49379095 driverless car documentation 3

7/25/2019 49379095 Driverless Car Documentation 3

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CHAPTER 1

INTRODUCTION

1.1 OverviewThe overview of this project is to implement a driverless car is an autonomous

vehicle that can drive itself from one point to another without assistance from a

driver. One of the main impetuses behind the call for driverless cars is safety. An

autonomous vehicle is fundamentally defined as a passenger vehicle. An

autonomous vehicle is also referred to as an autopilot, driverless car, auto-drive

car, or automated guided vehicle (A!". #ost prototypes that have been built so

far performed automatic steering that were based on sensing the painted lines in the

road or magnetic monorails embedded in the road.

1.2 Purpose

$urpose of the current wor% is to study and analy&e the driverless car technology.

This mobility is usually ta%en for granted by most people and they reali&e that

transportation forms the basis of our civili&ation. The need for a more efficient,

balanced and safer transportation system is obvious. This need can be best met by

the implementation of autonomous transportation systems.

1.3 Scope

'urrent wor% focuses on how to use the uture 'ar Technology That)s On the *oad

Today. +n the future, automated system will help to avoid accidents and reduce

congestion. The future vehicles will be capable of determining the best route and

warn each other about the conditions a head. #any companies and institutions

wor%ing together in countless projects in order to implement the intelligent

vehicles and transportation networ%s of the future.


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CHAPTER 2

LITERATURE SURVEY

A driverless car is an autonomous vehicle that can drive itself from one point to

another without assistance from a driver. ome believe that autonomous vehicles

have the potential to transform the transportation industry while virtually

eliminating accidents, and cleaning up the environment. According to urban

designer and futurist #ichael . Arth, driverless electric vehicles/in conjunction

with the increased use of virtual reality for wor%, travel, and pleasure/ could

reduce the world)s 0,, vehicles to a fraction of that number within a few

decades. Arth claims that this would be possible if almost all private cars re2uiring

drivers, which are not in use and par%ed 34 of the time, would be traded for

public self-driving ta5is that would be in near constant use.This would also allow

for getting the appropriate vehicle for the particular need /a bus could come for a

group of people, a limousine could come for a special night out, and a egway

could come for a short trip down the street for one person. 'hildren could be

chauffeured in supervised safety, 67+s would no longer e5ist, and 81, livescould be saved each year in the 7.. alone.

The control mechanism of an autonomous car consists of three main bloc%s as

shown below


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2.1 Hisor!

An early representation of the driverless car was :orman ;el eddes)s uturama

e5hibit sponsored by eneral #otors at the 1399 ab in ?apan. On a dedicated, clearly mar%ed course it

achieved speeds of up to 9 %m@h ( miles per hour", by trac%ing white street

mar%ers (special hardware was necessary, since commercial computers were much

slower than they are today".

+n the 130s a vision-guided #ercedes-;en& robot van, designed by rnst6ic%manns and his team at the ;undeswehr 7niversity of #unich in #unich,

ermany, achieved 1 %m@h on streets without traffic. ubse2uently, the

uropean 'ommission began funding the 0 million uro 7*A $rometheus

$roject on autonomous vehicles (130=B133C".

Also in the 130s the 6A*$A-funded Autonomous >and !ehicle (A>!" in

the 7nited tates achieved the first road-following demonstration that used laser

radar (nvironmental *esearch +nstitute of #ichigan", computer vision ('arnegie

#ellon 7niversity and *+", and autonomous robotic control ('arnegie #ellon

and #artin #arietta" to control a driverless vehicle up to 9 %m@h. +n 130=, D*>

>aboratories (formerly Dughes *esearch >abs" demonstrated the first off-road map

and sensor-based autonomous navigation on the A>!. The vehicle travelled over

Em at 9 %m@h on comple5 terrain with steep slopes, ravines, large roc%s, and

vegetation.

+n 1338, the twin robot vehicles !a#$ and !ita- of 6aimler-;en& and rnst

6ic%manns of 7ni;w# drove more than one thousand %ilometers on a $aris three-

lane highway in standard heavy traffic at speeds up to 19 %m@h, albeit semi-

autonomously with human interventions.


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+n 133C, the 'arnegie #ellon 7niversity :avlab project achieved 30.4

autonomous driving on a C %m (9-mile" F:o hands across AmericaF trip.

This car, however, was semi-autonomous by natureG it used neural networ%s to

control the steering wheel, but throttle and bra%es were human-controlled.

rom 133EB1, Alberto ;roggi of the 7niversity of $arma launched the A*O

$roject, which wor%ed on enabling a modified >ancia Thema to follow the normal

(painted" lane mar%s in an unmodified highway. The culmination of the project was

a journey of , %m over si5 days on the motorways of northern +taly dubbed

#ille#iglia in Automatico, with an average speed of 3 %m@h. 384 of the time the

car was in fully automatic mode, with the longest automatic stretch being C8 %m.

The vehicle had only two blac%-and-white low-cost video cameras on board, and

used stereoscopic vision algorithms to understand its environment, as opposed to

the Flaser, radar - whatever you needF approach ta%en by other efforts in the field.

