A nonlinear observer for integration of GPS and Inertial Navigation Systems

GPS and INS have complementary properties and they are therefore well suite d for integration. The integrated solution offers better long term accuracy than a stand-alone INS, and better integrity, availability and continuity than a stand-alone GPS receiver, making it suitable for demanding applicati ons. The integrated filter is nonlinear both in state and measurements, and the extended Kalman-filter has been used with good results. But the extend ed Kalman-filter has not been proven globally stable, and it is also comput ationally intensive, especially within a direct integration architecture. I n this work exponential stability of the origin of the combined attitude an d velocity error systems is proven along with robust stability in the prese nce of noise and unmodelled dynamics.