Hệ thống đa tác tử áp dụng cho vấn đề mô phỏng giao thông ở Việt Nam_2

List of Abbreviations MAS – Multi agent system ABM – Agent Based Model VTS – Vietnam Traffic Simulator VISSIM – Visual Traffic Simulation System KDT – Khuat Duy Tien TDH – Tran Duy Hung

ĐẠI HỌC QUỐC GIA HÀ NỘI TRƯỜNG ĐẠI HỌC CÔNG NGHỆ

NGƯỜI HƯỚNG DẪN KHOA HỌC: PGS TS BÙI THẾ DUY

Hà Nội - 2013

ORIGINALITY STATEMENT

‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at University of Engineering and Technology (UET/Coltech) or any other educational institution, except where due acknowledgement is made in the thesis Any contribution made to the research by others, with whom I have worked at UET/Coltech or elsewhere, is explicitly acknowledged in the thesis I also declare that the intellectual content

of this thesis is the product of my own work, except to the extent that assistance from others in the project’s design and conception or in style, presentation and linguistic expression is acknowledged.’

Hanoi, October 7th, 2013

Signed

ABSTRACT

The VTS is a system that allows users to design different road systems as well as

to create different simulation scenarios with different agent profiles It was built

in 2010 based on the theory of Agent and Multi Agent System During 2011 and

2012, it was improved and many experiments were performed regarding to the real data collected from VOV traffic online The results are promising and we hope that it could be able to help the traffic planners to solve the sore issues of traffic in Vietnam at the moment

PUBLICATION

*The Duy Bui, Duc Hai Ngo, Cong Tran, Multi-agent based Simulation of traffic in Vietnam, 13th International Conference, PRIMA, Kolkata, India, pp 636-648, 2010

TABLE OF CONTENT

List of Figures v

List of Tables v

List of Abbreviations vi

Acknowledgement vii

Chapter 1 Introduction 1

1.1 Motivation, objectives and approach 1

1.2 Outline of the thesis 2

Chapter 2 Literature Review 3

2.1 Models of traffic simulation 3

2.1.1 Scope 3

2.1.2 Time 9

2.1.3 Multi-agent system for traffic simulation 11

2.2 Conclusion 14

Chapter 3 Vietnam Traffic Simulator 15

3.1 Introduction to multi-agent system 16

3.1.1 Agent 16

3.1.2 Multi Agent Systems – MAS 18

3.1.3 Agent based model – ABM 19

3.1.4 ABM development 19

3.2 Modeling 20

3.2.1 The road system 21

3.2.2 Agents representing traffic participants 22

3.2.3 Agent’s planning 23

3.3 Improvement 26

3.3.1 Additional Features 26

3.3.2 Correction 27

Chapter 4 Evaluation 29

4.1 Method 29

4.2 Results 34

4.3 Discussion 37

Chapter 5 Conclusion 38

5.1 Conclusion 38

5.2 Future development 38

REFERENCES 39

List of Figures

Figure 1 VISSIM visual interfaces 4

Figure 2.VISSIM statistic fuction 4

Figure 3.Traffic light simulation system 10

Figure 4 Highway simulation system 12

Figure 5 A part of highway road 13

Figure 6 Road Area 22

Figure 7 Connection road areas .22

Figure 8 Detecting possible collisions .26

Figure 9 Interface and simulation of the traffic light 27

Figure 10 Some examples of real time traffic data 30

Figure 11 the Khuat Duy Tien – Tran Duy Hung crossroad in the simulator 30

Figure 12 the Khuat Duy Tien – Tran Duy Hung crossroad captured by the traffic camera 31

