CN108608942A - Anti-rear-collision method and early warning system for automobile - Google Patents

Abstract

The invention relates to a method and a system for preventing rear-end collision of an automobile.A controller of a pre-warning device is arranged on the automobile, the stepping depth of a brake pedal and the change rate of the pedal position are obtained through the controller of the pre-warning device, and the controller of the pre-warning device is used for identifying whether an emergency braking state is achieved or not and controlling the sound and light of danger warning of the automobile to achieve the pre-warning of preventing rear-end collision; in addition, the early warning device controller acquires the speed of the vehicle and the gradient of a running road surface to calculate the safe distance, and early warning is carried out by identifying whether the vehicle enters the road and detecting whether the distance between the two vehicles is less than the safe distance, so that the vehicle can be prevented from overtaking before the rear-end collision. The early warning device controller receives signals output by the brake pedal position sensor, the inclination angle sensor, the vehicle speed acquisition module and the visual analysis module, controls sound and light of vehicle danger warning, reminds a driver of the vehicle and gives a warning to the driver of a front vehicle and a rear vehicle, prevents the front vehicle from rear-end collision and the rear-end collision of the rear vehicle, and increases driving safety.

Description

Anti-rear-collision method and early warning system for automobile

technical field

The invention relates to the technical field of automobile safety, in particular to an early warning device for preventing automobiles from being rear-end collided (front and rear collisions).

Background technique

As automobiles enter people's daily life in large numbers, automobile driving safety has received more and more attention and attention. As far as common car rear-end collisions or being rear-ended accidents are concerned, most of them are caused by the failure of the rear car to respond in time after the front car brakes suddenly, the safe distance between the self-car and the front car is not enough, or the purpose of the front car's brake is not clear (emergency brake or Lightly step on the brakes), resulting in insufficient braking force, failing to stop in time within a limited time and distance, resulting in a rear-end collision accident. In order to effectively avoid and reduce the occurrence of automobile rear-end collision accidents, the prior art is generally to install active detection radar on automobiles, and when the distance between the two vehicles is less than the safe distance, the rear vehicle will automatically decelerate. But this kind method is active detection, passive induction, is affected by driving speed and driving environment etc., and the anti-rear-end collision effect is unsatisfactory. In addition, the existing active detection devices are relatively expensive to manufacture, and the implementation method is quite complicated. They can only be installed on relatively high-end automobiles, and it is not easy to popularize them.

Contents of the invention

The purpose of the present invention is to provide an automobile rear-end collision prevention method and an early warning system, which can remind the driver of the own vehicle and give warnings to the drivers of the front and rear vehicles, so as to reduce automobile rear-end collision accidents. The system is compact, cheap, and easy to install.

In order to achieve the above object, the present invention provides a method for preventing rear-end collisions of automobiles. The method is to install an early warning device controller on the automobile, and obtain the pedal depth of the brake pedal and the rate of change of the pedal position through the early warning device controller, so as to identify whether the emergency brake is reached. state, and control the sound and light of car danger warning to prevent rear-end collision warning; in addition, the early warning device controller obtains the vehicle speed and the slope of the driving road to calculate the safety distance, and detects two vehicles at the same time by identifying whether there is a vehicle entering the lane It will give an early warning if the distance between vehicles is below the safe distance, so as to prevent the vehicle from rear-ending the vehicle in front.

The early warning device controller controls the sound and light of automobile danger warning through bluetooth.

The safety distance refers to the sum of the safety distance corresponding to the vehicle speed of the vehicle and the safety distance corrected by the slope. The safety distance corresponding to the vehicle speed is obtained through image analysis and calculation, and the image is captured by a CCD camera to identify obstacles (vehicles). The size of the area is calculated indirectly. It can also be obtained jointly by image analysis and calculation combined with lidar ranging, so that the accuracy rate is higher; image analysis and calculation is a ranging algorithm based on inverse projection transformation. The principle of the algorithm is: when the focal length When a certain time, the product of the vehicle distance and the vehicle width on the image is a constant; set is the vehicle distance at the previous moment, is the vehicle distance at the next moment, is the number of pixels occupied by the width of the vehicle in the image at the previous moment, is the number of pixels occupied by the width of the vehicle in the image at the next moment, then:

Suppose the size of the image is W, then the distance ,or ; From the above formula, we can see that , record this constant as C, and record the values of d _i and w _i through n times of measurements, then the value of C for self-calibration can be obtained:

After obtaining the calibrated C value, the two-dimensional width W of the front car in the image can be further used to calculate the distance between the own car and the front car in the actual space ;

forward acceleration of the vehicle According to further calculation by the GPS positioning module based on the obtained vehicle speed, the vertical vibration displacement of the vehicle body at the front suspension is Z ₁ , and the rotation equation can be written from the moment of each force on the pendulum to the swing center O:

In the formula: J=mr ² , φ=θ-(α+β), g is the acceleration of gravity, ;

The above formula can be simplified to:

After further data analysis, processing and calculation, the approximate formula for calculating the road slope angle α can be obtained:

.

The anti-rear-end vehicle front warning includes in-vehicle language prompting the driver, the operation of hazard warning lights, the operation of horns or a combination thereof.

In order to achieve the above object, the automobile anti-rear-end collision early warning system provided by the present invention includes a brake pedal position sensor connected to the brake pedal, an early warning device controller, an inclination sensor, a vehicle speed acquisition module and a CCD visual analysis module. Image, identify obstacles, and indirectly calculate the vehicle distance according to the size of the obstacle area. The early warning device controller receives the above-mentioned sensor signal, and when the early warning condition is reached, it immediately controls the vehicle danger warning sound and light, reminds the driver of the own vehicle, and gives a warning to the drivers of the front and rear vehicles at the same time.

The early warning device controller adopts a highly integrated Car-cam motherboard MSC8328P, which has a DUAL600MHZ 32-BIT RISC processor, and configures DDR 4G memory and Bluetooth sending and receiving modules; the danger warning light switch and the horn switch of the car are all designed as Bluetooth and manual press controllable mode at the same time, the hazard warning light switch and the horn switch are connected to the early warning device controller through Bluetooth, the hazard warning light switch receives the signal output by the early warning device controller to control the work of the warning light; The signal controls the car horn to work.

The vision analysis module is a vision system based on a monocular CCD lens.

The self-vehicle speed acquisition module is a GPS positioning module or a vehicle speed signal module of the vehicle network CAN receiving instrument computer.

The brake pedal position sensor is a non-contact Hall brake pedal position sensor, which has a magnet and a Hall IC chip; the Hall IC chip is fixed, and the magnet moves with the brake pedal to change the incident angle of the magnetic force line, thereby affecting the position of the Hall IC chip. voltage output value.

The invention realizes reminding the driver of the own vehicle and giving warnings to the drivers of the front and rear vehicles, thereby not only preventing rear-end collision of the preceding vehicle, but also early warning of rear-end collision by the rear vehicle. The system is compact, cheap, easy to load, and does not change the appearance and wiring of the original car. Through the early warning device controller, the vehicle speed V, the slope a of the road surface, and the safety distance D _G are calculated, and by identifying whether the lane within the safety distance is The target vehicle enters within the safe distance to remind the driver of the own vehicle to prevent rear-end collision with the vehicle in front; in addition, in the case of emergency braking, the early warning device controller judges the emergency braking by receiving the signal output from the brake pedal position sensor. To a certain extent, the Bluetooth module is used to control the switch of the hazard warning light and the switch of the horn, so as to prevent being rear-ended by the car behind and to turn on the hazard warning light and the horn for early warning in case of an emergency to prevent secondary accidents and increase driving safety.

Description of drawings:

Accompanying drawing 1 is the structure schematic diagram of early warning system of the present invention;

Accompanying drawing 2 is the work flowchart of early warning system of the present invention;

Accompanying drawing 3 is that the monocular CCD visual system of the present invention recognizes the schematic diagram of vehicle distance;

Accompanying drawing 4 is the schematic diagram of the brake pedal position sensor of one embodiment of the present invention;

Accompanying drawing 5 is the schematic diagram of inclination sensor;

Accompanying drawing 6 is the vehicle model of calculating slope.

Detailed ways:

The idea, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention.

