smart emergency preemption system employing gps and fpga

SMART EMERGENCY PREEMPTION SYSTEM

EMPLOYING GPS AND FPGA

MORAALI

FACULTY OF COMPUTER SCIENCE AND

INFORMATION TECHNOLOGY UNIVERSITY OF MALAYA

KUALA LUMPUR

APRIL 2011

SMART EMERGENCY PREEMPTION SYSTEM

EMPLOYING GPS AND FPGA

MORAALI

DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR

THE DEGREE OF MASTER OF COMPUTER SCIENCE

FACULTY OF COMPUTER SCIENCE AND INFORMATION TECHNOLOGY

UNIVERSITY OF MALAYA KUALA LUMPUR

APRIL 2011

ABSTRACT

Emergency Vehicle Preemption (EVP) is a system that intervenes in the normal

operation of traffic control systems to grant emergency vehicles to pass through.

Conventional EVP relies on short range signals such as light, sound or radio wave

signals to interrupt the normal traffic light cycle to green. A higher response time is

expected when the blockage ahead is not preempted due to this short range signals

transmitted by the emergency vehicle. A short range signals only able to trigger one

traffic light intersection. In this thesis, Smart Emergency Vehicle Preemption system

(SEVP) is proposed to overcome these drawbacks by granting green lights to more than

one intersection within the distance or threshold set. Positioning technique and A-star

(A*) shortest path algorithm is used in the proposed system to permit the system to

control and to calibrate road traffic light systems using wireless communications

installed on emergency vehicles and traffic intersections. The system works by

installing tracking device on emergency vehicle and a modification on the traffic light

controller. For tracking purpose, FPGA embedded with Xilinx Microblaze soft

processor core and SIM 508 GPS/GSM modem is used. The FPGA will filter

unnecessary GPS data to get the current latitude and longitude of the emergency

vehicle. Then, the filtered data is transmitted via GSM modem. The current position of

the emergency vehicle and the position of emergency scene are then used by the centre

to calculate and find the shortest path route to destination. The centre will send interrupt

command to traffic controllers within the selected route and distance threshold set to

clear the cluttered traffic in front. The interrupt value is used to trigger the particular

traffic light to green and trigger the other traffic lights at the junction to be red. The

traffic light controller is then calibrated to normal mode after the emergency vehicle

passed each traffic light intersection. The ability to preempt ahead before emergency

vehicle approach traffic intersection significantly improves emergency vehicle response

time.

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ABSTRAK

Sistem Kenderaan Kecemasan Didahulukan (Emergency Vehicle Preemption (EVP))

adalah sebuah sistem yang mengawal operasi lalu lintas dengan memberikan laluan

kepada kenderaan kecemasan. EVP konvensional bergantung pada isyarat jarak pendek

seperti isyarat cahaya, bunyi atau isyarat gelombang radio untuk menyela kitaran lampu

lalu lintas kepada isyarat hijau. Oleh kerana isyarat dihantar kenderaan kecemasan

adalah dalam jarak yang pendek, kesesakan lalu lintas di hadapan tidak dapat dileraikan

ketika kecemasan. Isyarat jarak pendek hanya mampu mengawal lampu isyarat di satu

persimpangan lampu lalu lintas sahaja. Dalam tesis ini, Sistem Kenderaan Kecemasan

Didahulukan Pintar (Smart Emergency Vehicle Preemption (SEVP)) dicadangkan untuk

mengatasi kelemahan ini dengan memberikan isyarat hijau untuk lebih dari satu

persimpangan dalam jarak yang dihadkan. Teknik posisi dan algoritma A-star (A*)

untuk penghitungan jarak yang terpendek digunakan dalam sistem ini supaya operasi

pengawalan dan kalibrasi lampu lalu lintas dapat dilaksanakan dengan menggunakan

komunikasi wayarles yang dipasang pada kenderaan kecemasan dan pada persimpangan

lalu lintas. Sistem ini befungsi dengan cara peranti penjejakan (tracking device)

dipasang pada kenderaan kecemasan dan pengubahsuaian pada kontroler lampu lalu

lintas. Untuk menjejak, FPGA diprogramkan dengan soft processor core Xilinx

Microblaze dan SIM 508 GPS / GSM modem digunakan. FPGA akan menapis data

yang tidak perlukan oleh GPS untuk mendapatkan kedudukan garis lintang dan bujur

kenderaan kecemasan. Kemudian, data yang ditapis ini akan dihantar melalui modem

GSM. Kedudukan tempat kecemasan kemudian digunakan oleh pusat kawalan untuk

mengira dan mencari laluan jalan terpendek ke arah tempat tujuan. Pusat kawalan akan

menghantar arahan sampukan ke kontroler lalu lintas untuk memberi laluan kepada

jalan yang dipilih dalam batas jarak tertentu untuk meringankan lalu lintas di hadapan.

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Nilai sampukan digunakan untuk menyalakan lampu lalu lintas tertentu kepada hijau

dan menyalakan merah kepada lampu lalu lintas yang lain. Selepas kenderaan

kecemasan melewati setiap persimpangan lampu lalu lintas, kontroler lampu lalu lintas

ini akan dikalibrasikan kepada operasi asal. Kemampuan untuk mendahului kendaraan

di depan sebelum kenderaan kecemasan mendekati persimpangan lalu lintas boleh

meningkatkan waktu respon.

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ACKNOWLEDGEMENT

My upmost gratitude goes to my supervisors, Mr Mohd Yamani Idna Idris and Mr

Emran Bin Mohd Tamil for their endless guide in completing my thesis project. I also

thank the rest of System On Chip (SOC) group members including the lectures for their

moral support. Finally, I would like to take this opportunity to express my deepest

appreciation to my father, S.Sivalingam for supporting financially for my postgraduate

studies.

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TABLE OF CONTENTS

ABSTRACT vi

ABSTRAK vi

ACKNOWLEDGEMENT vi

TABLE OF CONTENT vi

LIST OF FIGURES vi

LIST OF TABLES xvii

LIST OF ABBREVIATIONS xx

CHAPTER 1: INTRODUCTION

1.0 Introduction 1

1.1 Project Objective 1

1.2 Project Scope 2

1.3 Thesis Arrangement 3

CHAPTER 2: LITERATURE REVIEW

2.1 Traffic Light System 5

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2.2 Preemption System 11

2.2.1 Decentralized System 11

2.2.1.1 Loop based system 12

2.2.1.2 Light based system 16

2.2.1.3 Radio based system 17

2.2.1.4 Sound based system 18

2.2.2 Centralized System 18

2.2.2.1 Vehicle information System 19

2.2.2.2 Path finding system 22

2.2.2.3 Collision Avoidance System 25

2.2.2.4 Multi Agent System 26

2.3 Conclusion 29

CHAPTER 3: RESEARCH METHODOLOGY

3.0 Introduction 32

3.1 Proposed Methodology 32

3.1.1 Requirement 33

3.1.2 Design 34

3.1.3 Development 35

3.2.4 Prototyping 36

3.2. 5 Testing 37

3.2.6 Maintenance 37

3.2 Conclusion 38

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CHAPTER 4: PROBLEM VERIFICATION AND SYSTEM DESIGN

4.0 Introduction 39

4.1 Real Time Traffic intersection Analysis 40

4.1.1 Perceiving Intersection Characteristic 42

4.1.1.1 Intersections 42

4.1.1.1.1 “Bird Eye” View 42

4.1.1.1.2 Time/Traffic Light Table 43

4.1.1.1.3 Intersection Phasing Diagram 44

4.1.2 Identifying Intersection Problem 45

4.1.2.1 Cluttered Intersection Problem 45

4.1.2.2 Alternative Route Problem 48

4.1.2.2.1 Shortest Path Discovery Problem 48

4.1.2.2.2 Incorrect Path Selection 50

4.2 Proposed System 51

4.3 Scenario Example 54

4.4 Conclusion 57

CHAPTER 5: SYSTEM IMPLEMENTATION

5.0 Introduction 58

5.1 Emergency Vehicle Tracking (Module 1) 58

5.1.1 Module 1 Discussion 58

5.1.2 Module 1 Result 64

5.2 Central Control System (Module 2) 72



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5.2.2.1 Interface Design 84

5.2.2.1.1 Main Page 86

5.2.2.1.2 Login 87

5.2.2.1.3 Design 88

5.2.2.1.4 Mapping 95

5.2.2.1.5 Dynamic Map 96

5.2.3 Scenario Example 98

5.3 Traffic Light Controller (Module 3) 100



5.4 Conclusion 122

CHAPTER 6: CONCLUSION 123

REFERENCES 126

APPENDIX : PERCEIVING INTERSECTION CHARACTERISTIC 130

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LIST OF FIGURES

NO TITLE PAGE

Figure 2.1 Real time phase design (Abdullah, 2009) 7

Figure 2.2 Cycle time 7

Figure 2.3 Phase split 8

Figure 2.4 Phase record 8

Figure 2.5 Detector loop (Abdullah, 2009) 12

Figure 2.6 An intersection of the general configuration 13

for a preemption system using existing traffic

loops (Aaron D. Bachelder, 2006b)

Figure 2.7 Schematic block diagram of the system general 14

configuration (Aaron D. Bachelder, 2006b)

Figure 2.8 Light based system (Jeffrey F.Paniati, 2006) 16

Figure 2.9 Radio based system (Park, 2007) 17

Figure 2.10 Sound based system(Jeffrey F.Paniati, 2006) 18

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Figure 2.11 Vehicle information system (Knockeart, 2004) 20

Figure 2.12 A simplified of RHODES operation 23

(Pitu B.Mirchandani 2004)

Figure 2.13 The CAPRI control architecture 24

(Pitu B.Mirchandani 2004)

Figure 2.14 A* path (Yanyan Chen, 2003) 25

Figure 2.15 CPN Model(Lefei Li, 2005) 28

Figure 3.1 Proposed methodologies 33

Figure 4.1 Google map of Petaling Jaya 40

Figure 4.2 Intersections at Petaling Jaya 41

Figure 4.3 Intersection A and intersection B traffic flow 42

diagram

Figure 4.4 Phases of intersection A 44

Figure 4.5 Phases of intersection B 44

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Figure 4.6 Intersection A and Intersection B from Figure 4.2 45

Figure 4.7 Cluttered intersection problem 45

Figure 4.8 Phase for intersection A and B 47

Figure 4.9 Phasing of intersection B 47

Figure 4.10 Blockages from Intersection B to Intersection A 48

Figure 4.11 Routes to University Hospital 49

Figure 4.12 Alternative path using the Intersection F path 50

Figure 4.13 Incorrect lane problem 51

Figure 4.14 Overview of proposed system 52

Figure 4.15 Module process implemented in SEVP 53

Figure 4.16 Smart Emergency Vehicle Preemption System 54

Figure 4.17 System Flow Chart 56

Figure 5.1 Block diagram of vehicle tracking 61

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Figure 5.2 Pseudocode for system module 1 63

Figure 5.3 Emergency vehicle tracking devices 64

Figure 5.4 UART ML401 connection diagram 64

Figure 5.5 UART ML401 datasheet 66

Figure 5.6 Bus Interface 67

Figure 5.7 Intellectual Property address 68

Figure 5.8 Intellectual Property ports 69

Figure 5.9 Block diagram for module 1 70

Figure 5.10 Data Input From GPS receiver 71

Figure 5.11 Filtered data 71

Figure 5.12 Central control system 72

Figure 5.13 Overall DFD 73

Figure 5.14 Specific DFD 74

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Figure 5.15 Specific DFD for Process 2 75

