CN105788363A - Driving early warning method, driving early warning device, and driving early warning system - Google Patents

Abstract

The present invention provides a driving warning method, device and system, comprising: acquiring the motion state parameters of a first car and a second car adjacent to the first car, the first car and the second car are in the same lane and the distance between the two cars is The distance is less than the preset distance; according to the motion state parameters of the first car and the second car at the current moment, determine the safety time of the second car; according to the safety time, the current moment of the first car and the second car The motion state parameters and the change information of the motion state of the first vehicle after the preset braking delay time generate early warning information, and the second vehicle adjusts the acceleration according to the early warning information. The embodiment of the present invention converts the safe distance of driving vehicles in different states into safe time, and generates corresponding early warning information according to the safe time, instructs the vehicle behind to adjust the acceleration, thereby avoiding vehicle collisions and effectively reducing traffic accidents incidence rate.

Description

A driving warning method, device and system

technical field

The invention relates to the technical field of vehicle collision avoidance, in particular to a driving warning method, device and system.

Background technique

With the rapid increase of car ownership, the traffic pressure on the road is increasing, and the number of traffic accidents is also increasing, which brings increasingly serious pressure on the road traffic safety environment. Casualties and property losses caused by traffic accidents have always been an urgent problem to be solved by the traffic department. In the prior art, the distance between the front and rear vehicles, the speed and acceleration of the front and rear vehicles, and other parameters are obtained, and the safety distance between the front and rear vehicles is determined according to the parameters of the speed and acceleration of the two vehicles, and the distance between the front and rear vehicles is combined. And the safe distance to judge whether the rear car collides with the front car and has an accident, etc., and sends an early warning message to the driver according to the judgment result, so that the driver can reduce the incidence of traffic accidents through safe driving.

However, by combining the distance between the front and rear vehicles and the safety distance to judge whether the rear vehicle collides with the front vehicle and has an accident, etc., when the vehicle speed is too high, the driver's reaction time is too short, so that the driver may not There is enough time to adjust the vehicle speed, etc., or the driver cannot react, and the vehicle speed adjustment lags behind, resulting in traffic accidents.

Contents of the invention

The purpose of the present invention is to provide a traffic warning method, device and system to solve the problem in the prior art of judging whether the rear vehicle collides with the front vehicle by the distance between the front and rear vehicles. , the driver cannot adjust the driving behavior in time, which is prone to traffic accidents.

In order to achieve the above object, the present invention provides a traffic warning method, comprising:

Acquiring the motion state parameters of the first car on the road and the second car adjacent to the first car, the motion state parameters at least include the speed, acceleration and position information of the car, wherein the first car and the The second vehicle is in the same lane and the distance between the two vehicles is less than the preset distance;

According to the motion state parameters of the first car and the second car at the current moment, determine the safety time of the second car;

According to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after a preset braking delay time, early warning information is generated, and the second car is used to generate warning information. The second vehicle adjusts the acceleration according to the warning information.

Wherein, the generating warning information is based on the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after the preset braking delay time. Steps include:

If the safety time is greater than the preset time threshold t _c , the warning information is not generated;

If the safety time is less than the preset time threshold t _c , and the safety time is less than or equal to the preset delay braking time τ, then generate first warning information;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, and v _f (τ)≥v _b (τ) , then generate the second early warning information, wherein, v _f (τ), v _b (τ) respectively represent the speed values of the first car and the second car at time τ;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, v _f (τ)<v _b (τ), and the first preset condition is met, the third warning information is generated, and the first preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2\stackrel{\&OverBar;}{a_b}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}<m,$ in, $\stackrel{\&OverBar;}{a_b}=-\frac{[v_b\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{t_f-\mathrm{\&tau;}},t_f=-\frac{[v_f\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{a_f^{*}};$ S _f (t _x ), S _b (t _x ) respectively represent the distance traveled by the first car and the second car within the time t _x ; a _cmin represents a more comfortable acceleration for the driver when decelerating ; M=Ds ₀ , D represents the distance between the rear of the first car and the front of the second car at the current moment, and s ₀ represents the safety distance required to be kept by the first car and the second car at the current speed; like ${\hat{a}}_f=\mathrm{Null},{\hat{v}}_{\min }=\mathrm{Null},$ but $a_f^{*}=a_f,v_{\min }^{*}=v_{\min },$ otherwise, $a_f^{*}={\hat{a}}_f,v_{\mathrm{miin}}^{*}={\hat{v}}_{\min },$ Indicates the acceleration indicated by the warning indication information, Indicates the lower limit of the deceleration speed indicated by the warning indication information, and v _min is the lower limit of the speed of the current lane;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, v _f (τ)<v _b (τ), and the first preset condition is not met, generating fourth warning information;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle is at a constant speed after τ time, and v _b (τ)≤v _f (τ) , the fifth warning message is generated;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ)>v _f (τ) , the sixth warning message is generated;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, and v _b (τ)≤v _f (τ), then Generate seventh early warning information;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, v _b (τ)>v _f (τ), And if the second preset condition is met, the eighth warning message is generated, and the second preset condition is and $\mathrm{\&gamma;}=\frac{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;};$

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, v _b (τ)>v _f (τ), And if the second preset condition is not met, generate ninth warning information.

Wherein, the first warning information includes first acceleration information, and the first acceleration information is Among them, a _min represents the minimum value of the vehicle acceleration;

The second warning information includes second acceleration information, and the second acceleration information is $a_b^{*}=\min \{-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$ Among them, a _cmin represents a more comfortable acceleration for the driver when decelerating;

The third warning information includes third acceleration information, and the third acceleration information is $a_b^{*}=\min \{\frac{v_b{\left(\mathrm{\&tau;}\right)}^2-{v_{\min }^{*}}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$

The fourth warning information includes fourth acceleration information, and the fourth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{{[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)]}^2}{2[m-S_b\left(\mathrm{\&tau;}\right)+S_f\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$

The fifth early warning information includes fifth acceleration information, and the fifth acceleration information is

The sixth warning information includes sixth acceleration information, and the sixth acceleration information is $a_b^{*}=\min \{-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$

The seventh early warning information includes seventh acceleration information, and the seventh acceleration information is

The eighth warning information includes eighth acceleration information, and the eighth acceleration information is

The ninth warning information includes ninth acceleration information, and the ninth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{v_f{\left(\mathrm{\&tau;}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\}.$

Wherein, the first warning information indicates that the second vehicle decelerates according to the first acceleration information;

The second warning information indicates that the second vehicle decelerates to

The third warning information indicates that the second vehicle decelerates to

The fourth warning information indicates that the second vehicle decelerates to

The fifth warning information indicates that the second vehicle is traveling at a constant speed according to the fifth acceleration information;

The sixth early warning information indicates that the second car maintains a constant speed after decelerating to v _f (τ) according to the sixth acceleration information;

The seventh early warning information indicates that the second car is traveling at a constant speed according to the seventh acceleration information;

The eighth warning information indicates that the second vehicle is traveling at a constant speed according to the eighth acceleration information;

The ninth warning information indicates that the second vehicle decelerates to $v_f\left(\mathrm{\&tau;}\right)+a_f^{*}\&Center\; Dot;\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}$ maintain a constant speed.

Wherein, the warning information is generated according to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after the preset braking delay time After the steps also include:

Create an early warning simulation model according to the position information, vehicle parameters and weather state parameters of the first car and the second car;

In the simulation model, it is judged whether the second car will collide with the first car after executing the warning information, and if so, adjust the warning information until the second car collides with the first car. The first car will not collide, and the adjusted warning information is sent to the second car.

Wherein, the step of creating an early warning simulation model according to the position information, vehicle parameters and weather state parameters of the first car and the second car includes:

Acquiring a road model corresponding to the position information in a road model library according to the position information of the first car and the second car;

According to the vehicle parameters of the first car and the second car, a simulation model of the vehicle is created by calling Carsim or PreScan, wherein the vehicle parameters include at least the dynamic parameters of the vehicle and the vehicle's internal and external shape;

Obtaining the weather state parameters of the positions of the first car and the second car, and creating the early warning simulation model according to the weather state parameters, the road model and the simulation model of the vehicle, the weather state parameters Including one or more of rainfall, snowfall, temperature, humidity, visibility, and road slipperiness.

