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REVIEW ON Adaptive Cruise Control IN AUTOMOBILES

(ACC)

Seminar by;

VISHNU SANKAR MECHANICAL ENGINEERING Toc H, Arakkunnam

OBJECTIVES2

To discuss about adaptive cruise control:HISTORYINTRODUCTION TO ACCCONVENTIONAL CRUISE CONTROL OPERATIONTYPESCOMPONENTS IN ACCPRINCIPLE OF ACCWORKINGADVANTAGESCONCLUSIONSREFERENCES

HISTORY3

The idea of driver assistance was started with ‘cruise control devices’, first appeared in 1970’s in USA.

When switched on, the device takes up the task of accelerating or braking to maintain a constant speed. But it could not consider other vehicles on road.

The ACC system was developed as next generation assisted the driver to keep a safe distance from vehicle in front. This system is now available in some luxury cars like merc s class,jaguar,volvo…

Introduction to ACC4

Adaptive Cruise Control (ACC) technology automatically adjust the vehicle speed and distance to that of a target vehicle.

ACC uses a long range radar sensor to detect a target vehicle up to 200 meters in front and automatically adjusts the ACC vehicle speed and gap accordingly.

ACC automatically decelerates or accelerates the vehicle according to the desired speed and distance settings established by the driver.

As per standard cruise control the driver can override the system at any time.

Conventional Cruise Control Operation5

A typical Conventional Cruise Control controls the vehicle speed by adjusting throttle position to maintain a speed set by the driver.

A control unit compares the actual vehicle speed and the desired set speed.

If there is a difference between this two values, a signal is sent to a throttle position actuator to adjust the throttle position to bring the vehicle to set speed.

Two types of ACC 6

• Radar-Based System :– Three overlapping radar-beams (76-

77kHz)-- Detects moving object up to 120 m – work in poor weather conditions• Laser-Based System (lidar) :– less expensive and easier to package – light beams are narrower than water

droplet and snowflakes

Radar-based Adaptive Cruise Control

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Source:http://motorola/semiconductor.com

Common Terms in ACC8

• Response time of the driver (t): time needed by the driver to respond safely to any unwanted disturbance (approximately about 2-3 sec)

• Safe distance: the minimum distance between vehicle equipped with ACC to the leading vehicle by which the driver is still able to respond safely in case of emergency braking by the vehicle in front

Safe distance = Vs * tVs = speed of ACC vehiclet = 2-3 sec

Adaptive Cruise Control - Components

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Parts related to a typical ACC system are highlighted and colour-coded in the illustration below:

Components of ACC10

CONTROLUNIT

SENSOR FUSIONSENSOR

RADAR

TA

RG

ET

D

ET

EC

TIO

N

TA

RG

ET

T

RA

CK

ING

USER INTERFACE

BAC

TAC TA

BA

Sensors:Four Wheel Sensors, Brake Pedal Sensor, Throttle Pedal Sensor, Radar …

Actuators:Brake Actuator, Throttle Actuator.

Controllers:High level & Low level controller.

Communication Medium

Source:http://path.Berkeley.edu.

PRINCIPLE OF ACC11

ACC works by detecting the distance and speed of the vehicles ahead by using either a Lidar system or a Radar system .

According to this, the brake and throttle controls are done to keep the vehicle in a safe position with respect to the other.

These are predominantly designed for highway applications with rather homogenous traffic behavior.

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• The second generation of ACC is the Stop and Go Cruise Control (SACC) whose objective is to offer the customer longitudinal support on cruise control at lower speeds down to zero velocity.• There is a clear distinction between ACC and SACC with respect to stationary targets.•The ACC philosophy is that it will be operated in well structured roads with an orderly traffic flow with speed of vehicles around 40km/hour .

How ACC works?13

TRACKING IN LANES14

System Configuration of ACC15

Source:http://path.Berkeley.edu.

Adaptive Cruise Control : Overview16

ACC is an extension of conventional cruise control systems. An ACC system is a driver convenience feature designed to maintain a set following distance from the vehicle ahead. ACC is not a collision warning or avoidance system.

An ACC system is designed to assist the driver and is not a fully independent driving system.

As with conventional cruise control system manual inputs from the driver, both to accelerator and brake, take priority over the ACC system.

Adaptive Cruise Control Functions17

• Preset and maintain the car speed• Measure the distance to the preceding car

and the relative speed• Adjust the car speed accordingly• Maximum deceleration = 3.5m/s^2

Source:http://path.Berkeley.edu.

Contn…18

• Change gear automatically• Function properly in poor weather

condition• Cannot pick up non-moving objects• Effective in the speed between 30km-

180km/h

ADVANTAGES19

The driver is relieved from the task of careful acceleration, deceleration and braking in congested traffics.

A highly responsive traffic system that adjusts itself to avoid accidents can be developed.

Since the braking and acceleration are done in a systematic way, the fuel efficiency of the vehicle is increased.

CONCLUSIONS20

The accidents caused by automobiles are injuring lakhs of people every year.

The safety measures starting from airbags and seatbelts have now reached to ACC,SACC and CACC systems.

Eventhough it will probably take few decades, car accidents will become as rare as plane accidents with these technologies.

But the road laws will have to be changed upto an extent, since the non-human part of vehicle controlling will become predominant.

REFERENCES21

“Adaptive cruise control with stop & go function using the state dependent non linear model predictive control approach’’, science direct, Payman Shakouri, 15th June 2012.

“Detection of new in-path targets by drivers using stop & go adaptive cruise control”, Neville A.stanton,18th Aug 2010.

“Keeping car from crashing”, IEEE Spectrum, Willie D. jones, Sep 2001.

“Introduction To RADAR Systems”, Merril I. Skolnik,Tata Mc Grawhill ,edition 2009.

http://motorola/semiconductor.com http://path.Berkeley.eduhttp://www.computer –solutions.co.uk.

THANK YOU FOR YOUR ATTENTION

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