方法的经纬网示意图；Fig. 3 is the schematic diagram of the latitude and longitude network of the safety anti-collision warning method based on the Internet of Vehicles in the present invention;

图4为本发明基于车联网的安全防碰撞预警方法的由经纬度判断车辆前后位置示意图；Fig. 4 is a schematic diagram of judging the front and rear positions of the vehicle by the longitude and latitude of the safety anti-collision warning method based on the Internet of Vehicles in the present invention;

图5为本发明基于车联网的安全防碰撞预警方法的两车的坐标表示示意图。FIG. 5 is a schematic representation of the coordinates of two vehicles in the safety anti-collision warning method based on the Internet of Vehicles in the present invention.

具体实施方式Detailed ways

为使发明的目的、技术方案和优点更加清楚明了，下面结合具体实施方式并参照附图，对发明进一步详细说明。应该理解，这些描述只是示例性的，而并非要限制本发明的范围。此外，在以下说明中，省略了对公知结构和技术的描述，以避免不必要地混淆本发明的概念。In order to make the purpose, technical solution and advantages of the invention clearer, the invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only, and are not intended to limit the scope of the present invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.

实施例：Example:

本实施例的基于车联网的安全防碰撞预警系统中车载终端以1HZ频率来获取GPS数据，计算本车行驶速度，以固定频率(如5HZ)从加速度模块获取本车加速度信息。当车辆刹车时，将通过实时无线通信来与周围车辆的车载终端交换自身的GPS信息，包括地面航向、经纬度坐标、速度、加速度等信息。In the safety anti-collision warning system based on Internet of Vehicles in this embodiment, the vehicle-mounted terminal obtains GPS data at a frequency of 1HZ, calculates the driving speed of the vehicle, and obtains the acceleration information of the vehicle from the acceleration module at a fixed frequency (such as 5HZ). When the vehicle brakes, it will exchange its own GPS information with the vehicle-mounted terminals of the surrounding vehicles through real-time wireless communication, including ground heading, latitude and longitude coordinates, speed, acceleration and other information.

如图1所示，当前车刹车时，自车将收到前车的预警信息。自车将执行基于车联网的高速公路主动安全系统的方法，对相应的信息进行处理，并在需要时给驾驶员发出语音预警信息。As shown in Figure 1, when the front car brakes, the own car will receive the warning information of the front car. The self-vehicle will implement the method of the highway active safety system based on the Internet of Vehicles, process the corresponding information, and send a voice warning message to the driver when necessary.

如图2所示，该方法包括以下步骤：As shown in Figure 2, the method includes the following steps:

(1)车载终端的GPS传感器获得车辆的位置信息(经纬度、地面航向角、时间)，通过GPS信息计算车辆当前行驶速度v。车载终端的加速度传感器获得车辆的行驶状态信息(加速度)；(1) The GPS sensor of the vehicle-mounted terminal obtains the location information of the vehicle (latitude and longitude, ground heading angle, time), and calculates the current driving speed v of the vehicle through the GPS information. The acceleration sensor of the vehicle terminal obtains the driving state information (acceleration) of the vehicle;

(2)当车辆刹车时，后向周围车辆发送自车的GPS位置、行驶速度、行驶方向等信息；(2) When the vehicle brakes, it will send information such as the GPS position, driving speed, and driving direction of the vehicle to surrounding vehicles;

(3)如果前车刹车(前车加速度小于阈值A_d)时，本车车辆将根据前车车辆和本车车辆的经纬度坐标计算两车之间的实际距离dis，并根据两车的车速差计算出两车的安全距离sd，并计算危险系数β；(3) If the front vehicle brakes (the acceleration of the front vehicle is less than the threshold A _d ), the vehicle will calculate the actual distance dis between the two vehicles according to the latitude and longitude coordinates of the vehicle in front and the vehicle, and calculate the actual distance dis between the two vehicles according to the speed difference between the two vehicles Calculate the safety distance sd between the two vehicles, and calculate the risk factor β;

(4)自车车辆选择危险系数最大的预警信息进行处理，并对驾驶员发出相应的语音提示。(4) The self-vehicle selects the warning information with the largest risk factor for processing, and sends corresponding voice prompts to the driver.

