EMBEDDED BASED INTELLIGENT SYSTEM FOR AUTOMOBILE COLLISION PREVENTION

R.PARANI M.KALEESWARAN

IV Yr, ECE IV Yr, ECE

SETHU INSTITUTE OF TECHNOLOY SETHU INSTITUTE OF TECHNOLOGY

Ph: 9600489012 Ph:9092238676

EMAIL ID: r.parani89@gmail.com EMAIL ID: karthi448@gmail.com

ABSTRACT

Most of the automobile accidents could be avoided if the brake had been applied at proper time and at proper distance. In this paper we are using embedded system which could be embedded in the automobile to remove the driver’s reaction time from the situation. The system, consisting of controllers, which analyzes possible accident situations based on the vehicle separation distance, their relative velocity and a static friction coefficient that represents the road conditions. The controller determines the sufficient brake pressure required to prevent collisions while providing a smooth ride for the vehicle’s passengers.

INTRODUCTION

Our work is to design controller to automate and optimize the application of brake pressure to an automobile’s brakes at proper time. So first requirement implies that the two vehicles should never have any physical contact, while the second one implies that the brakes should be used only in the amount necessary, e.g., they should not undergo large excursions to make small adjustments.

In general, if the automobile in front decelerate, then the vehicle behind it must decelerate to avoid the collision. Here, the controller tracks the vehicle and have its velocity as reference and applies the appropriate brake pressure at the proper time. So, the controller automatically decelerates to match the velocity of the tracked vehicle and avoid a collision.

NECESSITY OF ACCIDENT CONTROL

Countless automobile accidents could have been prevented or at least reduced in damage cost if the driver had applied a sufficient amount of brake pressure at the right time. Unfortunately, many times it doesn’t happen because of carelessness of driver, time taken by the driver to react and diversion to the driver. By automating the task of assessing the situation and deciding the correct amount of break pressure, we could prevent numerous accidents. This would significantly decrease the amount of property and monetary loss due to accident damage, and it could save lives.

IMPORTANT PARAMETER

The parameters that we took to avoid collision are

Separation between the two vehicles Velocity with which they approach

each other Surface conditions

For calculating these three parameter, Laser range finders could provide the first two measurements, while wheel-slip sensors currently used for automobile Traction Control Systems or Anti-lock Breaking systems (ABS) could estimate could estimate the third measurement.

BLOCK DIAGRAM OF THE SYSTEM

MODULES

We have three modules, they are

Distance finder –laser Intelligent control module Breaking system-ABS

Since my area of interest is embedded system and to limit the discussion, intelligent control module is discussed in detail with brief detail about distance finder and breaking system.

DISTANCE DETECTION

For finding the distance between the vehicles, we use the principle of laser range finder, which use the laser light to detect the distance of the object from the place it is mounted.

A laser rangefinder is a device which uses a laser beam to determine the distance to an object. The most common form of laser rangefinder operates on the time of flight principle by sending a laser pulse in a narrow beam towards the object and measuring the time taken by the pulse to be reflected off the target and returned to the sender.

So, by using the principle of sending and receiving the laser from the vehicle we can find the distance between the vehicles by using the formula.

Where D=distance between the vehicle, c=velocity of laser and t=time taken. These range finders are now mostly used in military weapons. Why we should not use it in safety device. The laser is controlled and received pulses are analyzed by the controller.

Laser sensor 1Laser sensor 2Laser sensor 3Laser sensor 4

A

mpA

A

A

Central Controller

Of System

Controller

EBD-ABS

Central Controller

Of System

Brakes of Tracking vehicle

Central Controller

Of System

BLOCK DIAGRAM OF DISTANCE DETECTION OF LASER DETECTION

INTELLIGENT CONTROL MODULE

Assumptions:

The tracking vehicle’s brakes have EBD-ABS (Electronic brake force distribution system- Antilock Braking System) or similar mechanism, ensuring that the wheels will not lock during breaking situations. This assumption limits the simulation to simulation to consider only static friction.

The application of brake pressure is linearly correlated with the deceleration the vehicle experiences, e.g., if 25% of the maximum brake pressure is applied, then the vehicle will decelerate by 25% of its maximum possible deceleration.

The variables used as inputs for the controller are available from on-board sensors.

Flowchart for breaking

Algorithm

NO

NO

Yes

Yes

Yes

Yes

NO

NO

Start

Uninterrupted laser Generation

Is laser received?

Pulsed laser

Generation

Is pulsed laser

received?

Distance calculation

D=ct/2

Is D<=13 M?

Velocity calculation of the vehicle ahead of us

Vtracking= Vtracked + dD/dt

Is Vtracking<=Vtracked

?

Breaking control process

D (t+dt)

Step 1: once the ignition key is inserted the laser transmitter starts production non-interrupted continuous laser beams.

