seminar report on embedded system in automobiles

7/27/2019 seminar report on embedded system in automobiles

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SEMINAR REPORT

EMBEDDED SYSTEM IN

AUTOMOBILES

BY

TOJO TOM

B.Tech in Electronics & Communication Engineering

2010-14

DEPARTMENT OF ELECTRONICS & COMMUNICATION

ENGINEERING

SAINTGITS COLLEGE OF ENGINEERING

PATHAMUTTOM, KOTTAYAM 686532

KERALA, INDIA



SAINTGITS COLLEGE OF ENGINEERING

KOTTAYAM

DEPARTMENT OF

ELECTRONICS AND COMMUNICATION ENGINEERING

2010-2014

CERTIFICATE

This is to certify that this report entitled “EMBEDDED SYSTEM IN

AUTOMOBILES” is a bonafide record of the seminar presented by

TOJO TOM, Seventh semester bearing Reg No: 10014351 towards the

partial fulfillment of the requirements for the award of B. Tech. Degree

in Electronics and Communication Engineering of Mahatma Gandhi

University during the year 2013- 2014.

Head of Department Staff Member In-Charge Seminar Guide



i

ABSTRACT

There are several tasks in which real time OSs beat their desktop

counterparts hands-down. A common application of embedded systems in the real world

is in automobiles because these systems are cheap, efficient and problem free. Almost

every car that rolls off the production line these days makes use of embedded technology

in one form or the other. RTOSs are performed in this area due to their fast response

times and minimal system requirements.

Most of the embedded systems in automobiles are rugged in nature, as

most of these systems are made up of a single chip. Other factors aiding their use are the

low costs involved, ease of development, and the fact that embedded devices can be

networked to act as sub modules in a large system. No driver clashes or ‘system busy’

condition happen in these systems. Their compact profiles enable them to fit easily under

the cramped hood of a car.

Embedded systems can be used to implement features ranging from

adjustment of the suspension to suit road conditions and the octane content in the fuel to

anti lock braking systems (ABS) and security systems. Speaking of the things nearer home

the ‘computer chip’ that control fuel injections in a Hyundai Santro or the one that

controls the activation of air bag in a Fiat in a weekend in nothing but an embedded

system. Right from brakes to automatic traction control to air bags and fuel/air mixture

controls, there may be upto 30-50 embedded systems within a present-day car. And this

is just a beginning.



ii

ACKNOWLEDGEMENT

First of all, I thank God almighty for His abundant grace and mercy which enabled

me in completing my seminar successfully.

With great pleasure I would like to thank all those who have provided their

valuable time with full support for completing my seminar successfully.

I am highly grateful to Mr. M. C. Philipose, Principal, Saintgits College of

Engineering, Pathamuttom and Prof. Susan Abe, HOD, ECE Department for allowing me

to use the college facilities for completing my seminar.

I would like to give my sincere gratitude to my guide as well as seminar coordinator

Er.Shajimon K John, Asst.Prof, ECE department for her valuable guidance and

inspiration throughout the seminar. Also, I thank all the staff members of our department

for their timely help and guidance.

This acknowledgement would be incomplete without expressing my gratitude to my

parents who act as a beacon light and inspired me unconditionally and to my friends who

motivated me during the tenure of study.



CONTENTS

CHAPTER NO: TOPIC PAGE NO:

LIST OF FIGURE iv

1. INTRODUCTION 5

2. EMBEDDED SYSTEM IN A CAR 7

2.1 EMBEDDED SYSTEMS INSIDE A MODERN CAR 8

2.2 BLOCK DIAGRAM 8

3. ADAPTIVE CRUISE CONTROL (ACC) 9

4. ACC WORKING PRINCIPLE 10

4.1 DOPPLER EFFECT 10

5. ACC TECHNICAL DETAILS 12

6. BEAUTY OF ADAPTIVE CRUISE CONTROL 14

7. ANTILOCK BRAKING SYSTEM (ABS) 15

8. ABS OPERATION 16

9. CONCLUSION 18

iii



LIST OF FIGURE

FIGURE NO: TITLE PAGE NO:

2.1 EMBEDDED SYSTEMS INSIDE A MODERN CAR 8

2.2 BLOCK DIAGRAM 8

3.1 ADAPTIVE CRUISE CONTROL 9

4.1 HIGHER PITCH SOUND 10

4.2 LOWER PITCH SOUND 10

4.3 ACC TRANSMITTING AND RECEIVING RADIO

WAVES 11

5.1 TECHNOLOGY BEHIND ACC 12

6.1 BEAUTY OF ACC 14

7.1 ANTILOCK BRAKING SYSTEM 15

8.1 ABS OPERATION 16

iv



CHAPTER 1

INTRODUCTION

An embedded system is any device controlled by instructions stored on a

chip. These devices are usually controlled by a micro processor that executes the

instructions stored on a read only memory(ROM) chip.

