Inference of Aircraft Intent via Inverse Optimal Control Including Second-Order Optimality Condition

This paper presents a method to infer the intent of an aircraft by using inverse optimal control. Assuming that the observed or estimated trajectory of the target aircraft is the approximate local optimum, the current method calculates the weight of each term of the objective function that represents the flight’s intent. The intent may include direct travel to a waypoint; circling around a waypoint; holding airspeed/heading/turn rate; avoiding certain regions such as those with adverse weather or special-use airspaces; and resolving conflicts with other aircraft. By incorporating the second-order optimality condition (i.e., the positive definiteness of the projected Hessian of the Lagrangian), the method approximately satisfies the sufficiency of the local optimality of the given trajectory. Moreover, the method also guarantees the uniqueness of the inferred intent. The effectiveness of the current method in terms of the reasonableness of the inferred intent as well as real-time applicability is demonstrated through numerical examples.