CN104537888A - Automobile collision alarming method based on mobile phone - Google Patents

Abstract

The invention relates to the field of automobiles, in particular to an automobile collision alarming method based on a mobile phone. A camera of the mobile phone shoots images of obstacles located in front of and behind the automobile; according to the positions of the obstacles in the images shot by the camera of the mobile phone, the actual distances dc between the obstacles and the automobile are calculated; according to the actual distances dc between the obstacles and the automobile and the speed v of the automobile, the collision time t is calculated, the time t is compared with an alarming threshold time T, and when t reaches the threshold time T, an alarm is given out. Due to the fact that the mobile phones are widely used in life, the automobile collision alarming method based on the mobile phone is low in cost and high in popular degree.

Description

A kind of car crass alarm method based on mobile phone

Technical field

The present invention relates to automotive field, particularly relate to a kind of car crass alarm method based on mobile phone.

Background technology

Car crass early warning system is at the front portion of automobile or rear portion mounting vehicle identification sensor, by the relative velocity of test front-and-rear vehicle distance, Ben Che and above or below automobile, calculate collision time, and at different time points (as 2.7 seconds, 0.9 second) warning of different urgency level is sent by the image of sound, different colours, reach the object of reminding driver.

Traditional vehicle identification sensor adopts the high-end equipments such as medium and long distance radar, vehicle-mounted proprietary camera.Because price is high, be equipped in luxurious car and high-end car more at present, have impact on universal.

Summary of the invention

The object of the present invention is to provide a kind of car crass alarm method based on mobile phone, it can utilize popular mobile phone camera to realize the object of active safety early warning.

Technical scheme of the present invention is, comprises the following steps:

Step 1: mobile phone camera picked-up vehicle front/rear barrier object image;

Step 2: the barrier position calculation in the picture according to mobile phone picked-up goes out the actual range d of this obstacle distance from car _c;

Step 4: according to the actual range d of obstacle distance from car _cwith the speed v from car, calculate the time t of distance collision;

Step 5: time t and alarm threshold value time T is contrasted, when reaching t and reaching threshold time T, reports to the police.

Further, described barrier distance is d from the actual range of car _c=d1+d2, d1 are the distance of the nearest visual field of mobile phone camera to this car front end/afterbody, and d2 is the distance of the nearest visual field and the barrier that image obtains, and d2 is obtained by following steps:

Step 1: the rectangle frame that the barrier choosing camera picked-up is formed in the picture, calculates the plane of delineation coordinate xl of rectangle frame base mid point, yl;

Step 2: the plane of delineation coordinate x2 asking for mobile phone screen base mid point, y2;

Step 3: by plane of delineation coordinate xl, yl and x2, y2 ask according to the mapping relations of plane of delineation coordinate and road surface coordinate and remove road surface coordinate Xl, Yl and X2, Y2;

Step 4: distance d2=((Yl-Y2) ²+ (Xl-X2) ²) ^0.5.

Further, the mapping relations of described plane of delineation coordinate and road surface coordinate are as follows:

$\left\{\begin{array}{c}{Y}_P=h*k_1*y_p*\frac{1+k_2^2}{1-k_2*k_1*y_p}\\ X_p=\frac{\mathrm{UG}+Y_p}{\mathrm{UG}*k_3*x_p*k_4}\\ y_p=\frac{Y_p/k_1}{h+h*k_2^2+Y_p*k_2}\\ x_p=\frac{\mathrm{UG}*X_p}{k_3*k_4(\mathrm{UG}+Y_p)}\end{array}\right.$

Wherein:

$\left\{\begin{array}{c}{k}_1=2\mathrm{tg}\left({\mathrm{\α}}_0\right)/H\\ k_2=\mathrm{tg}\left({\mathrm{\γ}}_0\right)\\ k3=h/\cos \left({\mathrm{\γ}}_0\right)\\ k_4=2\mathrm{tg}\left({\mathrm{\β}}_0\right)/W\\ \mathrm{UG}=\frac{h(\mathrm{tg}\left({\mathrm{\γ}}_0\right)-\mathrm{tg}({\mathrm{\γ}}_0-{\mathrm{\α}}_0))\cos ({\mathrm{\γ}}_0-{\mathrm{\α}}_0)}{\cos ({\mathrm{\γ}}_0-{\mathrm{\α}}_0)-\cos {\mathrm{\γ}}_0}\end{array}\right.$

(X _p, Y _p) be road surface coordinate, (x _p, y _p) be plane of delineation coordinate, H is the height of image, and w is the wide of image, and h is the distance on the optical axis distance ground of camera, 2 β ₀for the horizontal field of view angle of camera lens, 2 α ₀for the vertical visual field angle of camera lens, γ ₀for the angle of pitch of video camera.

Further, the time t=d of described distance collision _c/ v.

