UNIT-I & II-ACCIDENT
AVOIDANCE TRAINING
TABLE OF CONTENTS
INTRODUCTION
 ARMY Regulation
 Traffic Safety
 Vehicle Safety
 Defensive Driving
 Night Driving
Tactics
 Winter Driving
Tactics

Safe Driving
 Driving Safety
 Heads Up at the
Wheel: Home Safe
 Hands on Driving
Information
 SAFETY ALERTS &
Awareness Material
 FT LEE FORM 1082

INTRODUCTION

Driving can lead to a false sense of
security.
•
•


You take most risks for granted.
Driving becomes second nature.
Motor vehicle accidents are the single
largest cause of accidental death.
Leading cause of on-the-job
fatalities.
Introduction

Driving may be one of the most
dangerous activities you engage in on
the job.
 By
following the Ft. Lee Accident
Avoidance Training handbook, you may
be surprised to find that some of your
driving habits are not as harmless as
you thought. After all, even a good
driver can improve.
ARMY REGULATION
 AR
385-55: Prevention of Motor
Vehicle Accidents
•
requirement every 4 years
 AR
600-55: The Army Driver and
Operator Standardization Program
(Selection, Training, Testing and
Licensing)
VIEW VIDEOS
THE BASICS
MOTOR MANIA
TRAFFIC SAFETY
Why is it important to keep
your eyes and attention on
the driving task?
Distractions are a leading contributor to
vehicle accidents.


Taking your eyes and attention off the
driving task will mentally leave you blind
to the driving environment.
At highway speeds, a one second
distraction can permit you to travel blind
for over 100 feet.
Avoid inside and outside distractions to
the driving task.
What is the purpose of delaying your
start at a traffic light that has just
turned green?
 The
first three seconds after a light
turns green are the most dangerous.
•
Drivers facing the newly turned red light may
still be trying to make the light.
Remember, having a green light does
not give you the right to start
moving immediately.
Traffic Safety Discussion

What is the purpose of scanning 10-12
seconds ahead of your vehicle’s intended
path?
is meant by the concept road
management ?
 What
QUIZ
5 minutes
QUIZ
1. How far ahead should you scan your intended
driving path?
A. 0-2 seconds
B. 2-4 seconds
C. 10-12
C.
10-12seconds
seconds
D. 16-18 seconds
E. 20-22 seconds
2. What is the recommended safety cushion for
vehicles you are following?
A.
seconds
A. 33seconds
D. 6 seconds
B. 4 seconds
C. 5 seconds
E. 7 seconds
3. When stopping behind another vehicle, what
should you be able to see?
Reartires
tires
of vehicle
A. Tail lights of vehicle ahead D.
D. Rear
of vehicle
ahead
B. Bumper of vehicle ahead
touching
the ground
ahead
touching
ground
C. Rear tires of vehicle ahead
E. 15 feet of ground behind
the vehicle ahead
4. The recommended delayed starting time at a light is?
A. Delay not recommended
B. 1 second
C.
C. 33seconds
seconds
D. 5 seconds
E. 7 seconds
5. Proper seatbelt use reduces the likelihood of fatal
or serious injuries by:
A. Does not reduce likelihood
C. 24%
E. 44%
E.
44%
B. 14%
D. 34%
VEHICLE SAFETY
View Video
Do all vehicles handle and operate
the same?
 Each
vehicle and type of vehicle has
its own handling characteristics.
•
•
Drivers should be trained on the vehicle
they operate.
Follow the same driving rules on and
off-site.
What purpose do the lights on a
vehicle serve?


To illuminate the path of the
vehicle.
To help others locate the vehicle
and determine its activity (braking,
turning, backing, etc.).
What is the role of the braking
system of a vehicle?



To avoid collisions with other
objects in the vehicle’s path.
To hold the vehicle in place while
parked.
To slow the vehicle so it can stop
or make appropriate turns.
QUIZ
5 minutes
QUIZ
1. Which statement(s) about vehicles on a facility is
true?
A. Each vehicle has its
own operating procedures
B. Drivers must know & follow
each vehicle’s operating
procedures
C. Drivers should be trained
on vehicles they operate
D. All
All ofofthe
above
D.
the
above
E. None of the above
2. A vehicle’s lighting system exists for which of the
following purposes?
A.
B.
C.
D.
E.
To help the driver see his/her path of travel
To warn others of the vehicle’s presence
To inform others of the vehicle’s activity
All
above
Allofofthethe
above
None of the above
3. Based on the concept of one vehicle length per
every 10 mph of travel, how many vehicle lengths
should you be behind a vehicle traveling 30 mph?
C.
Three
A. One
C. Three
E. Five
B. Two
D. Four
4. What types of problems can the noise from some
industrial vehicles create?
Driver’s inability
to hear
C. Driver’s inability to steer the
A. Driver’s
inability
to
hear
warning
devices
warning
devices
vehicle
B. Driver’s inability to see
approaching vehicles or
pedestrians
D. All of the above
E. None of the above
SAFE DRIVING
View Videos:
5 Rules of Defensive Driving
Heads Up At the Wheel
Why should you check outside the
vehicle before putting the vehicle in
motion?
 To
ensure no objects will interfere with
the movement of the vehicle.
 To
ensure tires are in good condition.
 To
ensure the windows are clean.
 To
identify any unexpected body
damage to the vehicle.
If your vehicle is well maintained,
what else can affect motor vehicle
safety?

A driver not getting proper rest; and
not being alert.
What types of emergency equipment
should be with the vehicle?

Warning flares or triangles, jumper
cables, fire extinguisher, first aid kit,
& equipment to change a flat.
What is meant by properly
securing the driver and goods?

Driver properly belted in

Passengers wearing seatbelts

Cargo properly secured so it can’t
move around during travel.
How do senses other than vision
help in driving?

Provide warning that something is not
right.
•
smells alert you to something burning
•
unusual engine sounds may indicate a
mechanical problem
•
your body may alert you to bad brakes or
improper tire inflation by feeling the vehicle
pull to the left or right when braking
Good visual driving habits:
 Keep
eyes moving (check out your path of
 Look
15 seconds ahead of your vehicle.
 Scan
mirrors every 4-6 sec. (find out
travel)
(it provides a picture of what’s happening)
what’s happening behind and along side your
vehicle)
 Glance
at dashboard every 20 sec.
 Follow
vehicles ahead no closer than 3
(observe speed control and warning gauges)
sec. (allows for reaction time if needed)
QUIZ
5 minutes
QUIZ
1. Outside the vehicle, you should check for:
A. Objects that could interfere
C. Bad tire pressure or loss
in the movement of the vehicle
of fluids
B. Vehicle damage not
D.
thethe
above
D. All
Allofof
above
previously reported
E. None of the above
2. Taking care of the vehicle and yourself means?
A.
B.
C.
D.
E.
The driver getting plenty of rest
The vehicle receiving proper maintenance
Having emergency supplies in the vehicle
All
above
Allofofthethe
above
None of the above
QUIZ
3. Good visual search patterns while driving:
A. Provides
Provide the driver
driver with
needed
information
safely drive
from
A.
with
needed
info totosafely
drive
point A
to point
B. point B.
from
point
A to
B. Include looking inside of the vehicle and under the hood as
much as looking outside of the vehicle.
C. Include maintaining a minimum 10 sec following distance.
D. All of the above
E. None of the above
4. Seatbelts should be worn:
A. Only when traveling short distances
B. Only when traveling long distances
C.
timethethe
vehicle
is in motion
C. Any
Any time
vehicle
is in motion
D. Only when confronted with dangerous driving conditions
E. When your supervisor is present
QUIZ
5. When driving in bad weather, the driver should:
A.
B.
C.
D.
E.
E.
Allow more time to secure the cargo
Allow more time to stop the vehicle
Take fewer rest stops to get home faster
A and C
A
Aand
andB B
DRIVING SAFETY
Four strategies that make for a
safe driver:




Driver has behaviors and attitudes
appropriate to the driving task.
Driver follows appropriate driving behaviors.
Drivers see to it that their vehicle is properly
maintained and loaded/unloaded.
Drivers comply with organizational policies as
they relate to safe operation of a vehicle on
and off the facility.
Driving Safety Discussion
What is meant by the need to
develop a high emotional
tolerance level to other
drivers?
QUIZ
5 minutes
QUIZ
1. Which of the following behaviors is common to a
driver with an inappropriate driving attitude?
A. Speeding
B. Tailgating
C. Needless risk taking
D. Accelerating towards a
caution light
E. All
All ofofthe
above
E.
the
above
2. The minimum distance you should maintain when
following another vehicle is:
A. 4 seconds
B. 5 seconds
C. 6 seconds
D. 7 seconds
E.
thethe
above
E. None
Noneofof
above
QUIZ
3. Which of the following items should be
included in a pre-drive checklist?
A. Tires
D. All
All of
D.
ofthe
theabove
above
B. Wipers
C. Brakes
E. None of the above
4. Alcohol consumption followed by driving has
which of the following impacts on the driver?
A.
B.
C.
D.
E.
Improved vision
Improved hearing
Reduced concentration
Reduced
concentration
Reduced distractions
All of the above
QUIZ
5. Your organization’s policy on vehicle operation is
intended to protect:
A.
B.
C.
D.
E.
You the operator
Your supervisor
The organization
The product (equipment)
All
above
Allofofthethe
above
WINTER DRIVING TACTICS
View Video:
WINTER DRIVING
SAFETY ALERTS &
AWARENESS MATERIAL
HANDS ON DRIVER’S
TRAINING
 TIME:
1 hour
 1 Qualified Instructor - must be
with the student(s)
 Ensure travel map/driving
instructions are discussed prior
- choose variety of roadways
 Critique student
TRAINING COMPLETION
 Fill
out the Ft Lee Accident
Avoidance Training card (FT LEE
FORM 1082)
 Instructor’s signature & date
UNIT-III
SAFETY EQUIPMENTS
INTRODUCTION


Automobile Industry is undergoing a
BIG TRANSFORMATION never seen
before.
Today CAR’s are not only used for
personal Transport but they are
ENCOMPASSED with
•
•
•
Entertainment that vies with the fedility of your HOME
THEATRE
Seating arrangement more comfortable than your
RECLINER
SAFETY FEATURES making your car safer than a TANK
•Globally car companies Spend
nearly $36 billon annually for
influencing new TECHNOLOGIES
into their cars.
•Some of the big advancement in
Automotive Industry in last 10years
have come in a area of SAFETY.
In addition to Telematics based Services like
• Digital Satellite Radio
•In car E-mail
•GPS systems
Recent Advancement in Braking Technology have led to
•Shorter stopping distance
•Increased Control in PANIC situation
•More control on CURVED turns
Air Bags
•What’s the main function of the System?
•Material of Airbags?
•History
Actual Working
Airbag Before Collision
Airbag After Collision
Inflation unit
•How does it INFLATES?
Effectiveness
This system has proven its effectiveness
• In frontal crashes reduction in d rivers death
reduced by nearly 14%
•Passenger side airbags reducing death by nearly
11%
•NHTSA estimated
reduction
in risk by nearly 85%
Head Injury
Risk
Airbag of seat belt and
No Airbag
with the combination
airbags
Holden Commodore
48
compared than 28only seatbelt i.e60%
Car Model
Toyota Camry
20
44
Mitsubishi Magna
6
27
Ford Falcon
14
N. A.
This are some crash results which give the
effectiveness of the system
Different types of Airbags
DRIVERS SIDE AIRBAG
PASSENGER AIR BAG
Curtain Airbags
Anti-lock Braking System
• Introduction?
•Advancement in the system?
•Working?
Advancement in the system?
How Does the system Works?
Working
 Conventional
Braking
Whole process is controlled by driver applied break paddle
pressure;
 ABS
Braking
Electric Sensors monitor the wheel speed
ABS microprocessor Compares the wheel speed
Control valve is energized.
Effectiveness
ABS on a test track
Advantages:
Achives the Shortest Stopping distance
Better chance on Steering around obstacle
Reduced risk of skidding
Disadvantages:
Precautions should be taken while
driving
Proved less effective on gravel road or
road compacted by snow
Traction Control
 Next
Generation ABS
 Uses ABS as a Building block.
 Can be is a combination of ABS &
Engine control
Mainly the system has to control some
or all conditions
Retard or Suppress the spark to one or more
cylinders
Retard fuel supply to one or main cylinder
Break one or more wheel
Close the throttle, if the vehicle is fitted by
wire throttle
Electronic Stability Control
Main components of the
system
A) active wheel speed sensors;
B) steering angle sensor;
C) Yaw rate sensor
D) attached electronic control unit (ECU)
E) motor;
Steering Angle Sensor
Understeering (“plowing out”)
Oversteering (“spinning out”)
Some important ECS definitions
• ESC augments vehicle directional stability by
applying and adjusting the vehicle brakes individually
to induce correcting yaw torques to the vehicle.
• ESC is a computer-controlled system, which uses a
close-loop algorithm to limit under steer and over steer
of the vehicle when appropriate
Case Study
A S-Class Mercedes sedan testing Bosch's ESP sys
UNIT-IV-COLLISION
WARNING & AVOIDANCE
1. The Problem



Vehicles and highways have greatly improved
safety: total fatalities are down approximately
30% over the past 35 years
Even with those improvements, there are still
approximately 40,000 fatalities / year in the
US
People haven’t improved: in 90% of all
accidents, the driver is a contributing cause
The Solution




The Intelligent Vehicle Initiative (IVI) is a
USDOT program to use advanced electronics to
improve vehicles, with the dominant concern
being safety.
This tutorial is arranged around a series of
advanced functions, such as vehicle detection,
that contribute to safer and more intelligent
vehicles. For each function, the tutorial
discusses a set of possible technologies.
The next set of slides show the “user services”
for the IVI advanced vehicle control and safety
systems. The following charts show which
technology functions support each user service.
Note the synergy: each technical function
IVI User Services
categories:

Safety: (directly contributing to vehicle safety);
•
•
•
•
•
•
•
•

rear end collision warning
roadway departure warning
lane change / merge collision warning
intersection collision warning
railroad crossing collision warning
vision enhancement
location-specific warnings
collision notification
Safety Impacting: (potential to distract or aid the
driver);
•
•
•
navigation and routing
real-time traffic information
driver comfort and convenience features
More Services

Commercial Vehicle Services:
•
•
•
•
•
•

vehicle stability
vehicle diagnostics
driver condition monitoring
cargo identification
automated transactions
safety recorder
Transit:
•
•
•
•
obstacle and pedestrian detection
precision docking
passenger monitoring
passenger information
More Services

Specialty Vehicles:
•

full automation
Supporting Services:
•
•
•
low friction warning
longitudinal control
lateral control
Technical functions

There is a set of common vehicle functions that
underlie those user services:
•
•
•
•
•
•
•
•
•

sensing the position of other vehicles
sensing obstacles
sensing the position of the lane relative to your own
vehicle
sensing vehicle position and motion
estimating braking performance
communication
reliability
miscellaneous functions
sensor-friendly vehicles and roadways
The rest of this section shows how each of
these functions supports the various user
Safety 1
O th e r
V eh.
R ear
End

R o ad
D ep
L ane
C hnge

In te rSect

RR
O b st.
L ane
Pos
C ontro l
Pos +
m tio n
B ra k e
Com m
R e lia
b ility
M isc .
C lu tte r
    
  
    
  
  

  
   
  
   
 
Safety 2
O th er
V eh .
V ision
E n h ce
O b st.
L an e
Pos
C on trol
Pos +
m tion
  
B rak e
Com m
R elia
b ility
M isc.
  
L o csp ec
    
C o ll
N o tif

S m art
restrnt
 
C lutter
  
 
Safety Impacting
O th er
V eh .
O b st.
L an e
Pos
C on trol
Pos +
m tion
B rak e
Com m
R elia
b ility
M isc.
N av /
R ou t

  
R -T
traffic


D riv er
C o m f.


C lutter
Commercial Vehicle
O th er
V eh .
O b st.
L an e
Pos
S tab ility
D riv er
C on d .
C on trol
Pos +
m tion
B rak e
Com m
  
V eh icle
D iag .
C argo ID
S afety
reco rd er

  
M isc.
 

A u to
T ran sact.
R elia
b ility
C lutter
Transit
O th er
V eh .
O b st /
P ed
P rec.
D o ck
O b st.

L an e
Pos
C on trol
Pos +
m tion
B rak e
Com m
M isc.
C lutter


  

P ass
M ntr
P ass
In fo
R elia
b ility

Specialty
O ther
V eh.
F ull
A uto
O bst.
L ane
P os
C ontrol
P os +
m tion
B rake
C om m
R elia
bility
M isc.
C lutter
         
Supporting
O th er
V eh .
O b st.
Low
F riction
L an e
Pos
C on trol
Pos +
m tion
B rak e
Com m
R elia
b ility
M isc.
C lutter
  
L o ng
C trl
 
L at
C trl

      
  
   
Section 1 Questions:





How many accidents occurred in the most
recent year for which statistics are available?
Hint http://www.ohs.fhwa.dot.gov/info/saffacts.htm
l and http://www.census.gov/statab/www/
How many fatalities?
What was the dollar cost of those accidents?
What kind of economic justification is there for
the various AVCSS services?
Are there other on-vehicle functions that would
be useful?
2
Sensing Other Vehicles
Other vehicles need to be sensed in
front for adaptive cruise control and
forward collision warning; on the sides,
for blind spot and lane change / merge
warning; and behind, for backup warning
and for lane change / merge warning of
overtaking vehicles.
 Sensing has to work in all weather, and
at a variety of ranges

2.1 Basic Geometry
Sensing straight
ahead is not sufficient;
on a curving road, a
forward-looking
sensor needs to have
a wide field of view,
and sensed vehicle
position needs to be
combined with road
geometry to know
whether the lead
vehicle is in your lane,
another lane, or on the
shoulder.
2.2 Targets and Clutter



Other objects in the field of view can include
roadside signs, parked cars, overpasses, guard
rails, etc; this is referred to in the radar
literature as “clutter”.
Adaptive Cruise Control (ACC) systems, which
are only concerned with moving vehicles, can
reject any stopped object as clutter.
Rear-end collision warning systems need to
sense stopped vehicles, and so need high-acuity
sensing of vehicles and lanes in order to
separate targets (other vehicles) from clutter.
2.3 Radar




Radar is an excellent choice for seeing big metal objects
through fog, snow, or light rain
The currently approved frequency is 77 GHz. Radar
works at the speed of light, so sensing is almost
instantaneous.
Simple radar is be a single spot with no information on
bearing angle. More sophisticated versions sweep the
beam mechanically, or use two or more beams and various
processing schemes to measure bearing and range
Typical resolution (closest objects that can be
distinguised) is 1 meter in range, 3 degrees in bearing.
Radar Data
Data from a scanning radar.
Top image is video of the
scene, bottom is radar data,
with corresponding locations
marked. The radar data is
range (horizontal) and
bearing angle (vertical; up is
left, down is right).
Brightness indicates
strength of return. Car A is
close and he center of the
radar return (the video
image does not extend as
far to the right as the radar);
B is further and left; C is
further yet and is barely
visible above the roof of A; D
is much further and has a
2.4 Ladar



Ladar, lidar, and laser rangefinder are all synonyms.
They refer to measuring distance using the travel time of
a laser beam. The laser can be scanned over the scene
with mirrors to produce a “range image”.
Lasers can be focused to very small spots (fractions of a
degree), so they have much better resolution than radar.
Instead of sensing a blob with radar, a ladar can make
many measurements as it scans, and can measure fine
details of shape.
Since ladar is near visible light, it is blocked by the same
kinds of effects that impede human vision: fog, snow,
and heavy rain will block the signals.
Ladar Data




The figures on the next page show data from a highresolution scanning laser rangefinder. Each picture is
480,000 pixels (points), each corresponding to a separate
ladar measurement.
The top picture shows the reflectance data: this is the
amount of laser energy returned from that point in the
scene, and is roughly equivalent to a flash photo.
The lower picture shows range data. Brightness encodes
range: points that are further away are displayed more
brightly.
Note the fine details of shape and appearance visible in
this data. It is possible to build a computer program that
can identify which objects are cars, and which direction
they are facing; this can give early warning of which
Ladar Data
2.5 Sonar




Sonar works by measuring the time of flight of
sound.
Sound travels (relatively) slowly though air and
is hard to focus, so sonar is only useful for
detecting objects at ranges of a few meters or
less.
Sonars are inexpensive, and work in a most
weather conditions. The initial mass market
application was in Polaroid auto-focus cameras.
Sonars are commercially available for blind spot
sensors and back-up warning sensors.
Side and Rear Sensors
Sonars
Radar
This bus is
equipped
with rear
and side
sensors for
blind spot
coverage
2.6 Communications