Three 7 overnment funded military efforts %nown as 6emo + (7 Army", 6emo

++ (6A*$A", and 6emo +++ (7 Army", are currently underway. 6emo +++ (1"

demonstrated the ability of unmanned ground vehicles to navigate miles of difficult

off-road terrain, avoiding obstacles such as roc%s and trees. ?ames Albus at :+T

provided the *eal-Time 'ontrol ystem which is a hierarchical control system. :ot

only were individual vehicles controlled (e.g. throttle, steering, and bra%e", but

groups of vehicles had their movements automatically coordinated in response to

high level goals.

CHAPTER 3


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RECENT PRO"ECTS

The wor% done so far varies significantly in its ambition and its demands in terms

of modification of the infrastructure. ;roadly, there are three approachesG

ully autonomous vehicle

!arious enhancements to the infrastructure (either an entire area, or specific lanes"

to create a self-driving closed system.

FassistanceF systems that incrementally remove re2uirements from the human

driver (e.g. improvements to cruise control"

An important concept that cuts across several of the efforts is vehicle platoons. +n

order to better utili&e road-space, vehicles are assembled into ad-hoc train-li%e

FplatoonsF, where the driver (either human or automatic" of the first vehicle ma%es

all decisions for the entire platoon. All other vehicles simply follow the lead of the

first vehicle.

3.1 #ULLY AUTONO$OUS

ully autonomous driving re2uires a car to drive itself to a pre-set target using

unmodified infrastructure. The final goal of safe door-to-door transportation in

arbitrary environments is not yet reached though variables. The e5act orientation

and position of the ne5t object of wor% and (in the more advanced factories" even

the type of object and the re2uired tas% must be determined. This can vary

unpredictably (at least from the robot)s point of view".

One important area of robotics research is to enable the robot to cope with its

environment whether this be on land, underwater, in the air, underground, or in

space.


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A fully autonomous robot has the ability to

ain information about the environment.

ab. Argo was developed in 133E

and demonstrated to the world in 1330J ;*Ai! was developed in 0 and firstly

demonstrated in 3 at the + +! conference in Ki)an, 'hina.

tanford *acing Team)s junior car is an autonomous driverless car for paved

roads. +t is intended for civilian use

The !ol%swagen olf T+ C9L1 is a modified !ol%swagen olf T+ capable of

autonomous driving. The olf T+ C9L1 features a implemented system that can

be integrated into any car. This system is based around the #icroAuto;o5 from

dpace.


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3.1.2 #REE%RAN&IN& VEHICLES

There are four clusters of activity relating to free-ranging off-road cars. ome of

these projects are military-oriented.

The 7 6epartment O 6efence announced on the ?uly 9, a Frand

'hallengeF, for 7-based teams to produce a vehicle that could autonomously

navigate and reach a target in the desert of the south western 7A.

+n #arch 8, the first competition was held, for a pri&e-money of I1 million.

:ot one of the C entrants completed the course. Dowever, in the second

competition held in October C five different teams completed the 19C-mile (1=

%m" course, and the tanford 7niversity team won the I million pri&e.

:ovember 9rd, =, the third competition was held and I9.C million dollar in

cash automated and remotely-operated robots, for various military uses. ome of

the systems on display could be ordered and implemented +n August = a

civilian version of the event was held in wit&erland.

The mart Team from wit&erland presented Fa !ehicle for Autonomous

:avigation and #apping in Outdoor nvironmentsF. or pictures of their

>*O; demo, see this.

The +sraeli #ilitary-+ndustrial 'omple5

As a followup from its success with 7nmanned 'ombat Air !ehicles, and

following the construction of the +sraeli


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orean Autonomous !ehicle 'ompetition (A!'" organi&ed by Dyundai ia

Automotive roup

+n :ovember 1, the first competition was held, for a winning pri&e-money

of I1 thousand, and the Danyang 7niversity A1 team won the I1 thousand

pri&e.

3.2 PRE%'UILT IN#RASTRUCTURE

The following projects were conceived as practical attempts to use available

technology in an incremental manner to solve specific problems, li%e transport

within a defined campus area, or driving along a stretch of motorway.The

technologies are proven, and the main barrier to widespread implementation is the

cost of deploying the infrastructure. uch systems already function in many

airports, on railroads, and in some uropean towns.

3.2.1 DUAL $ODE TRANSIT%$ONORAIL

There is a family of projects, all currently still at the e5perimental stage, that would

combine the fle5ibility of a private automobile with the benefits of a monorail

system. The idea is that privately-owned cars would be built with the ability to

doc% themselves onto a public monorail system, where they become part of a

centrally managed, fully computeri&ed transport system/ more a%in to a driverless

train system (as already found in airports" than to a driverless car. This idea is also

%nown a 6ual mode transit. (ee also $ersonal rapid transit for another concept

along those lines, for purely public transport."

roups wor%ing on this concept areG

*7(6enmar%"

;i


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Tri Trac% (Te5as, 7nited tates"

$ONORAIL(

The > #onorail in uala >umpur #alaysia, a straddle-beam monorail.A

)o*or+i,is a rail-based transportation system based on a single rail, which acts as

its sole support and its guideway. The term is also used variously to describe the

beam of the system, or the vehicles traveling on such a beam or trac%

The term originates from the contraction of the words mono(one" and rail, from as

early as 103=, possibly from erman engineer ugen >angen who called an

elevated railway system with wagons suspended the Eugen Langen One-railed

Suspension Tramway (inschienige DNngebahn ystem ugen >angen". The

transportation system is often referred to as a railway. 'ollo2uially, the term

FmonorailF is often used erroneously to describe any form of elevated rail or

peoplemover. +n fact, the term solely refers to the style of trac%, not its elevation.