Wherein, the above-mentioned driving warning method also includes:

The road model in the road model library is updated in real time according to the change information of the weather state parameters, the terrain of the road, the use time of the road, the total amount of vehicles passing on the road, and the types of passing vehicles.

Embodiments of the present invention also provide a driving warning device, comprising:

An acquisition module, configured to acquire motion state parameters of a first car on the road and a second car adjacent to the first car, the motion state parameters at least including speed, acceleration and position information of the car, wherein the first A car is in the same lane as the second car and the distance between the two cars is less than a preset distance;

A determining module, configured to determine the safety time of the second car according to the motion state parameters of the first car and the second car at the current moment;

A generation module, configured to generate warning information according to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after a preset braking delay time , the acceleration is adjusted by the second car according to the warning information.

Wherein, the generating module includes:

A judging unit, configured to not generate the warning information if the safety time is greater than a preset time threshold t _c ;

A first generating unit, configured to generate first warning information if the safety time is less than the preset time threshold t _c and the safety time is less than or equal to the preset delayed braking time τ;

The second generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first car decelerates after τ time, and v _f (τ )≥v _b (τ), then generate the second early warning information, wherein, v _f (τ), v _b (τ) respectively represent the speed values of the first car and the second car at time τ;

A third generating unit, configured to decelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _f (τ) <v _b (τ), and the first preset condition is met, the third warning information is generated, and the first preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2\stackrel{\&OverBar;}{a_b}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}<m,$ in, $\stackrel{\&OverBar;}{a_b}=-\frac{[v_b\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{t_f-\mathrm{\&tau;}},t_f=-\frac{[v_f\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{a_f^{*}};$ S _f (t _x ), S _b (t _x ) respectively represent the distance traveled by the first car and the second car within the time t _x ; a _cmin represents a more comfortable acceleration for the driver when decelerating ; M=Ds ₀ , D represents the distance between the rear of the first car and the front of the second car at the current moment, and s ₀ represents the safety distance required to be kept by the first car and the second car at the current speed; like ${\hat{a}}_f=\mathrm{Null},{\hat{v}}_{\min }=\mathrm{Null},$ but $a_f^{*}=a_f,v_{\min }^{*}=v_{\min },$ otherwise, Indicates the acceleration indicated by the warning indication information, Indicates the lower limit of the deceleration speed indicated by the warning indication information, and v _min is the lower limit of the speed of the current lane;

A fourth generating unit, configured to decelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _f (τ) <v _b (τ), and the first preset condition is not met, generate fourth warning information;

The fifth generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and smaller than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ )≤v _f (τ), then generate the fifth early warning information;

The sixth generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ )＞v _f (τ), then generate the sixth early warning information;

A seventh generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , and v _b (τ)≤ v _f (τ), then generate the seventh early warning information;

An eighth generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _b (τ) >v _f (τ), and the second preset condition is met, the eighth warning message will be generated, and the second preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{1}{2}[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)](\mathrm{\&gamma;}-\mathrm{\&tau;})<m,$ and $\mathrm{\&gamma;}=\frac{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;};$

A ninth generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _b (τ) >v _f (τ), and the second preset condition is not satisfied, generate ninth warning information.

Wherein, the first warning information includes first acceleration information, and the first acceleration information is , where a _min represents the minimum value of vehicle acceleration;

The second warning information includes second acceleration information, and the second acceleration information is $a_b^{*}=\min \{-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$ Among them, a _cmin represents a more comfortable acceleration for the driver when decelerating;

The third warning information includes third acceleration information, and the third acceleration information is $a_b^{*}=\min \{\frac{v_b{\left(\mathrm{\&tau;}\right)}^2-{v_{\min }^{*}}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$

The fourth warning information includes fourth acceleration information, and the fourth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{{[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)]}^2}{2[m-S_b\left(\mathrm{\&tau;}\right)+S_f\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$

The fifth early warning information includes fifth acceleration information, and the fifth acceleration information is

The sixth warning information includes sixth acceleration information, and the sixth acceleration information is $a_b^{*}=\min \{-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$

The seventh early warning information includes seventh acceleration information, and the seventh acceleration information is

The eighth warning information includes eighth acceleration information, and the eighth acceleration information is

The ninth warning information includes ninth acceleration information, and the ninth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\}.$

Wherein, the first warning information indicates that the second vehicle decelerates according to the first acceleration information;

The second warning information indicates that the second vehicle decelerates to

The third warning information indicates that the second vehicle decelerates to

The fourth warning information indicates that the second vehicle decelerates to

The fifth warning information indicates that the second vehicle is traveling at a constant speed according to the fifth acceleration information;

The sixth early warning information indicates that the second car maintains a constant speed after decelerating to v _f (τ) according to the sixth acceleration information;

The seventh early warning information indicates that the second car is traveling at a constant speed according to the seventh acceleration information;

The eighth warning information indicates that the second vehicle is traveling at a constant speed according to the eighth acceleration information;

The ninth warning information indicates that the second vehicle decelerates to $v_f\left(\mathrm{\&tau;}\right)+a_f^{*}\&Center\; Dot;\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}$ maintain a constant speed.

Wherein, the above-mentioned traffic warning device also includes:

A creation module, configured to generate an early warning according to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after a preset braking delay time After information, create an early warning simulation model according to the position information, vehicle parameters and weather state parameters of the first car and the second car;

The simulation module is used to judge whether the second car will collide with the first car after executing the warning information in the simulation model, and if so, adjust the warning information until the The second car will not collide with the first car, and the adjusted warning information is sent to the second car.

Wherein, the creation module includes:

An acquisition unit, configured to acquire a road model corresponding to the position information in a road model library according to the position information of the first car and the second car;

The first creation unit is used to create a simulation model of the vehicle by calling Carsim or PreScan according to the vehicle parameters of the first car and the second car, wherein the vehicle parameters include at least the dynamic parameters of the vehicle and the inside and outside of the vehicle modeling;

The second creating unit is configured to obtain the weather state parameters of the locations of the first car and the second car, and create the warning simulation according to the weather state parameters, the road model and the simulation model of the vehicle model, the weather state parameters include one or more of rainfall, snowfall, temperature, humidity, visibility, and road slipperiness.

Wherein, the above-mentioned traffic warning device also includes:

The update module is used to update the road model in the road model library in real time according to the change information of the weather state parameters, the terrain of the road, the use time of the road, the total amount of vehicles passing on the road and the types of passing vehicles.

An embodiment of the present invention also provides a traffic warning system, including the traffic warning device as described above.

Embodiments of the present invention have the following beneficial effects:

The embodiment of the present invention converts the safe distance of a driving vehicle in different states into a safe time, and generates corresponding early warning information according to the safe time, and combines the simulation model of the vehicle, the model of the road on which the vehicle is currently driving, the current weather conditions and The early warning information simulates the driving conditions of the vehicles, so as to adjust the early warning information to avoid vehicle collisions, effectively reducing the incidence of traffic accidents.

Description of drawings

Fig. 1 is the method flowchart of the traffic warning method of the embodiment of the present invention;

Fig. 2 is the first relationship diagram of speed and time of the driving warning method of the embodiment of the present invention;

Fig. 3 is the second relationship diagram of speed and time of the driving warning method according to the embodiment of the present invention;

Fig. 4 is the third relationship diagram between speed and time of the driving warning method according to the embodiment of the present invention;

Fig. 5 is the fourth relationship diagram between speed and time of the driving warning method according to the embodiment of the present invention;

FIG. 6 is a fifth relationship diagram between speed and time of the driving warning method according to the embodiment of the present invention;

FIG. 7 is a sixth relationship diagram between speed and time of the driving warning method according to the embodiment of the present invention;

Fig. 8 is the seventh relationship diagram between speed and time of the driving warning method according to the embodiment of the present invention;

Fig. 9 is a structural block diagram 1 of a driving warning device according to an embodiment of the present invention;

FIG. 10 is a second structural block diagram of the traffic warning device according to the embodiment of the present invention.

