US Patent 7881868 Dual assessment for early collision warning

One embodiment of the present invention provides a system that facilitates warning of collision between a primary principal and one or more non-primary principals. The system includes a triggering mechanism and a preliminary assessment mechanism. During operation, the triggering mechanism determines whether a trigger condition is met based on the state of the primary principal. When the trigger condition is met, the preliminary assessment mechanism generates one or more collision scenarios associated with the trigger condition, assesses a preliminary probability of collision in a collision scenario, and, based on the preliminary probability of collision in the collision scenario, activates a specialized assessment mechanism to assess a refined probability of collision in the collision scenario.