步骤(3)中根据本车车辆的经纬度坐标和邻近车辆的经纬度坐标计算两车实际距离dis，公式为：In step (3), the actual distance dis between the two vehicles is calculated according to the latitude and longitude coordinates of the own vehicle and the latitude and longitude coordinates of adjacent vehicles, the formula is:

$dis dis = = 22 \times \times arcsin arcsin ((\sqrt{{sin sin}^{22} ((\frac{radLat radLat 11 - - radLat radLat 22}{22})) + + cos cos ((radLat radLat 11)) \times \times cos cos ((radLat radLat 22)) \times \times {sin sin}^{22} ((\frac{radLon radLon 11 - - radLon radLon 22}{22}))})) \times \times R R - - - - - - ((I I))$

其中，radLat1和radLat2分别表示两车的纬度，radLon1和radLon2分别表示两车的经度，R表示地球半径常量。Among them, radLat1 and radLat2 respectively represent the latitude of the two vehicles, radLon1 and radLon2 represent the longitude of the two vehicles respectively, and R represents the earth radius constant.

步骤(1)中根据本车车辆的经纬度坐标和邻近车辆的经纬度坐标计算本车车速v，公式为：In step (1), the vehicle speed v is calculated according to the latitude and longitude coordinates of the vehicle and the latitude and longitude coordinates of adjacent vehicles, the formula is:

$v v = = \frac{22 * * R R * * arcsin arcsin ((\sqrt{{sin sin}^{22} ((\frac{radLat radLat 11 - - radLat radLat 22}{22})) + + cos cos ((radLat radLat 11)) \times \times cos cos ((radLat radLat 22)) \times \times {sin sin}^{22} ((\frac{radLon radLon 11 - - radLon radLon 22}{22}))}))}{{t t}_{22} - - {t t}_{11}} - - - - - - ((II II))$

其中，t₂和t₁分别表示当前时间和上一次时间，radLat1和radLat2分别表示本车的上一位置的纬度和当前位置的纬度，radLon1和radLon2分别表示本车的上一位置的经度和当前位置的经度，R表示地球半径常量；Among them, t ₂ and t ₁ represent the current time and the last time respectively, radLat1 and radLat2 represent the latitude of the previous position of the vehicle and the latitude of the current position respectively, radLon1 and radLon2 represent the longitude and current position of the previous position of the vehicle respectively The longitude of the location, R represents the earth's radius constant;

步骤(3)中周围车辆是否在本车车辆的行驶前方是通过计算车辆前后关系得到的，公式为：In step (3), whether the surrounding vehicles are in front of the vehicle is obtained by calculating the relationship between the front and rear of the vehicle, and the formula is:

$\{\begin{matrix} ((radLon radLon 22 - - radLon radLon 11)) \times \times R R - - tan the tan ((Sur facecour se Sur face course 11 + + 4545)) \times \times ((radLat radLat 22 - - radLat radLat 11)) \times \times R R < < 00 \\ ((radLon radLon 22 - - radLon radLon 11)) \times \times R R - - tan the tan ((Sur facecour se Sur face course 11 - - 4545)) \times \times ((radLat radLat 22 - - radLat radLat 11)) \times \times R R > > 00 \end{matrix} - - - - - - ((III III))$

其中，radLat1和radLat2分别表示两车的纬度，radLon1和radLon2分别表示两车的经度，Surfacecourse1表示自身车辆的地面航向角，R表示地球半径常量。Among them, radLat1 and radLat2 represent the latitude of the two vehicles respectively, radLon1 and radLon2 represent the longitude of the two vehicles respectively, Surfacecourse1 represents the ground course angle of the self-vehicle, and R represents the earth radius constant.

步骤(3)中计算两车的安全距离sd的公式为：The formula for calculating the safety distance sd of the two vehicles in step (3) is:

sd＝T*|v₁-v₂| (IV)sd=T*|v ₁ -v ₂ | (IV)

其中，v₁是自车车速，v₂是邻车车速，T为反应时间。Among them, v ₁ is the speed of the own vehicle, v ₂ is the speed of the neighboring vehicle, and T is the reaction time.

计算两车的危险系数β的公式为：The formula for calculating the risk factor β of the two vehicles is:

$β β = = \frac{sd sd - - dis dis}{dis dis} - - - - - - ((V V))$

具体的，利用GPS数据中的经纬度坐标计算车节点间距离的原理如下：Specifically, the principle of using the latitude and longitude coordinates in the GPS data to calculate the distance between vehicle nodes is as follows:

经纬网图上，可以根据经纬度量算两点之间的距离。全球各地纬度1°的间隔长度都相等(因为所有经线的长度都相等)，大约是111km/1°。赤道上经度1°对应在地面上的弧长大约也是111km。由于各纬线从赤道向两极递减，60°纬线上的长度为赤道上的一半，所以在各纬线上经度差1°的弧长就不相等。在同一条纬线上(假设此纬线的纬度为α)经度1°对应的实际弧长大约为111cosαkm。因此，只要知道了任意两地间的纬度差，或者是赤道上任何两地的经度差，就可以计算它们之间的实际距离。两地间最近距离的判断：若两地经度差等于180°，则过两地的大圆为经线圈，两地最近距离为大圆中过两极点的劣弧；若两地经度差不等于180°，则过两地的大圆不是经线圈，而与经线圈斜交，两地最近距离不过极点，而是过两地。如图3所示，A、B分别表示两车的位置，纬度经度表示为(a1,a2),(b1,b2)，radLat1，radLon1分别对应a1，a2；radLat2，radLon2分别对应b1，b2，根据两车的经纬度坐标计算两车距离的公式为：On the graticule map, the distance between two points can be calculated according to the latitude and longitude. The interval length of 1° latitude is equal all over the world (because all longitude lines are equal in length), which is about 111km/1°. Longitude 1° on the equator corresponds to an arc length of about 111 km on the ground. Since each latitude line decreases from the equator to the two poles, the length on the 60° latitude line is half that on the equator, so the arc lengths with a longitude difference of 1° on each latitude line are not equal. On the same latitude (assuming the latitude of this latitude is α), the actual arc length corresponding to longitude 1° is about 111 cos αkm. Therefore, as long as the latitude difference between any two places is known, or the longitude difference between any two places on the equator, the actual distance between them can be calculated. Judgment of the shortest distance between the two places: if the longitude difference between the two places is equal to 180°, the great circle passing through the two places is a meridian loop, and the shortest distance between the two places is the inferior arc passing through the two poles in the great circle; if the longitude difference between the two places is not equal to 180° , then the great circle passing through the two places is not the meridian loop, but obliquely intersects with the meridian loop, the shortest distance between the two places is no more than the pole, but passes through the two places. As shown in Figure 3, A and B represent the positions of the two vehicles respectively, and the latitude and longitude are expressed as (a1, a2), (b1, b2), radLat1 and radLon1 correspond to a1 and a2 respectively; radLat2 and radLon2 correspond to b1 and b2 respectively, The formula for calculating the distance between two vehicles based on their latitude and longitude coordinates is:

其中，radLat1和radLat2分别表示两车的纬度(单位为弧度)，radLon1与radLon2分别为经度(单位为弧度)，R表示地球半径常量6378.137km。Among them, radLat1 and radLat2 represent the latitude (in radians) of the two vehicles respectively, radLon1 and radLon2 are longitudes (in radians) respectively, and R represents the earth radius constant 6378.137km.

介绍完计算车辆节点间距离的原理后，利用GPS计算车辆速度的公式(II)就能顺利推出了。公式(II)的分子部分表示车辆当前位置和上一次位置的距离，分母表示两次采集GPS数据的时间间隔。After introducing the principle of calculating the distance between vehicle nodes, the formula (II) for calculating vehicle speed using GPS can be successfully launched. The numerator part of the formula (II) represents the distance between the vehicle's current position and the previous position, and the denominator represents the time interval between two GPS data collections.

利用GPS数据判断车辆前后相对位置详细原理如下：The detailed principle of using GPS data to determine the relative position of the vehicle is as follows:

如图4所示，本车车与邻车的相对位置可以用经纬度来计算。由于两车距离不大(相比于地球)，所以看做两车处于同一平面上。如图5所示，以自车为坐标原点，以正北方向为x轴正方向，以正西为y轴正方向建立坐标轴；那么邻车的坐标(x，y)可通过两车经纬度之差来计算：As shown in Figure 4, the relative position of the vehicle and the adjacent vehicle can be calculated by latitude and longitude. Since the distance between the two vehicles is not large (compared to the earth), it is considered that the two vehicles are on the same plane. As shown in Figure 5, the coordinate axis is established with the self-vehicle as the coordinate origin, the north as the positive direction of the x-axis, and the due west as the positive direction of the y-axis; then the coordinates (x, y) of the adjacent vehicle can be obtained by the latitude and longitude of the two vehicles Calculate the difference:

$\{\begin{matrix} x x = = ((radLon radLon 22 - - radLon radLon 11)) \times \times R R \\ y the y = = ((radLon radLon 22 - - radLon radLon 11)) \times \times R R \end{matrix}$

本车行驶方向为本车的地面航向角surfacecourse1，即图5中的ɑ；那么与处于本车行驶前方的区域可由2条射线确定，即L1与L2之间的区域，其中L1与L2的斜率分别为tan(surfacecourse1+45),tan(surfacecourse1-45),。此区域可以用L1与L2的解析式来表达，即The driving direction of the vehicle is the ground course angle surface course1 of the vehicle, that is, ɑ in Figure 5; then the area in front of the vehicle can be determined by two rays, that is, the area between L1 and L2, where the slope of L1 and L2 They are tan(surfacecourse1+45), tan(surfacecourse1-45), respectively. This region can be expressed by the analytical expressions of L1 and L2, namely