Figure 5.16 Specific DFD for Process 76


Figure 5.18 A* Flow Chart 80

Figure 5.19 A* flow diagram 82

Figure 5.20 Connection of GSM and the PC 83

Figure 5.21 Project design summary 84

Figure 5.22 Main page 86

Figure 5.23 Admin page 87

Figure 5.24 Design page 88

Figure 5.25 Open recent map 89

Figure 5.26 Create a new map 89

Figure 5.27 Select Option 90

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Figure 5.28 Select Main Sensor 91

Figure 5.29 Select Secondary Sensor 92

Figure 5.30 Select Congestion 93

Figure 5.31 Select a name for the map 95

Figure 5.32 Insert the location for the map 96

Figure 5.33 Test the map 97

Figure 5.34 Example Map 98

Figure 5.35 Normal path used 99

Figure 5.36 Assign the congestion level 99

Figure 5.37 Alternative path 100

Figure 5.38 Block diagram of traffic light controller 101

Figure 5.39 Traffic Light controller flow chart 102


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Figure 5.41 Traffic light controller devices 105

Figure 5.42 Expansion header wiring 106

Figure 5.43 Example of four traffic lights at one intersection 107

Figure 5.44 All the traffic lights display AMBER 108

Figure 5.45 RTL Schematics 109

Figure 5.46 RTL Schematics on Top Level 110

Figure 5.47 Details of RTL schematics on system_i 111

Figure 5.48 Block diagram for module 3 112

Figure 5.49 Clock rate division 113

Figure 5.50 ISE clock division 114

Figure 5.51 Illustration clock rate division 115

Figure 5.52 Normal traffic light flow 116

Figure 5.53 Testbench of the traffic lights 121

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LIST OF TABLES

NO TITLE PAGE

Table 2.1 Phase calculation part 1 9

Table 2.2 Phase calculation part 2 9

Table 2.3 Phase calculation overall 10

Table 3.1 Hardware and software tools 36

Table 4.1 Time/Traffic light – Phase for intersection A 43

Table 4.2 Time/Traffic light – Phase for intersection B 43

Table 4.3 Intersection A 46

Table 4.4 Intersection B 46

Table 4.5 Amount of vehicles on certain lane at specific time 49

Table 5.1 GPRMC message form 59

Table 5.2 AT Command send text message for system module 1 71

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Table 5.4 Description of Figure 5.22 86









Table 5.13 The congestion level 99

Table 5.14 Expansion header pin location 107


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Table 5.16 Traffic light flow based on interrupt received 117

xix

LIST OF ABBREVIATION

EV Emergency Vehicle

FPGA Field-Programmable Gate Array

GPS Global Positioning System

GSM Global System for Mobile Communication

SEVP Smart Emergency Vehicle Preemption

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Chapter 1 Introduction

1.0 Introduction

Road congestion, which is caused by the traffic light phase coordination, has

provided difficulties for emergency vehicle to operate in an efficient and effective

manner. As a result, the signal priority is introduced to alleviate the problem. The signal

priority is a method that grants or preempts traffic lights for certain privileged vehicles

to pass through the intersection without waiting.

Emergency vehicle preemption systems have been long initiated by developed

countries. Light, sound or radio preemption systems are examples of decentralized

category. This kind of preemption only operates when it perceives any signal

transmitted by the vehicle. However, this preemption does not perform effectively if the

vehicle is caught in a heavy traffic jam. It is because it unable to trigger for preemption

because of its long distance from the system receiver. Therefore, a centralized type of

preemption is introduced. Centralized type will preempt traffic lights at each

intersection by tracking the vehicle by applying Global Positioning System (GPS) tools.

Inability to detect vehicle in a tunnel or in a flyover are some of the negative aspects of

centralized preemptions system.

The purpose of thesis is to identify the drawbacks of the decentralized as well as

the centralized in order to design an excellent prototype that can alleviate the classified

drawbacks of preemption system for emergency vehicle.

1.1 Project Objective

The project’s main objectives can be divided into four categories, which are:-

1

1. To design Smart Emergency Vehicle Preemption System (SEVP) based on the

existing emergency vehicle preemption drawbacks.

2. To develop a prototype of the designed SEVP.

1.2 Project Scope

The project scope is based on two modules, which are the software and the

hardware section. The software section is focus on the central system. This central

provides only one emergency vehicle at a time an appropriate route to the destination

that consumes less congestion. The administrator has the only privilege to insert and

delete road congestion based on the CCTV observation. The map used in the system is

only small simulated map that has a good scalability.

The hardware section operates in two ways autonomously for the central.

Firstly, it acts solely as a tracking device embedded in the emergency vehicle. With the

help of GPS, it will able to detect the current location of the vehicle. The location

variables will be sent to the central system to calculate the shortest path via Global

System for Mobile Communication (GSM).The second method is by triggering the

traffic lights based on the input receive from the central system through GSM. This

hardware is installed in the traffic light controller. It is very important to ensure proper

traffic lights are being triggered. Therefore a small lab scale traffic light intersection is

designed to provide a vivid of understanding.

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1.3 Thesis Arrangement

Chapter 1 Introduction

An overall background of the thesis, including problem statement, project

objective and research scope are explicated. The thesis organization for this research is

discussed.

Chapter 2 Literature Review

This chapter provides the drawbacks of conventional and current system. In the

discussion section of this chapter explain the reasons for the need to develop a system

that can alleviate the previous drawbacks.

Chapter 3 Methodology

The procedure steps taken based on a standard framework where various

hardware and software apparatus is applied for designing and testing the system is

clarified in detail.

Chapter 4 Problem Verification and System Design

The manageability of flow for traffic light signal at each intersection during

urgent situation in Malaysia is elucidated. It specifies the constraint which affects the

overall traffic light synchronization flow. The system’s idea for a system design is

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explained in form of flow charts, diagrams as well as pseudo codes in this chapter.

Chapter 5 System Implementation

The project’s result based on the techniques elucidated in Chapter 5 is shown

evidently by providing system snapshot.

Chapter 6 Conclusion

The success to satisfy the system project’s objectives, which were discussed in

the Introduction Chapter, is clarified in brief. In addition, extra ideas for future research

improvement and enhancement are provided.

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Chapter 2 Literature Review

Preemption system and traffic system shares common background and are

closely related to each other. To understand preemption system, overall architecture of

traffic system flow should be studied. For that reason, the beginning of this chapter will

present how traffic system works. Following that, various preemption systems including

the conventional and current systems will be reviewed and discussed.

2.1 Traffic Light System

Traffic signals have long been used to regulate the flow of traffic (Schwartz,

2008 ). Traffic lights at each intersection can alter their signal sequence based on

specific phase or stages with this timing mechanism. City intersections are often very

complex in their physical layout and often several intersections are mutually interacting

as heavy traffic flows. Therefore, the traffic light may have many different

configurations (Yang Chen, 2006). In addition, the pattern of traffic flow often varies

during the day.

There are two types of mode operation. The timing for the traffic light is function on

two mechanisms which are:-

• Fixed Time Mode

- It is permanent set by the authority based on the jurisdiction’s Multiplan.

• Vehicle Actuation Mode

- It is automatically function based on the dynamic input of the loop detector.

5

A signal group is a set of RED, AMBER and GEEN light display. This display is

relied on the vehicle direction path movement. There are three types of movements:-

• Through moving vehicles

• Right Turning vehicles

• Left Turning vehicles

Movements are usually group together to permit maximum efficiency of operation a

well as ensuring that the safety of the motorist is not compromised. In short, the

combination movement groups operating together are called as Phase. Phase is also

called as stage. Phase is the period or duration of time given to one set of non-

conflicting traffic streams. It can consist of one or more signal groups. The number of

phases should be kept to a minimum to maximize the use of time. This is to provide

flexibility for Vehicle Actuation Mode. As many movement should be allowed to run in

every phase. This is to increase the time optimization for particular lanes that are not

conflicting. A phase should have preferably consisted of non-conflicting movements.

This is done to avoid undesirable mishaps.

6

Figure 2.1: Real time phase design (Abdullah, 2009) Figure 2.1: Real time phase design (Abdullah, 2009)

The Figure 2.1 depicts a real time phase design. The phase design is shown in

the right corner of the diagram. The phases have its own fix cycle time. The cycle time

is referring to the time taken for all the phases to run once. This is shown in Figure 2.2

based on Figure 2.1.

The Figure 2.1 depicts a real time phase design. The phase design is shown in

the right corner of the diagram. The phases have its own fix cycle time. The cycle time

is referring to the time taken for all the phases to run once. This is shown in Figure 2.2

based on Figure 2.1.

Figure 2.2: Cycle time

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A B and C represent Phase A, Phase B and Phase C respectively. Specific timing

is assigned to each phase based on the timing calculated by the engineers to ensure there

is no any further congestion for each phase. The specific timing of the cycle time can be

shown in Phase Split. Phase Split is the proportion of green time allocated to each

phase, as shown in Figure 2.3.

Figure 2.3: Phase split

Owing to the green time duration, the Phase Split is also called as Green Split.

This phase sequence changes, which does not rely on loop detector input, is referred as

Fixed Time Mode.

PHASE APP MIN INC VIG MAX GAP AMB RED

A 6 70 4 3 2

B 6 30 4 3 2

C 6 30 4 3 1

Figure 2.4: Phase record

The Figure 2.4 display timing phase record in seconds, where:-

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• GREEN light timing actuation is based on MIN,MAX and GAP

• AMBER light timing actuation is based on AMB

• RED light timing actuation is based on RED

RED and AMBER light timing actuation is a normal operation. The GREEN

light timing actuation is very important to discuss. MIN actually represents the least

time needed for the traffic light intersection to be in GREEN, based on the specified

phases. After the MIN duration, the controller will provide another GAP period to

detect whether there is still vehicle on the loop detector. If achieve, it will continue to

provide an additional MIN time for the phase. This is shown in Table 2.1.


A 6 70 4 3 2

B 6 30 4 3 2

Table 2.1: Phase calculation


B 6 1 30 4 3 2

B 6 2 30 4 3 2


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This process will continue until it reach the MAX time where the added MIN

time is more or equal to MAX time as check in Table 2.2. Then another phase will take

its turn to operate from the beginning as depicted in Table 2.3. This approach is usually

applied on Vehicle Actuation Mode.


A 6 70 4 3 2

B 6 30 4 3 2

B 6 1 30 4 3 2

B 6 2 30 4 3 2

B 6 3 30 4 3 2

B 6 4 30 4 3 2

B 6 5 30 4 3 2

C 6 30 4 3 2


With timed signal lights, vehicles wait a certain amount of time before they are

presented with a green light to move. The vehicle must wait for the timer to expire

before the signal light presents them with a green light even though it is the only vehicle

at the intersection.

The timer is programmed in a processor in the controller. The processor contains

powerful 16-bit Intel CMOS microprocessor and supports circuits, as well as memory

expandable to 256kB of PROM and 8kB of RAM, Bell 103 modem and sockets

(Abdullah, 2009) .

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2.2 Preemption System

Although standard traffic lights discussed in the previous section have improved

the control, they cannot respond effectively for emergency vehicles to cross or enter the

intersection immediately. Therefore, emergency and other vehicles may be delayed

behind traffic while waiting for the light to change (Apitz and Dyer, 2001 ).