The invention relates to a method for preventing rear-end collisions of automobiles. The method is to install an early-warning device controller on the automobile, obtain the stepping depth of the brake pedal and the change rate of the pedal position through the early-warning device controller, and use it to identify whether a sudden braking state has been reached, and control the automobile. Hazard warning sound and light, to prevent rear-end collision warning; and through the early warning device controller to know the speed of the vehicle, the slope of the driving road, calculate the safety distance, and prevent rear-end collision by identifying whether there is a target vehicle in the lane within the safety distance. Vehicle ahead warning. Realize reminding the driver of the own car and giving warnings to the drivers of the front and rear cars, so as to prevent rear-end collision of the front car and early warning of rear-end collision by the rear car.

In this method, the controller of the early warning device controls the sound and light of the automobile danger warning through Bluetooth, which is convenient for control and transmission; the safety distance is the sum of the safety distance D _V corresponding to the vehicle speed and the safety distance D _ɑ corrected by the slope, that is, D _G =D _V +D _ɑ , the safety distance corresponding to the vehicle speed is obtained through image analysis and calculation. Through the images captured by the CCD camera, identify obstacles, and calculate the actual vehicle distance according to the size of the obstacle area . The anti-rear-end vehicle front warning includes in-vehicle language prompting the driver, the operation of hazard warning lights, the operation of horns or a combination thereof. Thus, the effect of preventing rear-end collision of the automobile is improved.

As shown in FIG. 3 , the image analysis method uses monocular CCD visual distance measurement, which is a distance measurement algorithm based on inverse projection transformation. This method is easy to implement and at the same time, the image processing speed is fast. The principle of the algorithm is: when the focal length When certain, the product of the vehicle distance and the vehicle width on the image is a constant. When the distance between the two vehicles is different, the size of the front vehicle in the image is different. Assume is the vehicle distance at the previous moment, is the vehicle distance at the next moment, is the number of pixels occupied by the width of the vehicle in the image at the previous moment, is the number of pixels occupied by the width of the vehicle in the image at the next moment, then:

Suppose the size of the image is W, then the distance ,or . It can be seen from the above formula, , record this constant as C, and record the values of d _i and w _i through n times of measurements, then the value of C for self-calibration can be obtained:

After obtaining the calibrated C value, the two-dimensional width W of the front car in the image can be further used to calculate the distance D between the own car and the front car in the actual space:

.

Referring to shown in Fig. 1～6, be the preferred embodiment schematic diagram of the present invention, automobile anti-rear-collision early warning system of the present invention, comprise the brake pedal position sensor 1 that connects brake pedal, early warning device controller 2, inclination sensor 3, automatically The vehicle speed acquisition module 4 and the visual analysis module 5, the early warning device controller 2 receives signals output by the brake pedal position sensor 1, the inclination sensor 3, the vehicle speed acquisition module 4 and the visual analysis module 5, and controls the sound and light of the vehicle danger warning , remind the driver of the own car and give warnings to the drivers of the front and rear cars. Early warning device controller 2 adopts highly integrated Car-cam motherboard MSC8328P, which has a DUAL 600MHZ 32-BIT RISC processor, is equipped with DDR 4G memory and Bluetooth sending and receiving module, and receives brake pedal position sensor 1, inclination sensor 3, vehicle speed Obtain the signals output by the module 4 and the visual analysis module 5, analyze and process them, and then send and accept module output instructions via Bluetooth. The hazard warning light switch 6 and the horn switch 7 of the automobile are all designed as bluetooth and manual press controllable modes at the same time, the hazard warning light switch 6 and the horn switch 7 are connected to the early warning device controller 2 by bluetooth, and the hazard warning light switch 6 receives the early warning The signal output by the device controller 2 controls the warning light 61 to work; the horn switch 7 receives the signal output by the early warning device controller 2 to control the car horn 71 to work. When working, the function module of preventing being rear-ended is based on the brake pedal stepping depth and the pedal position change rate signal to identify whether it has reached the emergency braking state. It is divided into two levels of early warning design. The level of warning response is that only the hazard warning lights operate. The anti-rear collision front vehicle function module is designed as a 2-level early warning response. The low-level early warning response is to verbally prompt the driver to slow down and keep a safe distance; the high-level early warning response includes two aspects: the language in the car prompts the driver and the danger The warning light works to remind the driver of the vehicle in front and behind that the vehicle is in a dangerous situation.