DUAL%$ODE TRANSITG

Du+, )o-e r+*si describes transportation systems in which vehicles operate

on both publicroads and on a guidewayJ thus using two modes of transport.

+n a typical dual mode transit system, private vehicles comparable to automobiles

would be able to travel under driver control on the street, but then enter a

guideway, which may be a speciali&ed form of *ailway or monorail, for automated

travel for an e5tended distance.

3.2.2 ED HI&HAY SYSTEAUTO$AT$S

Automated highway systems (AHS" are an effort to construct special lanes on

e5isting highways that would be e2uipped with magnets or other infrastructure to

allow vehicles to stay in the center of the lane, while communicating with other

vehicles (and with a central system" to avoid collision and manage traffic. >i%e the


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dual-mode monorail, the idea is that cars remain private and independent, and just

use the AD system as a 2uic% way to move along designated routes. AD allows

specially e2uipped cars to join the system using special )acceleration lanes) and to

leave through )deceleration lanes).


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simultaneously. +nstead of waiting after a traffic light changes to green for drivers

ahead to react, a synchroni&ed platoon would move as one, allowing up to a

fivefold increase in traffic throughput if spacing is diminished that much. This

system also allows for a closer headway between vehicles by eliminating reacting

distance needed for human reaction.

$latoon capability might re2uire buying new cars, or it may be something that can

be retrofitted. 6rivers would probably need a special license endorsement on

account of the new s%ills re2uired and the added responsibility when driving in the

lead.

mart cars with artificial intelligence could automatically join and leave platoons.

The automated highway system is a proposal for one such system, where cars

organise themselves into platoons of eight to twenty-five.

3.2.3 #REE%RAN&IN& ON &RID

rog :avigation ystems (the :etherlands" applies the *O (ree%r+*i* o*

ri-" technology. The technology consists of a combination of autonomous

vehicles and a supervisory central system. The company)s purpose-built electric

vehicles locate themselves using odometry readings, recalibrating themselves

occasionally using a Fma&eF of magnets embedded in the environment, and $.

The cars avoid collisions with obstacles located in the environment using laser

(long range" and ultra-sonic (short-range" sensors.

The vehicles are completely autonomous and plan their own routes from A to ;.The supervisory system merely administers the operations and directs traffic where

re2uired. The system has been applied both indoors and outdoors, and in

environments where 1L automated vehicles are operational (container port". At

this time the system is not suited yet for running the sheer number of vehicles

encountered in urban settings. The company also has no intention of developing

such technology at this time.


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The *O system is deployed for industrial purposes in factory sites, and is

mar%eted as a pilot public transport system in the city of 'apelle aan den +?ssel by

3.3 DRIVER%ASSISTANCE

Though these products and projects do not aim e5plicitly to create a fully

autonomous car, they are seen as incremental stepping-stones in that direction.

#any of the technologies detailed below will probably serve as components of any

future driverless car / meanwhile they are being mar%eted as gadgets that assist

human drivers in one way or another. This approach is slowly tric%ling intostandard cars (e.g. improvements to cruise control".

3.3.1 SENSORIAL%IN#OR$ATIVE

These systems warn or inform the driver about events that may have passedunnoticed, such as

>ane 6eparture 6


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There are two main types of systemsG

ystems which warn the driver (lane departure warning, >6".

The first production lane departure warning system in urope was developed by

the 7nited tates)s +teris 'ompany for #ercedes Actros commercial truc%s. The

system debuted in and is now available on most truc%s sold in urope

+n , the +teris system became available on reightliner Truc%s) truc%s in :orth

America. +n all of these systems, the driver is warned of unintentional lane

departures by an audible rumble strip sound generated on the side of the vehicle

drifting out of the lane. :o warnings are generated if, before crossing the lane, an

active turn signal is given by the driver.

Sensor types

>ane warning@%eeping systems are based onG

video sensors in visual domain (mounted behind the windshield, typically

integrated beside the rear mirror"

laser sensors mounted in the vehicle front

infrared sensors (mounted either behind the windshield or under the vehicle"

Audi began in = offering its Audi >ane Assist feature.

'LIND SPOT /VEHICLE(

A 0,i*- spoin a vehicle are areas around the vehicle that cannot be directly

observed under e5isting circumstances. ;lind spots e5ist in a wide range of

vehiclesG cars, truc%s, motorboats and aircraft.The blue car)s driver sees the green


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As one is driving an automobile, blind spots are the areas of the road that cannot be

seen while loo%ing forward or through either the rear-view or side mirrors. The

most common are the rearquarter blind spots, areas towards the rear of the vehicle

on both sides. !ehicles in the adjacent lanes of the road that fall into these blind

spots may not be visible using only the car)s mirrors. *ear 2uarter blind spots can

beG

chec%ed by turning one)s head briefly (ris%ing rear-end collisions",

eliminated by reducing overlap between side and rear-view mirrors, or

*educed by installing mirrors with larger fields-of-view.