Explanation of reference signs:

1-vehicle, 2-management platform.

detailed description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to specific embodiments and accompanying drawings.

The embodiment of the present invention solves the problem of judging whether the rear vehicle collides with the front vehicle to cause an accident in the prior art based on the distance between the front and rear vehicles. When the vehicle speed is too high, the driver cannot adjust the driving behavior in time, and traffic accidents are prone to occur. Problem, the embodiment of the present invention provides a traffic warning method, as shown in Figure 1, including:

Step S11: Obtain the motion state parameters of the first car on the road and the second car adjacent to the first car, the motion state parameters include at least the speed, acceleration and position information of the car, wherein the first car Be in the same lane as the second car and the distance between the two cars is less than a preset distance;

Step S12: Determine the safety time of the second car according to the motion state parameters of the first car and the second car at the current moment;

In a specific embodiment of the present invention, the safety time is from the current time to the time when the second car reaches the risk state, and the time when the risk state is reached is the time when the distance between the front and rear vehicles is less than the required safety braking distance.

Step S13: According to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after the preset braking delay time, generate warning information, by The second vehicle adjusts the acceleration according to the warning information.

In a specific embodiment of the present invention, the preset braking delay time includes human reaction time, vehicle brake coordination time and system delay time.

In a specific embodiment of the present invention, the first car and the second car may specifically be two adjacent cars in a continuous driving state, wherein the first car may be specifically the front car, and the second car The second car can be specifically the rear car. The present invention converts the safe distance of the driving vehicle in different states into a safe time. The longer the safe time, the longer the safe state can be maintained, that is, the smaller the risk. The size of the vehicle is used to judge the degree of risk, and finally an early warning is issued to the high-risk vehicle with a small safety time to control its current motion state to reduce the possible danger.

In a specific embodiment of the present invention, the step S12 includes:

1. Make parameter settings

Current moment t ₀ =0;

Input parameters:

Preset braking delay time τ = τ _person + τ _car + τ _system , where τ _person represents the reaction time of the person, τ _car represents the coordination time of the car brake, and τ _system represents the system delay time;

v _f (τ) and v _b (τ) represent the speed values of the front and rear vehicles at time τ, respectively;

S _f (τ) and S _b (τ) respectively represent the distance traveled by the front and rear vehicles within τ time;

a _cmin represents the more comfortable acceleration for the driver when decelerating;

a _cmax represents a more comfortable acceleration for the driver;

a _min represents the minimum value of the acceleration of the vehicle, that is, the acceleration value during sudden braking;

a _f and a _b are the accelerations of the front vehicle and the rear vehicle at the current moment respectively;

v _f and v _b are the speeds of the front vehicle and the rear vehicle at the current moment respectively;

v _max represents a speed upper limit determined by the maximum speed limit of the current lane, the maximum speed of the current vehicle group and the expected speed, the vehicle speed v∈[0, v _max ];

v _min is the lower speed limit of the current lane;

Indicates the acceleration corresponding to the new command issued by the system to the vehicle in front at the current moment. If the current system has no command to the vehicle in front, it will be recorded

Respectively represent the upper limit of the acceleration speed and the lower limit of the deceleration speed of the new command of the system to the vehicle in front. If the current system has no command to the vehicle in front, it is recorded as

D represents the distance between the rear of the current front vehicle and the front of the rear vehicle;

t represents the safety time;

t _c represents the safety time threshold, if t≤t _c , it means that the risk is relatively high;

s ₀ represents the safety distance that the front and rear vehicles need to keep at the current speed;

Note M=Ds ₀ .

Output parameters:

Indicates the safe acceleration of the rear vehicle prompted by the warning;

Indicates the final speed reached by the car after the warning prompt.

Intermediate parameters:

where, if ${\hat{a}}_f,{\hat{v}}_{\max },{\hat{v}}_{\min }=\mathrm{Null},$ Zeji $v_{\max }^{*}=v_{\max },a_f^{*}=a_f,v_{\min }^{*}=v_{\min },$ otherwise $a_f^{*}={\hat{a}}_f,v_{\max }^{*}={\hat{v}}_{\max },v_{\min }^{*}={\hat{v}}_{\min }.$

2. Safe time algorithm

Step 1: Initialize each parameter value, set the current time t ₀ =0, the number of iterations k=0, the iteration step size Δt=0.01, and the maximum number of iterations N=500. If M(0)≤0, it means that the risk is very high, define safety time t=0, go to step 4; otherwise k=k+1.

Step 2: Let t _x =k·Δt, and judge whether S _b (t _x )-S _f (t _x )≤M(t _x ) holds. If the inequality is not established, then t=(k-1)Δt; otherwise, k=k+1;

Among them, the expressions about S _b (t _x ) and S _f (t _x ) are as follows:

v _f (t _x )=min{max{v _f +a _f t _x , 0}, v _max }, v _b (t _x )=min{max{v _b +a _b t _x ,0}, v _max },

in ${\mathrm{\&delta;}}_f=\left\{\begin{array}{cc}\frac{v_{\max }-v_f}{a_f},& v_f<v_{\max }\\ 0,& v_f=v_{\max }\end{array}\right.$

in ${\mathrm{\&delta;}}_b=\left\{\begin{array}{cc}\frac{v_{\max }-v_b}{a_b},& v_b<v_{\max }\\ 0,& v_b=v_{\max }\end{array}\right..$

Step 3: Judging whether k≤N holds true, if true, return to step 2; otherwise t=+∞.

Step 4: Output the safety time t, turn to the next time t ₀ +ΔT, and return to step 1, where ΔT=N×Δt.

In a specific embodiment of the present invention, the safety distance between vehicles is converted into a safe time according to the above algorithm, because the smaller the safety time t, the greater the risk of driving. Therefore, in a specific embodiment of the present invention, when When the safety time is less than or equal to the safety time threshold _tc , an early warning message is generated, instructing the vehicle behind to adjust the acceleration to avoid traffic accidents.

In a specific embodiment of the present invention, the step S13 includes:

If the safety time is greater than the preset time threshold t _c , the warning information is not generated;

If the safety time is less than the preset time threshold t _c , and the safety time is less than or equal to the preset delay braking time τ, then generate first warning information, indicating that the second car - Acceleration information to decelerate;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, and v _f (τ)≥v _b (τ) , the second warning information is generated, indicating that the second car decelerates to

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, v _f (τ)<v _b (τ), and the first preset condition is met, the third warning information is generated, indicating that the second car decelerates to The first preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2\stackrel{\&OverBar;}{a_b}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}<m,$ in, $\stackrel{\&OverBar;}{a_b}=-\frac{[v_b\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{t_f-\mathrm{\&tau;}},$ $t_f=-\frac{[v_f\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{a_f^{*}};$

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, v _f (τ)<v _b (τ), and the first preset condition is not met, generate fourth warning information, indicating that the second car decelerates to ;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle is at a constant speed after τ time, and v _b (τ)≤v _f (τ) , the fifth early warning information is generated, indicating that the second vehicle is traveling at a constant speed according to the fifth acceleration information;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ)>v _f (τ) , then generate the sixth early warning information, indicating that the second car maintains a constant speed after decelerating to v _f (τ) according to the sixth acceleration information;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, and v _b (τ)≤v _f (τ), then generating seventh warning information, instructing the second vehicle to drive at a constant speed according to the seventh acceleration information;

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, v _b (τ)>v _f (τ), and the second preset condition is met, the eighth early warning information is generated, indicating that the second car is traveling at a constant speed according to the eighth acceleration information, and the second preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{1}{2}[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)](\mathrm{\&gamma;}-\mathrm{\&tau;})<m,$ and $\mathrm{\&gamma;}=\frac{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;};$

If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, v _b (τ)>v _f (τ), and the second preset condition is not met, generate ninth warning information, indicating that the second car decelerates to $v_f\left(\mathrm{\&tau;}\right)+a_f^{*}\&CenterDot;\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}$ maintain a constant speed.

