Some Aspects of Collision Avoidance

S aspects of the problem of collision avoidance for two chicles are examined by hypothesizing certain rationales for the vehicle operators and then computing the sets of initial conditions for which collision can occur. We first suppose that one operator may be unaware of any danger and so may control his vehicle in a hazardous fashion. To this operator we assign the role of pursuer, while the operator of the other vehicle is given the role of evader and a differential game is formulated. The set of initial conditions for which collision can occur despite any maneuvers by the evader is a dangerous (Red) zone. Clearly, a cautious pilot would not like a second vehicle to be in his Red zone, and a good collision avoidance system (CAS) should be effective in this zone. A second zone is defined by assigning a passive role (constant control) to the evader, while the other vehicle still pursues. The set of initial conditions for which no collision is possible is a particularly safe zone since no active avoidance is required. Any practical CAS should not call for unnecessary maneuvers in the (Green) zone. The points in neither the Red nor the Green zones form a Yellow zone in which some evasive maneuver may be required. A workable CAS should be active for initial points in the Yellow zone, so that the Red zone can be avoided.