The software for the embedded system is called firmware. The firmware will

be written in assembly language for time or resource critical operations or using higher

level languages like C or embedded C. The software will be simulated using micro code

simulators for the target processor. Since they are supposed to perform only specific

tasks, these programs are stored in read only memories(ROMs).Moreover they may need

no or minimal inputs from the user, hence the user interface like monitor, mouse and

large keyboard etc,may be absent.

Embedded systems are also known as real time systems since they respond to

an input or event and produce the result within a guaranteed time period. This time

period can be few microseconds to days or months. The computer system must meet

various timing and other constraints that are imposed on it by the real-time behavior of

the external world to which it is interfaced. Hence comes the name real time. Another

Name for many of these systems is reactive systems, because their primary purpose is to

respond to or react to signals from their environment. A real time computer system may

be a component of a larger system in which it is embedded; reasonably such a computer

component is called an embedded system.

Applications and examples of real time systems are ubiquitous and

proliferating, appearing as part of our commercial, government, military, medical,

educational, and cultural infrastructures. Included are:

• Vehicle systems for automobiles, subways, aircraft, railways and ships.

• Traffic control for highways, airspace, railway tracks and shipping lanes.

• Process control for power plants, chemical plants and consumer products such as

soft drinks and beer.

• Medical systems for radiation therapy, patient monitoring and defibrillation

5



• Military uses such as firing weapons, tracking and command and control.

• Manufacturing systems with robots.

• Telephone, radio and satellite communications.

• Computer games.

• Multi media systems that provide text, graphic, audio and video interfaces.

• House holds systems for monitoring and controlling appliances.

• Building managers that controls such entities as heat, light, Doors and elevators.

6



CHAPTER 2

EMBEDDED SYSTEM IN A CAR

Automotive electronics are the electronics used in automobiles. This

includes body electronics, in car entertainment, carputers, chassis electronics and telematics.

Automotive electronics first began with the need for better controls of the

engine. In fact, the first electronic parts in automobiles were used to control various engine

functions and were referred to as ECUs (Engine Control Units). However, as electronic

controls began to be used for other automotive applications, the acronym ECU took on the

more general meaning of “electronic control unit”. Today, specific ECUs are generally

referred to as modules [e.g. the engine control module (ECM) or the Transmission Control

Module (TCM)]. A modern car may have up to 100 electronic control units and a commercial

vehicle up to 40.

Automotive electronics or automotive embedded systems are distributed

systems and according to different domains in the automotive field they can be classified

into:

1. Engine Electronics

2. Transmission Electronics

3. Chassis Electronics

4. Active Safety

5. Driver assistance

6. Passenger Comfort

7. Infotainment systems

7



2.1 EMBEDDED SYSTEMS INSIDE A MODERN CAR

FIG 2.1: EMBEDDED SYSTEMS INSIDE A MODERN CAR

2.2 BLOCK DIAGRAM

FIG 2.2: BLOCK DIAGRAM

8



CHAPTER 3

ADAPTIVE CRUISE CONTROL (ACC)

Embedded systems can also make driverless vehicle control a reality. Major

automobile manufacturers are already engaged in work on these concepts. One such

technology is Adaptive Cruise Control (ACC).

FIG 3.1: ADAPTIVE CRUISE CONTROL

ACC allows cars to keep safe distances from other vehicles on busy highways. The

driver can set the speed of his car and the distance between his car and others. When traffic

slows down, ACC alters vehicle speed using moderate braking. This ensures that a constant

distance is maintained between cars. As soon as traffic becomes less, ACC moves up to the

desired cruise speed that has been set by the driver. The driver can over ride the system any

time he wants to be breaking.

Each car with ACC has a micro wave radar unit or laser transceiver fixed in

front of it to determine the distance and relative speed of any vehicle in the path. The ACC

computer (What else but an embedded system or a grouped system of embedded system)

constantly controls the throttle and brakes of the car. This helps to make sure that the set

cruise speed or adapted speed of traffic at that time is not exceeded.

9



CHAPTER 4

ACC WORKING PRINCIPLE

As already mentioned each car with ACC have a micro wave radar unit fixed in

front of it to determine the distance and relative speed of any vehicle in it’s path. The

principle behind the working of this type of radar is- the Doppler Effect.

4.1 DOPPLER EFFECT

Doppler Effect is the change in frequency of the waves when there is a relative

motion between the transmitting and receiving units. The two figures below clearly show the

Doppler Effect.

High Pitch Sound

FIG 4.1: HIGHER PITCH SOUND

In this case the vehicle is speeding towards the stationary listener. The distance

between the listener and the car is decreasing. Then the listener will hear a higher pitch

sound from the car, which means the frequency of sound, is increased.