Further, the described alarm threshold value time is at least one, exports the alarm tone of different frequency when described collision time reaches the different alarm threshold value time.

The invention has the beneficial effects as follows: obtain road barrier object image by mobile phone camera, again according to taking the photograph machine projection model, to be derived the relation obtained between road surface coordinate system and image coordinate system by geometry, thus draw the time travelled to barrier place, i.e. collision time.Collision time and alarm threshold value time are contrasted, carries out collision warning reaching the alarm threshold value time, thus reach the object utilizing mobile phone camera to realize active safety early warning.Mobile phone is widely used in life, make of the present invention with low cost, and popularization degree is high.

Accompanying drawing explanation

Fig. 1 is monocular vision geometric projection model a;

Fig. 2 is monocular vision geometric projection model b;

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Specific embodiment described herein only in order to explain the present invention, is not intended to limit the present invention.In addition, if below in described each embodiment of the present invention involved technical characteristic do not form conflict each other and just can mutually combine.

Mobile phone in the present invention is securely fixed on windshield before automobile or below by accurate Calculation and calibrated angle, makes mobile phone camera aim at the object in vehicle front or path, rear and obtain image information.

After mobile phone picked-up barrier (object namely in vehicle front or path, rear), image display translation.

As shown in Figure 1, plane ABU represents road plane, ABCD is the trapezoid area in the road plane that photographs of video camera, O point is camera lens central point, OG is camera optical axis, G point is the intersection point (be also simultaneously the visual field trapezoidal diagonal line intersection point) of camera optical axis and road plane, and I point is the vertical projection in the plane of O Dian road.In the coordinate system of road surface, G point is defined as coordinate origin, and vehicle forward direction is defined as Y direction.

As shown in Figure 2, a, b, c, d are 4 end points of picture planar rectangular to the corresponding point of G, A, B, C, D each point in the plane of delineation, H and W is respectively the height and width of picture plane.The mid point g of definition image rectangle is the true origin of photo coordinate system, and y-axis represents vehicle forward direction.Get 1 P in the plane of road, its coordinate at road plane coordinate system is (X _p, Y _p), the corresponding point of P point in the plane of delineation are P1, and its coordinate at photo coordinate system is (x _p, y _p).Utilize geometric relationship can derive corresponding relation between following road surface coordinate and image coordinate:

$\left\{\begin{array}{c}{Y}_P=h*k_1*y_p*\frac{1+k_2^2}{1-k_2*k_1*y_p}\\ X_p=\frac{\mathrm{UG}+Y_p}{\mathrm{UG}*k_3*x_p*k_4}\\ y_p=\frac{Y_p/k_1}{h+h*k_2^2+Y_p*k_2}\\ x_p=\frac{\mathrm{UG}*X_p}{k_3*k_4(\mathrm{UG}+Y_p)}\end{array}\right.---\left(1\right)$

Wherein:

$\left\{\begin{array}{c}{k}_1=2\mathrm{tg}\left({\mathrm{\α}}_0\right)/H\\ k_2=\mathrm{tg}\left({\mathrm{\γ}}_0\right)\\ k3=h/\cos \left({\mathrm{\γ}}_0\right)\\ k_4=2\mathrm{tg}\left({\mathrm{\β}}_0\right)/W\\ \mathrm{UG}=\frac{h(\mathrm{tg}\left({\mathrm{\γ}}_0\right)-\mathrm{tg}({\mathrm{\γ}}_0-{\mathrm{\α}}_0))\cos ({\mathrm{\γ}}_0-{\mathrm{\α}}_0)}{\cos ({\mathrm{\γ}}_0-{\mathrm{\α}}_0)-\cos {\mathrm{\γ}}_0}\end{array}\right.$

W is the wide of image, and h is the distance on the optical axis distance ground of camera, 2 β ₀for the horizontal field of view angle of camera lens, 2 α ₀for the vertical visual field angle of camera lens, γ ₀for the angle of pitch of video camera.

After drawing the mapping relations between picture planimetric coordinates and road surface planimetric coordinates, the calculating of barrier apart from vehicle really distance can be carried out.Barrier distance is d from the actual range of car _c=d1+d2, d1 is the distance (namely mobile phone camera foremost apart from the distance of this car front end/afterbody) of the nearest visual field of mobile phone camera to this car front end/afterbody, d2 is the distance of the nearest visual field and the barrier that image obtains, and d2 can be obtained by following steps:

Step 1: the rectangle frame that the barrier choosing camera picked-up is formed in the picture, calculates the plane of delineation coordinate xl of rectangle frame base mid point, yl;

Step 2: the plane of delineation coordinate x2 asking for mobile phone screen base mid point, y2;

Step 3: by plane of delineation coordinate xl, yl and x2, y2 ask according to the mapping relations of plane of delineation coordinate and road surface coordinate and remove road surface coordinate Xl, Yl and X2, Y2;

Step 4: distance d2=((Yl-Y2) ²+ (Xl-X2) ²) ^0.5.