Figure 13 Distribution of inflow vehicles in real data 33

Figure 14 Timegraph of inflow inflow vehicles in real data 33

Figure 15 The worst case of achieved results 34

Figure 16 The best case of achieved results 34

Figure 17 Normalization of achieved results 35

Figure 18 The decrease rate of velocity 36

Figure 19 Traffic light data observation 36

List of Tables Table 1 An example of randomized parameters 28

Table 2 Parameters of KDT – TDH crossroad 30

Table 3 The information query form 32

Table 4 An example of query data 32

Table 5 Default parameters of the simulation 32

List of Abbreviations

MAS – Multi agent system

ABM – Agent Based Model

VTS – Vietnam Traffic Simulator

VISSIM – Visual Traffic Simulation System KDT – Khuat Duy Tien

TDH – Tran Duy Hung

PH – Pham Hung

HL – Hoa Lac

Acknowledgement

First and foremost, I would like to express my deepest gratitude to my supervisor, Ass.Prof Bui The Duy, for his patient guidance and continuous support throughout the years He always appears when I need help, and responds

to queries so helpfully and promptly I would like to give my honest appreciation to my co-partner Ngo Duc Hai for his kindly support although he had to prepare for his study oversea I would also like to thank my friend, Vu Tien Thanh, for his kindly help I sincerely acknowledge all my lectures in University of Engineering and Technology, Vietnam National University, Hanoi, for guidance in my master study Finally, this thesis would not have been possible without the support and love of my family Thank you!

Chapter 1 Introduction

1.1 Motivation, objectives and approach

In Vietnam, the transportation system is now facing many problems in terms of congestions and accidents Especially in big cities like Hanoi, the transportation system is chaotic, due to narrow roads, increasing number of vehicles, and lack

of consciousness to follow the traffic rules from participants Many solutions have been proposed and implemented which imposed a great effect on the development of the transportation system itself as well as awareness of the whole society However, most of these solutions usually require a huge financial effort to be able to prove effectiveness Therefore, a method which helps reduce the cost of improving the current transportation situation should draw attention

of researchers It is the reason why I was motivated to do my thesis regarding to this theme

In developed countries, transportation planners always have to have a strategic vision which can identify a clear plan to develop the transport system Such knowledge could be attained by experimenting on traffic simulators With information provided by these simulators, the policy makers can figure a way to reduce the cost of traffic infrastructure building Literally, the use of multi agent system in simulating the behavior of the society is a common trend of solving problems like transportation Following this trend, we started to build the Vietnam Traffic Simulator (VTS) based on the multi agent system model under the guidance of Assc Prof Bui The Duy in 2010[17] This thesis mainly aims to strengthen the correctness of the VTS

To phrase it another way, the completion of the evaluation for this simulator is the main target of this thesis It requires some approaches in both proactive and reactive ways With the base knowledge acquired from research of MASs, I

added some additional features and improved the structure of VTS to be more suited for the traffic in Vietnam To be more specified, I had gathered data from many sources, had added a function, had corrected the behavior of the simulator and then I implemented to evaluation phase

1.2 Outline of the thesis

The outline of the thesis is as following: Chapter 2 will be the literature review about traffic simulation models and the approach based on the Multi-agent model Chapter 3 is about some main features of Vietnam Traffic Simulator, including some new improvement after the short paper presented in PRACSYS

2010 [17] The evaluation steps will be presented in chapter 4 The last chapter

is the conclusion and future research

Chapter 2 Literature Review

2.1 Models of traffic simulation

Traffic simulation can be used to: find treatments for a problem of a traffic system; test new designs of transportation facilities before the commitment of resources to construction; analyze safety of a system; or train traffic management personnel [6] Due to the complexity of the transportation system, there are two ways of modeling it with regards to scope and time In this section

we will introduce some models that are used to be the base stones of Vietnam Traffic Simulator with regards to three categories: time, scope and multi-agent based system

2.1.1 Scope

Simulation models of traffic can be categorized by level of detail: macroscopic [4, 8], microscopic [1, 9, 10, 11], mesoscopic [2, 7], and nanoscopic [3] A macroscopic model describes entities and their activities and interactions at a low level of detail For example, the traffic stream may be represented in some aggregate manner such as a statistical histogram or by scalar values of flow rate, density and speed A microscopic model describes both the system entities and their interactions at a high level of detail A mesoscopic model generally represents most entities at a high level of detail but describes their activities and interactions at a much lower level of detail than would a microscopic model With nanoscopic models, nano simulation attempts to model drivers’ steering behaviour and more detailed components of perception-reaction time in order to depict the the human performance

