Electrical and Computer Engineering

12/07/06

DSRC Accident Warning System at

IntersectionRicha Prasad ● Raza Kanjee ● Hui Zhu ● Thai Nguyen

Professor Prishro-NikAdvisor, Assistant Professor, ECE

Professor NiAdvisor, Assistant Professor, CEE

Team Pishro-Nik & Ni

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12/07/06

Content• Introduction

• The Design

• Deliverables

• System Block Diagram

• MDR Specifications

• Spec 1 – Latency Calculations

• Spec 2 – Transceiver

• Spec 3 – Traffic Light

• Power Specifications

• Product Cost

• PDR I Questions

• Summary

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12/07/06

Introduction

These situations at intersections represent about:

• 65% of injury accidents

• 70% of fatal accidents

Annual fatality rate > 40,000 for more than 30 years

© P

ReV

EN

T

Straight Crossing:

• 203,000 PAR crashes

• 200,000 non-PAR crashes

• Injury, casualty, traffic delay,

economic loss

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The DesignVII DSRC

• Vehicle Infrastructure Integration

Entertainment

Safety

Traffic

Routing

Weather

Tutor • Dedicated Short Range Communication

• 5.9 GHz Frequency Band

• Allocated for VII

• IEEE Standard: 802.11p

Path Suggestion

Speed Suggestion

Pedestrian Warning

Traffic Management

© P

ReV

EN

T

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DeliverablesRSU is

warned of traffic light turning red

Message sent to red car asking for speed

and position

OBU sends back speed and location

RSU calculates

whether red car will run

red light

If yes, blue car warned

1

2

3

4

GOALS

• Real-life demonstration

• Running light warning only

• Simulation of two cars – one moving, one at light

• Technical Documentation

© PReVENT © PReVENT

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System Block Diagram

Traffic Light

RSU

Speeding Car

Waiting Car

5 V Power Supply

External Clock

Simulated on Microcontroller

OBU

GPS

OBU

Laptop

TransceiverInformation Signal

Control Signal

Power Supply

SpeedLocation

Log dataTransfer

Do Nothing

Calculate if car will run

red light

Traffic light turning red?

No

Yes Alarm signal

Alarm signal

Laptop

Transceiver

Laptop

Transceiver

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12/07/06

System Block Diagram

Traffic Light

RSU

Speeding Car

Waiting Car

5 V Power Supply

External Clock

Simulated on Microcontroller

OBU

GPS

OBU

Laptop

Transceiver

Laptop

Transceiver

Laptop

Transceiver

Not Complete

Complete

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MDR SpecificationsAIM

• Changing conditions recognized by laptop

• Display of changing conditions on Bar LEDTraffic Light

• Hardware Simulation of traffic light

• Data communicated = random && != GPS

• Two-way communication between laptopsTransceiver

• Wireless connection between Bridge & AP

• Background for Accident Conditions

• Determination of car running red lightLatency

Calculations

• Distance for Vehicle Warning

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12/07/06

Spec 1 – Latency CalculationsMODEL SCENARIO

Car approaching intersection

Car waiting at intersection

If red car running light; both cars warned

Aim:

• Speeding Car – Emergency Braking

• Other cars warned; caution

Signalized Intersection, Straight Crossing Path

(SI/SCP)

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Spec 1 - Latency CalculationsBACKGROUND OF ACCIDENTS

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

0-5 6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 46-50 51-55 56+

Snowy or Icy 2%

Wet Pavement 19%

Dry 79% No Adverse Weather

66%

Rain 12% Snow/Sleet 12%

Daylight 72%

Dark, Lighted

22%

Dark, Unlighted

3%

Dawn/Dusk 3%

Travel Velocity (mph)

SI/SC

P C

rash

Occ

urr

ence

SI/SCP Crash Occurrence due to Pavement Condition

SI/SCP Crash Occurrence due to Ambient Weather Condition

SI/SCP Crash Occurrence due to Ambient Light Condition

Driver Inattention

36.4%

Failed to Obey Signal 23.2%

Tried to beat Signal 16.2%

Driver Intoxication

12.9%

Other 5.9%

Vision Obstructed 4.3% Vehicle Defect 1.9%

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Spec 1 – Latency CalculationsWARNING SYSTEM

Green Light?Start

Amber Light?

Red Light?

Car can clear?

Warning

No Action

No

No

No

No

Yes

Yes

Yes

Yes

Factors

• Travel Speed

• Duration of amber light

• Level of braking

• Driver + machine delays

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Spec 1 - Latency CalculationsROAD CALCULATIONS

SV

Car

B

SV

DczDilemma Zone

Dstop W

L

• Dcz = Clearance ZoneCar can cross easily. Safe passing guaranteed

• Dilemma Zone Car can’t stop on time; can’t cross safely• Dstop Distance required to come to a stop• L = length of car• W = width of intersection• SV = Subject Vehicle• Vsv = Velocity of Subject Vehicle• a = deceleration rate• trm + tmd = time delay due to human + machine

Distance traveled in time left before

red light

Length of Car

Width of IntersectionDcz = - -

svMDRTsv

stop vtta

vD )(

2

2

WLtvD ambersvcz

Distance for car to stop

Human + Machine DelayDstop = +

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Spec 1 - Latency CalculationsROAD CALCULATIONS

0

50

100

150

200

250

300

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Dcz30 Dcz25 Dcz20 Dcz15 Dcz10 Dcz5 Speed (kph)

Dcz

(m

)

Dcz at different speeds with different amounts of time left before red light

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Spec 1 - Latency CalculationsROAD CALCULATIONS

In Dcz?

a = + or 0?