Other areas that are sometimes called blind spots are those that are too low to see

behind, in front, or to the sides of a vehicle, especially those with a high seating

position, such as vans, truc%s, and 7!s. 6etection of vehicles or other objects in

such blind spots are aided by systems such as video cameras or distance sensors,

though these remain uncommon or e5pensive options in general-purpose

automobiles.

RADAR(

R+-+r is an object-detection system which uses electromagnetic waves /

specifically radiowaves / to determine the range, altitude, direction, or speed of

both moving and fi5ed objects such as aircraft, ships, spacecraft, guided missiles,

motor vehicles, weather formations, and terrain. The radar dish, or antenna,

transmits pulses of radio waves or microwaves which bounce off any object in

their path. The object returns a tiny part of the wave)s energy to a dish or antenna

which is usually located at the same site as the transmitter.

A long-range radar antenna, %nown as A>TA+*, used to detect and trac% space

objects in conjunction with A;# testing at the *onald *eagan Test ite.


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reflected bac% towards the transmitter are the desirable ones that ma%e radar wor%.

+f the object is movingeither closer or farther away, there is a slight change in the

fre2uency of the radio waves, due to the 6oppler ffect.

IRELESS VEHICLE SA#ETY CO$$UNICATION(


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Ni4 visio* is the ability to see in a dar% environment.


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ends out pulses and measures the reflection off

moving object.

ensor sends out microwave pulses and measures the reflection off a moving

object. imilar to a police radar gun.

ELECTRONIC STA'ILITY CONTROL(

E,ecro*ic S+0i,i! Co*ro, (ESC" is a computeri&ed technology that improves

safety througha vehicle)s stability by detecting and minimi&ing s%ids.


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system may reduce engine power or operate the transmission to slow the vehicle

down.

ANTI%LOC5 'RA5IN& SYSTE$ /A'S(

An +*i%,oc6 0r+6i* s!se)(A'S" is a safety system that allows the wheels on a

motor vehicle to continue interacting tractively with the road surface as directed by

driver steering inputs while bra%ing, preventing the wheels from loc%ing up (that

is, ceasing rotation" and therefore avoiding s%idding.

An A; generally offers improved vehicle control and decreases stopping

distances on dry and slippery surfaces for many driversJ however, on loose surfacesli%e gravel or snow-covered pavement, an A; can significantly increase bra%ing

distance, although still improving vehicle control.

ince initial widespread use in production cars, anti-loc% bra%ing systems have

evolved considerably. *ecent versions not only prevent wheel loc% under bra%ing,

but also electronically control the front-to-rear bra%e bias. This function, depending

on its specific capabilities and implementation, is %nown as electronic bra%eforce

distribution (;6", traction control system, emergency bra%e assist, or electronic

stability control ('".

HISTORY(

EARLY SYSTE$SG

The A; was first developed for aircraft use in 133 by the rench automobile and

aircraft pioneer, abriel !oisin, as threshold bra%ing on airplanes is nearly

impossible. An early system was 6unlop)s #a5aret system, which was introduced

in the 13Cs and is still in use on some aircraft models. These systems use a

flywheel and valve attached to a hydraulic line that feeds the bra%e cylinders. The

flywheel is attached to a drum that runs at the same speed as the wheel. +n normal

bra%ing, the drum and flywheel should spin at the same speed.


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'hrysler, together with the ;endi5 'orporation, introduced a computeri&ed, three-

channel, four-sensor all-wheel A; called Fure ;ra%eF for its 13=1 +mperial. +t

was available for several years thereafter, functioned as intended, and provedreliable. +n 13=1, eneral #otors introduced the FTrac%masterF rear-wheel only

A; as an option on their *ear-wheel drive 'adillac models. +n the same year,

:issan offered an A> (lectro Anti-loc% ystem" as an option on the :issan

$resident, which became ?apan)s first electronic A;.

OPERATION(

The anti-loc% bra%e controller is also %nown as the 'A; ('ontroller Anti-loc%;ra%e".

A typical A; includes a central electronic control unit ('7", four wheel speed

sensors, and at least two hydraulic valves within the bra%e hydraulics. The '7

constantly monitors the rotational speed of each wheelJ if it detects a wheel

rotating significantly slower than the others, a condition indicative of impending

wheel loc%, it actuates the valves to reduce hydraulic pressure to the bra%e at the

affected wheel, thus reducing the bra%ing force on that wheelJ the wheel then turns

faster. 'onversely, if the '7 detects a wheel turning significantly faster than the

others, bra%e hydraulic pressure to the wheel is increased so the bra%ing force is

reapplied, slowing down the wheel. This process is repeated continuously and can

be detected by the driver via bra%e pedal pulsation. ome anti-loc% system can

apply or release bra%ing pressure 1E times per second.The '7 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. or this same reason, a differential is used in virtually all

roadgoing vehicles.+f a fault develops in any part of the A;, a warning light will


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The modern A; applies individual bra%e pressure to all four wheels through a

control system of hub-mounted sensors and a dedicated micro-controller. A; is

offered or comes standard on most road vehicles produced today and is the

foundation for ' systems, which are rapidly increasing in popularity due to the

vast reduction in price of vehicle electronics over the years.

