A modified loosely coupled approach to INS/GPS integration

A popular INS/GPS integration strategy is the loosely coupled approach, however its main disadvantage lies in its inability to provide measurement updates during periods of partial GPS availability. In such cases the INS navigation solution drifts over time. This paper proposes the construction of fictitious GPS satellites in order to facilitate GPS receiver position and velocity solutions in cases of partial GPS availability. The paper demonstrates the contribution of the proposed approach via several field experiments, in which the introduction of synthetic GPS measurements reduced the navigation errors obtained by the standalone INS and facilitated the classical implementation of loosely coupled integration.