In a specific embodiment of the present invention, if the safety time t ≤ t _c , it means that the current situation is risky, and an early warning measure should be taken; otherwise, no early warning is required. When pre-warning the rear car, consider the movement state of the front and rear cars at the current moment and the possible state changes of the front car after τ time, and calculate the critical acceleration that the rear car should take at τ time, and then use the critical acceleration as a new acceleration command Provided to the following vehicle to instruct the following vehicle to avoid the risk.

In a specific embodiment of the present invention, after the safety time, the motion state parameters of the first car and the second car at the current moment, and the preset braking delay time, the motion state of the first car After the step of generating the early warning information, it also includes:

Create an early warning simulation model according to the position information, vehicle parameters and weather state parameters of the first car and the second car;

In the simulation model, it is judged whether the second car will collide with the first car after executing the warning information, and if so, adjust the warning information until the second car collides with the first car. The first car will not collide, and the adjusted warning information is sent to the second car.

In the embodiment of the present invention, after the early warning information is generated, the driving situation of the vehicle is simulated in combination with the simulation model of the vehicle, the model of the road on which the vehicle is currently driving, the current weather conditions, and the early warning information, so as to adjust the early warning information to avoid Vehicles collide, effectively reducing the incidence of traffic accidents.

The specific implementation process of the above-mentioned embodiment will be described with an example.

1. For the safety time t satisfying t≤t _c

(I) If the safety time t≤τ, the collision is probably unavoidable, and the system should immediately prompt the driver of the rear vehicle (the second vehicle) to take remedial measures to brake at the maximum deceleration, that is, the first acceleration information

(II) If the safety time t _c ≥ t > τ, it can be seen that at time τ, the difference between the distance traveled by the vehicle behind and the distance traveled by the vehicle in front (the first vehicle) satisfies S _b (τ)-S _f (τ) <M.

Obviously:

v _f (τ) = min{max{v _f + a _f τ, 0}, v _max },

v _b (τ) = max{min{v _b + a _b τ, v _max }, 0},

in ${\mathrm{\&delta;}}_f=\left\{\begin{array}{cc}\frac{v_{\max }-v_f}{a_f},& v_f<v_{\max }\\ 0,& v_f=v_{\max }\end{array}\right.$

in ${\mathrm{\&delta;}}_b=\left\{\begin{array}{cc}\frac{v_{\max }-v_b}{a_b},& v_b<v_{\max }\\ 0,& v_b=v_{\max }\end{array}\right..$

The control strategy for (II) will be discussed in three cases according to the positive or negative of the acceleration of the preceding vehicle after time τ:

1. The vehicle in front decelerates after time τ

1) If v _f (τ)≥v _b (τ),

If the following vehicle takes a new acceleration at time τ The deceleration is just enough to keep the two vehicles at a safe distance, that is, the speed of the rear vehicle reaches When the distance between two vehicles is s ₀ :

but $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2a_b^{*}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}=m$

critical acceleration $a_b^{*}=\frac{{{-v}_{\min }^{*}}^2+v_b{\left(\mathrm{\&tau;}\right)}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}-m]}.$

The driver of the vehicle behind should be prompted to accelerate $a_b^{*}=\frac{{{-v}_{\min }^{*}}^2+v_b{\left(\mathrm{\&tau;}\right)}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}-m]}$ When decelerating to the same speed as the vehicle in front, slow down to

For the sake of simplicity, the following driver is prompted to

Second Acceleration Information $a_b^{*}=\min \{-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}-m]},a_{c\min }\}$ slow down to That's it.

2) If v _f (τ) < v _b (τ),

because , it can be known that v _f (τ)>0.

make $t_f=-\frac{[v_f\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{a_f^{*}},\stackrel{\&OverBar;}{a_b}=-\frac{[v_b\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{t_f-\mathrm{\&tau;}}.$

①As shown in Figure 2, if $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2\stackrel{\&OverBar;}{a_b}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}<m,$ At time τ, the following vehicle accelerates with a new acceleration slow down to can be later than t _f .

untie $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{{2a}_b^{*}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}=m,$

Available $a_b^{*}=\frac{v_b{\left(\mathrm{\&tau;}\right)}^2-{v_{\min }^{*}}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}-m]}$

The driver of the vehicle behind should be prompted to accelerate $a_b^{*}\&le;\frac{v_b{\left(\mathrm{\&tau;}\right)}^2-{v_{\min }^{*}}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}-m]}$ slow down to

For the sake of simplification, the following driver is prompted to use the third acceleration information $a_b^{*}=\min \{\frac{v_b{\left(\mathrm{\&tau;}\right)}^2-{v_{\min }^{*}}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{\left(v_{\min }^{*}\right)}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}-m]},a_{c\min }\}$ slow down to That's it.

②As shown in Figure 3, if $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2\stackrel{\&OverBar;}{a_b}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{{2a}_f^{*}}\&Greater\; Equal;m,$ At time τ, the following vehicle accelerates with a new acceleration slow down to must be no later than t _f .

Assume that the rear vehicle takes a new acceleration at time τ When decelerating to γ time, the two vehicles are at the same speed,

consider $\left\{\begin{array}{c}{v}_b\left(\mathrm{\&tau;}\right)+a_b^{*}(\mathrm{\&gamma;}-\mathrm{\&tau;})=v_f\left(\mathrm{\&tau;}\right)+a_f^{*}(\mathrm{\&gamma;}-\mathrm{\&tau;})\\ S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+v_b\left(\mathrm{\&tau;}\right)(\mathrm{\&gamma;}-\mathrm{\&tau;})+\frac{1}{2}{a}_b^{*}{(\mathrm{\&gamma;}-\mathrm{\&tau;})}^2-v_f\left(\mathrm{\&tau;}\right)(\mathrm{\&gamma;}-\mathrm{\&tau;})-\frac{1}{2}{a}_f^{*}{(\mathrm{\&gamma;}-\mathrm{\&tau;})}^2=m\end{array}\right.$

Solutions have to $\left\{\begin{array}{c}\mathrm{\&gamma;}=\mathrm{\&tau;}+\frac{2[m-S_b\left(\mathrm{\&tau;}\right)+S_f\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}\\ a_b^{*}=a_f^{*}-\frac{{[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)]}^2}{2[m-S_b\left(\mathrm{\&tau;}\right)+S_f\left(\mathrm{\&tau;}\right)]}\end{array}\right.$

The driver of the vehicle behind should be prompted to accelerate When decelerating to the same speed as the vehicle in front, slow down to

For the sake of simplification, the following driver is prompted to use the fourth acceleration information $a_b^{*}=\min \{a_f^{*}-\frac{{[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)]}^2}{2[m-S_b\left(\mathrm{\&tau;}\right)+S_f\left(\mathrm{\&tau;}\right)]},a_{c\min }\}$ slow down to

2. The vehicle in front is at a constant speed after time τ

1) If v _b (τ)≤v _f (τ), the fifth acceleration information is Prompt the driver of the vehicle behind to drive at a constant speed of v _f (τ).

2) As shown in Figure 4, if v _b (τ) > v _f (τ), let γ represent the moment when the vehicle behind decelerates to v _f (τ) with the new acceleration.

consider

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; m</span>}\\ \frac{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\end{array}\right.$

$<span\; class="notranslate">\; \&DoubleRightArrow;</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\\ {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}\end{array}\right.$

It is only necessary to prompt the driver of the vehicle behind to accelerate Just keep the constant speed after decelerating to v _f (τ).

For the sake of simplification, the following driver is prompted to use the sixth acceleration information $a_b^{*}=\min \{-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\}$ Keep the constant speed after decelerating to v _f (τ).

3. The vehicle in front accelerates after time τ

1) If v _b (τ)≤v _f (τ), the following driver only needs to change to Just speed up.