If all vehicles on a roadway are equipped with ITS
features, inter-vehicle communications can be used to
determine relative positions.
Each vehicle can broadcast its current location, derived
from GPS or other positioning systems.
Vehicles can also broadcast other information, such as
speeds, intent to change lanes, or onset of emergency
braking. This is crucial in decreasing inter-vehicle spacing
to increase throughput, while maintaining safety.
This kind of scheme is most appropriate for high-end IVI
systems, such as automated highways.
The picture on the next page shows a “platoon” of
tightly-spaced automated vehicles, developed by the
PATH program at UC Berkeley. Platoons rely on
communications 20 times a second to keep all vehicles
Platoon
2.7 Driver models



Sensing the current location of a nearby vehicle
is not all: it would be even better to predict
future actions of the vehicle. Unless that
vehicle is fully automated, it is necessary to
model the behavior of that driver.
As shown in the next slide (and as everyone
knows from personal experience), there is a
great deal of variability in people’s driving
behavior.
If a particular vehicle can be observed for
some time, that driver’s behavior can be
estimated, and used to predict future actions.
Driver Differences
The five drivers
plotted here each
have different
behaviors for one
important component
of driving: average
lane position. They
have different mean
lane positions when
the road is straight,
and cut the corners
by different amounts
when the road
curves
Left curve
Straight
Right curve
Section 2 Questions:
 What
are the advantages and
disadvantages of using radar vs.
ladar?
 The speed of light is about 3*10^8
m/sec, or, for a rule of thumb, a
foot / nanosecond. How long does it
take a radar pulse to go to and
from an object 150 m away?
 Find two manufacturers of
3
Sensing Obstacles
Obstacle detection is much more difficult
than vehicle detection: obstacles can be
small, non-metallic, and much harder to
see
 Obstacles can be stationary or moving
(e.g. deer running across the road)
 For a passenger car at highway speeds,
obstacles need to be detected 100 m
ahead. For trucks, the distance is even
longer.

3.1 Obstacles on the Road





State DOTs report cleaning up construction debris, fuel
spills, car parts, tire carcasses, and so forth.
State highway patrols receive reports of washing
machines, other home appliances, ladders, pallets, deer,
etc.
A survey commissioned by a company that builds litterretrieval machines reports 185 million pieces of litter /
week.
Rural states report up to 35% of all rural crashes involve
animals, mostly deer but also including moose and elk as
well as farm animals.
A non-scientific survey of colleagues indicates that
people have hit tire carcasses, mufflers, deer, dogs,
even a toilet.
3.2 Sensors
Ladar, in its high-resolution scanning
formats, is useful for seeing small
objects
 A variant is to use the reflectance
channel of a ladar, and to look for
bright returns, which probably come
from objects sticking up out of the
roadway.
 Sonar has insufficient range
 Advanced radar and stereo vision

3.3 Polarimetric radar




Radar can be polarized in the same was as
light.
Just as polarized sunglasses help reduce light
reflected from shallow angles (glare), polarized
radar transmitters and receivers can separate
the return from different polarization
directions; this provides cues to distinguish
horizontal surfaces and from vertical surfaces.
Polarimetric radars built at U of Michigan are
much better than ordinary radar at separating
small obstacles from ground clutter.
There is also some evidence that polarimetric
radar will give different returns for wet or
snowy roads, giving some information on road
3.4 Stereo vision
 Stereo
works by finding the same
point in two or more cameras.
Intersecting the lines of view from
the cameras gives the 3D location
of the object.
Stereo Guided
Segmentation



Low-resolution stereo for detection and recognition of
nearby objects, used for side-looking sensors on a bus.
Left: Original image. Center: depth map from stereo;
brighter is close. Right: “blobs” of pixels at the same
distance. The overlays on the original image show
detected objects, two pedestrians and a car.
Further processing can examine each blob to separate
people from fixed obstructions, and generate appropriate
driver warnings
Long-Range Stereo
Top: One of three
images from a stereo
set. The objects on the
road are 15 cm tall at a
range of 100 m from
the camera.
Bottom: detected
objects in black.
Besides the obstacles
on the road, the
system has found the
person, the sign, grass
Section 3 Questions:
Look up the connection between posted
speeds and vertical curvature in the
AASHTO handbook. Is the line of sight
for a human driver, going over the crest
of a hill, better or worse than for a
sensor mounted in the front bumper?
 For extra credit, go out and run over
obstacles with your car, and decide what
is the largest object you would be willing
to hit, and therefore the smallest object
that needs to be detected.

4
Sensing Lane Position
 Knowing
lane position is necessary
for automated guidance and for
lane departure warning systems. It
is also important for rear-end
collision warning, to know which lane
your vehicle is in as well as which
lane preceeding vehicles are in.
 Requirements are somewhat
different for each application.
4.1 Requirements
•
•
•
•
•
reliability: high for warning systems, extremely
high for automated guidance
availability: must be available nearly 100% for
automated guidance; lower availability
acceptable for warning systems provided a
warning is given
weather: should operate in most weather, warn
and disable if not operating
accuracy: absolute accuracy of better than 30
cm needed; no high-frequency jitter allowed for
control applications
range: rear-end warning requires knowing lane
position of leading vehicle, to approx. 100m
4.2 Magnetics
UC Berkeley has pioneered the use
of permanent magnets, buried in the
center of the road, for lateral
guidance. The magnets can be
inexpensive magnets, as shown
here, for most applications; or more
expensive but much smaller
magnets for bridge decks where
drilling large holes would damage
the structure. The magnets are
sensed by magnetometers
underneath the front and rear
bumpers of the vehicle to provide
lateral position information.
The magnets can be installed north
pole up or down, providing a simple
More Magnets
An obvious advantage of
magnets is that they are
not affected by weather.
Here, they are used to
mark the edge of the
shoulder, to provide a
visual indicator to the
snow plow operator.
Besides buried magnets, there are also efforts to place
magnets in lane marking tape. This would be less
expensive to install, but requires more sophisticated
sensing, since the magnets are not directly underneath the
vehicle’s sensors.
4.3 Buried cables
The oldest way to perform
automated guidance, going back to
the 1950’s, is to follow a buried
cable. The automated trucks at the
Westrack pavement test site use
two cables for redundancy, with
pickup coils mounted in triangular
frames at both front and back of the
truck. Buried cables are all-weather,
and the signal on the cable can be
used to send messages (e.g.
“speed limit change”). But cable
installation and maintenance are
difficult.
4.4 Radar reflective surfaces
• Collision avoidance radar can
be used for lateral control with
modified lane-marking tape.
• Frequency-dependent tape
properties can provide
distance and other information
h ig h e r f
lo w e r f
(a )
Ra d a r
Hig h-Fre q ue nc y
Illum ina tio n
Lo w-Fre q ue nc y
Illum ina tio n
Ra d a r-Re fle c tive Strip e
(b )
• Conventional lane marking
tape (3M Corp.) punched with
specific hole pattern to provide
frequency-selective retroreflection
4.5 Vision
Typical vision system for
lane tracking.
The detected position of
the solid line is shown by
the blue dots; the
detected dashed line by
dark and light blue dots.
Overlayed on the image
is data from other
sensors, showing the
location of radar targets:
yellow X for right lane,
red X for current lane.
Experimenter interface
shown at bottom.
Section 4 Questions:
 What
would be the relative
advantages of magnetics vs. vision?
 What is the disadvantage of buried
cables?
5

