Inertial navigation systems aided by G.P.S.

Abstract : The present work is a Kalman filter study, in indirect feedback configuration, for a proposed integrated inexpensive Inertial Navigation System/Global Positioning System (I.N.S./G.P.S.). A one nautical mile per hour, local-level, two-accelerometer I.N.S. is used where the errors are represented by a 7 state linear model. G.P.S. is assumed to provide four range measurements from an equal number of satellites with the best relative position among those in view. I.N.S. error analysis showed error dependence on Schuler frequency and that it was possible to neglect Foucault modulation for navigation purposes. The present I.N.S./G.P.S. system has been shown to be quite effective since the navigation errors are reduced quickly for both short and long term periods without any divergence. (Author)