Calculate deceleration for v =0 at stop line

Comfortable range?

Time to reach stop line

Calculate Dstop

Dstop < Dloc

Warning

ts < tg

30s to Red

No Action

ts = time to reach stop line

tg = time for light to turn green

Dloc = distance from stop line

Yes

Yes

Yes

Yes

No

No

Yes

No

No

No

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Spec 1 - Latency CalculationsSYSTEM LATENCIES

Traffic Light

Laptop

Transceiver

GPS

Laptop

Transceiver

R

S

U

O

B

U

Almost Immediate Almost Immediate

Almost ImmediateAlmost Immediate

• 2400 baud = 19200 bps

• Longitude + Latitude + Speed Info = 12 bytes = 96 bits

• GPS Update = every 0.5s

• Size sent = 192 bps

• Available versus Used = 100:1

• Human + Machine Delay = 2.0s

• Comfortable deceleration = 0 to 3 m/s 2

• Status Messages: > 30s for red light

• Event Messages: < 30s for red light

1. Status Messages: RSU Laptop logs and saves data

2. Event Messages: RSU performs calculations 3. Status Messages: ALL calculations and data saved

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Spec 2 - TransceiverSPECIFICATIONS

• Airbornedirect Serial Bridge

• RS232 Serial Communication

• 802.11b/g Compliant

• 5 VDC External Supply

CONNECTIVITY

12 VDC

Ethernet

5 VDC

Serial

RSU OBU

Access Point

Bridge

802.11g

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Spec 2 - TransceiverOUTPUT

OBU

RSU

Video Available on Request!

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Spec 3 – Traffic LightSET UP

Bar LED Traffic Light

Power is on

Microprocessor programmed with traffic light code

Maxim chip – TTL to RS232 and vice versa

External Clock

JTAG programmer

Indicator of data transfer

Powered by USB

• Green to Warning – 60 s

• Warning to Yellow – 25 s

• Yellow to Red – 5 s

• Green to Red – 90 s

Warning – 30 s

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Spec 3 – Traffic LightSPECIFICATIONS

SV

Car

B

SV

DczDilemma Zone

Dstop W

L

Dilemma Zone

• Subject Vehicle cannot cross safely before red light

• Subject Vehicle cannot stop safely at stop line

Aim

• Reduce Dilemma Zone

Gazis et. Al:sv

svyDesignDelarDesignAmbe v

LW

a

Vtt

2Posted Speed Limit

tam

ber

5 s

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Spec 3 – Traffic LightSCHEMATIC

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Spec 3 – Traffic LightOUTPUT

Warning sent 30s before light turns red

Video Available on Request!

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Power Specifications

USB Cable

• USB provides 5 VDC

Powers:

- GPS

- Airbornedirect Bridge

- Traffic Light

• Laptop – self-powered

• Wireless Access Point – 12 VDC

• Solution – 5V to 12V Booster Circuit

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12/07/06

Product Cost

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12/07/06

PDR I Questions1. We can adjust the traffic light to prevent collisions. So why do we need the

system?

• System too dynamic, unreliable.

• Predictability of traffic lights lost

2. Elevation on highway. How check if signal received by RSU is from OBU on same highway at which RSU is located?

• GPS provides altitude data

• If RSU altitude != OBU altitude; ignore signal

3. Losing connection with GPS. Solution?

• OBD II Implementation

• DGPS prevents full loss of connection with GPS

4. Urban setting – Accuracy and loss of connection with GPS

• OBD II Implementation

• Video cameras, laser sensors

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PDR I Questions5. Plan for testing equipment?

• Step 1 – Test in Lab

• Step 2 – Test in field

6. Performance of project under different road and weather conditions?

• Specification 1 – Latency Calculations

• Majority of accidents – normal conditions

7. Theoretical Latency Measurements?

• Specification 1 – Latency Calculations

• Step 3 – Record all data in field

• Step 4 – Debug and test further in lab

8. Vehicle not on road approaching intersection?

• Specify road width

• If collision predicted, should warn regardless

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12/07/06

Summary

Traffic Light3

Transceiver2

Latency Calculations1

1. Traffic Light

2. Transceiver Communication

3. Latency Calculations

4. a. GPS-Laptop Communication

b. GPS data reception by RSU Laptop

5. RSU Laptop Road Calculation Algorithm

CHECKLIST

MDR SPECIFICATIONS