i DESIGN AND SIMULATION OF ADAPTIVE CRUISE CONTROL USING MATLAB/SIMULINK MOHD FIRDAUS BIN JAHAR This report is submitted in partial fulfillment of the requirements for the award of Bachelor of Electronic Engineering (Industrial Electronics) With Honours Faculty of Electronic and Computer Engineering Universiti Teknikal Malaysia Melaka APRIL 2009
ii UNIVERS TI TEKNIKAL MALAYS IA MELAKA FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA II Tajuk Projek Sesi Pengajian : DESIGN AND SIMULATION OF ADAPTIVE CRUISE CONTROL USING MATLAB/SIMULINK : 2008/2009 Saya MOHD FIRDAUS BIN JAHAR (HURUF BESAR) mengaku membenarkan Laporan Projek Sarjana Muda ini d isimpan di Perpustakaan dengan sy aratsyarat kegunaan seperti berikut: 1. Laporan adalah hakmilik Universiti Teknikal Malaysia Melaka. 2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan laporan ini sebagai bahan pertukaran antara in stitusi pengajian tinggi. 4. Sila tandakan ( ) : SULIT* (Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972) TERHAD* (Mengandungi maklumat terhad yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan) TIDAK TERHAD Disahkan oleh: (TANDATANGAN PENULIS) (COP DAN TANDATANGAN PENYELIA) Alamat Tetap: KAMPUNG BARU JALAN PANJANG, 28030 TEMERLOH, PAHANG DARUL MAKMUR. Tarikh: 30 APRIL 2009 Tarikh: 30 APRIL 2009
iii I hereby declare that this report is the result of my own work except for quotes as cited in the references. Signature : Name : MOHD FIRDAUS BIN JAHAR Date : 30 APRIL 2009
iv I hereby declare that I have this report and in my opinion this report is sufficient in terms of the scope and quality for the award of Bachelor of Electronic Engineering (Industrial Electronics) With Honours. Signature : Supervisor s Name : EN. ZULKARNAIN ZAINUDIN Date : 30 APRIL 2009
v Dedicated especially to my father and my beloved mother.
vi ACKNOWLEDGEMENT First and foremost, I would like to take this opportunity to thank my project supervisor, Zulkarnain bin Zainudin for his invaluable guidance, assistance and support throughout the project. Under his supervision, many aspects regarding on this project has been explored, and with the knowledge, idea and support received from him, this thesis can be presented in the time given. I also would like to thank all the lecturers at FKEKK for the lessons and guidance given. Not forget to all my friends and course mate for their help and ideas during the course of this study. Finally, I would like to thank my family for their continuous concerns, encouragement and support.
vii ABSTRACT This project presents the design and implementation of an adaptive cruise control (ACC), which is a system that maintains the speed of a car and also keeps a minimum distance to the closest vehicle in front. The speed of the car be maintained by using a Proportional-Integral-Derivative (PID) controllers that based on the desired speed from the driver. The classical method of tuning process of setting the P, I, and D tuning constants for the CC system is used.will be compare to the ACC system simulation. Further, the ACC system has been evaluated based on the eleven test cases with Signal Builder. The Simulink is used as the simulation software because of the short learning curve that most students require to start using it, its wide distribution, and its general-purpose nature. This project will demonstrate the advantages of using Simulink for analyzing the proposed PID Controllers in ACC system.
viii ABSTRAK Projek ini membincangkan mengenai merekabentuk dan mengaplikasikan Kawalan Adaptif Kelajuan Kenderaan (Adaptive Cruise Control), iaitu suatu sistem yang boleh mengekalkan kelajuan kereta dan juga mengekalkan jarak minimum kereta dengan kenderaan di hadapan. Kelajuan kereta ini dapat dikawal menggunakan pengawal PID berdasarkan kelajuan yang dikehendaki oleh pemandu. Proses klasik digunakan bagi menala pemalar P,I dan D untuk sistem CC akan dinilai dengan simulasi sistem ACC. Selanjutnya tindak balas respon ACC akan dinilai dan disimulasi berdasarkan sebelas ujian kes dengan pembina signal. Simulink diguna sebagai perisian pensimulasian kerana pembelajaran jangka pendek yang sangat diperlukan oleh pelajar untuk mula menggunakannya iaitu bidang yang luas dan pelbagai guna dengan alam semulajadi. Projek ini akan mendedahkan kelebihan menggunakan Simulink untuk menganalisis pengawal PID dalam sistem ACC.