Sensing vehicle position
and motion
An estimate of vehicle motion, and position on a
map, can be used in several ways, depending on
the resolution. For example:
•
•
•

coarse position (10s of meters) can be used to predict
that a corner is coming up
medium position (meters) can be used to warn a driver to
slow down, based on the design speed of the upcoming
curve
fine positioning (cm) can be used to tell if the driver is
drifting out of their lane through the curve
Several different technologies provide ways of
measuring absolute position and motion, at a
variety of resolutions.
5.2 GPS

The Global Positioning System is a satellitebased navigation system, originally developed by
the US military. It works by broadcasting very
accurate time signals from a constellation of
orbiting satellites. A ground-based receiver can
compare the times from several satellites; the
different in apparent times gives the difference
in time-of-flight of the signals from the
satellites, and therefore the difference in
distance to each satellite. Simple geometry
gives the location of the ground-based unit and
an accurate time.
More GPS

This simple picture is distorted by two
phenomena
•
•

The US government deliberately introduces
distortions into the civilian version of the
signal, in order to reduce the accuracy of the
system for potential enemies
Local atmospheric effects refract the signals
by varying amounts
The result is that raw GPS has an
accuracy of only 10’s of meters
Differential GPS


In Differential GPS, a base station has a GPS
receiver at a known location. It continually
compares its known position with the GPS
reported position. The difference is the error
caused by selective availability and atmospheric
distortion. The base station broadcasts the
correction terms to mobile units. By applying
the correction, the mobile units can reduce
their errors.
The accuracy of DGPS is on the order of a few
meters.
Carrier Phase GPS
In carrier phase systems, the base
station and the mobile units watch both
the broadcast time code, and the actual
waveforms of the carriers. By counting
waveforms, they can synchronize their
positions with each other to a fraction
of a wavelength.
 A good carrier-phase system, with good
conditions, can achieve accuracies of 2
cm or better.

GPS Difficulties
GPS requires a clear view of at least 4
satellites. For aircraft applications, or in
flat, open terrain, this is not a problem.
 In mountainous terrain, or in urban
canyons, GPS signals can be blocked or
(worse) can reflect from tall objects and
cause mistaken readings.
 Carrier-phase GPS is very sensitive to
losing lock on the satellites, and can
become confused even going under a
large road sign.

Bottom line on GPS
 GPS
is very useful for many
applications.
 It is not yet 100% reliable, so is
not ready for control applications.
 Research continues on filling in gaps
in GPS coverage, and integrating
GPS with other sensors, so there is
hope for the future.
Maps




Accurate position is not useful unless combined with
accurate maps.
The first generation of digital maps were produced from
paper maps, and therefore are no more accurate than
the paper products. Typical quoted accuracies are 14
meters. This is sufficient for in-vehicle navigation
systems; until more sophisticated uses arise, there is
little market demand for high accuracy.
The next generations of maps will be produced directly
from aerial photos and verified by driving selected routes
with accurate GPS, so the accuracies will improve.
To be completely useful, maps should have additional
information, such as design speed of curves, grade of
slopes, etc. This would aid e.g. in warning drivers of
excessive speed when entering a curve.
5.3 Inertial





Inertial sensing measures acceleration, then
integrates acceleration to give velocity and
again to give position.
Since position is doubly-integrated, small errors
in acceleration build up rapidly.
Inertial measurement is good for sensing
braking forces or for comparing wheel speed
with ground speed and calculating slip during
braking.
High-precision inertial navigation is not yet
affordable for the automotive market.
Inertial measurement is useful to fill in short-
5.4 Other sensors



“Dead reckoning” uses estimates of distance
travelled and direction of travel.
Odometry uses wheel encoders to measure
distance traveled. It is susceptible to errors
due to tire slip, incorrect estimates of wheel
circumference due to changes in tire inflation,
etc. Road Rally enthusiasts can calibrate their
odometry to 0.1%; this is not practical for
most vehicles.
Standard compasses are affected by nearby
metallic objects, such as bridges or buildings.
More Sensors


Image correlators directly measure vehicle
motion by watching the ground move by under
the vehicle. These systems are accurate to
better than 0.1%
Doppler radar is used in precision agriculture
applications, where it is important to measure
the speed of farm equipment even with
significant tire slip.
Section 5 Questions:
 Why
can’t you just use a magnetic
compass for heading?
 What’s the cheapest GPS unit you
can find on the web?
 Why would Japan have a higher
market penetration of GPS and
moving map displays than the US?
6
Predicting Braking
Performance
Braking performance is key to setting
many parameters in automated control
and in driver warning systems.
 To set safe following distance, ideally
the system should know its own braking
capability; the braking capability of the
lead car; and the reaction time of the
automated system or of the
 Braking performance of vehicles on
identical roadways can vary by a factor
of 4

6.1 Basic formulas

The basic formulas for the time and distance
required to bring a car to a stop are
• Time = reaction time + speed / deceleration
• Distance = speed * reaction time + ½ speed2 / deceleration

Typical highway speeds are approximately 30
meters / second; typical reaction times range
from 100 milliseconds for a fast computercontrolled sensor and brake actuator, to up to
2 seconds for a human driver. The dominant
unknown factor is deceleration, or braking
performance.
6.2 Wheel speeds and slip
Typical force vs. slip curve. As the
brakes are applied, the tires begin to
slip, which results in deceleration
force. As the slip increases, the force
increases to some maximum. After
that point, the wheels begin to lock
and skid, and the braking force
decreases. Note that the curves for
wet and dry pavement start off very
close to each other, but reach
different peaks. This means that
gently tapping the brakes is not
enough to tell surface type, and
therefore it is difficult to predict
maximum braking performance
without attempting hard braking.
Dry surface
Force
(g)
Wet surface
Slip (%)
6.3 Surface condition
sensing

Several methods have been attempted to sense
current surface conditions:
•
•
•
•

infrared spectrophotometers, tuned to detect
differences between ice, water, and dry pavement
microphones in the wheel wells listening for water splash
sounds
roadside mini-weather stations with sensors built into
the pavement
careful instrumentation of all wheels of a car, looking for
incipient slip on the driving wheels
None of the methods is completely successful
yet.
Section 6 Questions:
Have you ever encountered “black ice”
that you couldn’t tell was there?
 Calculate stopping distance for the
following parameters:

•
•
•
•
•

Truck with 1.0 sec reaction time and 0.3 g braking
Sedan with 1.0 sec reaction time and 0.7 g braking
Sedan with sleepy driver, 1.5 sec reaction time and 0.7 g
braking
Sedan with poor brakes, 1.0 sec reaction and 0.5 g
braking
Sports car with professional driver, 0.5 sec and 1.0 g
Which factors dominate stopping
7