* Visual Traffic Simulation System

In this subsection we introduce a system named Visual Traffic Simulation System (VISSIM) which is one of the mesoscopic systems developed by Thomas Fotherby [14] This system is diverse in many kinds of traffic systems simulations In details, it provides function to design the transportation infrastructure with detailed information of flowing vehicles such as numbers of cars, trucks and their velocities

Figure 1 VISSIM visual interfaces

Figure 2.VISSIM statistic fuction

This system consists four application components: Road Network Designer, Traffic Modelling Designer, Visual Simulation, Application Results We will summarize some main features of these components that are being used as suggestions for VTS as below:

 Road Network Designer

This section of the application should allow a user to quickly design simple schematic road diagrams (road networks)

Variables:

- The application should be to-scale (e.g x screen pixels per metre)

- The application should start by showing a drawing panel as a blank designing area (representing a x*x m square area)

- Assume terrain is always flat (a simplification)

- Road designs should be able to be saved and loaded

 Traffic-Modelling Tool (Pre-condition: a valid road network.)

For the application to be realistic and produce useful results the user must be able to specify the traffic data that the simulator will use This data may be based on real observations obtained from electronic detection devices and traffic surveys

Road network facts:

- A junction has inputs and outputs

- Each junction has unique input and output traffic-flow intensities

- The input traffic-intensity of one junction will be a function of the output traffic-intensities of other junctions

- A certain amount of cars will enter the system according to some kind

of control element

- A car can start at any input into the system and go to any output

- All cars should eventually exit the system (No infinite loops)

Requirements:

- For each input to the system users should be able to specify the average or exact number of cars per minute that will enter This will require labelling of the roads in the designed road network

- There should be an option to randomise the car input data each time the simulation is run, or otherwise the simulation will run with precisely the same data (the same number of cars enter at the same time)

Panel features:

- Traffic-flow models should be able to be saved and loaded

 Visual Simulation (Pre-condition: A valid road network.)

This section should present animated graphics with drawn-to-scale vehicles moving through the geometry of the system The traffic that is animated is generated and controlled according to statistics specified by the "traffic-modelling tool"

Vehicle behaviour model:

- Cars obey a speed limit This is their "top speed" An example maybe between 50 and 60 kilometres/hour (31-37mph)

- Cars enter the system at top speed at positions and times according to a set traffic-model specified by the "traffic-modelling tool"

- Cars do not collide

- Cars can only enter the system if they are in a valid position (Not a collision)

- Cars can only change lanes at junctions (No U-turns)

- Cars will always try to go at their top speed when possible but their speed is governed by the "car-following model" described below

- Cars can only change speed by accelerating or decelerating Acceleration will be a constant value (for example 5m/s2) De-acceleration measures should be sensible (i.e a car should not be able

to stop in no time)

- Cars do not take independent decisions A car travel route and the lane

it is in depends entirely on its starting position and the statistical decisions of the junctions it passes through

Car following model:

- A Car will travel at its top speed limit unless it is within 10m of another car

- It must de-accelerate to match the other cars speed by the time there is

a 3m distance

- It must never go within 1m of another car on the same lane

Car pull-up model:

- Cars follow this model when pulling up to red lights, give-way signs or

if there is stopped traffic ahead

- At a suitable distance before the obstruction the car will de-accelerate with a constant value to stop in time

Lane changing behaviour model:

- The project is simplified to not include overtaking

- A car will only change lane at junctions according to the junction traffic-model statistics

Vehicle behaviour at give-way junctions

- Cars on the main route are unaffected and travel as normal according

to the car-following model

- Cars on the slip roads "pull up" to the give-way line to check for oncoming traffic