#odern electronic stability control (' or $" systems are an evolution of the

A; concept. Dere, a minimum of two additional sensors are added to help the

system wor%G these are a steering wheel angle sensor, and a gyroscopic sensor. The

theory of operation is simpleG when the gyroscopic sensor detects that the direction

ta%en by the car does not coincide with what the steering wheel sensor reports, the

' software will bra%e the necessary individual wheel(s" (up to three with the

most sophisticated sveystems", so that the vehicle goes the way the driver intends.

The steering wheel sensor also helps in the operation of 'ornering ;ra%e 'ontrol

(';'", since this will tell the A; that wheels on the inside of the cur should

bra%e more than wheels on the outside, and by how much.

The A; e2uipment may also be used to implement a traction control system

(T'" or Anti-lip *egulation (A*" on acceleration of the vehicle. +f, when

accelerating, the tire loses traction, the A; controller can detect the situation and

ta%e suitable action so that traction is regained. #anufacturers often offer this as a

separately priced option even though the infrastructure is largely shared with A;.

#ore sophisticated versions of this can also control throttle levels and bra%es

simultaneously.

ELECTRONIC 'RA5E#ORCE DISTRI'UTION(

E,ecro*ic 0r+6eorce -isri0uio* /E'D orE'#D,E,ecro*ic 0r+6eorce

,i)i+io* /E'L or E,ecro*ic 0r+6e +ssis /E'Ais an automobile bra%e


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technology that automatically varies the amount of force applied to each of a

vehicle)s bra%es,

based on road conditions, speed, loading, etc. Always coupled with anti-loc%

bra%ing systems, ;6 can apply more or less bra%ing pressure to each wheel in

order to ma5imi&e stopping power whilst maintaining vehicular control. Typically,

the front end carries the most weight and ;6 distributes less bra%ing pressure to

the rear bra%es so the rear bra%es do not loc% up and cause a s%id. +n some systems,

;6 distributes more bra%ing pressure at the rear bra%es during initial bra%e

application before the effects of weight transfer become apparent.

OPERATION(

The job of the ;6 as a subsystem of the A; system is to control the effective

adhesion utili&ation by the rear wheels. The pressure of the rear wheels is

appro5imated to the ideal bra%e force distribution in a partial bra%ing operation. To

do so, the conventional bra%e design is modified in the direction of rear a5le

overbra%ing, and the components of the A; are used. ;6 reduces the strain on

the hydraulic bra%e force proportioning valve in the vehicle. ;6 optimi&es thebra%e design with regard toG adhesion utili&ationJ driving stabilityJ wearJ

temperature stressJ and pedal force.

;6 may wor% in conjunction with A; and lectronic tability 'ontrol (F'F"

to minimi&e yaw accelerations during turns. ' compares the steering wheel

angle to vehicle turning rate using a yaw rate sensor. FawF is the vehicle)s rotation

around its vertical center of gravity (turning left or right". +f the yaw sensor detects

more@less yaw than the steering wheel angle should create, the car is understeering

or oversteering and ' activates one of the front or rear bra%es to rotate the car

bac% onto its intended course. or e5ample, if a car is ma%ing a left turn and begins

to understeer (the car plows forward to the outside of the turn" ' activates the

left rear bra%e, which will help turn the car left. The sensors are so sensitive, and


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the actuation is so 2uic% that the system may correct direction before the driver

reacts. A; helps prevent wheel loc%-up and ;6 helps apply appropriate bra%e

force to ma%e ' wor% effectively.

TRACTION CONTROL SYSTE$(

Traction control system (T'" actuates bra%es or reduces throttle to restore traction

if driven wheels begin to spin. A r+cio* co*ro, s!se) (TCS", also %nown as

A*i%S,ip Reu,+io*

(ASR", is typically (but not necessarily" a secondary function of the anti-loc%

bra%ing system on production vehicles, and is designed to prevent loss of traction

of the driven road wheels, and therefore maintain the control of the vehicle when

e5cessive throttle is applied by the driver and the condition of the road surface (due

to varying factors" is unable to cope with the tor2ue applied.

The intervention can consist of one or more of the followingG

*educes or suppress the spar% to one or more cylinders

*educe fuel supply to one or more cylinders

;ra%e one or more wheels

'lose the throttle, if the vehicle is fitted with drive by wire throttle

+n turbo-charged vehicles, the boost control solenoid can be actuated to

reduce boost and therefore engine power.

Typically, the traction control system shares the electro-hydraulic bra%e actuator

(but does not use the conventional master cylinder and servo", and the wheel speed

sensors with the anti-loc% bra%ing system.

OPERATION(


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friction to the wheels that are spinning too fast. This bra%ing action on the slipping

wheel(s" will cause power to be transferred to the wheels that are not due to the

mechanical action within a differential. all-wheel drive vehicles also often have an

electronically controlled coupling system in the transfer case or transa5le that is

engaged (in an active part time A


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+n off roads vehiclesG Traction control is used instead or in addition to the

mechanical limited slip or loc%ing differential. +t is often implemented with, as

well as other computeri&ed controls of the engine and transmission. The spinning

wheel is slowed down with short applications of bra%es, diverting more tor2ue to

the non-spinning wheel.

