design space pruning heuristics and global optimization method for ...
design space pruning heuristics and global optimization method for ...
design space pruning heuristics and global optimization method for ...
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asteroid tour mission <strong>design</strong> problems <strong>and</strong> relies on user-defined parameters to<br />
effectively tailor the degree of <strong>design</strong> <strong>space</strong> <strong>pruning</strong> based on the available<br />
computational resources.<br />
(2) A <strong>global</strong> optimizer is combined with a low-thrust trajectory <strong>optimization</strong> <strong>method</strong><br />
to locate a broad suite of good solutions <strong>for</strong> the reduced problem. This approach<br />
combines an innovative branch-<strong>and</strong>-bound algorithm (to solve <strong>for</strong> the optimal<br />
asteroid sequence) with a genetic algorithm (which solves <strong>for</strong> the optimal<br />
departure date, times of flight, <strong>and</strong> stay times <strong>for</strong> a given asteroid sequence), <strong>and</strong><br />
finally with a low-thrust trajectory <strong>optimization</strong> program (which determines the<br />
optimal thrust profile that maximizes final mass). The <strong>global</strong> <strong>optimization</strong><br />
scheme is able to consistently locate the best known solution, along with a suite<br />
of good solutions across the <strong>design</strong> <strong>space</strong>. A strategy was developed to set the<br />
initial lower bound in the branch-<strong>and</strong>-bound algorithm (a user-defined parameter)<br />
as a means of controlling the number of required low-thrust <strong>optimization</strong>s<br />
required <strong>and</strong> the number of good solutions found.<br />
(3) When the <strong>global</strong> <strong>optimization</strong> scheme is combined with the heuristic screening<br />
process, a systematic <strong>method</strong>ology <strong>for</strong> identification of a broad suite of good<br />
solutions to low-thrust, multiple asteroid rendezvous, conceptual mission <strong>design</strong><br />
problems is achieved. In addition to a wide range on each of the continuous<br />
variables, the problems to which the <strong>method</strong>ology is applied in this investigation<br />
are characterized by as many as 41 billion discrete asteroid sequences. The key<br />
contribution of this <strong>method</strong>ology is the ability to locate a suite of good solutions,<br />
as opposed to just a single optimum solution. In locating these good solutions,<br />
the overall <strong>method</strong>ology is able to reduce the number of asteroid sequences that<br />
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