To make the matter worse, latest vehicles have been designed to be “air-type,

noise-reduction” which have limited driver’s awareness sudden changes of the traffic

light phase. Eventually, the emergency vehicle will not be given way to maneuver.

It has been widely accepted that, particularly in high density traffic area, there is

a vital need for such preemption control systems for emergency vehicles (Apitz and

Dyer, 2001 ). The main function of preemption control systems are providing an

unimpeded path to pass through an intersection and avoiding collision occur from the

approaching direction.

In order to explain the preemption system easily, the system is classified in two

categories, which is decentralized and centralized system.

2.2.1 Decentralized System

A decentralized system normally compromises transmitter, detector, processing

circuit, phase selector processor and traffic light controller (Schwartz, 2008b).

Emergency signal broadcasted from the vehicle based transmitter will be obtained by

the intersection receiver. Later the signal will be linked to a control circuitry where new

phase of traffic light sequence is actuated to permit the vehicle to pass through safely

the intersection. The new phase preempts the existing status of the traffic lights in

response to the approach of an emergency vehicle to an intersection under an

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emergency condition (Poursartip, 2003). The detector systems are loop based system,

light based system, sound based system and radio wave system.

2.2.1.1 Loop based system

The oldest traffic light switching systems is referred to as "loop detectors". This

loop detector is still been applied by many countries. Basically a conductive loop

detector embedded in the road as shown in Figure 2.5.

Figure 2.5: Detector loop (Abdullah, 2009)

The conductive loop generates an electromagnetic field. A signal is transmitted

to a traffic light controller if the proper numbers of vehicles have passed over the

conductive loop and through the electromagnetic field. The traffic light controller then

switches the traffic light, if appropriate. In addition to electromagnetic fields, prior

systems have also used pressure sensors to determine the presence of a vehicle (Matta,

2000).

“Car-active” or “Car-passive” are two types of systems have been designed to

utilize existing inductive traffic loops for preemption of emergency vehicle. In the “car-

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active” system, an emergency vehicle sent its position information to the traffic loop

control box when it is detected by the existing inductive traffic loop for preemption.

In the “car-passive” system, an intersection transceiver is activated to send a

signal to a radio frequency transponder that is affixed to the underside of the emergency

vehicle. This system will only respond based on the car vehicle identification number

(VIN) in the transponder. Transceiver at the intersection will transmit position

information to the traffic controller to preempt operation of the traffic signals after

obtaining response from the vehicle.

Figure 2.6: An intersection of the general configuration for a preemption system using existing traffic loops (Aaron D. Bachelder, 2006b).

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Figure 2.7: Schematic block diagram of the system general configuration (Aaron

D. Bachelder, 2006b)

Figure 2.6 and Figure 2.7 illustrate the design method. Once preempted, the

intersection must remain preempted for certain of time until it does not receive

“positive” preemptive signals from the same emergency vehicle.

Car- passive approach consists:-

Access Code (ACODE)

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Direction Code (DCODE)

The intersection transmitter/receiver monitors the intersection by sending the

A/DCODE signal continuously in the approach directions relative to the intersection. If

an emergency vehicle approaching the intersection receives the A/DCODE, the

emergency vehicle receives the signal and sends back to the intersection with vehicle

identification code ("VID") (Brown et al., 1992 ). If the authorization for the vehicle is

verified to be true, the intersection will be given a valid preemption.

Independent control of the traffic light controlled intersections has been made

possible through the introduction of embedded processor based traffic light controllers.

Traffic signals are typically determined by an intersection controller (Bonner and

Faerber, 1980 ). A majority of the signal controlled intersections now operate on a

stand-alone basis, receiving inputs from external sensors (Bentrott et al., 1999 ).

Physical loop detectors are considered primitive for conventional traffic light switching

systems. In addition, there are many problems regarding the loop detector, which is

permanently embedded in the roadway which cannot be quickly or easily moved or

modified.

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2.2.1.2 Light based system

Figure 2.8: Light based system (Jeffrey F.Paniati, 2006)

Light based system uses the visible light spectrum as the preemptive control

between the emergency vehicle and the intersection (Bentrott et al., 1999 ). This system

are limited by the line of sight up to almost 1,800 feet between the vehicle and the

intersection control unit (Gerald W. Pfleging, 2005) .

A flashing light beam is mounted on the emergency vehicle. As an emergency

vehicle approaches an intersection, the emergency vehicle emits a preemption request

comprised of a stream of light pulses occurring at a predetermined repetition rate as

shown in Figure 2.8.

The intersection will receive the emergency signal which is a stream of light

pulses via a detector channel which is called as photocell (Hall et al., 1996). The

microprocessor circuitry applies a windowing algorithm to validate that pulses of light

were transmitted from a valid optical traffic preemption system emitter. Hamer

(Schwartz, 2008 ) proposed variable data to be transmitted in a stream of light pulses by

segregating data pulses and priority pulses. These priority pulses are able to identify

vehicle for security purpose.

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After receiving, the main controller of the traffic lights will actuate the phase

selector which will trigger the traffic light signals for the emergency vehicle to pass

through(Hall et al., 1996).

Munkberg (Zhang and Mclaren, 2007 ) proposed an idea where preemption

system can be based on different priority level where the signal controller can

discriminate between requests of differing priority and give precedence to the higher

priority signal. Repetition rate light pulses are indicative of its priority level. This

method preempts an intersection in favor of the higher-priority vehicle when two

vehicles having different priorities approach the intersection simultaneously from

different directions

2.2.1.3 Radio based system

Figure 2.9: Radio based system (Park, 2007)

A system was proposed by J. C. Lesher where the system can prevent

interference of two emergency vehicles simultaneously attempting to control the traffic

lights (Morgan and Cross, 1990 ). The emergency vehicle broadcasts an encoded

microwave signal to preempt traffic lights.

A microwave antenna is mounted at an intersection. A transponder at

intersection receiver is used to confirm the direction of the transmitted signal of the

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vehicle(Zhang and Mclaren, 2007 ) as shown in Figure 2.9. When the signal is received

by the antenna, it will decode the signal with the aid of the traffic light controller to

decide the phase to trigger the traffic lights.

2.2.1.4 Sound based system

Figure 2.10: Sound based system(Jeffrey F.Paniati, 2006)

Sound signal or acoustical signal is used interchangeably in this section. The

siren emitted by the emergency vehicle will be received at the intersection as shown in

Figure 2.10. The intersection has a sonic receiver which is tuned to a certain sound

frequencies (Morgan and Cross, 1990 ).The sonic receiver will determine the direction

of approach to initiate the proper traffic light preemption sequence (Schwartz, 2008c).

2.2.2 Centralized System

Centralized system uses real time monitoring to track the position of emergency vehicle

and estimate time of arrival of the emergency vehicle at the intersection. The system

provides real-time feedback, monitoring and logging based on the intersection

18

preemption data. Accuracy of map-matching that able to determine the precise

emergency vehicle location can provides huge advantage on the efficiency of precise

phase’s changes process. This feature allows the intersection to alert the motorist and

pedestrians earlier to ensure safety. The timing of the pedestrian and clearing phases at

an intersection is incorporated into calculations to start preemption at any given

intersection (Aaron D. Bachelder, 2008). In addition, the system can able to calculate

shortest path and provide the shortest route to the emergency vehicle to employ. Vehicle

information system explains the mechanism of vehicle tracking which helps preemption

for intersection traffic lights. Instead of tracking, path finding system explicates the

obtainable appropriate pathways based on navigation abilities. The approach used to

refrain from accident with other vehicles from opposite direction during preemption is

discussed in collision avoidance system. Multi agent system provides a view on how

preemption priority is given to more than emergency vehicle.

2.2.2.1 Vehicle information System

Vehicle information systems have been developed to provide various types of

information to emergency drivers. The vehicle information systems compromise

information like the physical location of vehicular roadways, the number of traffic lanes

of each vehicular roadway, and the nominal speed limits of each vehicular roadway.

19

Figure 2.11: Vehicle information system (Knockeart, 2004)

Basically, an on-board map is installed in the vehicle to ease the driver to plan a

route from a starting point to a destination as shown in Figure 2.11. The destination is

specified by inputting the desired location destination or selecting an option listed, like

gas stations. Once the driver determines the destination, the system will provide a

planned route which consumes less travel time (Ames, 2006).This planned is presented

to the driver in two ways. The first way is by providing a sequence of discrete

instructions is given to the driver. This is to ensure the whether driver is prepared to

react at each intersection. For instance, alerting the driver to turn left when reach a

particular junction. The second approach is by using a map to displays the vehicle’s

location dynamically. The driver uses the map to decide when and where to turn in

order to follow the planned route

An emergency vehicle is equipped with a GPS receiver. The GPS receiver is

used to determine the emergency vehicle's location and heading (Aaron D. Bachelder,

2006a). Data based on the emergency vehicle's location and heading are transmitted

20

from the emergency vehicle to intersection controllers. The intersection controller uses

the data indicating the emergency vehicle position and heading to determine whether

the emergency vehicle is on any road that might lead to the intersection. If the

emergency vehicle is on any road heading toward an intersection, the intersection

controller actuates the traffic signals at the intersection to give the emergency vehicle

the right-of-way. GPS is used to estimate the position of a preempting vehicle. The

estimation accuracy is improved using map matching techniques (Aaron D. Bachelder,

2006b)

approach the intersection. The range of detection is about

2500 fe

llers. It is very important to

determine the appropriate phase for the emergency vehicle.

.

Automated vehicle location (AVL) and control (AVLC) system that

communicates with either a traffic signal controller at the intersection or with a control

central or combination of both (Poursartip, 2003 ). This system can be considered as

multi-million dollar satellite-based GPS systems. This system applies “entry” criteria

and “exit” criteria. If the emergency vehicle is a suitable distance to the intersection,

“entry” criteria” will be applied. After the emergency vehicle passed the intersection,

“exit” criteria will be applied (Knockeart, 2004). This system can perceive the location

of emergency vehicles as they

et (Poursartip, 2003) .

All the traffic lights are controlled from a central console. Usually the central is

located in any government building like the police radio room. Operator of the central

will always have two-way communication with the emergency drivers. Based on the

GPS mapping, the operator will guide the emergency driver to use certain path to reach

the destination faster. When the emergency vehicle reaches an intersection, the operator

actuates a certain traffic lights phase by granting green light for the emergency vehicle

to pass (Knockeart, 2004). The judgment activates a certain traffic lights phase is based

on received diagnostic information from intersection contro

21

Instead of the operator interference, there is another approach where operator

function is completely ignored. The emergency vehicle is equipped with devices, like

antenna, to determine the position of the emergency vehicle. The emergency vehicle has

to transmit GPS position data periodically to the control central. Then, the control

central will calculate the speed and estimated arrival time to determine if traffic signal

preemption is needed at the intersection. If confirm, the control central will send

preemption request, based on the vehicle priority status, to the traffic signal controller

(Bonner and Faerber, 1980 ).

When GPS signal is obstructed, dead reckoning techniques can be used to

alleviate the problem (Aaron D. Bachelder, 2006b) . This technique able to determine

the vehicle position based on the previous location and other relevant information like

speed and heading direction. Emergency vehicle is installed on-board-dead reckoning

system. When the emergency vehicle passes a traffic loop, it receives intersection ID to

be looked up in latitude/longitude location database estimate future positions. Primary

location information with a dead reckoning system provides location information when

poor reception prevents the GPS system from functioning.

2.2.2.2 Path finding system

Finding reliable path is not an easy task as lack of dynamic traffic data can be

acquired for the entire network especially during disaster. Therefore, preplanning best

route is very crucial for emergency vehicles to reduce rescue operation delay.