ix TABLE OF CONTENTS CHAPTER CONTENT PAGE PROJECT TITLE VERIFICATION FORM DECLARATION VERIFICATION DEDICATION ACKNOWLEDGEMENT ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS LIST OF APPENDICES i ii iii iv v vi vii viii ix xiii xiv xvii xviii I INTRODUCTION 1.1 Background of Project 1 1.2 Objectives of Project 4 1.3 Statement of Research Problem 5 1.4 Scope of Project 6 1.5 Method of Project 6 1.6 Outline of the Thesis 7
x II LITERATURE REVIEW 2.1 Signal Builder 8 2.2 ACC Controller 9 2.2.1 Stateflow chart 11 2.2.1.1 Stateflow Debugger 12 2.2.1.2 Stateflow Chart Model Coverage 13 2.2.1.3 Coverage Reports 14 2.2.2 PID Controller 16 2.2.2.1 Zero-Order Hold 17 2.2.2.2 Discrete-Time Integrator 17 2.2.2.3 IC 19 2.2.2.4 Unit Delay 20 2.2.2.5 Proportional 21 2.2.2.6 Integral 22 2.2.2.7 Derivative 23 2.3 Tuning a PID Controller 25 2.4 ACC vehicle dynamics 27 III METHODOLOGY 3.1 Modeling Process of ACC System 29 3.1.1 Defining the System 31 3.1.2 Identifying System Components 31 3.1.3 Modeling the System with Equations 32 3.1.4 Building the Simulink Block Diagram 32 3.1.5 Running the Simulation 32 3.1.6 Validating the Simulation Results 33
xi 3.2 Design Requirements 33 3.2.1 Creating Test Cases 33 3.2.2 Constructing the Test Cases 33 3.2.2.1 Test Case 1 34 3.2.2.2 Test Case 2 35 3.2.2.3 Test Case 3 36 3.2.2.4 Test Case 4 37 3.2.2.5 Test Case 5 38 3.2.2.6 Requirements 5 9 39 3.2.2.7 Custom Signals 42 3.2.3 Command Line API 43 3.2.4 Running the Tests 44 IV SIMULATION RESULT AND DISCUSSION 4.1 Simulation Parameters 45 4.2 Simulation of the Transfer Function 46 4.3 Implementation of the PID Controller 47 4.4 Tuning Results of PID Controller 48 4.5 Simulation of ACC system 54 4.6 Analysis and Discussion of ACC Performances 59 V CONCLUSION AND SUGGESTION FOR FUTURE DEVELOPMENT 5.1 Conclusion 62 5.2 Suggestion for Future Development 63
xii REFERENCE 64 APPENDIX A 66 APPENDIX B 67 APPENDIX C 68
xiii LIST OF TABLES NO. TITLE PAGE 2.1 Effects of each of controllers gain on a closed-loop system 26 2.2 Equation created by Ziegler Nichols 26 3.1 Functional Requirements 5 9 39 4.1 Values of constant and parameter used in the block diagram 46 4.2 Gain value by Ziegler Nichols for each controller 49 4.3 Gain value by Ziegler Nichols for each controller after adjustment 49
xiv LIST OF FIGURES NO. TITLE PAGE 2.1 Signal Builder block 9 2.2 Controller block 10 2.3 Graphical Components of a Stateflow 11 2.4 The Debugger main window 12 2.5 Summary for coverage report 15 2.6 PID Controllers 16 2.7 PID controller subsystem 16 2.8 Zero-Order Hold block 17 2.9 Discrete-Time Integrator 17 2.10 IC block 19 2.11 Unit Delay block 20 2.12 Proportional Gain 21 2.13 Integral Gain 22 2.14 Derivative Gain 23 2.15 Vehicle dynamics 27 2.16 Vehicle dynamics subsystem 27 2.17 Hills block for road resistance 28
xv 2.18 Hills setting values 28 3.1 Flowchart 30 3.2 Test Case 1 34 3.3 Requirement 1/Test Case 2 35 3.4 Requirement 2/Test Case 3 36 3.5 Requirement 4/Test Case 4 37 3.6 Test Case 5 38 3.7 Test Case 6 39 3.8 Test Case 7 40 3.9 Test Case 8 40 3.10 Test Case 9 41 3.11 Test Case 10 41 3.12 Accelerator pedal signal 42 4.1 Simulink block diagram for ACC 46 4.2 Open loop response for ACC 47 4.3 Simulink block diagram for CC with PID Controller 47 4.4 Open-loop poles from Root Locus 48 4.5 Open-loop value for gain and frequency 48 4.6 P Controller step response 50 4.7 PI Controller step response 50 4.8 PID Controller step response 51 4.9 PID Controller step response (after Tuning) 51 4.10 PID Controller step response (after Tuning) 52 4.11 Satisfied open-loop system 53 4.12 Satisfied open-loop system respond 53
xvi 4.13 Simulation results for Test case 1 54 4.14 Simulation results for Test case 2 54 4.15 Simulation results for Test case 3 55 4.16 Simulation results for Test case 4 55 4.17 Simulation results for Test case 5 56 4.18 Simulation results for Test case 6 56 4.19 Simulation results for Test case 7 57 4.20 Simulation results for Test case 8 57 4.21 Simulation results for Test case 9 58 4.22 Simulation results for Test case 10 58 4.23 Simulation results for Test case 11 59
xvii LIST OF ABBREVIATION ACC - Adaptive Cruise Control ADAS - Advanced Driver Assistance Systems CC - Cruise Control D - Derivative I - Integral P - Proportional PI - Proportional-Integral PID - Proportional-Integral-Derivative
xviii LIST OF APPENDICES NO. NAME PAGE A ACC system in Simulink 66 B Controller Subsystem 67 C Model Viewing Shortcuts 68
