Improving Research Aircraft Navigation by Incorporating INS and GPS Information in a Variational Solution

Abstract

With the new (potentially more accurate) Global Position System (GPS) measurements available, aircraft navigation systems are significantly improved. Since the GPS can drop out occasionally and exhibit other intermittent errors, it cannot be used exclusively for all navigational needs. The traditional Inertial Navigation System (INS) position and velocity measurements, on the other hand, suffer from large Schuler oscillation and drift errors over the duration of a flight. This work proposes and tests a variational method to determine improved aircraft positions and velocities when both INS and GPS data are available. This technique incorporates GPS position and velocity data and INS acceleration data. The data are weighted by the reciprocal of the variance of their errors. Error characteristics of the data are determined objectively by examining the internal consistency of the data themselves. The resulting improved position and velocity time series are fully internally consistent. The data used for this project come from the Tropical Ocean Global Atmosphere Coupled Ocean?Atmosphere Response Experiment field program conducted from November 1992 to February 1993.