Integration of GPS, Inertial and SAR Data for GPS-Degraded Navigation

ABSTRACT: Qunav proposes the development of GPS/INS/FeaTure-based SAR (GIFTS) integrated navigation architecture. The architecture exploits INS as a core sensor and applies GPS (when available) and SAR data to mitigate drift in inertial navigation outputs. Fusion of SAR and inertial data is implemented at two levels. Data fusion at the level of signal processing derives information about inertial error states from feature distortions in SAR images and applies this information for the INS error correction. Data fusion at the measurement level utilizes local and global feature-aided inertial mechanizations. Local aiding applies changes in parameters of features extracted from consecutive SAR images to update inertial navigation states, thus applying a tightly coupled version of velocity updates. Global aiding relates parameters of SAR image features to feature information extracted from a map of the environment in order to implement tight-coupling equivalent of INS position updates. Both local and global aiding are enhanced by integrity monitoring that removes outliers by a) exploiting INS-based feature matching; and b) redundancy in feature geometry. Phase I will demonstrate the feasibility of the integration approach and will evaluate its performance characteristics in high-fidelity simulation environments. System architectural studies will result in the initial prototype design approach. BENEFIT: Phase I effort will create a basis for prototyping and transitioning of the GIFTS technology. Successful accomplishment of Phase I technical tasks will enable a) development of algorithms for the GPS/SAR/inertial integration; b) demonstration of performance characteristics; and, c) preliminary design of the technological approach for prototyping. These anticipated results will ensure that a strong foundation is created for technology demonstration and prototyping during Phase II. If successfully demonstrated, GIFTS has a significant potential for both DOD applications and commercial users. Numerous platforms (both military and civilian) that perform layered sensing using SARs will benefit from improved navigation robustness in GPS-challenged environments. GIFTS will enable a) precise reconstruction of the flight trajectory; and, b) accurate geo-registration of SAR images. In addition, the technology will enable the use of lower-cost inertial measurement units. This will provide a significant overall reduction in cost, weight, size and power consumption thus enabling the system"s functionality on small-size platforms and creating new application cases for SAR sensors.