上述实例只为说明本发明的技术构思及特点，其目的在于让熟悉此项技术的人是能够了解本发明的内容并据以实施，并不能以此限制本发明的保护范围。凡根据本发明精神实质所做的等效变换或修饰，都应涵盖在本发明的保护范围之内。The above examples are only to illustrate the technical conception and characteristics of the present invention, and its purpose is to allow people familiar with this technology to understand the content of the present invention and implement it accordingly, and cannot limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A safety anti-collision early warning method based on Internet of Vehicles, is characterized in that, comprises the following steps:

(1) The vehicle-mounted terminal obtains the position information and driving state information of the vehicle, and sends the position information and driving state information of the vehicle when the vehicle brakes;

(2) If the vehicle-mounted terminal monitors the location information and driving status information of the vehicle in front, the vehicle-mounted terminal calculates the actual distance dis between the two vehicles, the safety distance sd and the risk factor β between the two vehicles;

(3) The vehicle-mounted terminal performs early warning processing according to the size of the risk factor, and issues voice prompts to the driver.

2. The safety collision avoidance warning method based on Internet of Vehicles according to claim 1, wherein the location information includes at least latitude and longitude, ground heading angle, and time; the driving state information includes at least driving direction and acceleration.

3. The safety anti-collision early warning method based on the Internet of Vehicles according to claim 1, wherein the front-rear relationship of the vehicle is obtained by the following formula:

\{\begin{matrix} ((radLon radLon 22 - - radLon radLon 11)) \times \times R R - - tan the tan ((Sur facecourse Surface course 11 + + 4545)) \times \times ((radLat radLat 22 - - radLat radLat 11)) \times \times R R < < 00 \\ ((radLon radLon 22 - - radLon radLon 11)) \times \times R R - - tan the tan ((Sur facecoursr Sur facecoursr 11 - - 4545)) \times \times ((radLat radLat 22 - - radLat radLat 11)) \times \times R R > > 00 \end{matrix}

Among them, radLat1 and radLat2 represent the latitude of the two vehicles, radLon1 and radLon2 respectively represent the longitude of the two vehicles, Surfacecousel represents the ground heading angle of the vehicle, and R represents the earth radius constant.

4. The safety anti-collision warning method based on the Internet of Vehicles according to claim 1, wherein the actual distance dis of the two vehicles is calculated according to the latitude and longitude coordinates of the vehicle, and the calculation formula is:

dis dis = = 22 \times \times arcsin arcsin ((\sqrt{{sin sin}^{22} ((\frac{radLat radLat 11 - - radLat radLat 22}{22})) + + cos cos ((radLat radLat 11)) \times \times cos cos ((radLat radLat 22)) \times \times {sin sin}^{22} ((\frac{radLon radLon 11 - - radLon radLon 22}{22}))})) \times \times R R

Among them, radLat1 and radLat2 represent the latitude of the two vehicles respectively, radLon1 and radLon2 represent the longitude of the two vehicles respectively, and R represents the earth radius constant.

5. The safety anti-collision warning method based on the Internet of Vehicles according to claim 1, wherein the formula for calculating the safety distance sd of the two vehicles is:

sd=T*|υ ₁ -υ ₂ |;

Among them, v ₁ is the speed of the vehicle, v ₂ is the speed of the front vehicle, and T is the reaction time.

6. The safety anti-collision warning method based on the Internet of Vehicles according to claim 5, wherein the vehicle speed v is calculated according to latitude and longitude coordinates, and the calculation formula is:

&upsi; &upsi; = = \frac{22 * * R R * * arcsin arcsin ((\sqrt{{sin sin}^{22} ((\frac{radLat radLat 11 - - radLat radLat 22}{22})) + + cos cos ((radLat radLat 11)) * * cos cos ((radLat radLat 22)) * * {sin sin}^{22} ((\frac{radLon radLon 11 - - radLon radLon 22}{22}))}))}{{t t}_{22} - - {t t}_{11}}

Among them, t ₂ and t ₁ represent the current time and the last time respectively, radLat1 and radLat2 represent the latitude of the previous position and the latitude of the current position respectively, radLon1 and radLon2 represent the longitude of the previous position and the longitude of the current position respectively, and R represents Earth radius constant.

7. The safety anti-collision warning method based on Internet of Vehicles according to claim 1, characterized in that

Therefore, the formula for calculating the risk factor β is:

β β = = \frac{sd sd - - dis dis}{dis dis} . .

8. A safety anti-collision warning system based on Internet of Vehicles, characterized in that it includes the acceleration information of the acquisition vehicle and an acceleration module for judging whether the vehicle brakes; the GPS module for collecting vehicle position information and judging the distance between the vehicle and the braking vehicle; Wireless communication module for communication and information processing; voice module for alarm prompt.