Henry L D Ritchie

US Patent:

59126434, Jun 15, 1999

Filed:

May 29, 1997

Appl. No.:

8/865541

Inventors:

Joseph N. Dmytrasz - Glen Head NY
Joseph Gatta - Port Washington NY
Henry F Ritchie - Bayside NY
Donald L. Sumner - Keller TX

Assignee:

Lockheed Corporation - Bethesda MD

International Classification:

G01S 302

US Classification:

342457

Abstract:

A Passive Navigation System (PNS) provides continuous updating of position, velocity, and attitude information of a vehicle without recourse to radiating or external navigation aids. The system accurately computes navigation information with the utilization of gravity sensors, gravimetric maps, vertical position, and velocity measurements. Sensor and map data are optimally processed by real time filtering to compute the best position, velocity, and attitude of the vehicle. The products of measured gravity gradients and the velocity of the vehicle are integrated over time to obtain a north, east, down gravity vector components which are combined with corresponding components obtained from a vertical deflection map in a complementary filter. North and east components of the combination are compared with the corresponding components from the vertical deflection map, while the down component of the gravity is compared to the down value obtained from a gravimeter. Residuals from these comparisons are utilized in a Kalman filter to provide corrections that render inertial measuring units in the system independent of the vertical deflections and gravity anomalies.