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

ABSTRACT: Qunav proposes the development of GPS/INS/FeaTure-based SAR (GIFTS) navigation architecture in order to enable accurate navigation in GPS-challenged and GPS-denied environments. The architecture exploits INS as a core sensor and applies SAR measurements to mitigate inertial drift. Fusion of SAR and INS data is implemented at two levels. Data fusion at the level of signal processing derives information about inertial error states from SAR signal data (such as slow-time IQ samples). Data fusion at the measurement level utilizes local and global feature-aided inertial mechanizations. Local aiding applies changes in parameters of unknown features that are extracted from SAR images thus providing a completely self-contained solution that does not require any prior knowledge of mission environments. Global aiding uses geo-referenced landmarks for the INS error reset. Both local and global aiding are enhanced by integrity monitoring that removes SAR measurement outliers using INS-based feature tracking. The ultimate goal of Phase II is to demonstrate GPS-like performance using SAR/inertial mechanization in GPS-denied flight test environments. Phase II will fully develop all components of the GIFTS navigation mechanization. SAR and inertial experimental data will be applied to verify the system functionality and evalute its characteristics in a post-processing operational mode. BENEFIT: 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 provide a) precise reconstruction of the flight trajectory; and, b) accurate geo-registration of SAR images. In addition, the technology will enable a 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. Commercialization for the DOD market will be based on collaboration with our subcontractor, Northrop Grumman Electronic Systems (NG ES). For technology transitioning, we envision insertion of the SAR/inertial navigation mechanization into NG ES existing and perspective embedded GPS/inertial (EGI) products. This will extend the product functionality envelope to include GPS-challenged and GPS-denied environments; and, will also lower the cost of inertial sensors. An ideal transition would include a technology spiral insertion designed to add new GIFTS capabilities to existing navigation systems.