Investigation of Cooperative Adaptive Cruise Control with Experimental Validation A Thesis SUBMITTED TO THE FACULTY OF UNIVERSITY OF MINNESOTA BY Pratik Mukherjee IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE Zongxuan Sun, Adviser July 2016 © Pratik Mukherjee, 2016 Acknowledgements It is with great honor that I will like to thank my adviser Professor Zongxuan Sun for giving me the opportunity to conduct research under his guidance for my Master’s Plan A thesis. His superior insight into the problem has allowed me to overcome many obstacles while working on the several problems that I have come across in the last two years. His consistent dedication of his time toward his students and focus on individual student’s progress has kept me on track to finish my work. Under his guidance, I have learned to work and think independently and I am constantly improving my problem solving skills which will definitely be an asset that I take with me after I leave this place. Without his continuous support to the whole research team, it would not have been possible for me to graduate on time, with quality. I will also like to thank the primary sponsors for the project, Federal Highway Administration(FHWA). Without their constant financial support and trust it would not have been possible to carry out various crucial tasks. Their constant interest in our progress motivated me to complete my work with dedication to provide quality solutions for every problem I solved, that will stand the test of time. I will also like to thank my lab mates Azrin, Yunli, Abhinav, Chen, Yongsoon, Yaoying and Keyan for constantly motivating me to work hard. Observing their work ethics over these past two years has made me aware of my weaknesses that I need to work on to constantly improve my skills. Pratik Mukherjee i Dedication I dedicate this thesis to my motherland India, my mother and father ii Abstract Increasing effects of global warming have concerned scientists and engineers for quite some time now. The major contributor to global warming has been the inefficient use of energy to fulfill the need for the ever growing human population. One of the major sources of energy is oil which fuels one of its largest consumer, the transportation sector. The Energy Information Administration reported that the U.S transportation sector contributed 28% to the total energy consumption and 72% to the total petroleum consumption in the year 2010. With these concerning developments, it has become critical to find a solution to improve the efficiency of transportation. A solution to this problem can be connected vehicles. Connected vehicle environment paves the pathway for future road transportation. Researches in this area have specifically focused to improve traffic mobility and safety, and also vehicles’ fuel consumption and emissions. A Hardware-in- the-Loop-System (HiLS) test-bed to evaluate the performance of connected vehicle applications has already been developed. A laboratory powertrain research platform, which consists of a real engine, a hydrostatic dynamometer and a virtual powertrain model to represent a vehicle, is connected using a software to a microscopic traffic simulator (VISSIM). Actual fuel and emissions measurements are obtained using this test-bed. This thesis documents the development of the software architecture that enables the different components of the HiLS to communicate with each other in real time. Different methodologies of software design are tested to demonstrate real time execution of HiLS with a 200ms time step. Further, using this test-bed a comprehensive evaluation of Cooperative Adaptive Cruise Control (CACC) application has been conducted to compare the fuel consumption and emissions of CACC vehicle and non-CACC vehicle in a traffic network simulated in VISSIM. In literature, CACC application is implemented using several different complex optimization methods based on prediction models derived from measurements of traffic information with the cost of computation power. In this thesis, a heuristic, averaged velocity approach to CACC is implemented using the information from the preceding vehicles which can be used in real time systems like the HiLS for a realistic evaluation of the CACC application. The algorithm designed uses information from iii multiple preceding vehicles to determine a velocity profile for the controlled vehicle which will obtain fuel benefits. The simulation and experimental results obtained using this CACC algorithm prove that using more preceding vehicle information provides higher fuel benefits. This phenomenon is described by the understanding that the accessibility of future information, with regards to the number of preceding vehicle velocity averages, by the controlled vehicle allows the CACC controller to obtain a smoothened velocity profile for the controlled vehicle with suppressed acceleration or decelerations which has a direct correlation with fuel savings. VISSIM traffic simulator is used to simulate different traffic conditions like city driving and highway driving. From the simulation, an individual vehicle is selected to be completely controlled by the CACC controller whereas the other vehicles are controlled byVISSIM’s internal driver model based on the Wiedmann Car following model. Then an extensive study is done through simulation of different traffic scenarios on the fuel consumption of the controlled and the immediate preceding vehicle which is evaluated using the Vehicle Specific Power (VSP) requirement. Further, to validate these simulation results, the HiLS is used to conduct experiments with selected scenarios from the simulations and actual fuel and emissions results for the CACC controlled vehicle and immediate preceding vehicle are compared. From the results obtained, it is realized that CACC application provides significant fuel saving, between 15- 18% approximately for both highway and city driving cases, for the controlled vehicle in comparison to the immediate preceding vehicle. Future work will focus on using the observations from the current CACC methodology and implementing a systematic method, possibly an online optimization method, to find out a general solution where the preceding vehicles’ information can be used. Then CACC application will be extended to evaluate more than one vehicle in a platoon of vehicles. Consequently, HiLS will be used to obtain experimental results. iv Table of Contents List of Tables …………………………………………………………………………………...viii List of Figures………………………………………………………………………….................ix Nomenclature…………………………………………………………………………................xii Chapter 1 Introduction and Background ................................................................................... 1 1.1 Connected Vehicles Application ........................................................................................ 1 1.1.1 Inter Vehicle Communication & Vehicle Infrastructure Integration ..................... 1 1.1.2 Vehicle Communication Devices ................................................................................. 3 1.2 CACC Controller ................................................................................................................ 4 1.2.1 CACC Controller Development .................................................................................. 5 1.2.2 A Simplified CACC Methodology .............................................................................. 6 1.2.3 CACC Simulation with HiLS ...................................................................................... 7 1.3 Experimental Validation of CACC Application .............................................................. 8 1.3.1 Components of HiLS .................................................................................................... 9 1.3.2 Powertrain Research Platform ................................................................................... 9 1.3.3 Virtual Hybrid Powertrain ....................................................................................... 10 1.3.4 Fuel and Emissions Measurement ............................................................................ 11 1.3.5 VISSIM Traffic Simulator ........................................................................................ 12 1.3.6 Integration of Various Software Platforms using Middleware .............................. 12 1.4 Thesis Contribution .......................................................................................................... 13 Chapter 2 Implementation and Evaluation of Cooperative Adaptive Cruise Control Using Simulation ..................................................................................................................................... 15 2.1 Introduction and Background ......................................................................................... 15 2.1.1 The Distance Corridor Constraints .......................................................................... 16 2.1.2 A Simplified Approach to CACC ............................................................................. 17 2.2 CACC Controller Design ................................................................................................. 19 2.2.1 Velocity Trajectory Generator Equation ................................................................. 20 2.3 Applying Constraints – Derivation of the Velocity Correction term ........................... 21 2.3.1 The Hard Constraints ...............................................................................................