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This research aims to expand the algorithmic capability for tasking sensors to investigate human-specified hypotheses about space objects (SOs). | ||
The goal is to improve the ability to evaluate internal- and physical- state hypotheses in cases where there are many objects and a collection of sensors with diverse capabilities. | ||
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**Problem Description** | ||
Describe the problem of catalog maintenance and hypothesis resolution | ||
<!-- **Problem Description** --> | ||
<!-- Describe the problem of catalog maintenance and hypothesis resolution --> | ||
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**Technical Approach** | ||
Describe our technical approach: | ||
1. Generating a base plan using ILP | ||
2. Plan only over the OOI, where an action is a change in the plan | ||
The approach can be broken down into two main steps: | ||
1. Generating a base plan using integer linear programming | ||
2. Generating a refined MCTS plan accounting for the object of interest | ||
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### 1) Integer Linear Program | ||
The base integer linear programming approach aims to judiciously allocate sensors to space objects in a manner where the severity of the worst-case scenario is minimized. | ||
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Formally, the ILP is given by | ||
<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script> | ||
$$ | ||
\begin{aligned} | ||
\text{maximize} \quad & t \\ | ||
\text{subject to} \quad & X_{ijt} \in \{0,1\}^{I\times J \times T} \\ | ||
& X_{ijt} \preceq O \\ | ||
& t \preceq \sum_{j,t} X_{ijt} \\ | ||
& \sum_{i} X_{ijt} \preceq 1 \, . | ||
\end{aligned} | ||
$$ | ||
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Here $$X_{ijt}$$ is a binary 3-dimensional control variable representing whether or not observer $$j$$ observers object $$i$$ at time step $$t$$, and $$O_{ijt}$$ represents whether or not observer $$j$$ *is able to* observe object $$i$$ at time $$t$$. | ||
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For ground based-sensors, the ILP plan can be visualized as follows: | ||
 | ||
. | ||
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### 2) Monte Carlo Tree Search | ||
Building on the ILP solution as a baseline, we assume the existence of an object of interest in the catalogue, for which we seek to resolve a specific hypothesis. This work focuses on determining the drag configuration for the object in question. To achieve this, we use Monte Carlo Tree Search (MCTS) applied to a belief Markov Decision Process (MDP). The goal of the MCTS solver is to minimize the entropy of the distribution over possible hypotheses while minimally disrupting the baseline catalogue maintenance plan. |
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