There are many varieties of method used to provide shortest path for emergency

vehicle. Mona (Mona E.Rizvi) proposed a Vehicular Ad Hoc Networks (VANETs)

based approach that operate with emergency vehicle preemption system in order to

22

provide suitable route information for emergency service vehicle with the intention of

reducing traffic chaos during evacuation and non-evacuation conditions.

Figure 2.12: A simplified of RHODES operation (Pitu B.Mirchandani 2004)

David (Pitu B.Mirchandani 2004) proposed Categorized Arrivals-based Phase

Reoptimization at Intersection (CAPRI) that integrates transit signal priority within

dynamic programming-based real-time traffic adaptive signal control system which

referred to as RHODES, which is shown in Figure 2.12. CAPRI allows dispatching

system to compute a real-time dynamic shortest path (PREDICT) to minimized delay.

The system flow is display in Figure 2.13.

23

Figure 2.13: The CAPRI control architecture (Pitu B.Mirchandani 2004)

Ioannis Kaparias (Yanyan Chen, 2003) proposed A-star (A*) algorithm as an

approach for preplanning emergency paths during earthquake.

24

Figure 2.14: A* path (Yanyan Chen, 2003)

A* algorithms is apply to calculate one to one shortest path problem by

evaluating the candidates of the emergency routes as shown in Figure 2.14.

2.2.2.3 Collision Avoidance System

Collision avoidance is an important aspect for centralized system preemption

system (Ohanes Ghazarian, 2002). This feature is applicable when there are more than

one emergency vehicle reaching at a same intersection from different direction, and

requesting for preemption at the same time. To make the matter worse, all the

emergency vehicles have the same priority status. Dreadful accidents will occur if all

the traffic lights at the particular intersection are actuated to green signal.

25

Therefore a system was proposed to alleviate the problem.The system will notify

the emergency vehicle driver the position and the direction of other emergency vehicles

which are approaching the same intersection. The direction can be perceived from the

information attained from the transceiver mounted on each emergency vehicle. The

transceiver microprocessor will calculate the direction vector based upon the received

direction signal of another emergency vehicle (Haagenstad et al., 1997 ). The direction

and position of other emergency vehicles are displayed on a graphical display so that

the drivers have the capability to determine sources of possible collisions with other

emergency vehicles. If the driver does not abide the warning signal alert, the vehicle

which is mounted with mount speed comparator collision avoidance unit will

implement the vehicle brake system (ABS). ABS will slow down the vehicle or bring

the vehicle down to full stop in order to avoid intersection collision.

2.2.2.4 Multi Agent System

Normal approach of evaluating all requests based on first-come-first service law

will results extra delay to the system. Colored Petri Nets (CPN) is invented as a method

to increase capable to make decision on priority type, priority degree, and service

sequence in time. Kurt Jensen (Lefei Li, 2005) introduced Colored Petri Nets (CPN)

which is a modeling language that is powerful in handling systems where

communication, synchronization, and resource sharing play a crucial role. CPN is

capable in handling preemption requests of different priority from multiple intersections

approaches. Priority evaluation and signal plan generation are flexible in CPN where it

can interface with algorithms without major changes based on the overall structure. A

traffic signal priority control system is able incorporated into a network which requires

more frequent interactions among system components.

26

CPN will compare the new request with the current highest priority request only.

If the new request has the higher priority than the current highest priority request,

preemption will occur. Otherwise the request will be added to the waiting list. Figure

2.15 displays the CPN model for traffic signal priority/preemption control system. CPN

has few components.

They are:-

• Emergent request

• Priority evaluation

• Preemption control

• Signal planning

• Update requests

• List maintenance

27

Figure 2.15: CPN Model(Lefei Li, 2005)

CPN model uses Color Set to decide the priority of different types of vehicle.

Subsequent to receiving a preemption request, the model will evaluate the type of the

vehicle. If it is an emergency vehicle request, signal will be sent to traffic signal

controller to convert the conflicting approach signal from green to red. The signal of the

emergency vehicle approaching direction will be converted from red to green if the

current signal is red or otherwise the signal is kept green till the emergency vehicle

passes the intersection. After the emergency vehicle passed, the preemption request will

be terminated.

28

On the whole, traffic lights are needed to control the flow of vehicles at each

intersection. There is a new system introduced where the concept of traffic light can be

ignored. Vehicles, including emergency vehicle and non-emergency vehicle, are

controlled by a computer and the intersections are equipped with wireless

communication system. This communication system corresponds with the oncoming

vehicles to permit passage for emergency vehicles. Every vehicle is equipped with

autonomous features making autonomous vehicle navigation possible. The basic idea is

to instruct or train the vehicles to be independent without relying on the centralized

control for passage aid. The concept of vehicles being autonomous agents is basically

based on Multi Agent Systems (MAS) theory (S. Saroiu, 2002). This MAS theory is a

subfield of artificial intelligent, where provide both ideologies for constructing complex

systems involving multiple agents with coordination methods for independent agents’

behaviors.

Vehicles have to abide by the intersection protocol to travel. This protocol is

relied on reservation-based system. Vehicles request and accept period slots from the

intersection. Based on reservation-based system, the custom traffic simulator allows

traffic to flow through the intersection much more efficiently compare to the traffic

light mechanism. Emergency vehicles are able to increase their response times when

congestion intersection is avoided.

2.3 Conclusion

In the early stage of this chapter, an overview of traffic light system is presented.

In this section, phase design has been briefly discussed. The phase design will be later

used in Chapter 4 to provide a clear view on intersections as well as routes problem

during preemption process.

29

Following the traffic light system overview, preemption system review is

performed. Preemption system is divided into decentralized and centralized system.

Decentralized system functions by focusing on the interaction between the emergency

vehicle and intersection controller. Intersection controller will alter the traffic light

phase according to the vehicle preemption signal received. Centralized system provides

an autonomous system that not only monitors the emergency vehicle current location,

but also navigates appropriate routes for the drivers to use. The system preempts traffic

intersection by perceiving the emergency vehicle current location.

The preemption system basically has their on shortcomings. For decentralized

system, cost of installing and maintaining the sensor device at every intersection for a

long run is high (Apitz and Dyer, 2001 ). In this system, the sensors might not perform

as expected if it is distracted by heavy climate or buildings which will cause the traffic

lights have difficulties to perceive the emergency vehicle emitted signal (Zhang and

Mclaren, 2007 ). The traffic lights can only receive signal from the vehicle from a short

distance. If the vehicle is stuck in a long-distance-congestion, it will unable to trigger

the road traffic lights. If it able to receive the signal, it unable to clear the road properly

in order to provide a safe path for the emergency vehicle to maneuver. Non-authorized

individuals can purchase the emitting devices online illegally and install it in the car to

change the sequence of traffic lights for their ease when traveling (Gerald W. Pfleging,

2005). The changes of one traffic light intersection might cause havoc for other adjacent

intersection traffic lights. Each sensor has a particular modulation scheme which is

implemented nonintegrated at every city jurisdiction for security purpose (Schwartz,

2008a). Nonintegrated system has high management difficulties.

For centralized system, installation and maintenance of wireless or wired

devices are very expensive (Apitz and Dyer, 2001 ). The diagnostic information of GPS

positioning data can be occluded by bridges, tunnels, road flyover or building (Yang

30

Chen, 2006). Human error such as stress can occur which will affect the operator

judgment on ad hoc interaction can occur easily when transmitting signal to the

intersection from the central (Coll et al., 1972 ). To avoid unnecessary traffic lights

interruption, estimation the time arrival (ETA) for the emergency vehicle is applied.

However, it is difficult to predict when the emergency vehicle to reach an intersection

precisely. Emergency drivers might be experiencing information delay due to the

processing time from the traffic lights actuation and the central transmission (Jones et

al., 1999 ). The next chapter will discuss a proposed method for this thesis project.

31

Chapter 3 Methodology

3.0 Introduction

In this chapter, a research methodology to solve and enhance emergency vehicle

preemption system problem is presented. The purpose of this research methodology is

to act as a standard of guidelines needed to attain on how to perform the activities

properly in order to develop a system successfully. It also help to detect and to alleviate

any inconsistencies as well as redundancies based on the development specification.

This will eventually reduce the required budget and schedule constraints.

3.1 Proposed Methodology

A prototype model needed to be inserted as a subset process in the waterfall

model to suit this thesis project requirement. In other word, the proposed framework

being used is a combination of waterfall model and prototype model as shown in Figure

3.1. The reason to combine both models is to improve the time taken and reduce the

cost expenses to create a product design based on the system requirements. This can be

done since any urgent improvement is not necessary performed at the Testing phase.

Iteration enhancement or refinement can also be done at the Development phase.

32

Figure 3.1: Proposed Methodology

3.1.1 Requirement

The requirement should involve defining the objectives and scope, generating

appropriate solutions and determining how the research should be executed based on the

hypothesis by reviewing literature. More information on the requirement is gathered by

visiting related sites and by interviewing relevant authorities.

The information necessities are prioritizes and translate into a written plan.

Based on the collected information, there are some significant shortcomings attained of

the conventional system. For example, the line of sight problem where signal emitted by

the emergency vehicle might be distracted by trees, noises, climate, buildings or curved

roads which will cause the sensor at the traffic light intersection have difficulties to

perceive the signal. If the traffic light can not perceive the emergency preemption

signal, congested vehicles ahead for the particular lanes can not be cleared and

hypothetically cluttered intersection can occur. Another shortcomings perceived from

the collected information on alternative shorter routes are unable to be informed to the

emergency vehicle drivers at the appropriate time.

33

3.1.2 Design

Based on the Requirement phase, a proposed idea is constructed. Design aspect

is a stage that illustrates a basic thought of how the project system will function. As

stated in the Requirement stage, line of sight quandary contributes to current emergency

preemption system problem. For that reason, the use of GPS technology is proposed to

overcome the drawback of cluttered intersection and shorter alternatives routes. The

design can be divided into software and hardware part.

The software part concentrates on calculating the suggested route from the

emergency vehicle to their destination. A central system will act independently to

control the traffic lights based on certain threshold set to ensure the emergency vehicle

does not get caught in the road congestion.

The hardware part focuses on the emergency vehicle preemption position, traffic

light controller and wireless transmission. For vehicle preemption position, GPS is used

to track whereabouts of the vehicle is currently situated by obtaining its location. The

location then been sent to the central control by using wireless transmission of GSM.

The central will be responsible to control particular intersections where the emergency

vehicle will maneuver. The central control the intersections by sending GSM output to

the traffic light controller receiver. Based on the central output, the controller will

trigger and calibrate the traffic lights flow.

In this design stage, the idea above will be presented in flow diagrams,

pseudocodes, flowcharts, block diagram and tables.

34

3.1.3 Development

Selection of hardware and software tools is focused in Development stage.

There are varieties of tools available in the market. Different hardware and software

apparatus has its own advantages, limitation and scope. Hence, it is crucial to plan and

prepare proper hardware and software to develop a project system. The equipments or

the devices utilized for this thesis project system are summarized in Table 3.1. The

detail description of each apparatus is explained in the Appendix.

