Strategic Trajectory Planning of Highway Lane Change Maneuver with Longitudinal Speed Control
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Strategic Trajectory Planning of Highway Lane Change Maneuver with Longitudinal Speed Control A Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Yuhao Shui, B.S. Graduate Program in Department of Electrical and Computer Engineering and Department of Mechanical Engineering The Ohio State University 2015 Master's Examination Committee: Umit¨ Ozg¨uner,Advisor¨ Junmin Wang, Advisor Lisa Fiorentini Chia-Hsiang Menq c Copyright by Yuhao Shui 2015 Abstract Even though extensive research has been conducted on vehicle high-way longitu- dinal control under simple driving scenario, real life implementation of such system requires considering of surrounding traffic situations and movements such as lane change, weaves, on-ramp and off-ramp merges. In this thesis, the concept of driver being responsible of lateral control with automated longitudinal control is deployed in order to realize the mobility and safety benefits and a fundamental framework has been built to investigate high-way longitudinal control with lane change trajectory generated by geometric high order polynomial. With the assumption of surrounding vehicles' position and velocity is available, high-way two lane situation with driver being advised by the lane change module for the operation is studied. This system consists of several different modules: vehicle single lane following control module, maneuver generation module, lane change tra- jectory generation module and Model Predictive Control (MPC) control while lane changing. Three controllers: PID cruise controller, transitional trajectory and vehi- cle following controller are used to achieve the functionality of vehicle following with a Finite State Machine (FSM) designed for controller switch decision making based on surrounding traffic movements. The following controller is needed to follow the preceding slower vehicle when driver does not intend to make a lane change. The ii vehicle maneuver generation module is first designed to inform the system, for exam- ple, whether an acceleration or deceleration lane change is needed to lead or follow the vehicle in the adjacent lane. Both Time to Collision and Inter Vehicular Time are used as collision indicators to ensure safety. All possible cases of high-way two lane situation with one slow preceding vehicle and one surrounding vehicle in the adjacent lane are integrated into the maneuver generation FSM design. Based on the suggested maneuver, the lane change trajectory generation module provides a desired trajectory for the longitudinal controller to follow. A pure geometric high order polynomial trajectory planning method is used to design obstacle avoidance lane change trajectory. In the end, an MPC controller is utilized to control the speed of the vehicle while lane changing. iii Dedication I would like to dedicate this study to my advisor professor Umit Ozguner. Thank you for providing me this precious research opportunity and offering valuable guidance and discussion through the project. It is been a great pleasure for me to work at Control and Intelligent Transportation Research lab. I would also like to thank prof. Junmin Wang for your assistance when I was first admitted to Mechanical Engineering program and opening the door of vehicle dynamics and control for me, thank prof. Lisa Fiorentini for uncountable times of encouragement and advise through my graduate study and thank prof. Chia-Hsiang Menq for your two wonderful control courses and your understanding, time and support. Finally, I want to thank my parents Hang Shui and Qing Shui. I would not be who I am today without your dedicated education, your patience and constant support in my every depression moment and thank Ruiqi for continuously accompanying and standing by me. iv Acknowledgments This research is partially supported by Leidos, Inc and Federal Highway Admin- istration (FHWA). v Vita August 27, 1991 . Born - Shanghai, China 2014 . .B.S. Electrical and Computer Engi- neering, The Ohio State University. 2013-present . .Electrical and Computer Engineering, Mechanical Engineering, The Ohio State University. Fields of Study Major Field: Electrical and Computer Engineering; Mechanical Engineering vi Table of Contents Page Abstract . ii Dedication . iv Acknowledgments . v Vita . vi List of Tables . x List of Figures . xi 1. Introduction . 1 1.1 Literature Review . 1 1.1.1 Adaptive Cruise Control (ACC) . 1 1.1.2 Lane Change and Merge . 3 1.1.3 Model Predictive Control . 8 1.2 Overview of Lane Change Trajectory Planning and Longitudinal Control module . 9 1.3 Structure of the Thesis . 