In this embodiment, Mstar motherboard MSC8328P is used, which is a highly integrated Car-cam solution. The main chip is a Dual 600MHz 32-bit RISC processor with built-in DDR. The GPS module can realize the function of recording vehicle speed and driving track . Support motion detection function, support lane detection. The CCD is a high-definition 1920x1080, 30fps lens, and supports H.264 storage compression; it can automatically cycle video, and the recording time of each file can be set. It also supports NTSC/PAL.TV output and HDMI output.

As shown in Figures 1 and 4, in this embodiment, the brake pedal position sensor 1 is a non-contact Hall brake pedal position sensor, which collects the brake pedal position in real time to calculate the brake pedal depth, and at the same time further calculates the pedaling speed, and works stably and accurately. . The sensor has a magnet 11 and a Hall IC chip 12; the Hall IC chip 12 is fixed, and the magnet 11 moves together with the brake pedal to change the incident angle of the magnetic force line, thereby affecting the voltage output value of the Hall IC chip 12 and obtaining a corresponding output signal. The danger warning light switch 6 and the horn switch 7 of the car are designed to be controlled by Bluetooth and manual pressing at the same time, so that the danger warning light switch 6 and the horn switch 7 are connected to the early warning device controller 2 through Bluetooth, and the danger warning light switch 6 receives the early warning device. The signal control warning light 61 work of controller 2 outputs; Horn switch 7 receives the signal control car horn 71 work of prewarning device controller 2 output; practicality. By detecting the rate of change of the brake pedal position sensor 1 and the pedal depression depth (maximum displacement of the position sensor) to identify whether a sudden braking state has been reached. If it is judged to be a sudden brake, the hazard warning light of the car is controlled through Bluetooth to make it work, and a timely warning is given to the car behind. If it is judged to be the emergency brake, in addition to the work of the hazard warning lights, the horn is also controlled to warn the vehicles behind.

As shown in Figures 1, 5 and 6, in the present embodiment, the inclination sensor 3 is a single pendulum angular displacement sensor, which measures the slope of the driving road surface and outputs a slope signal to the early warning device controller 2. The vehicle speed acquisition module 4 is a GPS positioning module or a vehicle speed signal module of the vehicle network receiving instrument computer. The visual analysis module 5 is a visual system based on a CCD lens. The distance to the vehicle in front is measured by image analysis and calculation. Obstacles (vehicles) are identified through the images captured by the CCD lens, and whether they are within the safe distance is indirectly calculated according to the size of the obstacle area. The installation is simple and convenient, low cost, and cost-effective.

As shown in FIG. 5 , the inclination sensor includes a single pendulum angular displacement sensor and a vibration displacement sensor, which are installed on the vehicle body at the front suspension, and the pendulum angle is measured by it as θ. When the vehicle is running on the slope, due to the influence of various forces at any moment, the pendulum produces a deflection angle θ relative to the forward direction. The θ angle is composed of the slope angle α, the deflection angle β caused by the pitching motion of the vehicle body, and the deflection angle caused by the joint action of the inertial forces F _js and F _jz It consists of three parts, that is, θ = α + β + φ.

forward acceleration of the vehicle According to further calculation by the GPS positioning module based on the obtained vehicle speed, the vertical vibration displacement of the body at the front suspension is Z ₁ , as shown in Fig. 6, and the moment of each force on the pendulum to the swing center O can be written as Rotation equation:

In the formula: J=mr ² , φ=θ-(α+β), g is the acceleration of gravity, .

The above formula can be simplified to:

After further data analysis, processing and calculation, the approximate formula for calculating the road slope angle α can be obtained:

.

Establishment of early warning model of safe vehicle distance:

The "Road Traffic Safety Law of the People's Republic of China" stipulates that when a motor vehicle is driving on the expressway, when the speed exceeds 100 kilometers per hour, the safe distance between vehicles is more than 100 meters, and when the speed is lower than 100 kilometers per hour, the minimum safe distance between vehicles must not be less at 50 meters. In actual driving, the lower the speed of the vehicle, the closer the distance between vehicles will be. The present invention is designed to stop the anti-rear-end vehicle warning function when the vehicle speed is lower than 40KM/h, and the anti-rear-end vehicle anti-rear collision early warning function is effective after it is turned on, as long as the early warning is reached. Conditions are warnings.

