Matstat seminarir fredagen 13 juni kl 13.15 i MH:227

Terrain navigation for underwater vehicles: methods, analysis and
evaluation.

Ola Wall, Lund


Abstract: 

Submarines must maintain high accuracy navigation without exposure.
The navigation system in a submarine is normally based on dead
reckoning of signals from gyros. Due to the dead reckoning approach,
errors cannot be attenuated and the position estimate will drift away
from the correct position. The navigation filter must therefore be
reinitialized periodically.

This work discusses different methods for obtaining position fixes
through aligning sonar measurements with maps of the sea
bed. Correlation methods are described and used as a tool for
analyzing the possibility of finding position fixes at all, and
possible as a tool for providing requirements on measurement precision
etc. Sequential Bayesian methods are presented, and although they are
based on a state space model of subsequent data, they are found to
provide attractive results also for batch oriented data sets.  When
estimating the posterior density functions, several integrals needs to
be evaluated. This is done using both standard quadrature and
simulation based integration.

The methods are evaluated using 3D sonar measurements of a sea
bed. From repeatedly collected data, a set of residuals were
generated. The residuals are used in Monte Carlo simulations for the
evaluation of the methods.