14 2. Vehicle Following Controller Design . 17 2.1 Vehicle Dynamic Modeling . 17 2.1.1 Longitudinal Point Mass Model . 17 2.1.2 Lateral Point Mass Model . 18 2.1.3 Bicycle Model . 19 2.2 Vehicle Longitudinal Controller Design . 21 2.2.1 System Overall Construction . 21 2.2.2 Cruise Control . 23 vii 2.2.3 Vehicle Following Control . 25 2.2.4 Transitional Trajectory . 29 2.3 Finite State Machine (FSM) Design . 29 2.3.1 Lane Change Command Input . 33 2.4 Vehicle Following Simulation . 34 3. Vehicle Maneuver Generation . 38 3.1 Introduction . 38 3.2 Collision Indicator - TTC & TIV . 39 3.3 Lane Change Maneuver Decision Making . 42 3.3.1 Lance Change Problem Formulation . 43 3.3.2 Faster Vehicle in the Adjacent Lane . 45 3.3.3 Slower Vehicle in the Adjacent Lane . 51 3.3.4 Finite State Machine for Lane Change Decision Making . 52 4. Lane Change Trajectory Generation . 57 4.1 Lane Change Trajectory Initial Design . 58 4.1.1 Calculation of trajectory parameters . 60 4.1.2 Trajectory Optimization . 63 4.1.3 Simulation of Sample Trajectories Generation . 68 4.2 Generation of Trajectories with One Obstacle . 69 4.2.1 Prediction of Surrounding Vehicles . 71 4.2.2 Overview of Trajectory Parameters Design . 72 4.2.3 Collision Detector - Gap between Vehicles . 74 4.2.4 Collision Avoidance Trajectory . 76 4.2.5 Vehicle Dynamic Constraints . 81 4.2.6 Simulation of Sample Trajectories with One Obstacle . 82 5. MPC Longitudinal Controller Design for Lane Changing . 91 5.1 MPC Controller Design . 91 5.1.1 Vehicle Longitudinal Dynamic . 91 5.1.2 Controller Synthesis . 92 5.1.3 Cost Function . 93 5.2 Vehicle Lane Change Control Simulation . 94 6. Conclusion and Future Work . 97 6.1 Conclusion . 97 6.2 Future Work . 98 viii Bibliography . 100 ix List of Tables Table Page 2.1 Bicycle Model Parameters . 21 2.2 Threshold Meanings . 30 2.3 Events and Threshold for Vehicle Following FSM . 32 3.1 State of Maneuver FSM . 54 3.2 Events and Threshold for Maneuver Generation . 55 3.3 Output Variables from Maneuver FSM . 55 3.4 Constant Parameters in Maneuver FSM . 56 3.5 State Variables in Maneuver FSM . 56 4.1 Boundary Conditions for Trajectory Generation I . 83 4.2 Boundary Conditions for Trajectory Generation II . 87 x List of Figures Figure Page 2.1 Bicycle Vehicle Model . 20 2.2 Hybrid Controller Design . 23 2.3 Feedbakc Control Loop for Cruise Control . 25 2.4 String of Vehicles . 27 2.5 Threshlod Distance for ACC System . 30 2.6 States Logic Flow for FSM . 31 2.7 Desired Steering Wheel Angle . 33 2.8 Velocity for Both Vehicles . 34 2.9 Lateral Position of the Ego Vehicle . 35 2.10 Inter-Vehicle Distance . 35 2.11 Longitudinal Position of Both Vehicles . 36 3.1 Time to Collision Possibility . 41 3.2 Inter-Vehicular Time Possibility . 42 3.3 Decision Making Problem Formulation . 44 3.4 Lane Change Event 1 - Example . 45 xi 3.5 Lane Change Event 2 - Example . 46 3.6 Lane Change Event 3 - Example . 47 3.7 Collision Free Selection of d . 48 3.8 Lane Change Event 5 - Example . 49 3.9 Lane Change Event 11 - Example . 52 3.10 Finite State Machine for Lane Change Maneuver Generation . 54 4.1 Single Lane Change with No Obstacle . 59 4.2 Lane Change Trajectory 5th order . 68 4.3 Longitudinal Velocity and Acceleration of the Trajectory 5th order . 69 4.4 Lateral Velocity and Acceleration of the Trajectory 5th order . 69 4.5 Distance to Obstacle . 75 4.6 Vehicle Representation - Circle . 78 4.7 Selection of a6 ............................... 84 4.8 Collision Free Path for Event 3 . 85 4.9 Position in x and y Direction for Event 3 . 85 4.10 Velocity and Acceleration in x Direction for Event 3 . 86 4.11 Velocity and Acceleration in y Direction for Event 3 . 86 4.12 Relative Distance between Two Vehicles for Event 3 . 86 4.13 Selection of a6 with Dynamic Constraints . 88 4.14 Collision Free Path for Event 11 . 88 4.15 Position in x and y Direction for Event 11 . 89 xii 4.16 Velocity and Acceleration in x Direction for Event 11 . 89 4.17 Velocity and Acceleration in y Direction for Event 11 . 89 4.18 Relative Distance between Two Vehicles for Event 11 . 90 5.1 Reference Trajectory versus Driver Trajectory . 95 5.2 Controlled Trajectory Comparion . 96 xiii Chapter 1: Introduction 1.1 Literature Review 1.1.1 Adaptive Cruise Control (ACC) Adaptive Cruise Control (ACC) can help to improve high way driving safety and increase the high way capacity. Also, by applying automated vehicle following system, the inter-vehicle spacing can be adequately reduce. Extensive research has been done on the longitudinal speed control of vehicles [27], [45]. However, most of them are implemented in simple scenarios. The final goal of the project is to implement longitudinal speed control during various traffic movements like lane changes, weaves,.