Ultratight GPS/Reduced-IMU Integration for Land Vehicle Navigation

A reduced inertial measurement unit (RIMU) is ultratightly (UT) integrated with a vector-based Global Positioning System (GPS) receiver using two approaches; vector delay and frequency lock loops (VDLL/VFLL), and a VDLL with a cascaded phase lock loop (CaP). A CaP plus a frequency discriminator (CaPF) composite loop is developed to provide reliable Doppler measurements and improves navigation performance by up to 20% compared with other methods using real world data.