Mixed Integer Linear Programming Trajectory Generation for Autonomous Nap-of-the-Earth Flight in a Threat Environment

This paper extends a recently developed approach to the optimal path planning of an autonomous vehicle in an obstacle field to three dimensions with specific applications to terrestrial navigation, with obstacle, terrain, and threat avoidance. We present a scenario where this approach can be applied to a rotorcraft performing nap-of-the-Earth flight in challenging terrain with multiple known surface threats, in both urban and non-urban type settings. Mixed-integer linear programming (MILP) is the underlying problem formulation, from which an optimal solution can be obtained through the use of a commercially available MILP solver such as CPLEX. The solution obtained would be optimal in terms of the cost function specified in terms of fuel, time, altitude and threat exposure, and other predefined criteria. A receding horizon implementation of this MILP algorithm makes it suitable for real-time or near real-time applications