The concept of local observability is introduced for linear time-varying systems. The concept is useful for the analysis of the observability of a system during a chosen time period. It has important applications in estimation involving multiple measurements. The observability matrix, used for testing complete observability, is also used to determine local observability. The condition number of the matrix is adopted as a scalar measure of degree of local observability. The use of the matrix and its condition number is illustrated by a practical application involving a terrain-aided inertial navigation system. Error covariance analysis, done by computer, is performed to confirm the local observability predicted by the condition number. >

Local observability and its application to multiple measurement estimation

A local observability matrix for a linear time-varying system is introduced. The matrix is useful for observability analysis; it is much easier to use than the usual observability grammian for linear time-varying systems. The matrix is applied to a terrain-aided inertial navigation system to reveal the observability of the system in terms of the nature of the terrain. Results of a simulated covariance analysis are presented and discussed. >

Local observability matrix and its application to observability analyses

Local Observability and Its Application to

A Land navigation Demonstration Vehicle (LDV) has been assembled which fully automates the navigation task and provides the operator with a color map display derived from Digital Terrain Elevation Data (DTED). The system relieves the operator of the burdens associated with the tactical use of paper maps by providing accurate 3-dimensional position information using a strapdown inertial navigation platform aided by the Sandia Inertial Terrain Aided Navigation algorithm (SITAN). The map display and navigation instruments consist of a multi-processor SANDia Aerospace Computer (SANDAC) and a commercial Image Processing System (IPS). These interactive devices allow real-time map annotation and corrections of vehicle position errors. 7 refs., 9 figs., 1 tab.

E.J. Nava

Papers

Land navigation Demonstration Vehicle with a color map display for tactical use