Highly constrained entry trajectory generation

doi:10.1016/j.actaastro.2013.01.024

2013-07-01

PRE

DOI：10.1016/j.actaastro.2013.01.024

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摘要

En 中文

An entry trajectory planning algorithm that generates flyable trajectories satisfying waypoints, no-fly zones, and other path and terminal constraints is' presented. The algorithm tactically divides the entry trajectory into the initial and glide phases. In the initial phase, a nominal angle of attack and a constant bank angle are used to generate the 3-D trajectory. In the glide phase, a planner is developed based on the evolved acceleration guidance logic for entry (EAGLE). The planner is divided into a longitudinal sub-planner and a lateral sub-planner. For longitudinal planning, the drag-energy profile is represented as five piecewise linear functions of the normalized non-conventional energy to make it consistent with both the desired trajectory length and the lateral maneuverability required to meet waypoint and no-fly zone constraints. The longitudinal sub-planner determines the magnitude of the bank angle, whereas the lateral sub-planner determines the appropriate sign of the bank angle for passing waypoints, avoiding no-fly zones, and minimizing the final heading error. The longitudinal and lateral sub-planners are iteratively employed until all path and terminal constraints are satisfied. Then, a tracker is employed to follow both the reference drag acceleration and the heading angle profiles to generate a feasible closed-loop entry trajectory. The approach is tested using the Common Aero Vehicle model. Simulations demonstrate that the generated trajectories can pass the predetermined waypoints, avoid no-fly zones, and achieve the desired target conditions within allowable tolerances. (C) 2013 IAA. Published by Elsevier Ltd. All rights reserved.

Keyword:

Entry trajectory

Waypoint

No-fly zone

Multiple constraints

Drag-energy profile

EAGLE