- Cars on the slip-road can join the main-route if they aren't going to obstruct the cars on the main-route I.e there must be a suitably large clear section of traffic on the main route This is the gap-acceptance model

Vehicle behaviour model at signalled junctions:

- Signals are independent for each input lane

- Cars will "pull-up" to the stop line if the signal is red

- The signal is two-phase Go is green, stop is red

- On a green signal the car is specified an output lane (according to the traffic-model of the junction) and will travel to the output lane in a direct route

- Traffic light timing intervals will be initially split fairly between different sets Later, traffic lights can be re-programmed to be more intelligent

- The colour of a traffic light will be conveyed on the screen by the colour of the stop line at a particular lane In addition if the light for a lane is green there should be arrows displayed on the junction specifying where cars have the option of going

Dynamic traffic controls:

- For each input to the system there should be a control to increase or decrease the traffic entering at that input

 Application Results

Each component of the simulated traffic system should log data:

- Each input and output of the system should have a log of how many cars passed through

- Every junction should log how many cars passed through each input and output lane

- Each traffic-light junction should store the timing intervals of each light

- There should be traffic flow data for the system as a whole (Number

of cars passed through per second)

- There should be a value estimating total surface area of road surface used in the current network design

*All of these features are implemented in the VTS

2.1.2 Time

Time is a basic independent variable in almost all traffic simulation models Continuous simulation models describe how the elements of a system change state continuously over time in response to continuous stimulation Discrete simulation models represent real-world systems by asserting that their states change abruptly at points in time There are generally two types of discrete models: discrete time (e.g [9, 1]) and discrete event (e.g [7]) With discrete time models, activities which change the states of the system elements are computed within each time interval The discrete event models only perform the calculation based on the happening of events

* Intelligent Traffic light control system

In this subsection we introduce a simulator named Green Light District Simulator developed by Utrecht University (Netherland) [7] This is a system which supports the determination in duration of traffic lights

Figure 3.Traffic light simulation system

Basically, it is a microscopic traffic simulation system However, it also includes discrete events based on time and some parameters such as the density of traffic, average velocities of vehicles, etc… These information are used to automatically suggest the duration of traffic lights

The main components of this system are:

- Drive Lane consists of two parallel lines

- Road made by 2 Drive Lane It includes information about direction, incoming and outgoing gates which form the transportation network

- Node is the term describing cross cuts between conjuction and crossroad

- EdgeNode describes areas in which cars go in and out

- Sign describes the traffic lights These places are the points where the duration adjustment algorithm is deployed automatically

- Cars play an important role in the simulation However, due to the main target of this simulation is automatic traffic light adjustment, the model of moving vehicles is simplified

During the simulation phase, the system gathers statistical data such as density, number of incoming and outgoing vehicles in order to provide parameters for the duration adjustment algorithm of traffic lights

2.1.3 Multi-agent system for traffic simulation

As a powerful tool of microscopic simulation, multi-agent based simulation has been used for traffic domain, e.g [13, 11] Giving each vehicle three subsystems, including Controller, Sensors and Driver model, Sukthankar et al [13] have simulated every detailed movement of vehicles By calculating the movement of each agent based on finite state machine, Wan and Tang [11] have simulated a traffic flow which comprises of autonomous agents/vehicles Both systems use 3D graphics to display the simulation

* Simulated Highways for Intelligent Vehicle System

This is a simulator developed by Rahul Sukthankar, Dean Pomerleau and Charles Thorpe [13] The name of this system is Simulated Highways for

Intelligent Vehicle Algorithms (SHIVA) and it is a microscopic traffic simulation system due to the exquisite length of the highway in constrast with the low density of traffic lights and houses Usually, the speed of the vehicles travelling on the highway are really high, it is the reason why this system focus

on calculation of the details of the vehicles to ensure the safety of the highway

Figure 4 Highway simulation system

The system includes 2 models: Highway road model and transportation model

 Highway road model:

