A Multiposition Initial Alignment Method of Portable MIMU/FOG Compound Navigation System

In the future, a pedestrian navigation system (PNS) will be widely applied. In navigation system, an initial alignment is essential before starting navigation. There are two primary alignment methods, one is an inertial/magnetometer assisted alignment method, the other is a multiposition rotation modulation alignment method. However, magnetometer is susceptible to magnetic disturbance, and the large volume of rotary modulation system is not suitable for PNS. To solve these problems, a compound navigation system (CPNS) is proposed. It consists of a single-axis fiber-optic gyro (FOG) and a triaxial microelectromechanical system inertial measurement unit (MIMU) without modulation mechanism. CPNS is placed in different positions. According to the variation law of cosine function, FOG data in multiposition are used as fitting alignment, MEMS gyro tracks attitude changes between different positions. The experimental results demonstrate that initial alignment accuracy can be well calculated with several multiposition schemes under different conditions. This method could be a novel solution for PNS's initial alignment.