Integration of the Global Positioning System with an Inertial Navigation System

Navigation is the determination of the position and velocity of a moving vehicle. Navigation systems used to measure this state vector can be one of two types, either positioning or dead-reckoning. Positioning systems, such as the Global Positioning System GPS measure the state vector without regard to the path traveled by the vehicle in the past. On the other hand, dead-reckoning navigation systems, such as the Inertial Navigation System INS determine the state vector from a continuous series of measurements relative to an initial position. By integrating the unique and complementary characteristics of each system into one integrated INSGPS system, accuracies as well as additional benefits can be achieved even though unattainable by either system independently. The optimal method of integrating these two systems is through the use of a Kalman filter. This mathematical technique is used for computing the best estimate of the state of a process which varies with time. Approaches to this filtering can either be centralized in a main filter or federated, where filtering is done at individual sensors. This theory can then be applied to real world scenarios, whether it be an aircraft during flight, an aircraft during precision approach landings, or the failure detection and isolation of a GPS signal.