The safe vehicle distance has an important relationship with the braking distance of the car. The braking distance S=V ² /2gμ (g=9.8m/s ² ) mainly depends on the vehicle speed and the friction between the tire and the ground. The square of the braking distance and the vehicle speed Proportional to and inversely proportional to the coefficient of friction. When the car is running on a conventional asphalt road, the friction coefficient is 0.8, and the braking deceleration speed is 6m/s ² . The braking distance depends on the speed of the car. If the speed of the car doubles, the braking distance will increase to four times. It takes a period of reaction time to step on the brakes to slow down when you see danger. This period includes the reaction time of people and the response time of cars. We take the average reaction time of most people as 1 second. The actual emergency braking distance data calculated from this is as follows:

Table 1 A set of data of vehicle speed and emergency braking distance:

Vehicle speed/km/h 40 50 60 70 80 90 100 110 120 130 140 150 The time required for the corresponding vehicle speed to stop/s 1.9 2.3 2.8 3.2 3.7 4.2 4.6 5.1 5.6 6.0 6.5 6.9 The distance required for the above braking time/m 10.3 16.1 23.1 31.5 41.2 52.1 64.3 77.8 92.6 108.7 126.0 144.7 Emergency braking distance including human-vehicle reaction time/m 19.0 26.2 34.4 43.6 53.7 64.9 77.0 90.1 104.2 119.3 135.3 152.4 Increased distance/m 8.7 10.1 11.2 12.0 12.6 12.8 12.7 12.3 11.6 10.6 9.3 7.7 The death time of the above safety distance/s 1.7 1.9 2.1 2.2 2.4 2.6 2.8 2.9 3.1 3.3 3.5 3.7

The speed of the car can be obtained by the GPS module, and the distance of the real car is obtained by analysis and calculation of the CCD vision module. The present invention is designed in the CCD measurement image, and the detected vehicle in front will be marked with a green rectangular frame beyond the safe distance. When the vehicle distance is less than or equal to the emergency braking distance at the corresponding speed, the advanced warning will be activated, and the rectangular frame will also change. It is an alarm flashing prompt in red, green and blue.

In order to reduce the risk of rear-end collision with the vehicle in front, the emergency braking distance calculated above is relatively insufficient in safety, so it is set as a high-level early warning. Before the advanced warning, it is necessary to add 0.6S to the emergency braking distance corresponding to each vehicle speed according to the driving experience data. The braking distance is shown in Table 2 (deceleration rate is 6m/s ² ). The outside is marked with a green rectangular frame. When the vehicle distance is less than or equal to the safety distance corresponding to the speed, the low-level warning will be activated, and the rectangular frame will turn into a red flashing prompt. At this time, with the system language prompt, the driver can be reminded in advance to brake and reduce speed in time to maintain a reasonable distance between vehicles.

Table 2 A set of data of vehicle speed and safety distance (according to empirical values):

Vehicle speed/km/h 40 50 60 70 80 90 100 110 120 130 140 150 Safe braking distance with increased reaction time/m 25 35 45 55 65 80 95 105 125 140 155 175 Death time after increasing the safety distance/s 2.3 2.5 2.7 2.8 2.9 3.2 3.4 3.4 3.8 3.9 4.0 4.2 Increased reaction time/s 0.5 0.6 0.6 0.6 0.5 0.6 0.6 0.5 0.6 0.6 0.5 0.5

Of course, the present invention has been described in detail above in conjunction with the embodiments, only to illustrate the technical conception and characteristics of the present invention, and its purpose is to allow those familiar with this technology to understand the content of the present invention and implement it. Substantial equivalent changes or modifications shall fall within the protection scope of the present invention.

Claims (10)

1. a kind of automobile anti-rear end collision method, it is characterised in that：This method is the installation prior-warning device controller on automobile, by pre- Alarm device controller knows that brake pedal tramples depth and pedal position rate, to identify whether to reach emergency brake car state, And vehicle hazard warning acousto-optic is controlled, reaching prevents by early warning of knocking into the back；And by prior-warning device controller know from vehicle speed, The gradient of track calculates safe distance, and whether this track has target to enter safe distance in safe distance by identifying Within carry out preventing from knocking into the back front truck early warning.

