Publication Date:
2022-05-25
Description:
Submitted to the Joint Program in Applied Ocean Science & Engineering
in partial fulfillment of the requirements for the degree of Doctor of Philosophy
at the Massachusetts Institute of Technology
and the Woods Hole Oceanographic Institution
June 2005
Description:
This thesis describes a vision-based, large-area, simultaneous localization and mapping (SLAM) algorithm that respects the low-overlap imagery constraints typical of autonomous underwater vehicles (AUVs) while exploiting the inertial sensor information that is routinely available on such platforms. We adopt a systems-level approach exploiting the complementary aspects of inertial sensing and visual perception from a calibrated pose-instrumented platform. This systems-level strategy yields a robust solution to underwater imaging that
overcomes many of the unique challenges of a marine environment (e.g., unstructured terrain, low-overlap imagery, moving light source). Our large-area SLAM algorithm recursively incorporates relative-pose constraints using a view-based representation that exploits exact sparsity in the Gaussian canonical form. This sparsity allows for efficient O(n) update complexity in the number of images composing the view-based map by utilizing recent multilevel relaxation techniques. We show that our algorithmic formulation is inherently sparse unlike other feature-based canonical SLAM algorithms, which impose sparseness via pruning approximations. In particular, we investigate
the sparsification methodology employed by sparse extended information filters (SEIFs)
and offer new insight as to why, and how, its approximation can lead to inconsistencies in
the estimated state errors. Lastly, we present a novel algorithm for efficiently extracting consistent marginal covariances useful for data association from the information matrix. In summary, this thesis advances the current state-of-the-art in underwater visual navigation by demonstrating end-to-end automatic processing of the largest visually navigated dataset to date using data collected from a survey of the RMS Titanic (path length over 3 km and 3100 m2 of mapped area). This accomplishment embodies the summed contributions of this thesis to several current SLAM research issues including scalability, 6 degree of
freedom motion, unstructured environments, and visual perception.
Description:
This work was funded in part by the CenSSIS ERC of the National Science Foundation
under grant EEC-9986821, in part by the Woods Hole Oceanographic Institution through a
grant from the Penzance Foundation, and in part by a NDSEG Fellowship awarded through
the Department of Defense.
Keywords:
Underwater imaging systems
;
Underwater navigation
;
Submersibles
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
Format:
24143873 bytes
Format:
application/pdf
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