TRACTION CONTROL IN CORNER

Traction control can prevent this from happening by limiting power to the wheels.

+t cannot increase the limits of grip available and is used only to decrease the effect

of driver error or compensate for a driver)s inability to react 2uic%ly enough to

wheel slip.

Automobile manufacturers state in vehicle manuals that traction control systems

should not encourage dangerous driving or encourage driving in conditions beyond

the drivers) control.

#OUR HEEL DRIVE(

our wheel drive (A


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a5le". 8P means a four-wheel vehicle in which engine power is transmitted to only

two a5le-endsG the front two in front-wheel drive or the rear two in rear-wheel

drive.

7D VS ALL HEEL DRIVE(

The termfour-wheel drivetypically describes truc%-li%e vehicles that may allow

the driver to manually switch (sometimes with an automatic option" between two-

wheel drive mode (if available" for streets and four-wheel drive mode for low-

traction conditions such as ice, mud, snow, or loose gravel.

All-wheel drive (A"". 7ses various sensors to intervene when the car


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senses a possible loss of control. The car)s control unit can reduce power from the

engine and even apply the bra%es on individual wheels to prevent the car from

understeering or oversteering.

E,ecro*ic S+0i,i! Co*ro, (ESC" is a computeri&ed technology that improves

safety througha vehicle)s stability by detecting and minimi&ing s%ids.


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system may reduce engine power or operate the transmission to slow the vehicle

down.

CO$PONENTS AND DESI&N(

' incorporates yaw rate control into the anti-loc% bra%ing system (A;". aw is

a rotation around the vertical a5isJ i.e. spinning left or right. Anti-loc% bra%es

enable ' to bra%e individual wheels. #any ' systems also incorporate a

traction control system (T' or A*", which senses drive-wheel slip under

acceleration and individually bra%es the slipping wheel or wheels and@or reduces

e5cess engine power until control is regained. Dowever, ' achieves a different

purpose than A; or Traction 'ontrol.

The ' system uses several sensors to determine what the driver wants (input".

Other sensors indicate the actual state of the vehicle (response". The control

algorithm compares driver input to vehicle response and decides, when necessary,

to apply bra%es and@or reduce throttle by the amounts calculated through the state

space (set of e2uations used to model the dynamics of the vehicle". The '

controller can also receive data from an issue commands to other controllers on the

vehicle such as an all wheel drive system or an active suspension system to

improve vehicle stability and controllability.

The sensors used for ' have to send data at all times in order to detect possible

defects as soon as possible. They have to be resistant to possible forms of

interference (rain, holes in the road, etc.". The most important sensors areG

teering wheel angle sensorG determines the driver)s intended rotationJ i.e.

where the driver wants to steer. This %ind of sensor is often based on A#*

elements.

aw rate sensorG measures the rotation rate of the carJ i.e. how much the car

is actually turning. The data from the yaw sensor is compared with the data

from the steering wheel angle sensor to determine regulating action.


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>ateral acceleration sensorG often based on the Dall-effect. #easures the

lateral acceleration of the vehicle.

ongitudinal acceleration sensorG similar to the lateral acceleration sensor in

design but can offer additional information about road pitch and also provide

another source of vehicle acceleration and speed.

*oll rate sensorG similar to the yaw rate sensor in design but improves the

fidelity of the controller)s vehicle model and correct for errors when

estimating vehicle behavior from the other sensors alone.

' uses a hydraulic modulator to assure that each wheel receives the correct

bra%e force. A similar modulator is used in A;. A; needs to reduce pressure

during bra%ing, only. ' additionally needs to increase pressure in certain

situations and an active vacuum bra%e booster unit may be utili&ed in addition to

the hydraulic pump to meet these demanding pressure gradients.

The brain of the ' system is the lectronic 'ontrol 7nit ('7". The various

control techni2ues are embedded in it. Often, the same '7 is used for diverse

systems at the same time (A;, Traction control system climate control, etc.". The

input signals are sent through the input-circuit to the digital controller. The desired

vehicle state is determined based upon the steering wheel angle, its gradient and

the wheel speed. imultaneously, the yaw sensor measures the actual state. The

controller computes the needed bra%e or acceleration force for each wheel and

directs via the driver circuits the valves of the hydraulic modulator. !ia a 'A:

interface the '7 is connected with other systems (A;, etc." in order to avoid

giving contradictory commands.

#any ' systems have an FoffF override switch so the driver can disable ',

which may be desirable when badly stuc% in mud or snow, or driving on a beach,


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3

or if using a smaller-si&ed spare tire which would interfere with the sensors. ome

systems also offer an additional mode with raised thresholds so that a driver can

utili&e the limits of adhesion with less electronic intervention. Dowever, '

defaults to FOnF when the ignition is re-started. ome ' systems that lac% an

Foff switchF, such as on many recent Toyota and >e5us vehicles, can be

temporarily disabled through an undocumented series of bra%e pedal and

handbra%e operations. urthermore, unplugging a wheel speed sensor is another

method of disabling most ' systems. The ' implementation on newer ord

vehicles cannot be completely disabled even through the use of the Foff switchF.