Reliability
Reliability engineering in intelligent
vehicles is difficult. Several
characteristics of automobiles are much
different than, e.g., aircraft:
 Cost sensitivity: Usual practices that involve triplex
redundancy of critical components may not be
affordable in automobiles.
 Equipment used until end-of-life: In most safetycritical tasks, preventive maintenance schedules call
for replacing electronics before the end of their
design life. In the automotive environment, many
More Reliability
 Operation in uncontrolled environment: Vehicles
operate in harsh environments, with relatively
unskilled and untrained operators.
 Very large scale of deployment: An extremely
improbable event, one that occurs once in 109 hours,
would cause one failure in 73 years in the US
commercial air fleet. That same probability would
cause a failure once every 4.5 days in the US
automotive fleet, due to the much higher number of
vehicles. Even though the risk to a passenger might
be the same in both cases, the public perception of
risk could be much higher for cars.
7.1 Redundancy



Duplex redundancy refers to having two copies
of a subsystem (e.g. computer). If a failure is
detected in one system, the other can be used.
Triplex redundancy has three copies. for
computers, the output of all three can be
compared, and the majority wins; this provides
automatic detection and correction of single
errors.
Heterogeneous redundancy refers to doing the
same function with different means. For
instance, if a steering actuator fails on an
automated vehicle, some steering authority is
available by differentially applying the right or
7.2 System-level solutions
 System
level solutions build safety
into the system by considering the
entire system. In automated
highways, the California PATH
approach of Platoons is designed to
mitigate the effects of an (unlikely)
crash by having vehicles so closely
spaced that any collision would be
at a small relative velocity.
Questions:
 How
reliable is your car? Your
computer? Would you trust your life
to them?
 Describe heterogeneous redundancy,
and give an example.
8
Emerging technologies
A number of other technologies are being
developed that will support intelligent
vehicles.
 Some, such as electronic controls, are
being developed for other purposes (e.g.
handling), but will be useful for
intelligent vehicles.
 As drivers become more accustomed to
electronics in vehicles, prices will fall,
consumer acceptance will increase, and
the pace of adoption of new technology

8.1 Control



Current IVI applications are focused on driver
assistance rather than vehicle control;
nevertheless, partial and full automation will
eventually be important.
A wide variety of standard and advanced
controls techniques are being applied to road
vehicles
Vehicles to date have been designed for human
control, not automated control. For example,
current steering system geometry is designed
for “good handling”, i.e. predictable response
for humans. The underlying hardware may need
to be modified for optimal automatic control.
Difficulties

Automated control is especially difficult in some
situations:

Emergency maneuvers: Control systems optimized for
smooth performance at cruise will not work for abrupt
maneuvers in emergency situations.

Equipment failure: Special controllers need to be
designed to cope with tire blowout or loss of power
brakes or power steering.

Heavy vehicles: The load, and the distribution of the
load, vary much more for a heavy truck than for a
passenger car. Truck controllers need to be much more
adaptable than light vehicle controllers.
More Difficulties

Low speeds: Engine and transmission dynamics are
hardest to model at slow speeds. Applications such as
automated snow plows or semi-automated busses will
require careful throttle control design.

Low-friction surfaces: As addressed above, it is difficult
to predict the effective coefficient of friction on a
particular road surface. This affects not only braking
performance but also the design of throttle and steering
controllers.
8.2 Actuation



Full or partial automation will require actuators,
i.e. computer-controlled motors that can move
the throttle, brake, and steering.
The state of the art is rapidly improving:
vehicles are available on the market with
electronic fuel injection, electronic power
steering, and electronic power brakes, all driven
by performance and weight improvements for
manually-driven cars. This makes it much easier
to add computer control.
Special-purpose actuators will still be needed in
some applications, such as quick-response
throttles for closely-spaced platoons of cars.
8.3 Driver condition
 It
is important to assess driver
alertness, both in a drowsy driver
warning system, and in an
automated system that is preparing
to return control to the driver.
 Alertness can be sensed indirectly,
by watching lane-keeping
performance; or directly, by
watching for eye blink rate and
Perclose
Measuring percentage of
time eyes are closed. This
system illuminates the face
with two IR wavelengths,
one of which reflects from
the retina. Subtracting the
images will create a blank
image (if the eyes are
closed) or an image with
two bright spots (if the
eyes are open).
Top left: image with retinal
reflections
Top right: no retinal reflections
Bottom left: difference image, note
two bright dots for reflections
8.4 Communications




Infrastructure-based ITS projects are building roadwayto-vehicle communications for traffic and routing
information.
Dedicated Short Range Communication (DSRC) is being
developed for warning of local conditions, such as ice,
sharp curves, changes in speed limit, or stopped traffic
out of sight around a bend.
Vehicle-vehicle communications will be increasingly
important for collision warning systems. The lead vehicle
can communicate speed, braking, intent to change lanes,
traffic status ahead, etc.
In the platoon version of full automation, vehicles need to
communicate with low latency, e.g. 20 times / second.
This creates interesting research questions on creating
local nets, on managing both inter- and intra-platoon
Communications
Technologies
Most communications schemes rely on
radio, using a variety of bands.
 Schemes currently under research
include:

•
•
•
modulating the radar reflectivity of a surface, so radarequipped trailing vehicles can get information as well as
range
powering a transponder with radar energy, again to
communicate to a following radar-equipped vehicle
modulating LED brake lights so trailing vehicles equipped
with detectors tuned to that particular wavelength can
pick up information
Section 8 Questions:
 What
makes vehicle control
difficult?
 What makes communications
difficult?
9 Sensor-friendly
roadways and vehicles
On-board sensing would work better if
the environment were designed for
sensing.
 Current roadways have significant
variability (Bott’s dots, painted lines,
thermoplastic stripes, etc).
 Current roadways have many objects
that cause radar “clutter” (returns from
objects that are not of interest), such
as guard rails, roadside signs, bridge
overpasses

9.2 Path prediction
“Path Prediction” refers to estimating
where the vehicle’s current lane goes, so
an obstacle detection system knows
where to look for stopped cars and other
obstructions.
 Sensor friendly systems will improve path
prediction by enhancing lane visibility.
 They will also improve obstacle detection
by reducing clutter from off-road
objects and increasing returns from
other vehicles.