1 CHAPTER I INTRODUCTION 1.1 Background of Project The cars of tomorrow [8] will be more and more equipped with Advanced Driver Assistance Systems (ADAS) to support the driver in the driving task. One of the ADAS is the Adaptive Cruise Control (ACC). Pauwelussen and Minderhoud in [8] noted that the ACC could be defined as an extension of the Cruise Control (CC) and maintains, next to a certain set speed, a certain set distance with respect to the lead vehicle. The conventional CC only has control over the engine, which means that it cannot switch gears and it cannot break. This means that it is only used on roads where the velocity of the car is somewhat constant, for example on highways. The driver cannot relax too much though, since the CC does not care about vehicles in front. This is what the ACC is trying to solve. The ACC takes both a desired (maximum) velocity and a desired (minimum) distance as input values from the driver. As long as no vehicle in front is closer than the desired distance, the ACC functions exactly as a CC. If a vehicle in front comes closer than the desired minimum distance the ACC will adapt the velocity to follow the vehicle. In order to keep this set distance, the ACC is able to accelerate and decelerate the vehicle. The acceleration and deceleration of the system is limited,
2 because of comfort reasons and by law [8]. This means that the driver has to intervene if the system is not able to achieve the required needs [8]. Ideally, the driver only has to control the steering and only interrupt the ACC at takeovers or situations that might lead to accidents [9]. The ACC is mainly a comfort system that takes over the car-following task, but the driver remains responsible for steering and collision avoidance. If the deceleration of the ACC is not sufficient enough to avoid a collision, the ACC warns the driver with a warning sound [8]. This system is usually used on the highway, where it is common to cruise at a constant velocity for long periods of time, as a relief for the driver [9]. These system [11], use radar to measure the distance from the vehicle they are in to the car ahead and its speed relative to theirs. If a car crosses into the lane ahead, and the distance is now less than the preset minimum, the system applies the brakes, slowing the car with a maximum deceleration until it is following at the desired distance [11]. If the leading car speeds up or moves out of the lane, the system opens the throttle until the trailing car has returned to the cruise control speed set by the driver [11]. The advanced features of ACC systems include the ability to track a car in the lane ahead using forward looking radar. If the distance to a vehicle in front is below a pre-set value, the ACC system is designed to slow the car down, using brakes if required, to track the speed of the vehicle in front, then returning the car to its pre-set speed once the lane ahead is clear. Next, an intelligent lane prediction using steering angle and yaw rate sensors predict curves in the road, and to ensure that any vehicle ahead being tracked is in the same lane as the car itself. One of the potential advantages of ACC is the foundation that it provides for next generation advancements in collision avoidance systems that are expected to include radar and cameras. ACC is also anticipated to be beneficial in cities and towns with heavy urban stop-and-go traffic by functioning at low stop/start speeds in city traffic. It is expected to have the ability to stop the car completely when sitting
3 in traffic, re-starting and following the car in front when the traffic begins to move again. Potential Key benefits of ACC are reduction in accident rate for vehicles fitted with collision avoidance type systems, reduction in driver fatigue and increase in fuel efficiency due to very gradual speed increase / decrease in traffic. The controller developed for ACC consists of PID controller and Stateflow. The PID controller is a closed loop controller; designed to make the throttle decisions (control). The controller is created using parameters to allow easy modification (tuning) of the operation of the controller. This controller also included the Stateflow chart that is used to address design challenges that often occur when developing and implementing embedded software. Matlab is the main software used for computation, model implementation, and simulation. The Matlab simulation tool Simulink, which is used for modeling and simulating dynamic systems, has been playing a major role during this work [12]. MATLAB/Simulink is a high-level technical computing language and object orientated environment for algorithm development, data visualization, data analysis, and numerical computation. MATLAB/Simulink allows the development of a solution