Research on North-Seeking Based on Dual FOGs and Virtual Inertial Instruments

North-seeking system based on dual FOGs and virtual inertial instrument is put forward in this paper. According to the practical engineering background, two dynamic restriction assumptions are satisfied nearly by means of analyzing and actual measurement. So the gyroscope and accelerometer of up direction in normal system can be replaced by virtual inertial instruments. Thereby the cost and the volume of system are reduced. In accordance with the dynamic restriction of vehicle, the equivalent output expression of virtual gyroscope and virtual accelerometer has been presented. Then a Kalman filter was designed for initial alignment in accordance with the error equation of initial alignment on static base. Ultimately, the experiment concerned on north-seeking at the real working condition is given. Experiment results show that, at the condition of vehicle dynamic restriction, fine north seeking result can be realized based on two horizontal gyroscopes and accelerometers by the way of adopting virtual up direction gyroscope and accelerometer.