For the sake of safety, remind the driver behind to maintain a constant speed, that is, the seventh acceleration information

2) If v _b (τ) > v _f (τ),

①As shown in Figure 5, if $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{1}{2}[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)](\mathrm{\&gamma;}-\mathrm{\&tau;})<m,$ in $\mathrm{\&gamma;}=\frac{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;};$ Then the acceleration of the rear car Can be greater than 0.

remember $t_f=\frac{v_{\max }^{*}-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;},$ Obviously t _f >τ.

i) As shown in Figure 6, if $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{1}{2}[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)](t_f-\mathrm{\&tau;})<m,$

Let t _b ′ mean that the following vehicle accelerates to Obviously there is t _b ′<t _f at the moment of .

consider

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\frac{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; *</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; m</span>}\\ {\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

Solutions have to

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}\\ {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}\end{array}\right.$

The following driver should be notified of the new acceleration $a_b^{*}\&le;\frac{{[v_{\max }^{*}-v_b\left(\mathrm{\&tau;}\right)]}^2}{[v_{\max }^{*}-v_f\left(\mathrm{\&tau;}\right)](t_f-\mathrm{\&tau;})-2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}$ drive to

For the sake of safety, remind the driver of the vehicle behind to maintain a constant speed, that is, the eighth acceleration information

ii) As shown in Figure 7, if $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{1}{2}[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)](t_f-\mathrm{\&tau;})\&Greater\; Equal;m,$ Let σ represent the moment when the rear vehicle accelerates to the same speed as the front vehicle with a new acceleration,

consider:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; *</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; m</span>}\\ {\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

Solutions have to $\left\{\begin{array}{c}\mathrm{\&sigma;}=\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}+\mathrm{\&tau;}\\ a_b^{*}=a_f^{*}+\frac{v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)}{\mathrm{\&sigma;}-\mathrm{\&tau;}}=a_f^{*}-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}\end{array}\right.$

The following driver should be notified of the new acceleration accelerate to

For the sake of safety, remind the driver of the vehicle behind to maintain a constant speed, that is, the eighth acceleration information

②As shown in Figure 8, if $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{1}{2}[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)](\mathrm{\&gamma;}-\mathrm{\&tau;})\&Greater\; Equal;m,$ in $\mathrm{\&gamma;}=\frac{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;},$

Then the new acceleration of the rear car Must be less than or equal to 0. Let σ represent the moment when the rear vehicle decelerates to the same speed as the front vehicle with the new acceleration,

consider

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; *</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; m</span>}\\ {\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

Solutions have to $\left\{\begin{array}{c}\mathrm{\&sigma;}=\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}+\mathrm{\&tau;}\\ a_b^{*}=a_f^{*}+\frac{v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)}{\mathrm{\&sigma;}-\mathrm{\&tau;}}=a_f^{*}-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}\end{array}\right.$

The following driver should be notified of the new acceleration Decelerate to the same speed as the vehicle in front and then use the new acceleration accelerate.

For the sake of safety, the driver of the vehicle behind is prompted to use the ninth acceleration information Decelerate to σ time, that is, the speed reaches $v_f\left(\mathrm{\&tau;}\right)+a_f^{*}\&CenterDot;\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}$ maintain a constant speed.

In a specific embodiment of the present invention, the step of creating an early warning simulation model according to the position information of the first car and the second car, vehicle parameters and weather state parameters includes:

Acquiring a road model corresponding to the position information in a road model library according to the position information of the first car and the second car;

According to the vehicle parameters of the first car and the second car, a simulation model of the vehicle is created by calling Carsim or PreScan, wherein the vehicle parameters include at least the dynamic parameters of the vehicle and the vehicle's internal and external shape;

Obtaining the weather state parameters of the positions of the first car and the second car, and creating the early warning simulation model according to the weather state parameters, the road model and the simulation model of the vehicle, the weather state parameters Including one or more of rainfall, snowfall, temperature, humidity, visibility, and road slipperiness.

In a specific embodiment of the present invention, after determining the early warning information that needs to be sent to the vehicle behind, determine the road section information of the current location of the vehicle according to the vehicle's position information, and call the pre-established road model of the road section according to the road section information. The currently collected vehicle parameters are combined with the model of the road section and the simulation model of the vehicle to simulate whether an accident will occur after the rear vehicle executes a new acceleration command, and determine whether the rear vehicle among the multiple vehicles in the continuous driving situation executes a new acceleration. Whether serial rear-end collisions or single-vehicle rear-end collisions will occur within a certain period of time after the command is issued. If serial rear-end collisions or single-vehicle rear-end collisions will occur within a certain period of time, adjust the new acceleration command and re-simulate until the multiple When the rear vehicle in a vehicle executes the new acceleration command and does not collide within a certain period of time, send the new acceleration command to the rear vehicle (the number of cycles cannot exceed the preset value, so as not to end the loop simulation process If there is a rear-end collision or it is too late to adjust, the number of cycles can be adjusted according to the safety time length).

The embodiment of the present invention also provides a driving warning device, as shown in Figure 9, comprising:

An acquisition module 91, configured to acquire motion state parameters of a first car on the road and a second car adjacent to the first car, where the motion state parameters at least include speed, acceleration and position information of the car, wherein the The first car and the second car are in the same lane and the distance between the two cars is less than a preset distance;

A determining module 92, configured to determine the safety time of the second car according to the motion state parameters of the first car and the second car at the current moment;

The generation module 93 is used to generate an early warning according to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after a preset braking delay time information, and the second vehicle adjusts the acceleration according to the warning information.

In the driving warning device of the embodiment of the present invention, the generating module 93 includes:

A judging unit, configured to not generate the warning information if the safety time is greater than a preset time threshold t _c ;

A first generating unit, configured to generate first warning information if the safety time is less than the preset time threshold t _c and the safety time is less than or equal to the preset delayed braking time τ;

The second generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first car decelerates after τ time, and v _f (τ )≥v _b (τ), then generate the second early warning information, wherein, v _f (τ), v _b (τ) respectively represent the speed values of the first car and the second car at time τ;

A third generation unit, configured to decelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _f (τ) <v _b (τ), and the first preset condition is met, the third warning information is generated, and the first preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2\stackrel{\&OverBar;}{a_b}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}<m,$ in, $\stackrel{\&OverBar;}{a_b}=-\frac{[v_b\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{t_f-\mathrm{\&tau;}},t_f=-\frac{[v_f\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{a_f^{*}};$ S _f (t _x ), S _b (t _x ) respectively represent the distance traveled by the first car and the second car within the time t _x ; a _cmin represents a more comfortable acceleration for the driver when decelerating ; M=Ds ₀ , D represents the distance between the rear of the first car and the front of the second car at the current moment, and s ₀ represents the safety distance required to be kept by the first car and the second car at the current speed; like ${\hat{a}}_f=\mathrm{Null},{\hat{v}}_{\min }=\mathrm{Null},$ but $a_f^{*}=a_f,v_{\min }^{*}=v_{\min },$ otherwise, Indicates the acceleration indicated by the warning indication information, Indicates the lower limit of the deceleration speed indicated by the warning indication information, and v _min is the lower limit of the speed of the current lane;

A fourth generating unit, configured to decelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _f (τ) <v _b (τ), and the first preset condition is not met, generate fourth warning information;

The fifth generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and smaller than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ )≤v _f (τ), then generate the fifth early warning information;

The sixth generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ )＞v _f (τ), then generate the sixth early warning information;

A seventh generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , and v _b (τ)≤ v _f (τ), then generate the seventh early warning information;

An eighth generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _b (τ) >v _f (τ), and the second preset condition is met, the eighth warning message will be generated, and the second preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{1}{2}[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)](\mathrm{\&gamma;}-\mathrm{\&tau;})<m,$ and $\mathrm{\&gamma;}=\frac{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;};$

A ninth generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _b (τ) >v _f (τ), and the second preset condition is not satisfied, generate ninth warning information.