to technical computing problems faster than with traditional programming languages, such as C, C++, and Fortran. The easy of development along with the extensive toolboxes and functions available were the major reasons for selecting MATLAB/Simulink as the simulation environment. The simulation environment starts as an overview of the implementation of the PID controller to the CC model. Next, the second model about the ACC model incorporates the high-level system blocks representing, the signal input, vehicle dynamics, distance and velocity controller will be designed to get the performances of the proposed controller. The goals for the simulation environment were to be able to create the test cases based on 10 high-level requirements. To ensure that the controllers meet those
4 requirements, we need to build test cases that check the design against each requirement. The simulation environment is flexible and if someone is interested in testing out another ACC algorithm, the controller is a single function that can be replaced easily. Simulink software models, simulates, and analyzes dynamic systems. It enables user to pose a question about a system, model the system, and see what happens. With Simulink, we can easily build models from scratch, or modify existing models to meet our needs. Simulink supports linear and nonlinear systems, modeled in continuous time, sampled time, or a hybrid of the two systems can also be multirate-having different parts that are sampled or updated at different rates. 1.2 Objectives of Project The objectives of this project are: i) To design the ACC system in MATLAB/Simulink. ii) To evaluate the simulation of ACC system. The main objective of this project is to design the ACC system in MATLAB/Simulink. This design process is the important part in this thesis. The PID controller is used to observe the characteristics of each controller gain. The evaluation of the simulation is completed using MATLAB/Simulink. Results obtained from PID controller s step response will evaluate to study the controller s performances in order to draw a conclusion of this simulation study [1].
5 1.3 Statement of Research Problem A lot of drawbacks of the designed ACC system in the real life environment pursue the researcher make the analysis and of the system in various aspect before the system will implemented to the wide range of country. This is because of the difference in weather condition in the other country. Thus, in Asian country the most challenge drawback problem is the effectiveness of the ACC system in heavy rain. In the rain periods, the degree of fog and rain also increased over time, and then decreased symmetrically; the sight distance similarly decreased from 1000 to 10m at 90s then gradually increased back to 1000m [10]. Rain degraded the ability of the radar to detect vehicles ahead, as it attenuated the sensor sensitivity, masking the sensors and causing them to fail temporarily. With no lead vehicle detected, vehicle speed will increase [10]. As the intensity of the rain increased, the sensors failed for longer periods and failed more frequently. The momentary failure of the sensors to detect vehicles ahead compromised the ability of the ACC to maintain at safely headway In contrast, Malaysia s geographical system has various structured condition. So the road system in Malaysia will give road resistance to the ACC system. Then, the road resistance will use to assume the disturbance to the ACC system. We only focus to the road resistance as the disturbance because the hills block already built in the Simulink. Thus, hills will represent as the load to the ACC system. So the rain will be the other choices to use as the disturbance and also give the big challenge to implement the ACC system
6 1.4 Scope of Project The scope of work for this project includes: i) Designing and modeling the ACC system in based on previous model. ii) Implementing the PID controller into the ACC system. iii) PID Controller with derived transfer function. iv) Auto tuning PID Controller which is used as a comparison in analyzing the performance of the controller in part (iii). v) Simulation study conducted in MATLAB/Simulink on the vehicle speed, road resistance and set distance with respect to the lead vehicle. 1.5 Method of Project The research work is undertaken in the following stages: 1) Design the ACC system based on the previous model. 2) Use PID controller with Stateflow. 3) Simulation of the proposed controller in MATLAB/Simulink. 4) Comparison of the performance of PID controller in CC system and ACC system. 5) Analysis of the simulation results.