Category Apparatus

Development Platform • Window XP

Programming Infrastructure • Microsoft Visual Studio.Net

• Xilinx Integrated Software

Environment (ISE)

• Xilinx Embedded Development

Kit (EDK)

• Software Development Kit (SDK)

Programming Language • C Programming

• C# Programming

• VHDL

• AT Command

Database Server • Microsoft Access

Hardware • Xilinx Virtex-4 LX-25

• GPS/GSM modem

• LEDs

35

• Breadboard

• Loop Back Serial Cable

• Subscriber Identity Module (SIM)

card

Table 3.1: Hardware And Software Tools

3.1.4 Prototyping

This stage is a phase where trial model is produced. This stage also concentrates

on the software and hardware part. As stated in the design stage, software part

concentrates on suggesting suitable route to the emergency vehicle. In the prototyping

stage, shortest path algorithm is coded using C#.Net programming language. C#.Net is

also use to code for serial port communication with the GSM.

Hardware part is further divided into two where the first part is focusing on

hardware programming while the other on physical wiring. Hardware programming

involves controller design to acquire emergency vehicle position and to control traffic

light. For hardware programming, Base System Builder (BSB) is applied to create more

customized Microblaze processor design. EDK provides ample Intellectual Properties

(IP) for programmers to use. BSB saves time because it automates basic hardware and

software platform configuration tasks common to most processor designs. Software

development is done in SDK which embed C programming. ISE is a platform for

coding in vhdl or verilog language. After completing the design, FPGA bitstream and

the Executable and Linkable Format file (ELF) are downloaded to the target device.

Expansion Header of the Xilinx ML401 FPGA is used to wire a breadboard for

physical wiring. The breadboard is designed to create second serial port connected to

36

GPS tools. Another breadboard is used for an intersection design of four traffic lights.

By employing the tools, a system model will be produced.

3.1. 5 Testing

Testing is done to identify whether the project system is functioning in a proper

order or vice versa. In the software segment, debugging tools in C#.Net is applied to

make sure the entire program flow and operate in the approved manner.

ISE simulator is used to verify the hardware part of process and behavior

structure. In addition, computer Hyperterminal interface is employed to check hardware

and PC interfacing. Requirement stage is called upon if any testing process provides

undesirable output in order to solve the quandary.

3.1.6 Maintenance

The whole system is integrated by three modules that are correlated.

Scrutinizing and observing the modules to functions properly is not a difficult process.

All the modules are loosely coupled. Hence modification on each of the modules can be

made easily without worrying whether it will affect the other modules.

Any new technology or apparatus that appears in the market can be used by

embedding it in the system. In order to embed in the system, the project‘s validation

condition must comply in the Requirement stage. This system eventually will help to

increase scalability and enhance flexibility.

37

3.2 Conclusion

A well robust designed is discussed and presented to be best fit for this research

study. This proposed methodology is generally a guideline for solving a problem, with

specific components such as phases, tasks, methods, techniques and tools. Techniques,

methods, ways, and procedures need to be applied to collect, gather and group together

all relevant information for the research. This methodology provides successful study

results in a uniform approach where the research might have no output but successfully

complete. It also help to detect and to alleviate any inconsistencies as well as

redundancies based on the development specification. Ultimately it will reduce the

required budget and schedule constraints. The next chapter will elucidate on the project

design.

38

Chapter 4 Problem Verification and System Design

4.0 Introduction

In the earlier chapter of this thesis, high traffic is expected to cause emergency vehicle

to get caught in cluttered intersection problem even though preemption system is

employed. Other problem includes the green traffic light is not triggered based on the

route that the emergency vehicle is heading. These typical preemption system

drawbacks will be verified in the following sections by using data collection and

observation method at the traffic intersection site. The data collection is taken from

streets in Petaling Jaya. The first data collection is made by observing traffic light

changes in several intersections. The purpose of this observation is to come out with the

phase design for the selected intersections. Based on the phase design and other

observation, a new preemption system is proposed to alleviate the identified quandaries.

Then, each module of the proposed system is illustrated in diagrams and flowcharts.

39

4.1 Real Time Traffic intersection Analysis

Figure 4.1: Google map of Petaling Jaya

Figure 4.1 displays a map that will be used as an example to explain the problem

of quandary road intersection. Figure 4.2 presents a clearer view of intersections based

on Figure 4.1. The description of each symbol in the diagram is clarified in Figure 4.2.

40

Figure 4.2: Intersection at Petaling Jaya

The Figure 4.2 provides a view on how an emergency vehicle will usually travel

by using a path where intersection-D, intersection-C, intersection-B and intersection-A

is connected. There is alternative path where intersection-F is involved.

41

4.1.1 Perceiving Intersection Characteristic

Understanding each intersection traffic light phase will ultimately provide a

clearer view of the problem faced by the emergency vehicles. Thus, intersection A and

intersection B phases are illustrated in diagrams and tables. Illustration of other

intersections traffic lights phase is explained in Appendix. “Bird Eye” view presents a

sight taken from above the sky. The table provides facts on the phases changes

according to the time period. The changes of phase are also shown in diagrams. It is

very important to understand the phase design in order to comprehend the overall traffic

lights flow. The problems occur due to the inefficiency of intersection phases is made

clear in the next section.

4.1.1.1 Intersections

4.1.1.1.1 “Bird Eye” View

Figure 4.3: Intersection A and intersection B traffic flow diagram

42

4.1.1.1.2 Time/Traffic Light Table

A-1 A-2 A-3 A-4 A-5 A-6 PHASE

6:29:00pm G R G R R R 1

6:30:05pm Y R Y R R R 1

6:30:08pm R G R G R R 2

6:31:03pm R Y R Y R R 2

6:31:06pm R R R R G G 3

6:31:40pm R R R R Y Y 3

6:31:46pm G R G R R R 1

Table 4.1: Time/Traffic light – Phase for intersection A

B-1 B-2 B-3 PHASE

6:29:00pm R R G 1

6:29:22pm R R Y 1

6:29:48pm R G R 2

6:30:11pm R Y R 2

6:30:13pm G R R 3

6:31:06pm Y R R 3

6:31:10pm R R G 1

Table 4.2: Time/Traffic light – Phase for intersection B

43

4.1.1.1.3 Intersection Phasing Diagram

Figure 4.4: Phases of intersection A

Figure 4.5: Phases of intersection B

4.1.2 Identifying Intersection Problem

44

4.1.2.1 Cluttered Intersection Problem

The distance between intersection B and intersection A is approximately 2 meter

as show

n in Figure 4.6. This can be considered as a short distance. According to Figure

4.7, even though intersection B is green, emergency vehicle (the square in blue) might

encounter a standstill if the intersection A is still red. This problem is referred to as

cluttered intersection problem.

Figure 4.6: Intersection A and Intersection B from Figure 4.2

Figure 4.7: Cluttered intersection problem

To describe the problem clearly, data has been collected and tabulated as in

Table 4.3 and Table 4.4.

45

A-1 A-2 A-3 A-4 A-5 A-6 PHASE

6:29:00pm G R G R R R 1

6:30:05pm Y R Y R R R 1

6:30:08pm R G R G R R 2

6:31:03pm R Y R Y R R 2

6:31:06pm R R R R G G 3

6:31:40pm R R R R Y Y 3

6:31:46pm G R G R R R 1

Table 4.3: Intersection A

B-1 B-2 B-3 PHASE

6:29:00pm R R G 1

6:29:22pm R R Y 1

6:29:48pm R G R 2

6:30:11pm R Y R 2

6:30:13pm G R R 3

6:31:06pm Y R R 3

6:31:10pm R R G 1

Table 4.4: I rsection B

On the table (red colored text), it can be seen that A-1 traffic light is given red

nte

light while B-1 is given green. Phasing design as displayed in Figure 4.8 lasted for a

short period of time. Therefore the path from intersection B to intersection A cannot be

cleared entirely. As the result, vehicles from intersection B might not be able to enter

path to intersection A though the light is green.

46

Figure 4.8: Phase for intersection A and B

Besides shorter period of phase, cluttered intersection problem can also occur

because of vehicle coming in from the intersection B-2 without traffic light interruption

as shown in Figure 4.9. While the intersection A1 or A2 is triggered green, this will not

clear up the vehicles in between the intersection B and intersection A. It is because

vehicles in lane B2 will hastily fill up the empty space of the A1 and A2 path.

Consequently, vehicles in B-1 path are unable to enter lane A-1 or A-2, even though B-

1 path is given green signal.

Figure 4.9: Phasing of intersection B

47

Figure 4.10: Blockage from Intersection B to Intersection A

Figure 4.10 displays a case where intersection B is green and intersection A is red.

Vehicles from intersection B-1 are compelled to halt at the yellow box. Therefore,

emergency vehicle will find itself standstill at the intersection.

4.1.2.2 Alternative Route Problem

4.1.2.2.1 Shortest Path Discovery Problem

Besides the cluttered intersection problem, there is another issue regarding the

path used by the emergency drivers to reach to the destination. In a critical condition,

the drivers usually will not have the heed to consider an easier path. Easier path is

measured as route with less congestion. Path with a lot of traffic light intersections

usually consume a lot of time. It is because vehicles have to wait for their turn to move.

Logically, vehicles need to wait longer if the numbers of vehicles queuing up is a lot.

This delay consequently creates congestion.

48

Figure 4.11: Routes to University Hospital

1(D to C) 2(C to B) 3(B to A) 4(D to F) 5(F to A)

6:00pm - 6:01pm 15 30 17 10 15

6:15pm - 6:16pm 10 27 15 12 16

6:30pm - 6:31pm 17 22 14 15 11

6:45pm - 6:46pm 19 26 15 17 16

6.59pm - 7:00pm 18 29 16 11 9

Table 4.5: Amount of vehicles on certain lane at specific time

Table 4.5 displays the amount of vehicles on certain lanes per range of time

based on Figure 4.11 that are routed to the hospital. Lane 1, lane 2 and lane 3 appears to

have more vehicles when added together compared to lane 4 and lane 5. Path shown in

Figure 4.12 appears to be less congested if Table 4.5 is scrutinized properly. It would

better if the driver uses alternative path, via intersection F which consume less time to

reach the destination.

49

Figure 4.12 Alternative path using the Intersection F path

4.1.2.2.2 Incorrect Path Selection

Figure 4.13 displays an intersection where there are two lanes named as M1 on

the left and M2 on the right. The light blue rectangular is a sensor installed in the road a

meter away from the traffic lights. Normal conventional preemption systems trigger

particular traffic light based on the sensor detection. For instance, if an emergency

vehicle is detected on the left lane, only M1 traffic light is triggered green to allow the

vehicle to maneuver to the left with waiting. The concept is same for M2 traffic light on

the right lane.

This concept provides difficulties for the emergency vehicle when the vehicle is

caught up is heavy traffic congestion. Without any navigation guide, the emergency

vehicle might locate itself at the wrong lane if it tries to maneuver the heavy traffic jam.

Wrong traffic light is triggered when the vehicle located itself at the wrong lane.

50

Figure 4.13: Incorrect lane problem

4.2 Proposed System

Intersection problems have contributed bad impact on the operation of

emergency vehicle. In cluttered intersection problem, emergency vehicle is compelled

to be standstill even green signal is given, because of the intersection ahead is triggered

red. If the emergency vehicle tries to maneuver in the congested traffic, it might locate

itself in a wrong lane where traffic sensor is installed. Eventually the vehicle might

mistakenly use a long time-consuming route without any proper navigation guide. This

misguided route issue is referred to alternative route problem.

