Optimal three dimensional aircraft terrain following and collision avoidance

Military aircraft must often fly in close proximity to terrain. In this article, optimal terrain following is considered as a minimax optimal control problem, which is solved using direct transcription of the continuous optimal control problem. Within a very general framework for solving such problems, we transform the nonsmooth cost function into a constrained nonlinear programming problem. In the formulation, we solve for optimal collision avoidance manoeuvres. To ensure smooth derivatives of general three dimensional terrain, it is approximated using B-splines. A receding horizon tracking controller tracks the optimal trajectories with disturbances to the aircraft model and initial conditions.