According to cellphone GPS signal, the travelling speed V of vehicle can be calculated, thus the time t=d of distance collision can be calculated _c/ v.Alarm threshold value time T is stored in control module ₁, T ₂deng the urgency level representing vehicle and object proximity.When t equals T from being greater than to be reduced to ₁(as 2.7 seconds), control module exports and represents certain urgency level early warning signal; When t is from T ₁be reduced to and equal T ₂time (T ₂> T ₁, as 0.9 second), control module exports the high early warning signal of urgency level.After these early warning signals are received in warning system, early warning signal is converted to the different voice signal of frequency degree or image glisten signal.Urgency level is higher, and frequency is higher, namely with T ₂corresponding early warning sound or image glisten frequency should higher than with T ₁corresponding early warning sound or image glisten frequency.

The above, be only the specific embodiment of the present invention, it should be pointed out that any those of ordinary skill in the art are in the technical scope disclosed by the present invention, the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.

Claims (5)

1., based on a car crass alarm method for mobile phone, it is characterized in that, comprise the following steps:

Step 1: mobile phone camera picked-up vehicle front/rear barrier object image;

Step 2: the barrier position calculation in the picture according to mobile phone picked-up goes out the actual range d of this obstacle distance from car _c;

Step 4: according to the actual range d of obstacle distance from car _cwith the speed v from car, calculate the time t of distance collision;

Step 5: time t and alarm threshold value time T is contrasted, when reaching t and reaching threshold time T, reports to the police.

2. a kind of car crass alarm method based on mobile phone as claimed in claim 1, is characterized in that: described barrier is apart from being d from the actual range of car _c=d1+d2, d1 are the distance of the nearest visual field of mobile phone camera to this car front end/afterbody, and d2 is the distance of the nearest visual field and the barrier that image obtains, and d2 is obtained by following steps:

Step 1: the rectangle frame that the barrier choosing camera picked-up is formed in the picture, calculates the plane of delineation coordinate xl of rectangle frame base mid point, yl;

Step 2: the plane of delineation coordinate x2 asking for mobile phone screen base mid point, y2;

Step 3: by plane of delineation coordinate xl, yl and x2, y2 ask according to the mapping relations of plane of delineation coordinate and road surface coordinate and remove road surface coordinate Xl, Yl and X2, Y2;

Step 4: distance d2=((Yl-Y2) ²+ (Xl-X2) ²) ^0.5.

3. a kind of car crass alarm method based on mobile phone as claimed in claim 2, is characterized in that: the mapping relations of described plane of delineation coordinate and road surface coordinate are as follows:

$\left\{\begin{array}{c}{Y}_P=h*k_1*y_p*\frac{1+k_2^2}{1-k_2*k_1*y_p}\\ X_p=\frac{\mathrm{UG}+Y_p}{\mathrm{UG}*k_3*x_p*k_4}\\ y_p=\frac{Y_p/k_1}{h+h*k_2^2+Y_p*k_2}\\ x_p=\frac{\mathrm{UG}*X_p}{k_3*k_4(\mathrm{UG}+Y_p)}\end{array}\right.$

Wherein:

$\left\{\begin{array}{c}{k}_1=2\mathrm{tg}\left({\mathrm{\α}}_0\right)/H\\ k_2=\mathrm{tg}\left({\mathrm{\γ}}_0\right)\\ k3=h/\cos \left({\mathrm{\γ}}_0\right)\\ k_4=2\mathrm{tg}\left({\mathrm{\β}}_0\right)/W\\ \mathrm{UG}=\frac{h(\mathrm{tg}\left({\mathrm{\γ}}_0\right)-\mathrm{tg}({\mathrm{\γ}}_0-{\mathrm{\α}}_0))\cos ({\mathrm{\γ}}_0-{\mathrm{\α}}_0)}{\cos ({\mathrm{\γ}}_0-{\mathrm{\α}}_0)-\cos {\mathrm{\γ}}_0}\end{array}\right.$

(X _p, Y _p) be road surface coordinate, (x _p, y _p) be plane of delineation coordinate, H is the height of image, and w is the wide of image, and h is the distance on the optical axis distance ground of camera, 2 β ₀for the horizontal field of view angle of camera lens, 2 α ₀for the vertical visual field angle of camera lens, γ ₀for the angle of pitch of video camera.

4. a kind of car crass alarm method based on mobile phone as claimed in claim 1, is characterized in that: the time t=d of described distance collision _c/ v.

5. a kind of car crass alarm method based on mobile phone as claimed in claim 1, is characterized in that: the described alarm threshold value time is at least one, exports the alarm tone of different frequency when described collision time reaches the different alarm threshold value time.