Counter-Intuitive Behavior in Locally Optimal Solar Sail Escape Trajectories
Hartmann, John W.
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https://hdl.handle.net/2142/85094
Description
Title
Counter-Intuitive Behavior in Locally Optimal Solar Sail Escape Trajectories
Author(s)
Hartmann, John W.
Issue Date
2005
Doctoral Committee Chair(s)
Coverstone, Victoria L.
Department of Study
Aerospace Engineering
Discipline
Aerospace Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Aerospace
Language
eng
Abstract
Minimum-time escape trajectories using an idealized solar sail for propulsion are presented. Results obtained using a trajectory propagator that maximizes the instantaneous rate of increase in total orbital energy to achieve escape---an intuitive control strategy originally presumed to generate near-optimal results---are compared to optimized trajectories generated using optimal control theory. This comparison indicates that the intuitive method is capable of approximating locally optimal escape trajectories for a wide range of initial conditions; however, results demonstrate the same method can produce inefficient escape times, and that the conditions leading to production of inferior trajectories are present throughout the space of initial conditions and acceleration levels. Optimal performance is, at times, achieved by adopting a control strategy that moves counter to the assumed intuition, temporarily decreasing orbital energy at opportune points along the escape trajectory. These results have motivated the development of a feasible trajectory generator using a search technique known as a rapidly-exploring random tree. This method is capable of negotiating non-convex search spaces to find escape trajectories exhibiting counter-intuitive behavior that better approximates locally optimal solutions, while also providing increased robustness through incorporation of obstacle avoidance capabilities.
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