Abstract
An online estimation algorithm of landing footprints based on the drag acceleration-energy profile is proposed for an entry hypersonic vehicle. Firstly, based on the Evolved Acceleration Guidance Logic for Entry (EAGLE), drag acceleration-energy profiles are designed. To track the drag acceleration-energy profile obtained by the interpolation, a drag acceleration tracking law is designed. Secondly, based on the constraint model of the no-fly zone, flying around strategies are proposed for different conditions, and a reachable area algorithm is designed for no-fly zones. Additionally, by interpolating the minimum and maximum drag acceleration profiles, the terminal heading angle constraint is designed to realize the accurate calculation of the minimum and maximum downrange ranges by adjusting the sign of the bank angle. In this way, the distribution of landing footprints is more reasonable, and the boundary of a reachable area is more accurate. The simulation results under typical conditions indicate that the proposed method can calculate landing footprints for different situations rapidly and with the good adaptability.
Highlights
Landing footprints provide key information for the mission planning, such as the terminal area energy management (TAEM) guidance for a shuttle entry [1]
The results show that the method can obtain landing footprints based on the direct physical concept under the no-fly zone constraint
Entry trajectory optimization problems for a hypersonic vehicle have been significantly addressed in the past years, the reachable area considered in this paper focuses on the generation algorithm of multiple trajectories
Summary
Landing footprints provide key information for the mission planning, such as the terminal area energy management (TAEM) guidance for a shuttle entry [1]. Lu et al [31, 32] proposed a closestapproach method to obtain the maximum crossrange trajectory at a particular downrange by setting up a nonreachable virtual target The centerpiece of this method is a closedform near-optimal bank angle control law that can solve landing footprints rapidly and reliably. We focus on the following three aspects of contribution: (1) we designed the drag acceleration profile tracking law and introduced the terminal heading angle constraint to realize the accurate calculation of initial landing footprints. Different relative trajectories were transformed into corresponding terminal heading angle constraints to realize the fast calculation of reachable areas under the constraint of the no-fly zone. Entry trajectory optimization problems for a hypersonic vehicle have been significantly addressed in the past years, the reachable area considered in this paper focuses on the generation algorithm of multiple trajectories.
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