2. a kind of automobile anti-rear end collision method according to claim 1, it is characterised in that：The prior-warning device controller passes through Bluetooth control vehicle hazard alerts acousto-optic.

3. a kind of automobile anti-rear end collision method according to claim 1, it is characterised in that：The safe distance is that speed corresponds to Safe distance and the sum of the modified safe distance of the gradient, the corresponding safe distance of speed is obtained by image analysis calculation, is made The image shot with CCD camera, cognitive disorders object calculate indirectly according to the size of barrier area；Or use image point Analysis calculations incorporated laser radar range obtains jointly；Image analysis calculation is a kind of location algorithm based on Inverse projection, should The principle of algorithm is：Work as focal lengthOne timing, the product of spacing and vehicle width on image is a constant；IfWhen being previous The spacing at quarter,For the spacing of later moment in time,For the pixel number shared by vehicle width in previous moment image,It is rear Pixel number in one time chart picture shared by vehicle width, then：

Assuming that the size of image is W, then distance, or；It can by above formula Know,, this constant is denoted as C, record d is measured by n times_iAnd w_iValue, you can ask Coming from the C values that vehicle is calibrated is：

After obtaining the C values of calibration, the two-dimentional width W of front truck in image can be further utilized, is calculated in real space From vehicle at a distance from front truck；

The acceleration that vehicle advancesIt is further calculated and can be obtained according to the speed of acquisition by GPS positioning module, vehicle body is preceding Up-down vibration displacement at suspension is Z₁, its rotation equation can be written to the square of oscillation center O in each power suffered by pendulum:

In formula:J=mr², φ=θ-(alpha+beta), g are acceleration of gravity, ；

Above formula again can abbreviation be：

It processes and calculates by further data analysis, can get the approximate formula for calculating road grade angle α：

。

4. a kind of automobile anti-rear end collision method according to claim 1, it is characterised in that：It is described to prevent the front truck early warning packet that knocks into the back Include interior verbal cue driver, hazard warning light work, loudspeaker work or its combination.

5. a kind of automobile anti-rear end collision early warning system, it is characterised in that：It include the brake pedal position sensing for connecting brake pedal Device（1）, prior-warning device controller（2）, obliquity sensor（3）, from vehicle speed acquisition module（4）, visual analysis module（5）, institute State prior-warning device controller（2）Receive brake pedal position sensor（1）, obliquity sensor（3）, from vehicle speed acquisition module （4）And visual analysis module（5）The signal of output, control vehicle hazard alert acousto-optic, to being reminded from the driver of vehicle and Give the driver alert of front and back vehicle.

6. a kind of automobile anti-rear end collision early warning system according to claim 5, it is characterised in that：The prior-warning device controller （2）Matched with DUAL 600MHZ 32-BIT RISC processors using highly integrated Car-cam mainboard MSC8328P It sets DDR 4G memories and bluetooth sends receiving module；The warning against danger lamp switch of the automobile（6）And horn switch（7）Design For bluetooth and Manual press while controllable pattern, warning against danger lamp switch（6）And horn switch（7）It is filled by bluetooth connection early warning Set controller（2）, warning against danger lamp switch（6）Receive prior-warning device controller（2）The signal of output controls emergency warning lamp（61）Work Make；Horn switch（7）Receive prior-warning device controller（2）The signal of output controls car horn（71）Work.

7. a kind of automobile anti-rear end collision early warning system according to claim 5, it is characterised in that：The brake pedal position passes Sensor（1）It is contactless Hall brake pedal position sensor, there is magnet（11）With Hall IC chip（12）；Hall IC core Piece（12）It is fixed, magnet（11）It is moved with brake pedal, changes magnetic line of force incident angle, thereby influence Hall IC chip （12）Voltage output value.

8. a kind of automobile anti-rear end collision early warning system according to claim 5, it is characterised in that：The obliquity sensor（3） It is single pendulum angular displacement sensor.

9. a kind of automobile anti-rear end collision early warning system according to claim 5, it is characterised in that：It is described to obtain mould from vehicle speed Block（4）It is the speed signal module that GPS positioning module or In-vehicle networking receive instrument computer.

10. a kind of automobile anti-rear end collision early warning system according to claim 5, it is characterised in that：The visual analysis module （5）It is the vision system based on monocular CCD camera lenses or laser radar formation in combination.