Lower Pitch Sound

FIG 4.2 : LOWER PITCH SOUND

10



In this case the vehicle is moving away from the listener. The distance between

and the car is increasing. Then the listener will hear a lower pitch sound from the car, which

means the frequency of sound, is decreased. So that is the Doppler Effect in case of sound

waves.

Similarly the radar unit in ACC will be continuously transmitting radio waves.

They will be reflected and echo singles (reflected waves) will be having the same frequency

or different frequency depending on speed/position of the object due to which the echo

singles originate. If the echoes singles have the same frequency it is clear that there is no

relative motion between the transmitting and receiving ends. If the frequency is increased it is

clear that the distance between the two is decreasing and if the frequency is decreased it

means that the distance is increasing.

The figure below shows a car having ACC transmitting and receiving radio

waves.

FIG 4.3: ACC TRANSMITTING AND RECEIVING RADIO WAVES

In the above case, the gun transmits the waves at a given frequency toward an

oncoming car. Reflecting waves return to the gun at a different frequency, depending on how

fast the car being tracked is moving. A device in the gun compares the transmission

frequency to the received frequency to determine the speed of the car. Here, the high

frequency or the reflected waves indicate the motorist in the left car is speeding.

The embedded system is connected to the radar unit and its output will be sent to breaking

and accelerating unit as early mentioned the embedded system is a device controlled by

instructions stored in a chip. So we can design the chip or ACC having an algorithm such that

it will give output only when the input signals are less than the corresponding safe distancevalue. So only when the between the car and the object in front of it is less then the same

distance value the embedded system will give output to the breaking and the accelerating

units. Thus the safe distance will be kept always. That’s how the ACC works.

11



CHAPTER 5

ACC TECHNICAL DETAILS

Adaptive cruise control typically uses radar in a frequency band that doesn’t

compete with police radar and doesn’t trigger radar detectors. For full-range ACC, some

automakers use two radars — one for close range out to about 100 feet and a second that sees

out to about 600 feet, or about 6-7 seconds at highway speeds. Partial ACC is usually a single

unit, while some full-range ACC implementations are now able to use a single radar as well.

FIG 5.1: TECHNOLOGY BEHIND ACC

12



Radar-based systems employ a variety of sensing and processing methods to

determine the position and speed of the vehicle ahead. A fairly simple scheme (like the one

used by Mercedes) switches rapidly among three beams by changing feed points along the

antenna, creating a scanning effect inexpensively and with no moving parts. The beams are

wide enough to ensure that each overlaps those adjacent, providing a combined 12-degree

field of view. An advantage is that the wider beams permit the use of a smaller antenna.

More advanced and costlier sensing schemes rely on an antenna that is

mechanically scanned and that emits a narrow beam. These systems scan between 64 and 128

points in the radar's field of view, also typically 12 degrees, so that resolution is much higher

than for a three-beam system. The beams are much narrower than in the three-beam models,

however, so the antenna has to be larger. And the multiplicity of beams requires much more

processing power to handle the streams of data that pour out as the radar scans across the

multiple points of focus to determine the leading car's position and speed.

Regardless of the scanning mechanism, the radars typically operate in the

millimeter-wave region at 76-77 GHz. The automakers refused to alter the shape or

construction of their vehicles to accommodate ACC, so designers had to build systems small

enough to be mounted inside a car's front grille. That stringent size requirement in turn

demanded a compact antenna, which in turn forced the use of the high frequencies, antenna

size being inversely related to frequency. At 76-77 GHz, frequencies are high enough to work

with small antennas, yet not so high that the components are exotic and stupendously

expensive. A typical automotive radar, produced by Delphi Delco Electronics Systems, of

Kokomo, Ind., is roughly the size of two stacked paperback books--just 14 by 7 by 10 cm.

The radar and the cameras work together to track the car ahead and distinguish

it from extraneous nonmoving objects more rapidly than would be possible with either alone,

according to Keiji Fujimura, a senior manager at Fujitsu Ten. While the radar homes in on the

lead car's rear bumper, the stereo camera is constantly measuring the widths of all the items

in its wide field of view [see illustration, above ]. To calculate them, it uses an algorithm

based on the detection of vertical edges and the distance. Bridges, trees, and other stationary

objects that are much wider or narrower than a car are quickly rejected as reasons for the

system to apply the brakes. The concentration on vertical edges also helped hold down the

cost and complexity of the optical system.

13



CHAPTER 6

BEAUTY OF ADAPTIVE CRUISE CONTROL

As the driver in the next lane swerves in front of you, you feel that gas back off

and the brakes grab in the car you’ re driving- a Mercedes Benz S-class luxury vehicle, the

first passenger car equipped with a technology called adaptive cruise control. The technology

makes these adjustments even though you haven’t touched the brake or gas pedal.