In the driving warning device of the embodiment of the present invention,

The first warning information includes first acceleration information, and the first acceleration information is , where a _min represents the minimum value of vehicle acceleration;

The second warning information includes second acceleration information, and the second acceleration information is $a_b^{*}=\min \{-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$ Among them, a _cmin represents a more comfortable acceleration for the driver when decelerating;

The third warning information includes third acceleration information, and the third acceleration information is $a_b^{*}=\min \{\frac{v_b{\left(\mathrm{\&tau;}\right)}^2-{v_{\min }^{*}}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$

The fourth warning information includes fourth acceleration information, and the fourth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{{[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)]}^2}{2[m-S_b\left(\mathrm{\&tau;}\right)+S_f\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$

The fifth early warning information includes fifth acceleration information, and the fifth acceleration information is

The sixth warning information includes sixth acceleration information, and the sixth acceleration information is $a_b^{*}=\min \{-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$

The seventh early warning information includes seventh acceleration information, and the seventh acceleration information is

The eighth warning information includes eighth acceleration information, and the eighth acceleration information is

The ninth warning information includes ninth acceleration information, and the ninth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{v_f{\left(\mathrm{\&tau;}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\}.$

In the driving warning device of the embodiment of the present invention,

The first warning information indicates that the second vehicle decelerates according to the first acceleration information;

The second warning information indicates that the second vehicle decelerates to

The third warning information indicates that the second vehicle decelerates to

The fourth warning information indicates that the second vehicle decelerates to ;

The fifth warning information indicates that the second vehicle is traveling at a constant speed according to the fifth acceleration information;

The sixth early warning information indicates that the second car maintains a constant speed after decelerating to v _f (τ) according to the sixth acceleration information;

The seventh early warning information indicates that the second car is traveling at a constant speed according to the seventh acceleration information;

The eighth warning information indicates that the second vehicle is traveling at a constant speed according to the eighth acceleration information;

The ninth warning information indicates that the second vehicle decelerates to $v_f\left(\mathrm{\&tau;}\right)+a_f^{*}\&CenterDot;\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}$ maintain a constant speed.

The driving warning device of the embodiment of the present invention also includes:

A creation module, configured to generate an early warning according to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after a preset braking delay time After information, create an early warning simulation model according to the position information, vehicle parameters and weather state parameters of the first car and the second car;

The simulation module is used to judge whether the second car will collide with the first car after executing the warning information in the simulation model, and if so, adjust the warning information until the The second car will not collide with the first car, and the adjusted warning information is sent to the second car.

In the driving warning device of the embodiment of the present invention, the creation module includes:

An acquisition unit, configured to acquire a road model corresponding to the position information in a road model library according to the position information of the first car and the second car;

The first creation unit is used to create a simulation model of the vehicle by calling Carsim or PreScan according to the vehicle parameters of the first car and the second car, wherein the vehicle parameters include at least the dynamic parameters of the vehicle and the inside and outside of the vehicle modeling;

The second creating unit is configured to obtain the weather state parameters of the locations of the first car and the second car, and create the warning simulation according to the weather state parameters, the road model and the simulation model of the vehicle model, the weather state parameters include one or more of rainfall, snowfall, temperature, humidity, visibility, and road slipperiness.

The driving warning device of the embodiment of the present invention also includes:

The update module is used to update the road model in the road model library in real time according to the change information of the weather state parameters, the terrain of the road, the use time of the road, the total amount of vehicles passing on the road and the types of passing vehicles.

In a specific embodiment of the present invention, as shown in Figure 10, various sensor devices, early warning devices and positioning systems are installed on the vehicle 1, wherein the sensor devices include acceleration sensors, angular velocity sensors, speed sensors, etc. The speed, acceleration, steering wheel angle and other information; the positioning system can locate the vehicle in real time, and obtain the current position of the vehicle and the lane it belongs to.

As shown in Figure 10, in a specific embodiment of the embodiment of the present invention, the vehicle 1 and the management platform 2 can communicate through the Internet of Vehicles system, and the vehicle's license plate number (or ID), position information, speed information, acceleration information , angular velocity information, etc. are reported to the management platform 2 in real time. The vehicle 1 can also receive early warning information issued by the management platform 2 in real time, for example, new acceleration instructions and the like. The vehicle 1 reports the current parameters of the vehicle 1 to the management platform 2 in real time, such as the vehicle's speed, acceleration, position, steering wheel angle, engine speed, vehicle type, accelerator pedal and other information.

As shown in FIG. 10 , the determination module in the embodiment of the present invention may be specifically a safety time calculation module, and the generation module may be specifically an early warning information generation module. The safety time calculation module is used to calculate the safety time of each vehicle under continuous driving before reaching the dangerous state according to the speed, acceleration, position, steering wheel angle and other information of each vehicle; the early warning information generation module is used to calculate the safety time of each vehicle according to the safety time and running The status determines whether each vehicle in the chain rear-end collision situation will be in danger while maintaining the running state, and the time when the danger occurs, and generates early warning information, instructing the vehicle to adjust the acceleration to the preset value or instruct the vehicle to adjust the speed to the preset value according to the acceleration. Preset values, and an optional start time and an optional end time, etc. indicating that the vehicle is tuned to the preset values.

As shown in FIG. 10 , in a specific embodiment of the present invention, the acquisition unit may specifically be a road model library module, and the simulation module may specifically be an early warning information simulation module. Among them, the road model library module is mainly used to store the road model of each road and each road section of each road. The road model of each road or each road section can be established by importing 3D map information. The road model includes road grade, number of lanes, Road boundary line, road geometry, road elevation, slope, road friction and other information, the road model library module can provide the road model corresponding to the vehicle's current location to the early warning information simulation module according to the current location of the vehicle. The road model library update module can obtain the current change values of road parameters from the traffic platform in real time, for example, the change value of road surface friction, whether there are obstacles on the road, etc., and report the above parameters to the road model library module, so that the road model library The module adjusts or supplements the corresponding road model according to the above parameters.

As shown in FIG. 10 , in a specific embodiment of the present invention, the first creating unit may specifically be a vehicle dynamics simulation module. The main function of the vehicle dynamics simulation module is to establish a vehicle simulation model based on the current parameters of the vehicle. For example, the vehicle dynamics simulation model can obtain vehicle dynamics parameters, vehicle interior and exterior shapes, etc. from the vehicle management platform, and establish it by calling Carsim, PreScan, etc. The simulation model of the vehicle; and by changing the parameter data of the vehicle dynamic model, the characteristic parameters of each system of the vehicle can be defined in detail to meet the simulation needs of different types of vehicles. In addition, the sensor model can be installed on the vehicle, and relevant settings can be made on the sensor model, so that the vehicle can sense the driving environment outside.

As shown in FIG. 10 , in a specific embodiment of the present invention, the second creation unit may specifically include a weather condition acquisition module. Among them, the weather condition acquisition module can obtain one or more of the current rainfall, snowfall, temperature, humidity, visibility, road slipperiness and other parameters of the vehicle location from the weather service platform according to the location of the vehicle. These parameters are provided to the early warning information simulation module. Specifically, the weather service platform can obtain the above-mentioned weather parameters from weather forecasts, cloud data, and the like.

In the driving warning device of the embodiment of the present invention, the vehicle reports the current parameters of the vehicle to the management platform in real time, such as the speed, acceleration, position, steering wheel angle, engine speed, vehicle type, accelerator pedal, etc. of the vehicle; The moment when the risk state is reached, that is, the moment when the distance between the front and rear vehicles is less than the required safe braking distance. When pre-warning the rear car, according to the movement state of the front and rear cars at the current moment and the possible state changes of the front car after τ time, calculate the critical acceleration that the rear car should take at τ time, and send an early warning message to the rear car, that is, new acceleration command. In the simulation model, the new acceleration command is cyclically simulated until the following vehicle executes the new acceleration command to avoid serial rear-end collisions, thereby effectively reducing the incidence of traffic accidents.

It should be noted that each road model in the road model library can be established after each road is built, and can be specifically a collection of some basic road models, such as only straight roads, circular curve roads, flat roads, and uphill roads. , downhill road, etc. When the vehicle sends the current parameters of the vehicle to the management platform, it can simultaneously send the road information collected by the vehicle, such as road width, curvature, and slippery road conditions, to the management platform; the road model library module can be based on Road surface information Select the nearest basic model from the road model library, and make appropriate corrections to obtain the road model of the road section the vehicle is currently driving, or the road model library module can use Google Earth GoogleEarth satellite real-time map for real-time monitoring after obtaining the vehicle position , and after obtaining the specific information of the road where the vehicle is located, revise the road model according to the obtained specific information.