Therefore a new system named as Smart Emergency Vehicle Preemption

System (SEVP) is proposed to alleviate the intersection problems. SEVP can solve

cluttered intersection problem by changing the phase design for more than one

intersection based on certain threshold distance between the intersections for emergency

vehicle to maneuver easily. SEVP able to solve alternative route problem by providing

calculated path with less congestion and by triggering green traffic light based on the

51

route that the emergency vehicle is heading as well as directing the emergency vehicle

to be in the correct lane before reaching the intersection.

SEVP will guide the emergency vehicle to the emergency scene by applying

shortest path and then permit the drivers to pass through the traffic intersections

smoothly by altering the traffic light actuation. Combination of Global Positioning

System (GPS) apparatus as well as A-Star (A*) shortest path algorithm is utilized for

this proposed system. The general idea of the proposed system methodology is depicted

in Figure 4.14.

Figure 4.14: Overview of proposed system

The proposed traffic emergency vehicle preemption system include of three

main modules which are:-

• Emergency vehicle tracking (Module 1)

52

• Central control system (Module 2 )

• Traffic light control (Module 3)

The three modules work together in tandem to carry out the main task of the

system is shown in Figure 4.15.

Figure 4.15: Module process implemented in SEVP

53

4.3 Scenario Example

Figure 4.16: Smart Emergency Vehicle Preemption System

Map in Figure 4.16 is used as an example to explain the process of the system

which capable to solve the intersection problems. An emergency vehicle in Jalan Puspa

needs to reach Jalan Kelicap 6 where the emergency scene has occurred. After the

driver switch on the tracking device, the device starts detecting the vehicle current

location by using GPS. The tracking device is installed in the vehicle. The device will

extract only the latitude and longitude from the raw data of the GPS and transmit them

to the central system. The central system will request for the destination location from

the driver once it received the current location of the vehicle. The driver will insert the

destination location. Then the central system will calculate the shortest path for the

vehicle. The system will continually receive the vehicle current location for shortest

54

path calculation until the vehicle reaches the destination. By iteratively calculating, any

congestion path can be detected earlier to avoid to the driver to use the path which

previously recommended by the central system.

According to the map, the level of congestion in Lorong Hang is higher then

Lorong Tun. Therefore the system will direct the vehicle to use Lorong Tun instead of

Lorong Hang. Each intersection will have a unique GSM number (i.e. 3584, 9246 and

8216) so that the central system can send interrupt signal to specific intersections. Once

the vehicle is sensed in an intersection radius, the system will alter the intersection

traffic lights phasing earlier for the emergency vehicle to pass through the intersection

without any interruption. The intersection radius is approximately 200 meters. The

system had set a distance threshold where the distance is about one kilometer. If the

distance of each adjacent intersection is within the threshold distance, the particular

intersections will be triggered green at once to avoid cluttered intersections problem.

For example, intersection 9246 and intersection 8216 distance is less than one

kilometer. Therefore, the intersections phasing design is altered at once. Early traffic

light triggering provides navigation for the emergency vehicle. In this way, the vehicle

will obtain a clearer view when driving and eventually avoid the alternative path

problem. Once the vehicle had pass through an intersection, that particular intersection

will be calibrated to normal phasing. The system flowchart is shown as in Figure 4.17.

55

Figure 4.17: System Flow Chart

56

4.4 Conclusion

Normal traffic light phasing design contributes quandaries for emergency

vehicles. Therefore, traffic phase design information has been collected and scrutinized

from several intersections site. Based on the result, problems faced by the emergency

vehicle are identified. The problem is divided as cluttered intersection and alternative

path problem. To alleviate this problem, a new system named as SEVP is proposed.

SEVP solve intersection problems by providing calculated path with less congestion

and directing the emergency vehicle to be in the path before reaching the intersection.

Green signal is triggered based on the distance threshold set between each intersections.

The SEVP operation is elucidates in three modules. In the module 1, it discussed the

method used to perceive the emergency vehicle location. With this diagnostic location

information, the process of module 2 which is the central control system is explained.

Then, the traffic lights intersection controller actuation process is clarified for module 3.

A scenario example is used to clarify the ability of SEVP to solve the problem.

57

Chapter 5 System Implementation

5.0 Introduction

Smart Emergency Vehicle Preemption system (SEVP) includes three modules.

They are emergency vehicle tracking (Module 1), central control system (Module 2),

and traffic light control (Module 3). Module 1 explains the process of attaining and

sending the emergency vehicle current location to the central system. In module 2, the

obtained location is calculated to provide best path from the emergency vehicle position

to the emergency scene. The best path is referred to as route that consume less time. The

calculated shortest path result is used to disrupt several traffic intersections within range

set using n radius threshold of the emergency vehicle position in the emergency route

path. The traffic lights disruption is done by transmitting interrupt signals to the

particular intersection controllers. These traffic light controllers in module 3 will control

and calibrate the traffic light phase to permit or to grant green light for the emergency

vehicle. In this chapter, each module clearly presents its discussion and result. A

scenario example is used to show how the system calculates the path based on its

congestion weight.

5.1 Emergency Vehicle Tracking (Module 1)

5.1.1 Module 1 Discussion

Vehicle location is obtained by the central of the system to calculate the shortest

path from the emergency vehicle position to the emergency scene. To track the location,

Global Positioning System (GPS) technology is used. GPS receiver communication is

58

defined within National Marine Electronics Association (NMEA) standard

specification. In this design, GPRMC is used because it has the minimum recommended

data. GPRMC contains almost all GPS data needed in this application where the

latitude, longitude speed, bearing, satellite-derived time, fix status, and the magnetic

variation are packed in one comma-delimited sentence, as shown in Table 5.1. This

Message has the following format:

$GPRMC,hhmmss.ss,a,ddmm.mmm,n,dddmm.mmm,w,z.z,y.y,ddmmyy,d.d,v

*cc<CR><LF>

Field Description

hhmmss.ss UTC time in hours,minutes, seconds of the GPS position

a Status is valid if a = A, status is invalid if a = V

ddmm.mmmmm Latitude in degrees, minutes, and decimal minutes

n S = N or s = S, for North or South latitude

dddmm.mmmmm Longitude in degrees, minutes, and decimal minutes

w S = E or s = W, for East or West longitude

z.z Ground speed in knots

y.y Track made good,referenced to true north

ddmmyy UTC date of position fix in day, month, year

d.d Magnetic Variation in degrees

v Variation sense v = E = East, v = W = West

*cc Checksum

<CR><LF> Carriage return and line feed

Table 5.1: GPRMC message form

59

An example of GPRMC data is

$GPRMC,040302.663,A,3939.7,N,10506.6,W,0.27,358.86,200804,,*1A

where

3939.7 is the latitude

10506.6 is the longitude

Incoming data from the GPS has to be filtered in order to extract the latitude and

longitude. Most of the current tracking devices employ standard microcontroller such as

PIC, Atmel and etc to filter the unused incoming data from the GPS. However, a soft

processor core for Xilinx FPGA known as Microblaze is utilized in this thesis. The

reason to choose Microblaze is because these embedded processors provide more

flexibility for the system designer to work on processor based system. In the future, a

user designed hardware module can be interfaced with this soft processor core within

the FPGA itself. The coprocessor interface accelerates complex algorithms by

transferring parts or the wholeness of the computation to a user-designed hardware

module.

Figure 5.1 displays the block diagram used for module 1. The UART Intellectual

Properties (IP) is employed to communicate with GPS/GSM tool. Microblaze processor

will filter GPS raw data to extract the latitude and longitude of the current emergency

vehicle. The diagnostic location in latitude and longitude will be transmitted to the

central system via GSM by applying AT command. PLB is a bus that connects all the

blocks together. The pseudocode is shown in Figure 5.2.Once the latitude and longitude

60

is obtained, Global System for Mobile (GSM) modem will send the control central

system shortest path calculation

Figure 5.1: Block diagram of vehicle tracking

61

Tracking Module

1. START

2. While (tracking device is on) // Start when the FPGA is switched on

3. Do

4. {

5. Write “AT “ // Send to GSM

6. Wait for input // Wait reply from GSM

7.

8. Write “AT + CMGF=1” // Send to GSM


10.

11. Write “AT + GMGS= “phone num” ” // Send to GSM

12. Wait for input // Wait reply from GSM to insert the message

13.

14. While (Receive GPS data) // Receive GPS raw data

15. Do

16. {

17. If (raw data is GPRMC message form) // If it is a GMRC format

18. {

19.

20. While(Latitude) // If the GPS format segment is latitude

21. Do

22. {

23. Receive Latitude // Receive latitude segment by single byte

24. Write Latitude // Send the byte to the GSM

62

25. }

26. End Loop

27.

28. While(Longitude) // If the GPS format segment is longitude

29. Do

30. {

31 Receive Longitude // Receive longitude segment by single byte

32. Write Longitude // Send the byte to the GSM

33. }

34. End Loop

35.

36. BREAK // End Loop and go to number 43

37.

38. }

39. End If

40. }

41. End Loop

42.

43. Write “\x1A” // Send to GSM


45.}

46.End Loop

47.END

Figure 5.2: Pseudocode for system module 1

63

5.1.2 Module 1 Result

Figure 5.3: Emergency vehicle tracking devices

The emergency vehicle location position is needed to determine the starting

node for the shortest path calculation. To attain the location, Global Positioning System

(GPS) technology is used. The tracking device is shown in Figure 5.3. From the

diagram, the GPS is connected through the expansion header of the chip as its second

UART.

Figure 5.4: UART ML401 connection diagram

64

Virtex 4 ML401 FPGA device has only one UART port. However, two UART

port is needed to for this project design. Therefore, through the Expansion Header,

another UART is created using MAX3232 transceiver as shown in Figure 5.4. The

MAX3232 transceiver has a proprietary low-dropout transmitter output stage which

facilitates RS-232 performance from a 3.0V to 5.5V supply. The datasheet diagram

Figure 5.5.

65

Figure 5.5: UART ML401 datasheet

Microblaze soft core processor will perform GPS data extraction process in the

emergency vehicle. The Xilinx Platform Studio (XPS) project is created with two serial

peripheral devices (XPS_UARTLITE) to receive the GPS data and to send command to

GSM modem. The relationship between Microblaze, UART, GPS receiver and GSM

modem is depicted in Figure 5.6, Figure 5.7, Figure 5.8 and Figure5.9.

66

Figure 5.6: Bus Interface

67

Figure 5.7: Intellectual Property address

68

Figure 5.8: Intellectual Property ports

69

70

Figure 5.9: Block diagram for module 1

The first UART will receive raw data input from the GPS receiver, as shown in

Figure 5.10. Later the Microblaze will filter the raw data into GPRMC data, as shown in

Figure 5.11. The GPRMC data is further filtered into latitude and longitude data to be

sent to GSM modem by using the second UART.

Figure 5.10: Data Input From GPS receiver

Figure 5.11: Filtered data

COMMAND DESCRIPTION

AT Attention.

AT + CMGF = 1 Set the SMS to text mode.

AT + GMGS= num

> write message

Write an SMS text message to

recipient. Ctrl+Z ( \x1A) to

send the message

Table 5.2: AT Command send text message for system module 1

GSM modem is controlled using de-facto standard AT-command language

provided by the Microblaze soft core processor. The commands which are needed to

send the latitude and longitude data is shown in Table 5.2.

71

5.2 Central Control System (Module 2)


Figure 5.12: Central control system

The central system architecture is shown in Figure 5.12 where the GSM modem

receives the emergency vehicle 2D position. The latitude and longitude coordinate is

then set as the starting node for the shortest path calculation. Emergency vehicle

position is defined as the start node and the emergency scene is defined as the end node.

