Hierarchical hybrid control of automated highway systems

The goal of this dissertation is to design controllers that guarantee collision-free operation of vehicles on an Automated Highway Systems (AHS) using platooning. In this scheme, traffic is organized into closely spaced platoons to increase capacity and safety of the existing highways. Platooning requires vehicles to be automatically controlled. A hierarchical control architecture has already been proposed for platooning. Each vehicle is governed by a hybrid controller consisting of a discrete event system called coordination layer, that coordinates platoon maneuvers with its neighbors, and a set of continuous controllers that calculate throttle, brake and steering inputs, called regulation layer. Coodination layer protocols have already been designed. The design of regulation layer control laws and their interaction with the coordination layer is the topic of this dissertation.; First, an autonomous cruise controller for the lead vehicle of a platoon is designed which maintains safe spacing from the preceding vehicle while following its velocity. Longitudinal control laws for platooning maneuvers, namely merge, split and lane change, are also designed. These control laws achieve a balance between safety and passenger comfort. An interface is designed to combine the regulation layer control laws with the coordination layer protocols.; Simulation analysis of the combined hybrid system occasionally displays undesirable characteristics (vehicle crashes). The collisions were not predicted by individual layer verifications since, the finite state abstraction of the continuous dynamics used in discrete layer design was not rich enough to take into account physical limitations of a vehicle. The design was modified to avoid crashes by changing certain maneuver control laws and interface safety checks. This points out that the design and verification of consistent abstractions in a hierarchically organized hybrid control system is an important research area.; Safety issues at the entrances and exits of the AHS are more pronounced as they involve transfer of control between manual and automated driving. Control laws for entry and exit are designed that achieve safety and adequate throughput for successful implementation of AHS.; Although the AHS considered in this dissertation uses platooning, the regulation layer control laws are applicable for alternative methods of AHS.