In a specific embodiment of the present invention, the update module includes a road model library model update module, and the road model library model update module can update each road model in the road model library in real time. For example, the road model library model update module can obtain the change value of road parameters from the traffic platform, for example, the change value of road surface friction, whether there are obstacles on the road, etc., and report the above parameters to the road model library module, so that the road model The library module adjusts or supplements the corresponding road model according to the above parameters.

Optionally, when modifying the road model in combination with the current weather conditions, the road section model can also be modified in real time in combination with the terrain, usage time, total vehicle traffic, and vehicle types of the road section. For example, for a downhill road section with a large slope, because the vehicle will limit the speed by continuously stepping on the brakes when passing, the friction coefficient of this road section may be lower than that of the road section with the same usage time. When the road section model is simulated, the friction factor of the road section model needs to be modified to make the simulation results more accurate. For another example, for a road section where most of the passing vehicles are large cargo vehicles, due to the pressure of heavy cargo, the road surface flatness of this road section may be worse than that of the road section with the same usage time, and the road surface may have more depressions or protrusions. In this way, the road surface conditions of the road section can be analyzed in combination with the historical accident conditions of the road section or the driving parameters of the vehicle on the road section, such as the degree of vehicle bumps, and the road section model can be adjusted in real time. When the above-mentioned risk warning is given to the vehicle driver, the risk warning information can be pushed to the vehicle driver in the form of a vehicle broadcast. Or the current parameters of the vehicle also include vehicle engine parameters or license plate number, and the vehicle early warning system can also find the registered mobile phone number of the driver corresponding to the engine parameter or license plate number, thereby pushing a risk warning message to the mobile phone number.

It should be noted that the device is a device corresponding to the above method embodiment, and all the implementation modes in the above method embodiment are applicable to the device embodiment, and can also achieve the same technical effect.

An embodiment of the present invention also provides a traffic warning system, including the traffic warning device as described above.

The driving warning method, device and system of the embodiments of the present invention convert the safe distance of the driving vehicle in different states into the safe time, and generate corresponding early warning information of the rear vehicle according to the safe time, and combine the simulation model of the vehicle, the current driving of the vehicle The model of the road, the current weather conditions and the early warning information of the rear vehicle are used to simulate the driving conditions of the vehicles, so as to adjust the early warning information to avoid vehicle collisions and effectively reduce the incidence of traffic accidents.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (15)

