Three-Dimensional Trajectory Optimization Satisfying Waypoint and No-Fly Zone Constraints

Abstract

To support the U.S. Air Force's global reach concept, a Common Aero Vehicle is being designed to support the global strike mission. Waypoints are specified for reconnaissance or multiple payload deployments and no-fly zones are specified for geopolitical restrictions or threat avoidance. Because of time critical targets and multiple scenario analysis, an autonomous solution is preferred over a time-intensive, manually iterative one. Thus, a real-time or near real-time autonomous trajectory optimization technique is presented to minimize the flight time, satisfy terminal and intermediate constraints, and remain within the specified vehicle heating and control limitations. This research uses the hypersonic cruise vehicle as a simplified two-dimensional platform to compute an optimal analytical solution. An up-and-coming numerical technique is a direct solution method involving discretization and then dualization, with pseudospectral methods and nonlinear programming used to converge to the optimal solution. This numerical technique is first compared to the previously derived 2-D hypersonic cruise vehicle analytical results to demonstrate convergence to the optimal solution. Then, the numerical approach is applied to the 3-D Common Aero Vehicle as the test platform for the flat Earth three-dimensional reentry trajectory optimization problem. The culmination of this research is the verification of the optimality of this proposed numerical technique, as shown for both the two-dimensional and three-dimensional models. Additionally, user implementation strategies are presented to improve accuracy, enhance solution convergence, and facilitate autonomous implementation.