Non-linear mathematical model for integrated global positioning/inertial navigation systems
In recent years there has been a major upsurge of interest in the integrated global positioning system (GPS)/inertial navigation system (INS) as a cost-effective way of providing accurate and reliable navigation aid for civil and military vehicles (ships, aircrafts, land vehicles). In this paper an error model is developed which can be used for GPS/INS filter mechanization. It is shown that the model has a linear and a non-linear part. The latter consists of a quadratic function of system states and may be approximated by a noise term thereby allowing the use of the well-known Kalman filter (KF) design technique. The KF algorithm suitable for this application is also developed; and preliminary computer simulation results are given. Filter implementation issues for system operation under varying measurement set (such as for state-6 and state-3 operation, selective availability condition, and variable satellite constellation) are discussed.