9.1 Dealing with clutter

Clutter can be:
 Moved: Sign posts could be placed farther from the travel
lanes.
 Masked: Radar Absorbing Material (RAM) could be applied to
objects such as bridge abutments
 Marked: Polarizing reflectors, or filters that absorb only a
narrow frequency band, could be applied to large objects. They
would then still appear in a radar return, but would be marked
in the radar signal as known fixed objects
 Mapped: The locations and signatures of fixed objects could be
stored in a map, and provided to individual vehicles.
Sensor-Friendly Features
 Besides
clutter suppression, sensorfriendly systems can improve
visibility:
•
•
Lane markings can be improved with
pigments that reflect radar or nearvisible wavelengths
Vehicle visibility can be improved with
radar reflectors, either fixed or
modulated for communications
Microstrip patch
retroreflector antenna

Without a stable aiming
point, radar-based vehicle
tracking is difficult. Lead
vehicle appears to wander • OSU patch retro-reflector
provides a distinctive,
wideband, vehicle marker.
Compact form factor is easily
attached to vehicles.
• Angle-invariant return provides
aim-point stability.
• Wide bandwidth permits good
range resolution.
Freq. [GHz]
Angle
Section 9 Questions:
 List
four ways of handling clutter.
 How can sensor-friendly features
help with the path prediction
problem?
10 Comments and
conclusions



Many of these technologies work best in
combination: e.g. lane tracking aids both lane
departure and rear-end warnings.
Many of these work best with some
infrastructure assistance: e.g. lane departure
systems need at least good road delineation,
and can take advantage of better markings.
In many cases, the technology is approaching
readiness; the remaining obstacles to
deployment are legal and institutional.
Acknowledgements


My thanks to the CMU Navlab group, and the Automated
Highways Tech Team. Much of the research described
here was supported by NHTSA and FHWA.
Photo credits: thanks to Liang Zhao (stereo), Todd
Williamson (stereo), Richard Grace (perclose), Gerald
Stone and California PATH (magnets and snowplow), Bill
Stone and California PATH (platoon), Colin Ashmore
(buried wire), Umit Ozguner, Jon Young, and Brian A.
Baertlein (radar reflective surfaces and microstip
antenna), K2T Inc (ladar), Dirk Langer (radar), Parag
Batavia (driver differences chart), Assistware
Technologies (vision system) and Todd Jochem (bus). All
pictures copyright by their owners; reproduced by
permission.
UNIT-V-Vehicle network systems
A primary purpose of automotive networked systems is
to reduce the amount of wire that is used.
15 kg of wire can be eliminated by the use of
networking on a single vehicle
For example, systems such as traction control and engine
management that make use of the engine speed sensor can make
use of a single engine speed sensor by placing the reading on the
data bus as required (i.e. the sensor is multiplexed), instead of
having a separate sensor for each system. Similar economies are
possible with a range of systems and this can result in a reduction in
the total number of sensors on a vehicle.
THE PRINCIPLE OF A BUS-BASED VEHICLE SYSTEM
There are several areas of vehicle control where data buses can be used
to advantage. Some of these, such as lighting and instrumentation
systems, can operate at fairly low speeds of data transfer, e.g. 1000 bits
per second. Others such as engine and transmission control require
much higher speeds, probably 250 000 bits per second, and these are
said to operate in ‘real time’. To cater for these differing requirements
the Society of Automotive Engineers (SAE) recommends three classes
known as Class A, Class B and Class C.
•Class A. Low speed data transmission, up to 10 000 bits/s,
used for body wiring such as exterior lamps etc.
•Class B. Medium speed data transmission, 10 000 bits/s up to
125 000 bits/s, used for vehicle speed controls,
instrumentation, emission control etc.
•Class C. High speed (real time) data transmission, 125 000
bits/s up to 1 000 000 bits/s (or more), used for brake by wire,
traction and stability control etc.
The system comprises four subsystems.
1. The Lucas EPIC (Electronically-programmed injection control ) system.
2. The Lucas flow valve anti-lock braking system.
3. A clutch management system (CMS). This replaces the normal clutch pedal linkage
with a computer controlled, hydraulically actuated system.
4. Adjustable rate dampers are fitted. The damping rate is adjusted by the computer
(ECM) to provide optimum damping during rapid steering input, braking and
acceleration.
Master controller
Each of the above systems has a CAN interface, which permits them to be
connected to the master controller. A network of twisted pair cables connects each of
the above subsystems to the master controller and this allows the transfer of sensor
information and control signals with reliable safety checking and minimal wiring. The
master controller thus receives information from the subsystems via the CAN bus
(cables).
The master controller is directly connected to a switch pack (for cruise and
damper control), two accelerometers and an inclinometer (for hill detection). This
means that the master controller ‘knows’ the complete status of the vehicle and the
driver’s requirements. The vehicle status information is processed by the master
controller to generate control signals which are sent to the subsystems. These
“Master” signals over-ride the normal operation of the subsystems to operate another
tier of systems known as the integrated systems. In the event of CAN failure, each
subsystem defaults to stand-alone operation.
The integrated systems
The four subsystems, i.e. EPIC, ABS, damper control and
clutch management, are integrated (made to work together) to
provide seven additional functions of vehicle management.
The computer programs that do this controlling are executed
by the master controller. These seven integrated systems are:
1. traction and stability control
2. cruise control
3. power shift
4. engine drag control
5. hill hold
6. damper control
7. centralized diagnostics.
These use one or more serial networks to
achieve the following objectives:
• Reduction of the number of wires within the wiring looms
of a vehicle;
• Improved system failure diagnosis;
• Distributed control centers in or off the vehicle which can
talk and interact with one another;
• Improved manufacturing techniques and increased
reliability due to a reduction in the number of wires and
connectors
GLOBAL POSITIONING SYSTEM (GPS)
Three Segments of the GPS
Space Segment
User Segment
Control Segment
Ground
Antennas
Master Station
Monitor Stations
1.Space Segment:
The space segment of GPS consists of 24 satellites fielded in nearly circular orbits with a radius of 26,560 km,
period of nearly 12 hours and stationary ground tracks. The satellites are arranged in six orbital planes
inclined at 55° relative to the equatorial plane, with four satellites distributed in each orbit. With this
constellation, almost all users with a clear view of the sky have a minimum of four satellites in view. Each
satellite receives and stores information from the control segment; maintain very accurate time through on
board precise atomic clocks.
2. Control Segment:
The control segment of GPS consists of five tracking stations distributed around the earth of which one,
located in Colorado Springs, is a Master Control Station. The control segment tracks all satellites, ensures
they are operating properly and computes their position in space. The computed positions of the satellites
are used to predict where the satellite will be later in time. These parameters are uploaded from the control
segment to the satellites and referred to as broadcast ephemeredes.
3.User Segment:
The GPS user segment consists of the GPS receivers and the user community. Almost all GPS tracking
equipment have the same basic components: an antenna, an RF (Radio Frequency) sections a
microprocessor, a control and display unit (CDU), recording device and a power supply. Usually all
component, with the exception of the antenna, are grouped together and referred to as a receiver. GPS
receivers convert SV signals into position, velocity, and time estimates. Four satellites are required to
compute the four dimensions of X, Y, Z (position) and time. GPS receivers are used for navigation,
positioning, time dissemination, and other research.
4.GPS Signals:
Each GPS satellite continuously broadcasts ranging signals containing wealth of information. The information
contained in GPS signals includes the carrier frequencies (L1 & L2), codes (coarse acquisition [C/A] & Precise
[P]) and the navigational message. These allow users to measure their pseudo ranges and to estimate their
positions in passive, listen only mode.
The basic principle of determining the position by using GPS satellites is based on measurement of distances
from the point of observations to the satellite. This is done by comparing the reading of transmitter antenna
time with the receiver antenna time. It cannot be assumed that the two clocks will be strictly in
synchronization since the clocks used in the present type of receivers are quartz clocks to reduce the cost of
the receiver. The observed signal time will have a systematic synchronization error. Since the measured
range has got this systematic error in it, the computed distances will also be biased, and therefore, these are
called pseudo-range. To compute the position based on this pseudo-range, the error due to time bias has to
be corrected and therefore, this is also taken as an unknown and determined before deriving the true range.
As we know from the simple formulate of distance computation that
R = Ö ((X – Xi) 2 + (Y –Yi) 2 + (Z –Zi)) 2
Where X, Y & Z are the co-ordinate of the station, therefore unknown and Xi, Yi & Zi are
the co-ordinates of the satellite, which is broadcast information.
To find the true range the time bias t is also has to be considering,
therefore
R = ((X – Xi) 2 + (Y –Yi) 2 + (Z –Zi)) 2 + TC
Where C is the velocity of light, R is pseudo-range and T is travel time.
Now in this equation, there are four unknown therefore, to solve this at
least 4 satellites will have to be observed. The minimum requirement in
this case is
1.To know the co-ordinates of satellite antenna
GPS APPLICATIONS:
MOVING BEYOND AUTOMATIC VEHICLE
LOCATION TO
FULL ENTERPRISE
INTEGRATION
1.Location Verification
2.Route Analysis
3.Mobile Navigation
Vehicle Navigation System (VNS)
A Vehicle Navigation System (VNS) is a driving assist
system that combines digital maps, vehicle position, route
optimization, route guidance, and other technologies.
It is one of the most important components of advanced
traffic and traveler information systems in Intelligent
Transportation Systems (ITS) and is an important application
and research field in Geographic Information Systems for
Transportation (GIS-T).
A Framework for
Network based VNS
A framework for network
based VNS is illustrated in
Figure. Four components are
encompassed in the proposed
framework, namely, the content
supported layer, the service
center, the communication layer,
and navigation terminals.
1)
2)
3)
4)
The Content Supported
Layer
The Service Center
The Communication Layer
Navigation Terminals
The integration of traffic information and road network
ROAD INFORMATION – FIXED SENSORS NETWORK
MESSAGE – Mobile Environmental
Sensing System Across a Grid Environment





