An efficient INS/GPS impulse response model for bridging GPS outages

The integration of Inertial Navigation System (INS) and Global Positioning System (GPS) architectures can be achieved through the use of many time-domain filters such as, extended Kalman, unscented Kalman, divided difference, and particle filters. The main objective of these filters is to achieve precise fusion of the data from GPS and INS to provide INS-only navigation solution during GPS outages. The prediction mode performance of all state-of-the-art time-domain filters is poor with significant drift in the INS-only solution. In this paper, a new frequency-domain dynamic response method is proposed to model the INS/GPS system. The input to this dynamic system is the INS-only solution and the output is the INS/GPS integration solution that help derive the transfer function. The discrete Inverse Least Squares Frequency Transform (ILSFT) of the transfer function is applied to estimate the impulse response of the INS/GPS system. It is shown that the long-term motion dynamics are recovered by 72%, 42%, 75%, and 40% for north velocities, east velocities, north positions, and east positions respectively when compared with INS-only solution (prediction mode of the INS/GPS filter).