At a safe distance behind, your Mercedes settles to a speed matching that of the

driver in front of you. That’s too slow, so after a look in your rear view mirror you pull into

the empty outside lane and feel the acceleration as your car speeds up to the preset cruising

speed. You still haven’t press the accelerator pedal. That’s the beauty of this racing star of the

auto industry, a millimeter- wave radar technology that promises not only to make driving

easier, but to ignite a market for gallium arsenide and other compound semi conductor

components.

Although grey hound buses and some heavy- goods vehicles have been fitted with

automotive radar systems, the Mercedes is reckoned to be the first passenger automobile to

sport this advanced use of electronics, and observers say it is likely to lead a proliferation of

the technology. The Mercedes Benz system uses a 77-GHz Doppler radar linked into the

electronic control and braking system to maintain a safe distance between a car with the

system and the vehicle in front of it. Daimler Benz Aero space has completed the design of a

hybrid 77-GHz radar, called Tempo mat, which is being considered for deployment

FIG 6.1: BEAUTY OF ACC

14



CHAPTER 8

ABS OPERATION

FIG 8.1: ABS OPERATION

The anti-lock brake controller is also known as the CAB (Controller Anti-

lock Brake.Typically ABS includes a central electronic control unit (ECU), four wheel speed

sensors, and at least two hydraulic valves within the brake hydraulics. The ECU constantly

monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower

than the others, a condition indicative of impending wheel lock, it actuates the valves to

reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force

on that wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning

significantly faster than the others, brake hydraulic pressure to the wheel is increased so the

braking force is reapplied, slowing down the wheel. This process is repeated continuously

and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply

or release braking pressure 15 times per second.[17]

Because of this, the wheels of cars

equipped with ABS are practically impossible to lock even during panic braking in extreme

conditions.

16



The ECU is programmed to disregard differences in wheel rotative speed below

a critical threshold, because when the car is turning, the two wheels towards the center of the

curve turn slower than the outer two. For this same reason, a differential is used in virtually

all roadgoing vehicles.

If a fault develops in any part of the ABS, a warning light will usually be

illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is

rectified.

Modern ABS applies individual brake pressure to all four wheels through a

control system of hub-mounted sensors and a dedicated micro-controller . ABS is offered or

comes standard on most road vehicles produced today and is the foundation for electronic

stability control systems, which are rapidly increasing in popularity due to the vast reduction

in price of vehicle electronics over the years.[18]

Modern electronic stability control systems are an evolution of the ABS

concept. Here, a minimum of two additional sensors are added to help the system work: these

are a steering wheel angle sensor, and a gyroscopic sensor. The theory of operation is simple:

when the gyroscopic sensor detects that the direction taken by the car does not coincide withwhat the steering wheel sensor reports, the ESC software will brake the necessary individual

wheel(s) (up to three with the most sophisticated systems), so that the vehicle goes the way

the driver intends. The steering wheel sensor also helps in the operation of Cornering Brake

Control (CBC), since this will tell the ABS that wheels on the inside of the curve should

brake more than wheels on the outside, and by how much.

ABS equipment may also be used to implement a traction control system (TCS) on

acceleration of the vehicle. If, when accelerating, the tire loses traction, the ABS controller

can detect the situation and take suitable action so that traction is regained. More

sophisticated versions of this can also control throttle levels and brakes simultaneously.

Upon the introduction of the Subaru Legacy in 1989, Subaru networked the four

channel anti-lock brake function with the all wheel drive system so that if the car detected

any wheel beginning to lock up, the variable assists the all wheel drive system installed on

vehicles with the automatic transmission would engage to ensure all wheels were actively

gripping while the anti-lock system was attempting to stop the car.

17



CHAPTER 9

CONCLUSION

There are lot of scope for the development of newer technologies in the

Automotive electronics domain. Electronic Control Units (ECU) can be designed to provide

optimum driving conditions which increases the efficiency.

Areas such as firmware, dedicated intelligence chips and ECUs are in demand inthe Automotive Electronics Industry. The recent trends in the automobile industry highlights

the scope for electronics in the industry. On an average any automobile has 50 ECUs. 13% of

manufacturing cost is for the software developed. 35% of the cost of the car comes from the

electronics involved in it. Also 80% of the automotive innovation in the recent years has been

from Automobile electronics.

18



CHAPTER 10

REFERENCE

[1]. www.spectrum.ieee.org

[2]. www.extremetech.com

[3]. www.auto.howstuffworks.com

[4]. www.wiki.fot-net.eu

[5]. www.wikipedia.com

[6]. Report of 5th Meeting of the U.S. Software System Safety Working Group April 12th

14th 2005 @ Anaheim, California USA

seminar report on embedded system in automobiles

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