CN103818313A - Dynamic pre-warning method for automobile rear-end prevention device - Google Patents

Abstract

The invention relates to the safety pre-warning technology of vehicle driving, and particularly discloses a dynamic pre-warning method for an automobile rear-end prevention device. The method overcomes the defect that the jumping of relative speed of a vehicle since a noise problem cannot be captured in time in the prior art, and provides a method capable of obtaining the distance between vehicles and the change speed of the distance in time so as to quickly capture the jumping of the speed of the distance between the vehicles and capable of dynamically estimating the optimum safety distance during the driving process of the vehicles according to the relative vehicle speed.

Description

A kind of dynamic method for early warning for Anti-tail collision for automobiles

Technical field

The invention belongs to vehicle safety travel technical field, specifically a kind of dynamic method for early warning for Anti-tail collision for automobiles.

Background technology

Along with socioeconomic development, traffic safety problem is more and more important.Along with development and the progress of network technology, mechanics of communication and electron controls technology, the safety of automobile is subdivided into two kinds of active safety and passive securities.Passive security technology has formed ripe product, as safety strap, safety air bag, bumper/spoiler etc., after the accident that is applied to occurs, saves to greatest extent the security of the lives and property from damage, reduces the loss; Active safety technology, to prevent trouble before it happens as object, can initiatively take measures automobile, avoids the generation of accident.Such as being contained in the facility such as collision avoidance radar, blind spot detector at the each position of vehicle body, controlled by computing machine, overtaking other vehicles, move backward, change, dense fog, rainy day etc. provide motor vehicle environment necessity at any time to chaufeur with sound, light form information in the situation that of easily causing danger, and can automatically take measures, Accident prevention occurs.Current main automobile active safety technology has: ABS(anti-skid brake system) [12,13], EBD(EBD (Electric Brakeforce Distribution)) [13], LDWS (lane departure warning system) [14] etc.For anti-situation about knocking into the back, mainly contain front anticollision forewarn system (FCWS), auto against forewarn system (AWS), in patented invention, also there is relevant document, such as patent documentation 200810094275.0 discloses a kind of " automobile collision preventing control method and automobile collision preventing warning device ", patent documentation 201210323188.4 discloses one " automobile active tail-end collision prevention control system and control method " etc.

The distance-finding method that the existing anti-control setup that knocks into the back adopts has ultrasonic ranging (being usually used in, in short range range finding, being generally applied on reversing automobile collision avoidance system), laser ranging (more expensive), camera system range finding (slower), infrared distance measuring (disturbing more), radar ranging (automatic bumper for car adopt mainstream technology).There is following defect in the current anti-control setup that knocks into the back:

In warning algorithm, the calculating of safe spacing is only relevant with this vehicle speed.The situation of dwindling with larger speed at following distance, the pre-warning time deficiency of existing algorithm, has increased the risk knocking into the back.

Summary of the invention

Noise problem the object of the invention is to overcome prior art because can not catch the shortcoming of vehicle relative velocity sudden change in time, the sudden change of a kind of energy Quick Catch to following distance speed is provided, Real-time Obtaining following distance and pace of change thereof, and can be according to a kind of dynamic method for early warning for Anti-tail collision for automobiles of the best safety spacing in relative speed of a motor vehicle dynamic estimation Vehicle Driving Cycle process.

A kind of dynamic method for early warning for Anti-tail collision for automobiles provided by the invention, comprises the steps:

The first step, the following distance with this car of spacing sensor measurement with adjacent front truck, obtains the following distance signal with noise;

Second step, removes noise to the following distance signal with noise obtained in the previous step, obtains following distance;

The 3rd step, calculates following distance pace of change; Utilize the difference of the following distance that adjacent double sampling obtains to calculate divided by the sampling interval;

The 4th step, measures this car instantaneous velocity with car speed sensor, obtains this car instantaneous velocity signal with noise;

The 5th step, removes noise to this car instantaneous velocity signal with noise obtained in the previous step, obtains this car instantaneous velocity;

The 6th step, computationally secure following distance=(this car instantaneous velocity × 60%+ following distance pace of change × 40%) × emergency braking time; The emergency braking time can be according to vehicle performance setting;

The 7th step, when following distance is less than or equal to accident-free vehicle spacing, output early warning signal.