1. A traffic warning method, characterized in that, comprising: Acquiring the motion state parameters of the first car on the road and the second car adjacent to the first car, the motion state parameters at least include the speed, acceleration and position information of the car, wherein the first car and the The second vehicle is in the same lane and the distance between the two vehicles is less than the preset distance; According to the motion state parameters of the first car and the second car at the current moment, determine the safety time of the second car; According to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after a preset braking delay time, early warning information is generated, and the second car is used to generate warning information. The second vehicle adjusts the acceleration according to the warning information. 2. The driving warning method according to claim 1, characterized in that, after the safety time, the motion state parameters of the first car and the second car at the current moment and the preset braking delay time, The step of generating the warning information for the change information of the first vehicle motion state includes: If the safety time is greater than the preset time threshold t _c , the warning information is not generated; If the safety time is less than the preset time threshold t _c , and the safety time is less than or equal to the preset delay braking time τ, then generate first warning information; If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, and v _f (τ)≥v _b (τ) , then generate the second early warning information, wherein, v _f (τ), v _b (τ) respectively represent the speed values of the first car and the second car at time τ; If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, v _f (τ)<v _b (τ), and the first preset condition is met, the third warning information is generated, and the first preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2\stackrel{\&OverBar;}{a_b}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}<m,$ in, S _f (t _x ), S _b (t _x ) respectively represent the distance traveled by the first car and the second car within the time t _x ; a _cmin represents a more comfortable acceleration for the driver when decelerating ; M=Ds ₀ , D represents the distance between the rear of the first car and the front of the second car at the current moment, and s ₀ represents the safety distance required to be kept by the first car and the second car at the current speed; like ${\hat{a}}_f=\mathrm{Null},{\hat{v}}_{\min }=\mathrm{Null},$ but $a_f^{*}=a_f,v_{\min }^{*}=v_{\min },$ otherwise, $a_f^{*}={\hat{a}}_f,v_{\min }^{*}={\hat{v}}_{\min },{\hat{a}}_f$ Indicates the acceleration indicated by the warning indication information, Indicates the lower limit of the deceleration speed indicated by the warning indication information, and v _min is the lower limit of the speed of the current lane; If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle decelerates after τ time, v _f (τ)<v _b (τ), and the first preset condition is not met, generating fourth warning information; If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle is at a constant speed after τ time, and v _b (τ)≤v _f (τ) , the fifth warning message is generated; If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ)>v _f (τ) , the sixth warning message is generated; If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, and v _b (τ)≤v _f (τ), then Generate seventh early warning information; If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, v _b (τ)>v _f (τ), And if the second preset condition is met, the eighth warning message is generated, and the second preset condition is and $\mathrm{\&gamma;}=\frac{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;};$ If the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle accelerates after τ time, v _b (τ)>v _f (τ), And if the second preset condition is not met, generate ninth warning information. 3. The driving warning method according to claim 2, characterized in that, The first warning information includes first acceleration information, and the first acceleration information is Among them, a _min represents the minimum value of the vehicle acceleration; The second warning information includes second acceleration information, and the second acceleration information is $a_b^{*}=\min \{-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$ Among them, a _cmin represents a more comfortable acceleration for the driver when decelerating; The third warning information includes third acceleration information, and the third acceleration information is $a_b^{*}=\min \{\frac{v_b{\left(\mathrm{\&tau;}\right)}^2-{v_{\min }^{*}}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$ The fourth warning information includes fourth acceleration information, and the fourth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{{[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)]}^2}{2[m-S_b\left(\mathrm{\&tau;}\right)+S_f\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$ The fifth early warning information includes fifth acceleration information, and the fifth acceleration information is The sixth warning information includes sixth acceleration information, and the sixth acceleration information is $a_b^{*}=\min \{-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$ The seventh early warning information includes seventh acceleration information, and the seventh acceleration information is The eighth warning information includes eighth acceleration information, and the eighth acceleration information is The ninth warning information includes ninth acceleration information, and the ninth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{v_f{\left(\mathrm{\&tau;}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\}.$ 4. The driving warning method according to claim 3, characterized in that, The first warning information indicates that the second vehicle decelerates according to the first acceleration information; The second warning information indicates that the second vehicle decelerates to The third warning information indicates that the second vehicle decelerates to The fourth warning information indicates that the second vehicle decelerates to The fifth warning information indicates that the second vehicle is traveling at a constant speed according to the fifth acceleration information; The sixth early warning information indicates that the second car maintains a constant speed after decelerating to v _f (τ) according to the sixth acceleration information; The seventh early warning information indicates that the second car is traveling at a constant speed according to the seventh acceleration information; The eighth warning information indicates that the second vehicle is traveling at a constant speed according to the eighth acceleration information; The ninth warning information indicates that the second vehicle decelerates to $v_f\left(\mathrm{\&tau;}\right)+a_f^{*}\&Center\; Dot;\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}$ maintain a constant speed. 5. The driving warning method according to claim 1, characterized in that, according to the safety time, the motion state parameters of the first car and the second car at the current moment and the preset braking delay time After the change information of the motion state of the first car, after the step of generating early warning information, it also includes: creating a warning simulation model according to the position information, vehicle parameters and weather state parameters of the first car and the second car; In the simulation model, it is judged whether the second car will collide with the first car after executing the warning information, and if so, adjust the warning information until the second car collides with the first car. The first car will not collide, and the adjusted warning information is sent to the second car. 6. The driving warning method according to claim 5, characterized in that, according to the position information, vehicle parameters and weather state parameters of the first car and the second car, the step of creating a warning simulation model comprises: Acquiring a road model corresponding to the position information in a road model library according to the position information of the first car and the second car; According to the vehicle parameters of the first car and the second car, a simulation model of the vehicle is created by calling Carsim or PreScan, wherein the vehicle parameters include at least the dynamic parameters of the vehicle and the vehicle's internal and external shape; Obtaining the weather state parameters of the positions of the first car and the second car, and creating the early warning simulation model according to the weather state parameters, the road model and the simulation model of the vehicle, the weather state parameters Including one or more of rainfall, snowfall, temperature, humidity, visibility, and road slipperiness. 7. The driving warning method according to claim 6, further comprising: The road model in the road model library is updated in real time according to the change information of the weather state parameters, the terrain of the road, the use time of the road, the total amount of vehicles passing on the road, and the types of passing vehicles. 8. A driving warning device, characterized in that it comprises: An acquisition module, configured to acquire motion state parameters of a first car on the road and a second car adjacent to the first car, the motion state parameters at least including speed, acceleration and position information of the car, wherein the first A car is in the same lane as the second car and the distance between the two cars is less than a preset distance; A determining module, configured to determine the safety time of the second car according to the motion state parameters of the first car and the second car at the current moment; A generation module, configured to generate warning information according to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after a preset braking delay time , the acceleration is adjusted by the second car according to the warning information. 9. The driving warning device according to claim 8, wherein the generating module comprises: A judging unit, configured to not generate the warning information if the safety time is greater than a preset time threshold t _c ; A first generating unit, configured to generate first warning information if the safety time is less than the preset time threshold t _c and the safety time is less than or equal to the preset delayed braking time τ; The second generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first car decelerates after τ time, and v _f (τ )≥v _b (τ), then generate the second early warning information, wherein, v _f (τ), v _b (τ) respectively represent the speed values of the first car and the second car at time τ; A third generating unit, configured to decelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _f (τ) <v _b (τ), and the first preset condition is met, the third warning information is generated, and the first preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{{v_{\min }^{*}}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2\stackrel{\&OverBar;}{a_b}}-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}<m,$ in, $\stackrel{\&OverBar;}{a_b}=-\frac{[v_b\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{t_f-\mathrm{\&tau;}},t_f=-\frac{[v_f\left(\mathrm{\&tau;}\right)-v_{\min }^{*}]}{a_f^{*}};$ S _f (t _x ), S _b (t _x ) respectively represent the distance traveled by the first car and the second car within the time t _x ; a _cmin represents a more comfortable acceleration for the driver when decelerating ; M=Ds ₀ , D represents the distance between the rear of the first car and the front of the second car at the current moment, and s ₀ represents the safety distance required to be kept by the first car and the second car at the current speed; like but otherwise, Indicates the acceleration indicated by the warning indication information, Indicates the lower limit of the deceleration speed indicated by the warning indication information, and v _min is the lower limit of the speed of the current lane; A fourth generating unit, configured to decelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _f (τ) <v _b (τ), and the first preset condition is not met, generate fourth warning information; The fifth generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and smaller than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ )≤v _f (τ), then generate the fifth early warning information; The sixth generating unit is configured to: if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , the first vehicle will be at a constant speed after τ time, and v _b (τ )＞v _f (τ), then generate the sixth early warning information; A seventh generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , and v _b (τ)≤ v _f (τ), then generate the seventh early warning information; An eighth generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _b (τ) >v _f (τ), and the second preset condition is met, the eighth warning message will be generated, and the second preset condition is $S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)+\frac{1}{2}[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)](\mathrm{\&gamma;}-\mathrm{\&tau;})<m,$ and $\mathrm{\&gamma;}=\frac{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}{a_f^{*}}+\mathrm{\&tau;};$ A ninth generating unit, configured to accelerate the first car after τ time if the safety time is greater than the preset delayed braking time τ and less than the preset safety time threshold t _c , v _b (τ) >v _f (τ), and the second preset condition is not satisfied, generate ninth warning information. 10. The driving warning device according to claim 9, characterized in that, The first warning information includes first acceleration information, and the first acceleration information is Among them, a _min represents the minimum value of the vehicle acceleration; The second warning information includes second acceleration information, and the second acceleration information is $a_b^{*}=\min \{-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{\left(v_{\min }^{*}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]}{a}_{c\min }\};$ Among them, a _cmin represents a more comfortable acceleration for the driver when decelerating; The third warning information includes third acceleration information, and the third acceleration information is $a_b^{*}=\min \{\frac{v_b{\left(\mathrm{\&tau;}\right)}^2-{v_{\min }^{*}}^2}{2[S_b\left(\mathrm{\&tau;}\right)-S_f\left(\mathrm{\&tau;}\right)-\frac{{v_{\min }^{*}}^2-v_f{\left(\mathrm{\&tau;}\right)}^2}{2a_f^{*}}-m]},a_{c\min }\};$ The fourth warning information includes fourth acceleration information, and the fourth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{{[v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)]}^2}{2[m-S_b\left(\mathrm{\&tau;}\right)+S_f\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$ The fifth early warning information includes fifth acceleration information, and the fifth acceleration information is The sixth warning information includes sixth acceleration information, and the sixth acceleration information is $a_b^{*}=\min \{-\frac{{[v_f\left(\mathrm{\&tau;}\right)-v_b\left(\mathrm{\&tau;}\right)]}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\};$ The seventh early warning information includes seventh acceleration information, and the seventh acceleration information is The eighth warning information includes eighth acceleration information, and the eighth acceleration information is The ninth warning information includes ninth acceleration information, and the ninth acceleration information is $a_b^{*}=\min \{a_f^{*}-\frac{v_f{\left(\mathrm{\&tau;}\right)}^2-v_b{\left(\mathrm{\&tau;}\right)}^2}{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]},a_{c\min }\}.$ 11. The traffic warning device according to claim 10, characterized in that, The first warning information indicates that the second vehicle decelerates according to the first acceleration information; The second warning information indicates that the second vehicle decelerates to The third warning information indicates that the second vehicle decelerates to The fourth warning information indicates that the second vehicle decelerates to The fifth warning information indicates that the second vehicle is traveling at a constant speed according to the fifth acceleration information; The sixth early warning information indicates that the second car maintains a constant speed after decelerating to v _f (τ) according to the sixth acceleration information; The seventh early warning information indicates that the second car is traveling at a constant speed according to the seventh acceleration information; The eighth warning information indicates that the second vehicle is traveling at a constant speed according to the eighth acceleration information; The ninth warning information indicates that the second vehicle decelerates to $v_f\left(\mathrm{\&tau;}\right)+a_f^{*}\&CenterDot;\frac{2[m+S_f\left(\mathrm{\&tau;}\right)-S_b\left(\mathrm{\&tau;}\right)]}{v_b\left(\mathrm{\&tau;}\right)-v_f\left(\mathrm{\&tau;}\right)}$ maintain a constant speed. 12. The driving warning device according to claim 8, further comprising: A creation module, configured to generate an early warning according to the safety time, the motion state parameters of the first car and the second car at the current moment, and the change information of the motion state of the first car after a preset braking delay time After information, create an early warning simulation model according to the position information, vehicle parameters and weather state parameters of the first car and the second car; The simulation module is used to judge whether the second car will collide with the first car after executing the warning information in the simulation model, and if so, adjust the warning information until the The second car will not collide with the first car, and the adjusted warning information is sent to the second car. 13. The driving warning device according to claim 12, wherein the creation module comprises: An acquisition unit, configured to acquire a road model corresponding to the position information in a road model library according to the position information of the first car and the second car; The first creation unit is used to create a simulation model of the vehicle by calling Carsim or PreScan according to the vehicle parameters of the first car and the second car, wherein the vehicle parameters include at least the dynamic parameters of the vehicle and the inside and outside of the vehicle modeling; The second creation unit is configured to acquire weather state parameters at the locations of the first car and the second car, and create the warning simulation according to the weather state parameters, the road model and the simulation model of the vehicle model, the weather state parameters include one or more of rainfall, snowfall, temperature, humidity, visibility, and road slipperiness. 14. The driving warning device according to claim 13, further comprising: The update module is used to update the road model in the road model library in real time according to the change information of the weather state parameters, the terrain of the road, the use time of the road, the total amount of vehicles passing on the road and the types of passing vehicles. 15. A traffic warning system, characterized by comprising the traffic warning device according to any one of claims 8-14.