This model describes a net of highway road including many long roads connected together The basic element is called RoadSegment The width of these roads are varies, but they are always equal to a multiplier of a number called “lanewidth” Besides, they also include information about some narrowed part called RoadSlice, the connector to connect different roads together and the maximum velocity of the vehicles travelling on that Segment

Figure 5 A part of highway road

 Transportation model

This is a complicated model, it includes 3 components: Controller, sensor, driver

- Controller component: this component will control the behavior of the drivers including angle and direction steering and speed adjustment

- Sensor: This is the component which allows the driver to sens other vehicles’ behavior such as: increasing speed, decreasing speed, steering It is flexible enough for the controller component to function

- Driver: This component is the component making decisions such as lane choosing Based on the information gathered from sensor component, an algrorithm will be executed to calculate the most intelligent decision of the drivers

The system allows users to define different types of big vehicles such as: trucks, cars, containers They can define not only the size but also other parameters such as the ability to adjust speed

2.2 Conclusion

Recent section is about some main features of some traffic simulation systems that we conducted research Most of these systems are microscopic system; it means they simulate the behavior of drivers in details Furthermore, these systems allow users to create a flexible road system Moreover, they all have a fully supported report component A traffic simulation system takes a “scenario”, e.g a road system or a highway network configuration, and produces the simulation results in two formats: statistical and graphical Quantitative descriptions of what is likely to happen can be provided by the statistical results while the graphical and animated results can provide the user with insights to understand why the system is behaving this way

In the next section, we will briefly introduce our model used in a simulator named VTS which applies the multi-agent based model

Chapter 3 Vietnam Traffic Simulator

Through experiences and knowledge gained by learning these models, it is our decision to choose a model to apply for the traffic situation in Vietnam As stated above, the Vietnamese transportation system is more complicated than other systems oversea due to the existence of motorbikes - the flexible and convenient but indiscipline vehicles What do we mean about this indiscipline vehicle is that it usually goes unpredictable, for example, it can turn right or left

or even turn round back without regards to the traffic rules Follow that, cars or buses sometimes also make complicated moves In short, they do not give way according to the traffic rules The problem is much worse when the traffic participants do not recognize the benefit of following rules As a result, they behavior follows their instinct For example, logically we can understand that when waiting for the vehicles in front, stopping in the intersection is obstruct-ing the traffic flow But instead of waiting on their lanes, the traffic participants will always try to fill in any space in front of them, or even to the left or the right

of the opposite lane if there is obstruction in front In addition, the road in Vietnam is also more complex with many different structures, narrow roads, small crossroads center, etc It is ought to understand that the simulators presented cannot be used a tool to solve this problem since the behavior of the entities in these simulators are much simpler That is the reason why we decided

to build a whole new simulator which is dedicated to be the best suited for the traffic in Vietnam

As described, the simulation of traffic in Vietnam has too many different parameters Thus, finding a mathematic model for this problem is very difficult The multi-agent based model is our choice to apply to the simulator we were going to build at that time It has a flexible capacity which allows interactions

between drivers and drivers to environment (road segments, traffic lights) Therefore, it is an advantage to model the traffic situation in Vietnam currently

3.1 Introduction to multi-agent system

In this section, we would like to introduce a few basic concepts of agents and multi-agent based systems These are relatively new concepts which attract many researchers

 “An agent is an entity that senses its environment and acts upon it” (Russell, 1997);

 “The term agent is used to represent two orthogonal entities The first is the agent’s ability for autonomous execution The second is the agent’s ability to perform domain oriented reasoning.” (the MuBot Agent);

 “Intelligent agents are software entities that carry out some set of operations

on behalf of a user or another program, with some degree of independence or autonomy, and in so doing, employ some knowledge or representation of the user’s goals or desires.” (the IBM Agent);

 “An autonomous agent is a system situated within and a part of an environment that senses that environment and acts on it, in pursuit of its own agenda and so as to effect what it senses in the future.” (Franklin, Gasser, 1997)