Compared with prior art, advantage of the present invention and effect:

The present invention has overcome prior art because noise problem can not catch the shortcoming of vehicle relative velocity jumping phenomenon in time, and a kind of energy Real-time Obtaining following distance and pace of change thereof are provided, and energy Quick Catch is to the method for following distance velocity jump.Designed spacing signal processing algorithm has design to be realized simply, the feature of good wave filtering effect, and can, according to the best safety spacing in relative speed of a motor vehicle dynamic estimation Vehicle Driving Cycle process, reduce to greatest extent the generation of rear-end collision.

The specific embodiment

The sampling period unification of this algorithm sensor used is set to T(unit s), and sampling time sequence is counted { k|k=1,2,3 ....

1) remove Noise Algorithm:

If u (k) represents filter input signal, y (k) represents filter output signal, and its computing formula is:

Y (k)=p*y (k-1)+(1-p) * u (k), wherein p is adjustable parameter.

The self adaptation that the present invention has provided p regulates algorithm: p=0.1+0.4*e ^-β

Wherein β=α * (| y (k-1)-u (k-1)+... + y (k-N)-u (k-N) |)/(u (k-1)+... + u (k-N) |), N is error-sensitivity parameter, N value is positive integer, N is larger, and sensitivity is lower, and N is less, sensitivity is higher, can regulate according to the size in sensor sample cycle, desirable less N when the sampling period is large, on the contrary get larger N.α is fine setting parameter, and parameter value scope is arithmetic number, and default value is 0.1.

2) following distance signal filtering

Note is s (k) with the following distance signal of noise, using s (k) as 1) input of median filter, obtain filtered following distance x (k).

3) calculate following distance pace of change

If v (k) represents the following distance pace of change of this car and front truck, its computing formula is:

V (k)=(x (k)-x (k-1))/T, using v (k) as 1) input of median filter, obtain filtered following distance pace of change v_filtered (k).

4) this car instantaneous velocity signal filtering

If it is v that car speed sensor obtains this car instantaneous velocity signal of this car band noise ₀(k), by v ₀(k) as 1) input of median filter, obtain filtered car instantaneous velocity v ₀_ filtered (k).

5) calculating of safe distance between vehicles

Safe distance between vehicles is d (k), and d (k) computing formula is:

D (k)=(v ₀_ filtered (k) * 0.6+v_filtered (k) * 0.4) * h, wherein h represents the emergency braking time, can be according to vehicle performance setting.

6) early-warning conditions

If early-warning conditions variable is y (k), the computing formula of y (k) is: y (k)=(x (k) >d (k))

Above formula represents: when spacing is greater than safe distance between vehicles, y (k) value is 1, if do not met, y (k) value is 0.

Designed early-warning conditions is: y (k)=0 o'clock triggers alarm device.

Claims (2)

1. for a dynamic method for early warning for Anti-tail collision for automobiles, it is characterized in that, comprise the steps:

The first step, the following distance with this car of spacing sensor measurement with adjacent front truck, obtains the following distance signal with noise;

Second step, removes noise to the following distance signal with noise obtained in the previous step, obtains following distance;

The 3rd step, calculates following distance pace of change;

The 4th step, measures this car instantaneous velocity with car speed sensor, obtains this car instantaneous velocity signal with noise;

The 5th step, removes noise to this car instantaneous velocity signal with noise obtained in the previous step, obtains this car instantaneous velocity;

The 6th step, computationally secure following distance=(this car instantaneous velocity × 60%+ following distance pace of change × 40%) × emergency braking time;

The 7th step, when following distance is less than or equal to accident-free vehicle spacing, output early warning signal.

2. a kind of dynamic method for early warning for Anti-tail collision for automobiles as claimed in claim 1, is characterized in that, described following distance pace of change is that the difference of the following distance that obtains with adjacent double sampling was calculated divided by the sampling interval.