Heterogeneous fixed and
mobile sensors on
infrastructure, vehicles and
people
Sensors communicate via
wireless and wired networks
Positioning via GPS +
wireless ranging
Integration of processing
along the data path
Multiple application studies
in different local contexts
Camden Town, London
Processing
Sensor Network for Traffic Accident Detection and
Notification
Designing a sensor network that will inform incoming vehicles of
these accidents/congestions well in advance so that the drivers of
the vehicles may take appropriate actions.
Present traffic monitoring systems use expensive devices such as
video cameras, magnetic loop detectors that are expensive,
difficult to deploy and not very scalable
Vehicular network solutions differ greatly in their design,
protocol and implementation. As such a vehicle that uses one
vehicular solution will not be able to communicate with other
vehicles along the road unless they all implement the same
solution. This can be a very grave problem
Challenges



Sensors are very resource-constrained:
computation.
- minimizes resource consumption.
power,
memory,
Vehicles on highways usually travel at high speeds between 65 to
70 mph. They need to be informed of the accident/congestion up
ahead as quickly as possible before it is too late.
- designed to sense accidents as soon as they occur and
communicate this information to the rest of the relevant network
very quickly.
Users are often unwilling to learn (or just plain lazy) how to use
new systems.
- requires minimal interaction with the user and will be
perceived as very uncomplicated by the user
Sensor Network for Traffic Accident Detection and
Notification
1. It integrates an ad-hoc sensor network with a
vehicular network to create an effective, energyefficient traffic accident detection and notification
system without all of the problems mentioned above.
2. BY introduce the new concept of Virtual Group and
Watchdog Group of sensors that will track the motion
of a car and will greatly increase the reliability of
the network while decreasing the energy-consumption
of the sensors.

Sensors placed along-side highway roads will detect a
traffic accident and will communicate this message to
sensors further down the road, which will in turn
notify incoming vehicles of the accident up-ahead.
Assumptions:
1. Highways
2. Unidirectional traffic
3. Vehicles are equipped with bi-directional radios that
can do two things:
i. Transmit alarm message when accident occurs.
ii. Receive notification of accident broadcast by
sensor.
1. Watchdog Groups: Sensors are divided
into groups of n each, say three sensors S1,
S2 and S3. When there is no traffic on the
highway, in each group one sensor (S1) will
be on for a certain fixed period of time
while the other two (S2 and S3) remain off.
After this fixed period S2 will wake up and
S1 and S3 will sleep and so on. Synchronized
timers will be used to control the
sleep/wake cycle of sensors in each group.
Watchdog Group
n=3
asleep
awake
asleep
awake
Watchd
og
group 1
awake
asleep
awake
asleep
asleep
awake
Watchd
og
group 2
asleep
awake
2. Virtual Groups: Sensors are again
divided into groups of n each. But in this
case, the group is not “fixed” but rather
“moves” along the highway following the
motion of the vehicle being sensed.
Virtual Group
n=3
Virtual
Group
 Normal
Operation:
- Car approaches junction.
- Special sensor (always on) at junction
detects car, alerts closest neighboring
sensor, S1.
- S1 will alert S2, S2 will alert S3. Now
S1, S2 and S3 will be awake (Virtual
Group 1).
Normal Operation
Virtual
group
Special
Sensor
Accident Occurs:
-
-
Detection of accident: Air-bag trigger in cars that
detects the accident will trigger the car radio to
broadcast accident alarm message.
uses air-bag triggers because:
i. It provides greater accuracy in detecting actual
accidents and not just false alarms.
ii. It simplifies the work of the sensors (lesser
sensing, lesser computation).
ii. Air-bag triggers are already present in vehicles;
does not require additional add-ons.
-
The sensor closest to the car that receives the alarm
message will wake up the sensors behind it (if they are
already not awake).
-
The sensor will then broadcast an Event Notification
message with the TTL field set to a fixed value so
that the message does not propagate further than is
Case Accident
Special Cases
1. Very long stretch of highway with no exits:
- Accident occurs.
- Vehicle must be informed before it leaves all exits
behind.
- To relay message from one sensor to next until it
reaches car will be too slow.
- Use access point to convey message directly to
sensor closest to next-to-last exit (as far in
advance as feasible).
- Sensor will inform vehicle before it reaches last
exit and looses all chances to re-route.
Very long stretch of road
w/no exit
Long stretch of road
with no exit
Special Cases contd.
2. Backup Case - In case of sensor
failure:
- Normally sensors communicate with
each other on a per-hop basis.
- If a sensor goes down, its immediately
neighboring sensors on both sides will
increase their sensing and
communication range.
- The increase in power consumption is a
Backup Case
n=3