自動車輛駕駛縱向暨橫向控制設計

Abstract

車輛駕駛自動化是先進車輛系統(Advanced vehicle systems)主要研究部份之一，Taiwan iTS-1是由交通大學自行開發之自動駕駛實驗車。在本論文中，我們介紹此一多模式自動駕駛之系統，內容包含控制目標之決定、系統架構設計、車輛動態模型驗証、控制演算法、以及路上測試。此系統實現於Taiwan iTS-1並於真實交通環境高速道路及市區道路測試，驗證其正確及有效性。我們設計一個階層控制的自動駕駛系統，上層控制(Upper-level control)判斷道路交通環境並決定是否啟動道路保持、道路切換、定速及適應巡航控制、以及停走操作模式，並計算該模式操作所需之安全車速及行駛軌跡，再交由車體控制(Vehicle-body control)來執行。為使系統能像駕駛人一般控制車輛行駛速度以及轉向，我們採用模糊控制技術來設計車體控制器，因系統除了具有像駕駛人之模式決策(Decision-making)，也模仿駕駛人之智能及行為，並展現可與駕駛人比擬之加速、剎車、以及轉向操控。另外，考慮到車輛縱向及橫向動態耦合(Coupling)之特性，我們發展一種具有三自由度之非線性車輛動態模型，設計一個整合縱向及橫向之控制器，並藉由CarSim模擬環境來驗證此控制演算法之可行性及實用性。

Vehicle automation is an important research topoic of advanced vehicle systems (AVS). Taiwan iTS-1 is an experimental autonomous vehicle developed by National Chiao Tung University (NCTU). In this dissertation, a complete process of developing a multi-mode automated driving system is presented. This process consists of control objectives determination, system configuration design, vehicle dynamics modeling and validation, control algorithm development, and on-road testing. A hierarchical-control structure is proposed in the system to achieve the integrated longitudinal and lateral vehicle control. Upper-level control perceives road environment and determines the proper and safe operation modes including lane-keeping, lane-change, cruise control, adaptive cruise control, and stop-and-go. In each mode, the desired-velocity and reference-trajectory are primarily determined, and then are forwarded to vehicle-body control. To incorporate well driving tasks of human drivers into our system, vehicle-body control utilizes the fuzzy control technique to regulate the vehicle to adapt to the desired command (velocity and trajectory). In addition to the decision-making scheme, our system can mimic a human’s intelligence and behavior to manage throttle, brake, and steering actuators in a driver-compatible way. Besides, to consider the coupling effects between the longitudinal and the lateral motion of a vehicle, a nonlinear three-degree-of-freedom vehicle dynamics is developed for a combined longitudinal and lateral vehicle controlling design. This controller is subsequently evaluated on a virtual vehicle in CarSim with remarkable results. The developed system has been verified repeatedly on highway and urban environments, respectively, with great success.