The calculated shortest path result is used to disrupt several traffic intersections within

range set using n radius threshold of the emergency vehicle position in the emergency

route path. Figure 5.13 displays the data flow diagram (DFD) of the module 2 of the

system. Tracking device provides current location of the vehicle to the system. The

central will do calculation process on the diagnostic information to control the traffic

light controller. Figure 5.14 displays the DFD in details. Specification on Process 2 and

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Process 4 is shown in Figure 5.15 and Figure 5.16 respectively. Figure 5.17 shows the

flow of the system for central control system. Figure 5.18 shows the flow chart of A-

star shortest path algorithm.

Figure 5.13: Overall DFD

73

Figure 5.14: Specific DFD

74

Figure 5.15: Specific DFD for Process 2

75

Figure 5.16: Specific DFD for Process

76

Central Control

1. START

2. Write “AT “ // Send to GSM

3. Sleep for 10 seconds

4.



7.

8. Write “AT + CMGD =1” // Send to GSM to ensure message in index 1 is deleted


10.

11.Wait for input // Wait for message receive

12.

13.Write “AT+CMGR=1” // Send to GSM to read the message in index 1

14.Extract the first value and insert in latitude textbox

15.Extract the second value and insert in longitude textbox

16.

17.Write “AT + CMGD =1” // Send to GSM to delete message in index 1

18.

19.Insert the destination coordinate //User insert the destination location

20.Search for a path // Execute the system to search an appropriate path

21.

22.If (Achieve path) // If there is a path

23.{ While(Path Available)

24. Do

25. {

77

26. If (path reaches “Secondary Sensor”)

27. {

28. //Send to particular intersection number based on thereshold

29. Write “AT + GMGS= “phone num” ”


31.

32. //Send the the particular traffic light to be triggered

33. Write “Traffic light number”


35.



38. }

39. Else (If path reach “Main Sensor”)

40. {

41. //Send to particular intersection number

42. Write “AT + GMGS= “phone num” ”


44.

45. //Send the the particular traffic light to be calibrated

46. Write “Traffic light number”


48.



51. }

78

52. Else If path reach “Destination”

53. {

54. GOTO // go to number 11

55. }

56. End If

57. }End Loop

58.}

59.Else( If no path found) //If there is not any path found

60.{

61. GOTO // go to number 11

62. }

63.End If

64.END Figure 5.17: Pseudocode for system module 2

79

Figure 5.18: A* Flow Chart

In the central system, shortest path route is calculated to provide navigation of

path that consume less time to the emergency vehicle. There are many shortest path

algorithms available but A-star has been chosen in this project. A-star algorithm was

developed in year 1968 by Peter Hart, Nils Nilsson, and Bertram Raphael with the

80

purposed of finding path. A* algorithm has two significant features which are path

scoring and shopping list. In path scoring, the equation “F = G + H” is a key element of

A* as shown in the 8th figure. The variable G represents the movement cost to move

from the starting point A to a given square on the grid, following the path generated to

get there. H is the estimated movement cost to move from that given square on the grid

to the final destination. F is the current estimated shortest path. F is the true shortest

path which is not discovered until the A* algorithm is finished. The algorithm uses

shopping list to determine whether a node need to be calculated or not. The A* structure

consists of two lists: Open and Closed list. The Open list is a list of all cells that have

yet to be saved. The Close list contains the list of all cells that have been saved. Once

the goal is located, the shortest path can easily be obtained.

81

82

Figure 5.19: A* flow diagram

This flow of this algorithm can be clarified Figure 5.19, where the blue grid of S

and D is initial node and goal node respectively. The black grid is obstacle and the

yellow grid is the path used. The green grid is the shortest path.


Module 2 connection is shown in Figure 5.20. The picture on the left side

displays the PC which acts as a server. The picture on the right side displays the GSM

connection.

Figure 5.20: Connection of GSM and the PC

The current location of the emergency vehicle, in latitude and longitude, is

obtained by the server via GSM. The location is then set as the start node and the

destination is defined as the end node.

Then the central system will continuously calculates the shortest path from the

emergency vehicle position to the emergency scene until the vehicle reaches its

destination. The iterative calculation is to identify any changes in congestion level along

to the path being used. The calculated shortest path result is used to disrupt several

83

traffic intersections within range set using n radius threshold of the emergency vehicle

position in the emergency route path.

The control central will transmit interrupt signals via GSM to the particular

traffic light controllers.

5.2.2.1 Interface Design

Figure 5.21: Project design summary

In the Main Page, there are two buttons. If User button is clicked, it will

directly goes to Dynamic Map where user can find the appropriate path to use. If

Admin button is clicked, it will request the user to insert login password. The system

will verify the login password authentication.

If it is valid, it will direct the user to Design where the user can create a new

map or modify the existing map. If the user does not want to design map, they can click

Back where the user will be logged out form the system and direct it to the Main Page.

84

Map is saved after designing in Mapping. If the user clicks Back, the user will able to

design another map. If the user clicks Test, the user will be logged out form the system

and directed to the Dynamic Page. The user can test the map design. If the user is not

satisfied, the user needs to click Back to go the Main Page and click on Admin button.

The same process is continued as shown in Figure 5.21.

Table 5.3 displays the AT command used for PC server to communicate with the

GSM.

COMMAND DESCRIPTION

AT Attention.


AT+CMGD = n Delete message at index n

AT + GMGR= n

Read message at index n

AT + GMGS= num

> write message

Write an SMS text message to

recipient. Ctrl+Z ( \x1A) to

send the message


85

5.2. 2.1.1 Main Page

Figure 5.22: Main page

Main Page Description

User Goes to Dynamic Map page where the

shortest path operation is applied

Admin Goes to Design page where map

configuration is done

Exit End the application

Table 5.4: Description of Figure 5.22

86

5.2.2.1.2 Login

Admin button needs password authorization as shown in Figure 5.23.

Figure 5.23: Admin page

Login Description

Login Verify the Username and Password. If

true, it will go to Design page. It will

request the user to login again if the

verification was false

Reset Clear the Username and Password

textbox.

Back Go to the Main page


87

5.2.2.1.3 Design

Figure 5.24: Design page

Design (Map Selection) Description

New Create a new map

Open Open saved map

Exit Go back to the Main page

Next Go to Design(Option) page

Previous Go to Design page and reset everything


After the password had been verified to be correct, the design page will appear

as shown in Figure 5.24. The admin can create a new map or open the existing map

which is shown in Figure 5.25 and Figure 5.26 respectively.

88

Figure 5.25: Open recent map

Figure 5.26: Create a new map

Based on the option, the admin can modify, add or delete any components to suit

the map. Admin can click the check box to add the components on the screen. Once

satisfied, the admin can continue by clicking Next button to add more components as

shown in Figure 5.27 till Figure 5.33. If the admin is not satisfied, the admin can use the

Previous button to go back and alter the map.

89

Figure 5.27: Select Option

Design(Option) Description

Light Add traffic light

Home Add building

Up, Down, Left, Right One way road

Wall Obstruction

Road Road path

Previous Go to Design page and reset everything

Next Go to Design(Main Sensor) page


90

Figure 5.28: Select Main Sensor

Design(Main Sensor) Description

Main Sensor Insert at each junction

TrafficNum Insert the telephone number

X_Sensor Insert its X coordinate

Y_Sensor Insert its Y coordinate

Send Save the TrafficNum, X_Sensor and

Y_Sensor in the database

Previous Go to Design(Option) page

Next Go to Design(Secondary sensor) page


91

Figure 5.29: Select Secondary Sensor

Design(Secondary sensor) Description

Sensor Insert near to its Main Sensor

Distance Insert the distance between two Main

Sensors on the same road path where the

Secondary Sensor is located. This is to

calculate the threshold during the A*

operation

SensorID The uniqueness of the Secondary sensor

X_Sensor Insert its X coordinate of the sensor

Y_Sensor Insert its Y coordinate of the sensor

TrafficNum Insert the telephone number of its Main

Sensor

TrafficLight Insert which traffic light to be triggered

X_Traffic Its Main Sensor X coordinate

Y_Traffic Its Main Sensor Y coordinate

92

Send Save the Sensor, Distance, SensorID,

X_Sensor, Y_Sensor, TrafficNum,

TrafficLight ,X_Traffic and Y_Traffic in

the database

Previous Go to Design(Congestion) page

Next Go to Design(Main Sensor) page


Figure 5.30: Select Congestion

93

Design(Congestion) Description

Congestion Insert congestion on the road or junction

Cost Insert how heavy is the road traffic

congestion

Place The uniqueness of the Congestion

Go Spot the Congestion based on its Place

number

Clear Remove the Congestion based its Place

number

Clear_All Remove all the Congestion

Previous Go to Design(Secondary sensor) page

Next Save the map in Mapping page


94

5.2.2.1.4 Mapping

After designing the map, the admin must save the map as shown in Figure 5.31

and Figure 5.32.

Figure 5.31: Select a name for the map

95

Figure 5.32: Insert the location for the map

Mapping Description

Save Save the map particulars in the database

Reset Rewrite the particulars

Test Go to Dynamic Map page to analyze the

map


5.2.2.1.5 Dynamic Map

Then, the admin can test the design in USER page as shown in Figure 5.33. Start

x,y will automatically display the location of the emergency vehicle once the vehicle

switch on the tracking device. After the destination location is inserted, the Send button

is clicked. The system will guide the emergency vehicle providing shortest path route

using dead-reckoning techniques. GSM information is displayed in the Status box.

96

Figure 5.33: Test the map

DynamicMap Description

Select Map Choose the map from the above combo

box

Start X,Y It will automatically inserted once the

tracking device is switched on

Destination X,Y User need to insert the destination

location

Location X.Y Display the user the location of the map

when the mouse hover over the map

97

Send Start the A* calculation. It only need to

be clicked once. It will iterate until the

user reaches it destination

Back Go to the Main page

Exit End the application

Reset Map Clear the path shown in the map

Status Show the GSM operation whether it fails

or succeed to send the message


5.2.3 Scenario Example

Figure 5.34 display a map that is similar as discussed in Chapter 4. The

emergency vehicle drivers usually use the same path as shown in Figure 5.35 without

noticing the high congestion in ahead.

Figure 5.34 : Example Map

98

Figure 5.35: Normal path used

Congestion ID Congestion Weight

1 99

2 66

Table 5.13: The congestion level

Figure 5.36: Assign the congestion level

99

This example shows you how congestion feature can enhance the emergency

vehicle response time at Figure 5.36 and Figure 5.37. If there is a heavy congestion

between intersection B and A, the cluttered intersection issue can be solved by using

alternative path shown in Figure 5.37 based on the congestion table at Table 5.13.

Figure 5.37: Alternative path

5.3 Traffic Light Controller (Module 3)


The control central will transmit interrupt signals to the particular traffic light

controllers. These traffic light controllers will alter the traffic light phase to permit or to

grant green light for the emergency vehicle.

100

Figure 5.38: Block diagram of traffic light controller

Figure 5.38 shows block diagram on how the connection between traffic light controller

modules is done. UART communicate with the GSM to attain short message service

(SMS) data which is needed to interrupt GPIO of the traffic lights. Microblaze

processor uses the SMS data to trigger GPIO (Expander headers). PLB is a bus which

connects all the blocks. A breadboard of LEDs is connected to the expander headers to

illustrate the traffic flow when preempted and calibrated. Blocks of traffic lights

(Traffic Light 1, Traffic Light 2, Traffic Light 3, Traffic Light 4) based on Figure 5.38

are referred to as breadboard of LEDs. Figure 5.39 shows how the GPIO signals are

used to preempt the intersection. Figure 5.40 shows the module 3 program pseudocode.

