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

If a smooth, closed, and embedded curve is deformed along its normal vector field at a rate proportional to its curvature, it shrinks to a circular point. This curve evolution is called Euclidean curve shortening and the result is known as the Gage-Hamilton-Grayson theorem. Motivated by the rendezvous problem for mobile autonomous robots, we address the problem of creating a polygon shortening flow. A linear scheme is proposed that exhibits several analogues to Euclidean curve shortening: The polygon shrinks to an elliptical point, convex polygons remain convex, and the perimeter of the polygon is monotonically decreasing.