Distance Fields Over Grids Method for Aircraft Envelope Determination

In this research, the concept of posing the flight envelope as a reachable set is ex- plored further and it is investigated whether the "Distance Fields Over Grids (DFOG)" method for reachability computations is a viable method for envelope determination. The DFOG method approximates the reachable set of a dynamic system by solving a number of optimal control problems over a grid in the state-space. Then, the end- points of the resulting optimal trajectories are used to provide an approximation of the reachable set. The DFOG method is improved by using a 2nd order RK method for the state discretization and developing a new adaptive grid selection approach. This method is then applied to the computation of a four-dimensional reachable set of a nonlinear high-fidelity F-16 model. The results are compared to results obtained pre- viously with level sets and show that the DFOG method provides a less conservative approximation to the reachable set. 1