101

Figure 5.39: Traffic Light controller flow chart

102

Traffic light controller

1. START

2. Write “AT “// Send to GSM

3. Wait for input

4.


6. Wait for input

7.

8. Write “AT + CMGD =1” // Send to GSM

9. Wait for input // Wait for GSM reply for GMGD request

10.

11.Sleep for 10 seconds

12.Wait for input // Wait for any message receive

13.

14.Write “AT + CMGR=1”

15.Read String

16.

17. If String = 0

18. {

19. Output = “001” // Calibrate all the traffic lights to normal

20. }

21. Else If String = 1

22. {

23 Output = “010” // Trigger the 1st traffic light to green and the rest red

24. }


103

26. {

27. Output = “011” // Trigger the 2nd traffic light to green and the rest red

28. }


30. {

31. Output = “100” // Trigger the 3rd traffic light to green and the rest red

32. }


34. {

35. Output = “101” // Trigger the 4th traffic light to green and the rest red

36. }

37. End If

38.

39.GOTO // go to number 8

40.

41.

42.END

Figure 5.40: Pseudocode for system module 3

104


Figure 5.41: Traffic light controller devices

The concept of this traffic light operation is similar to the pelican-crossing. The

only dissimilarity is that traffic light actuation is based on the data received from the

central instead of input from people who want to cross the road. The connection of the

devices is shown in Figure 5.41.

In this design, Traffic Light Controller will be function to control the traffic light

cycle. The controller will receive interrupt signal sent by the central system via its GSM

modem.

The expansion header is used to trigger the LED. The breadboard LED

represents 4 traffic lights in an intersection. There are many more expansion headers

that can be used to create more traffic lights as shown in Figure 5.41. The clearer view

of the traffic lights connection is shown in Figure 5.42. The connections at FPGA pins

are shown in Table 5.14.

105

Figure 5.42: Expansion header wiring

Components FPGA Pin

LED_1_GREEN J6,Pin 2

LED_1_YELLOW J6,Pin 4

LED_1_RED J6,Pin 6



LED_2_RED J6,Pin 18



LED_3_RED J6,Pin 30



LED_4_RED J6,Pin 42

106

Interrupt_0 J6,Pin 32



System clock AE14

Table 5.14: Expansion header pin location

Figure 5.43 : Example of four traffic lights at one intersection

Figure 5.43 displays the flow of four traffic lights. In Figure 5.44, all the traffic

lights are triggered yellow before turning to different phase during calibration. When

the traffic lights start to calibrate, all the traffic lights will be in blinking YELLOW state

before coming to a normal phase. This is to alert the pedestrians and the non-emergency

vehicles about the calibration.

107

Figure 5.44: All the traffic lights display AMBER.

COMMAND DESCRIPTION

AT Attention.


AT+CMGD = n Delete message at index n

AT + GMGR= n

Read message at index n


Table 5.15 shows the AT command used for GSM communication. Each

intersection has their distinctive GSM number. The interrupted signal is converted by

the Microblaze softcore processor into three bits GPIO signals to control four traffic

lights in a single intersection. The RTL design in ISE is shown from Figure 5.45 to

Figure 5.47. Figure 5.48 displays the block diagram in EDK.

108

Figure 5.45: RTL Schematics

109

Figure 5.46: RTL Schematics on Top Level

110

Figure 5.47: Details of RTL schematics on system_i

111

Figure 5.48: Block diagram for module 3

ML401 is functioning at 100 MHz. Therefore, it needs to be slowed down to

1Hz. 1Hz is equivalent to 1 second for a single traffic light cycle. The calculation is

shown in Figure 5.49

112

Figure 5.49: Clock rate division

113

Figure 5.50: ISE clock division

Figure 5.50 displays the clock rate is divided by 10 for 8 times to make it

become 1Hz. The illustration of division idea is clearly shown in Figure 5.51. The

output is then port map to supply clock rate at 1Hz for the program.

114

Figure 5.51: Illustration clock rate division

115

Figure 5.52: Normal traffic light flow

Figure 5.52 displays the overall flow of the four traffic lights for an intersection.

001, 010 and 100 in the circle represent green, yellow and red signal respectively for

particular traffic light. Table 5.16 and Figure 5.53 displays the changes of traffic lights

based on the interruption received. Every traffic light will trigger yellow signal once it

receives calibration interrupt. This is to avoid the drivers from sudden shock of the

traffic light signal changes.

116

Table 5.16: Traffic light flow based on interrupt received

117

118

119

120

Figure 5.53: Testbench of the traffic lights

121

5.4 Conclusion

The implementation process of the SEVP is explained in this chapter. The SEVP

process is explained in each module in order to provide a vivid understanding of the

system. Module 1 and module 3 of the system is focused on hardware aspect. Module 2

provides clarification on the software feature. Chapter 4 intersection site is taken as a

case example to demonstrate how SEVP capable to solve cluttered intersection problem

and alternative route problem.

.

122

Chapter 6 Conclusion

Emergency Vehicle Preemption (EVP) is a system that intervenes in the normal

operation of traffic control systems to grant emergency vehicles to pass through. In this

thesis, conventional EVP is studied in order to identify their problems and room for

improvements. Based on the information collected, three main problems are identified.

The first problem is related to short range signal (e.g. light, sound or radio wave signals)

utilized in the conventional system. The short range signal has the drawback to only

trigger one traffic light intersection at a time. The inability to preempt more than one

traffic light intersections will lead to cluttered intersection problem where red

intersections ahead will halt the emergency vehicle from passing through the green pre-

empted intersection. The following problem is classified as the lane preemption

problem. In the conventional system, the emergency vehicle must use exact lane to

trigger the intersection ahead. The exact lane has to be chosen since the sensor is

located at each lane. To trigger the left traffic light which leads to the left path for

instance, the emergency vehicle must use the left lane. This restriction is not suitable in

emergency cases since emergency personnel will generally decide on a faster lane. The

third problem is classified as alternative route problem where in this class, conventional

EVP does not provide a clear navigation of alternative path that consume less time. All

the problems are verified using data collection method in the earlier chapter.

Smart Emergency Vehicle Preemption system (SEVP) is proposed to overcome

the drawbacks of short range signal difficulty, incorrect lane problem and alternative

route quandary. The system grants green lights to more than one intersection within the

distance or threshold set. Positioning technique and A-star (A*) shortest path algorithm

is used in the proposed system to permit the system to control and to calibrate road

traffic light systems using wireless communications installed on emergency vehicles

123

and traffic intersections. The SEVP is divided into three modules where the first module

focuses on tracking the emergency vehicle. FPGA embedded with Xilinx Microblaze

soft processor core and SIM 508 GPS/GSM modem is installed on the emergency

vehicle for tracking purpose. The FPGA will filter unnecessary GPS data to get the

current latitude and longitude of the emergency vehicle. Then, the filtered data is

transmitted to the central control via GSM modem. In the second module, the central

control will receive the current position of the emergency vehicle as well as the location

of the emergency scene and then process the A* algorithm to obtain shortest path route

to the destination. The centre will send interrupt command to traffic controllers within

the selected route and distance threshold set to clear the cluttered traffic in front.

Modification on the traffic light controller is done in the third module. The intersection

controller will use the interrupt value to trigger the particular traffic light to green and

trigger the other traffic lights at the junction to be red. The controller is then calibrated

to normal mode after the emergency vehicle passed each traffic light intersection.

Testing process is done to verify whether the project system is functioning in a

proper manner or vice versa. Debugging tools in C#.Net is used to ensure the entire

program flow operate correctly for the third module. ISE simulator is used to validate

the hardware part of process and behavior structure in first module and second module

of the system. In addition, computer Hyperterminal interface is employed to check

hardware and PC interfacing.

For future enhancement, the system can be improved by discarding the central

control intervention. Microblaze soft processor core for Xilinx FPGA provides more

flexibility for the system designer to work on processor based system. User designed

hardware module can be interfaced with this soft processor core within the FPGA itself.

The coprocessor interface accelerates complex algorithms by transferring parts or the

wholeness of the computation to a user-designed hardware module. In order to omit the

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central intervention, all the GPS core, GSM core, and A-star core can be embedded in

one Xilinx FPGA which able to provide appropriate path to the driver and able to

interrupt the traffic light phase.

The system only allocates a calculation of one emergency case at one time.

Future enhancement can be done by implementing calculation on more than one vehicle

at a time. This can perk up the efficiency of the system.

Security aspect is not covered for the design of this system. But for future

enhancement, security can be focus on the SMS aspect. There is a security issue occurs

in this system which involve the interrupt value sent by SMS. If anyone who perceives

the line number of the traffic light’s GSM modem and the value for interruption, he can

triggers the interruption anytime.To avoid from unauthorized use, Xilinx FPGA can be

embedded with encryption technique for security purpose.

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APPENDIX : Perceiving Intersection Characteristic Understanding the each intersection traffic light phase will ultimately provide a clear view of the problem faced by the emergency vehicles. Thus, each intersection phases (except intersection F) are explained. 1 Intersection A 1.1 “Bird Eye” View

Fig 15: Traffic intersection A flow diagram

1.2 Time/Traffic Light Table

A-1 A-2 A-3 A-4 A-5 A-6 PHASE6:29:00pm G R G R R R 1 6:30:05pm Y R Y R R R 1 6:30:08pm R G R G R R 2 6:31:03pm R Y R Y R R 2 6:31:06pm R R R R G G 3 6:31:40pm R R R R Y Y 3 6:31:46pm G R G R R R 1

Table 2: Time/Traffic light – Phase for intersection A 1.3 Intersection-A Phasing Diagram

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Fig 16: Phase 1 of Intersection A


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2 Intersection B 2.1 “Bird Eye” View

Fig 19: Traffic intersection B flow diagram


B-1 B-2 B-3 PHASE 6:29:00pm R R G 1

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6:29:22pm R R Y 1 6:29:48pm R G R 2 6:30:11pm R Y R 2 6:30:13pm G R R 3 6:31:06pm Y R R 3 6:31:10pm R R G 1

Table 3: Time/Traffic light – Phase for intersection B

2.3 Intersection-B Phasing Diagram

Fig 20: Phase 1 of Intersection B


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3 Intersection C 3.1 “Bird Eye” View

Fig 23: Traffic intersection C flow diagram

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C-1 C-2 C-3 C-4 PHASE 6:29:00pm Y R R R 1 6:29:26pm R R R G 2 6:30:01pm R R R Y 2 6:30:03pm R G R R 3 6:30:33pm R Y R R 3 6:31:01pm R R G R 4 6:31:20pm R R Y R 4 6:31:03pm G R R R 1

Table 4: Time/Traffic light – Phase for intersection C

3.3 Intersection-C Phasing Diagram

Fig 24: Phase 1 of Intersection C

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4 Intersection D 4.1 “Bird Eye” View

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Fig 28: Traffic intersection D flow diagram


D-1 D-2 D-3 PHASE 6:29:00pm R R Y 1 6:29:04pm G R R 2 6:29:59pm Y R R 2 6:30:01pm R G R 3 6:30:29pm R Y R 3 6:30:33pm R R G 1

Table 5: Time/Traffic light – Phase for intersection D

4.3 Intersection-D Phasing Diagram

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Fig 29: Phase 1 of Intersection D


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