Low-cost Inertial Navigation System (INS) sensor technology has evolved rapidly over the last decade with the development of less-expensive and higher-accuracy inertial measurement units (IMU). Developments in the field of the Global Positioning System (GPS) have also matured over the past decade to provide reliable centimeter-level accuracy in a relative sense for stand-alone GPS, and in an absolute sense for differential GPS (DGPS). Integrated GPS/inertial aviation applications are highlighted, with an emphasis on achieving centimeter-level inertial-based positioning for improved GPS tracking margins and increased continuity. To study the feasibility of centimeter-level integration of a low-cost IMU with a GPS receiver, a data collection system was designed, implemented and tested. A standard Kalman filter mechanization with 15 state-variables was used, in combination with precisely synchronized measurements. In addition, the IMU and the GPS antenna were co-located to within 0.1 m to minimize lever-arm effects. The performance of the integrated system was evaluated through both van and flight tests under different dynamic conditions. It was found that centimeter-level agreement between the IMU and GPS measurements is feasible for integration times of up to 1 second.
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