Code:

Laser_pin=1;

Step 2: once the transmitted laser beam is received, the controller starts producing the pulsed beam in laser_pin. Time taken by the beam to hit the object and comes back is calculated.

Code:

If (laser_rx==1)

{

Laser_pin=0;

Delay ();

Laser_pin=1;

Star timer0( );

If (laser_rx==1)

Stop timer0( );

Start time1( );

}

Else

{

Goto step1( );

}

Step 3: calculate the distance D.

Code:

D= (c*t)/2;

Where c is the velocity of the laser, t is the time taken calculated from step 2.

Step 4: check the D and if it is less than 13M, compare the velocity of both the vehicles.

Code:

If (D<=13)

{D0=D;

Stop timer1 ( );

goto step2 ( );

goto step3 ( );

Start timer0 ( );

difference= (D-D0)/t1;

V_tracked=V_tracking +difference;

If (V_tracked>V_tracking)

{goto step2();

}

Else

{goto step5();

}

}

Else

{

Goto step2();

}

Step 5: Breaking control process

Now, we need to calculate the break pressure that to be applied.

The minimum stopping distance equation

To reduce the kinetic energy to zero:

so the stopping distance is

From this we can calculate the velocity to be maintained to stop the vehicle under calculated distance.

V_required=sqrt(2*µ*g*d)/0.2777 km/hr

To achieve this velocity, the percentage of braking can be calculated from the equation.

% of braking=((V_tracking-V_required)/V_tracking)*100

Code:

V_required=sqrt(2* µ*g*d)/0.2777;

Braking=((V_tracking-V_required)/V_tracking)*100;

Step 6: This Braking should give as input to the controller of EBD unit of the breaking system and go back to step 1.

These steps should be written as coding in the microcontroller. Each variable takes a registers in the controller.

Robustness of the system

1. within the city limit:

If(Vtracking<=15)

{

Distance separation=1m;

}

and

If(Vtracking <=5)

{

No braking process();

}

2. Tracked Vehicle compatibility:

No of sensors for the detection has been increased to 6,so as the track any kind of vehicles in the highway.

The priority of the sensor depends upon the least distance value of the tracked vehicle.

3. At the sharp curved turnings:

The indicator system disables the system for the predetermined time period ,so that normal working is not affected by the installation of the braking systems.

Distance VS braking characteristics

BREAKING SYSTEM-EBD-ABS

Antilock Brake System (or Anti-locking Brake System) - enables you to steer whilst keeping the brake pedal full on. Can be felt as a vibration through the pedal when it cuts in. Also useful in stopping in a straight line if one side is on slippery stuff and the other on grippy stuff (non-ABS will tend to spin).

Electronic Brake Distribution (or Electronic Brake-force Distributor) - alters how much of the brake force goes to the front and how much to the rear. Cars always have more braking on front as if the rears lock before the front then the car will spin. How much braking you can do with the rears depends on how much weight is in the vehicle so EBD dynamically adjusts this balance. Without it, the manufacturer sets up the balance so the rears don't lock when the vehicle is empty which is less braking than is possible when the vehicle is full.

This Braking system consist of a controller which control the brake pressure depends on the signal from the brake pedal. Now, we couple our signal to that controller so that it applies the brake according to the signal.

Thus the vehicle is sensed; braking is calculated and given to EBD unit.

CONCLUSION

In conclusion, the controller system trained with an algorithm work very well for the stated problem. For the cases where stopping the vehicle without a collision was possible the system consistently applied sufficient and appropriate brake pressure to stop the vehicle in time with a final separation distance of approximately 3 meters. By having a computer react immediately to a potential collision situation, accidents that could be avoided were. In situations where an accident was physically unavoidable, the controller still reacted immediately and applied a significant amount of brake pressure, minimizing the vehicle velocity at impact and thus reducing the significance of(damage due to) the collision.

FUTURE WORK

Here, we have worked only on the braking unit but the accelerator unit is not controlled. So, we are trying control both braking and accelerator unit linearly.

Horizontal deployment of similar technology to the heavy vehicles where the braking system is different.

Bibliography:

http://www.mpi.mb.ca/PDFs/DVL_PDFs/AirBrakeManual/ABM_Section7.pdf

http://www.csgnetwork.com/stopdistcalc.html

http://www.abs-education.org/faqs/faqindex.htm

http://en.wikipedia.org/wiki/Laser_range_finder

http://www.eos-optronics.com/documents/Paper-KLRF_SPIE_Cardiff_7115-21.pdf

http://www.lexellaser.com/techinfo_wavelengths.htm

http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/electronic-brake-force-distribution1.htm

http://www.wabco.info/intl/pdf/820/001/302/8200013023.pdf

http://www.engineeringtoolbox.com/friction-coefficients-d_778.html