Adaptive integration techniques for low-cost integrated navigation systems

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Navigation technologies are expanding at a phenomenal rate, especially within the civil community, with devices such as vehicle and personal navigators becoming commonplace within our everyday lives. Most current navigation systems rely primarily on the Global Positioning System "GPS" for position and velocity estimates. But with the growing demand for solutions that works in harsh GPS environments, such as in downtown areas, under heavily treed canopies, or in the presence of jamming, the limits of GPS signal availability are being reached where the navigation solution becomes temporarily unavailable. To help provide a continuous navigation solution, Inertial Navigation Systems (INS) have typically been integrated with GPS. The applicant, and others research, have been involved with the development of integrated GPS/INS systems for many navigation application. Unfortunately most of the focus of these integrated systems has been for high precision applications (requiring high cost inertial systems) due to several factors: (a) The high cost of navigational or tactical grade inertial sensors (thousands of dollars), (b) The relatively large size of these high quality inertial units, (c) Government restrictions/regulations. The introduction of micro-electro mechanical systems (MEMS) inertial sensors has helped minimize these factors. MEMS are inexpensive, they are small enough to be embedded within a handheld GPS receiver, the government restrictions are minimal and they are commonly used with single point positioning GPS (SGPS) without the need for precise updates. For civil applications, MEMS inertial sensors combined with SGPS represent an efficient and practical solution for navigating in harsh GPS environments. But the gains in cost, size and regulations come with a price in terms of navigation accuracy. MEMS have much larger error characteristics than their higher grade counterparts meaning that the integration strategy is paramount to the success and accuracy of these sensors. The proposed research will address several issues with the current integration scheme including tuning, temperature and residual misalignment errors for integrated MEMS INS/SGPS systems.