The ' will automatically reactivate at highway speeds and below that if it

detects a s%id with the bra%e pedal depressed.

ELECTRONIC DI##RERENTIAL LOC5(

A ,oc6i* -iere*i+,, -i%,oc6 or ,oc6er is a variation on the standard

automotive differential. A loc%ing differential may provide increased traction

compared to a standard or FopenF differential by restricting each of the two wheels

on an a5le to the same rotational speed without regard to available traction ordifferences in resistance seen at each wheel.

A loc%ing differential is designed to overcome the chief limitation of a standard

open differential by essentially Floc%ingF both wheels on an a5le together as if on a

common shaft. This forces both wheels to turn in unison, regardless of the traction

(or lac% thereof" available to either wheel individually.


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9

TYPES

AUTO$ATIC LOC5ERS(

Automatic loc%ers loc% and unloc% automatically with no direct input from thedriver. ome automatic loc%ing differential designs ensure that engine power is

always transmitted to both wheels, regardless of traction conditions, and will

Funloc%F only when one wheel is re2uired to spin faster than the other during

cornering. They will never allow either wheel to spin slower than the differential

carrier or a5le as a whole. The most common e5ample of this type would be the

famous F6etroit >oc%er,F also %nown as the F6etroit :o-pin,F which replaces the

entire differential carrier assembly. Others sometimes referred to as Flunchbo5

loc%ers,F employ the stoc% differential carrier and replace only the internal spider

gears and shafts with interloc%ing plates. An e5ample of a Flunchbo5 loc%erF

would be the partan >oc%er, manufactured by 7A tandard ear. ;oth types of

automatic loc%ers will allow for a degree of differential wheel speed while turning

corners in conditions of e2ual traction, but will otherwise loc% both a5le shafts

together when traction conditions demand it.

o $rosG Automatic action, no driver interaction necessary, no stopping

for (dis-" engagement necessary

o 'onsG +ntensified tire wear, noticeable impact on driving behaviour

(most people often tend to understeer".

ome other automatic loc%ers operate as an FopenF, or unloc%ed differential until

wheel spin is encountered and then they loc%up. This style generally uses an

internal governor to sense a difference in wheel speeds. An e5ample of this would

be #)s Fov->o%.Fome other automatic loc%ers operate as an Fopen,F or

unloc%ed differential until high tor2ue is applied and then they loc%up. This style


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91

generally uses internal gears systems with very high friction. An e5ample of this

would be M Fsliding pins and camsF available for use in early !8 >oc%er.F

lectronic solenoids and (electromagnetics" li%e aton)s F>oc%er.F

Dowever, O#s are beginning to offer electronic loc%ers as well. :issan

'orporations electric loc%er found as optional e2uipment on the rontier

(:avarra" Q Kterra. 11 ord super duty -C and *< -9C 858

models have a electronic loc%er as 93. 76 option.

$rosG Allows the differential to perform as an FopenF differential for

improved

driveability, maneuverability, provides full loc%ing capability when it is

desirable or needed

'onsG #echanically comple5 with more parts to fail. ome loc%ers re2uire

vehicle to stop for engagement. :eeds human interaction and forward-thin%ing

regarding upcoming terrain. n-s!illeddrivers often put massive stress on

driveline components when leaving the differential in loc%ed operation on

terrain not re2uiring a loc%er.

SPOOL(

The internal spider gears of an open differential may also be welded together to

create a loc%ed a5leJ however, this method is not recommended as the welding


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9

process seriously compromises the metallurgical composition of the welded

components, and can lead to failure of the unit under stress. +f it is desirable to

have a spooled a5le, the better option is to install either a mini-spool, which uses

the stoc% carrier and replaces only the internal components of the differential,

similar in installation to the lunchbo5 loc%er, or a full spool which replaces the

entire carrier assembly with a single machined piece. A full spool is perhaps the

strongest means of loc%ing an a5le, but has no ability to differentiate wheel speeds

whatsoever, putting high stress on all affected driveline components.

UNDERSTEER(

U*-erseer and overseer are vehicle dynamics terms used to describe the

sensitivity of a vehicle to steering. Automotive engineers originally defined

understeer and oversteer based on the gradient of the steering needed to ma%e a

turn in a steady-state condition (constant speed, constant radius" on a flat and level

ground surface. 'ar and motorsport enthusiasts often use the terminology more

generally in maga&ines and blogs to describe vehicle response to steering in all

%inds of maneuvers, even on ban%ed turns. imply put, oversteer is what occurswhen a car turns (steers" by more than (over" the amount.

CHAPTER 7

E9ISTIN& AND $ISSIN& TECHNOLO&IES

+n order to drive a car, a system would need toG

1. 7nderstand its immediate environment (ensors"

2. now where it is and where it wants to go (:avigation"


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99

3. ind its way in the traffic(motion planning"

4. Operate the mechanics of the vehicle (Actuation"

Arguably, R of these problems are already solvedG :avigation and Actuation

completely, and ensors partially, but improving fast. The main unsolved part is

the motion planning.

