Towards a Fault Tolerant AHS Design

We propose a hierarchical control architecture for dealing with faults and adverse environmental conditions on an Automated Highway System (AHS). Our design builds on a previously designed control architecture that works under normal conditions of operation. The faults that are considered in our design are classified according to capabilities remaining on the vehicle or roadside after the fault has occurred. Information about these capabilities is used by supervisors in each of the layers to select appropriate control strategies. We outline the extended control strategies that are needed by these supervisors of each layer of the hierarchy and, in certain cases, give examples of their detailed operation. A companion paper develops and verifies protocols for extended coordination layer strategies and maneuvers.