Observability Criteron Guidance for Passive Towed Array Sonar Tracking
Tom Northardt
Abstract
Nonlinear sonar contact tracking always presents a significant observability challenge. Observability as it relates to sonar tracking is the metric used to determine if a state estimate is uniquely identifiable given a history of measurements. Poor observability is troublesome to all nonlinear tracking filters to varying degrees. Observability criteria are used to assess the degree of observability and many observability criteria require, in some way, an observer maneuver. But when observability criteria are evaluated with real data they are evaluated in the presence of “micromaneuvers” due to unmodeled forces. The issue associated with these micromaneuvers is that they satisfy, mathematically, observability criteria but hold little practical value for obtaining trustworthy state estimates. This article chooses a recent observability criterion and examines its utility for passive sonar tracking with a towed array. The analysis performed provides guidance to all similar observability criteria when applied to the passive sonar tracking with a towed array and implies such criteria will be most valuable in applications with minimal navigation perturbations.