7.1 SENSORS(

ensors employed in driverless cars vary from the minimalist A*O project)s

monochrome stereoscopy to #obileye)s inter-modal (video, infra-red, laser, radar"

approach. The minimalist approach imitates the human situation most closely,

while the multi-modal approach is FgreedyF in the sense that it see%s to obtain as

much information as is possible by current technology, even at the occasional cost

of one car)s detection system interfering with another)s.

S ?apanese infra-red article

S ome things from the 6A*$A challenge....

S *oad-sign recognition

7.2 NAVI&ATION(

There are now available as standard car fittings, and use satellite transmissions to

ascertain the current location, and an on-board street database to derive a route to

the target. The more sophisticated systems also receive radio updates on road

bloc%ages, and adapt accordingly. There are also sensors that greatly affect the

whole nature of it.

&LO'AL POSITIONIN& SYSTE$(

The lobal $ositioning ystem ($" is a space-based global navigation satellite

system (:" that provides reliable location and time information in all weather

and at all times and anywhere on or near the arth when and where there is an


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98

unobstructed line of sight to four or more $ satellites. +t is maintained by the

7nited tates government and is freely accessible by anyone with a $ receiver.

CHAPTER :

5EY PLAYERS

INTERNATIONAL(

The uropean 7nion has a multi-billion uro programme to support *esearch and

6evelopment by ad-hoc consortia from the various member countries, called

ramewor% $rogrammes for *esearch and Technological 6evelopment. everal of

these projects pertain to the subject of driverless cars, e.g.G +:*+A)s >a *oute

Automatise project gathered much useful data about the actual and possible

deployments of 6riverless 'ars for public transport. The main system discussed is

based on *O.

#any of the 7-sponsored projects are coordinated by a group called rtico.

O!*:A#:TG

7AG

+T - Turner-airban% Dighway *esearch 'enter

+ce 6etection and 'ooperative 'urve

'atalog

7:+!*+T+ A:6 $*O+O:A> ;O6+G

y 7' ;er%eley - 'alifornia $ATD


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9C

1y #+T #edia >ab 'ity'ar

y !is>abG Artificial !ision and +ntelligent ystems >ab at 7niversity of $arma,+taly

9y 6epartment of 'omputing at +mperial 'ollege >ondon.

8y !irginia Tech

Cy Austin *obot Technology @ 7T Austin

S + has a ociety (the +ntelligent Transportation ystems ociety", runs

an important scientific ?ournal, and organi&es conferences

Ey ?apanese Automobile *esearch +nstitution

Advanced 'ruise-Assist Dighway ystem *esearch Organi&ation

'arnegie #ellon 7niversity :avlab

1 ray#atter +nc. - a division of the ray Team.

S +nstitute of Autonomous ystems TechnologyGU8V at ;undeswehr

7niversity of #unich S A' >ab (Automotive 'ontrol and lectronics >ab"

at Danyang 7niversity, eoul, orea

$*+!AT

'O#$A:+G

oogle driverless car

eneral #otors :-!

!O>7:TA* A:6 DO;;+T *O7$G

Autonomous *obots #aga&ine


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9E

1 American +ndustrial #agic httpG@@aimagic.org entered 9 vehicles in the 8

6A*$A challenge.

CHAPTER ;

IN #IL$

+TT, the automated $ontiac TransAm in the T! series night *ider could driveby itself upon command

The 1303 film ;atman, starring #ichael eaton, the ;atmobile is shown to be ableto drive itself to ;atman)s current location.

1 The 133 film Total *ecall, starring Arnold chwar&enegger, features ta5is

apparently controlled by artificial intelligenceJ it is not clear, however, whether

these are truly autonomous vehicles or simply conventional vehicles driven by

androids.

The 1339 film 6emolition #an, starring ylvester tallone, set in 9, features

vehicles that can be self-driven or commanded to FAuto #odeF where a voice

controlled computer operates the vehicle.

9 The 1338 film Timecop, starring ?ean-'laude !an 6amme, set in 8 and 1338,

has cars that can either be self-driven or commanded to drive to specific locations

such as FhomeF.

8 Another Arnold chwar&enegger movie, The Eth 6ay (", features a driverless

car in which #ichael *apaport sets the destination and vehicle drives itself while

*apaport and chwar&enegger converse.

C The film #inority *eport, set in


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9=

protagonist ?ohn Anderton is transporting him when its systems are overridden by

police in an attempt to bring him into custody.


38/39

CONTENTS

CHAPTER%1

INTRODUCTION%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%1

CHAPTER%2

LITURATURE SURVEY%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%2

2.1HISTORY%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%3

CHAPTER%3

RECENT PRO"ECTS%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%:

3.1 #ULLY AUTONO$OUS%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%:

9.1.1!AD+'> O* 7*A'6 *OA6------------E

9.1.*-*A:+: !D+'A> -------------------------------=

3.2 PRE%'UILT IN#RASTRUCTURE%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%=

9..167A> #O6 T*A:+T #O:O*+A>------------------0

9..6 D+D-+:O*#AT+!----------------------1E

CHAPTER%7

E9ISTIN& AND $ISSIN& TECHNOLO&IES

7.1SENSORS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%32

7.2NAVI&ATION%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%32

CHAPTER%:

5EYPLAYERS%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%37

CHAPTER%;

IN #IL$ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%3;


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49379095 driverless car documentation 3

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