Inertial reference unit in a directional gyro mode of operation

This paper deals with a cost effective inertial reference unit design providing both MEMS based navigation unit calibration means and an attitude and heading measurement system in a directional gyro mode of operation. A main contribution of this paper is a novel design of such a universal system not primary relying on a magnetometer (MAG) or GPS aiding. Generally, without this aiding Attitude and Heading Reference Systems (AHRSs) are not directionally stable. Also, having precise reference in a calibration process is crucial and in most cases the solution is expensive. We thus replaced an expensive solution of both applications with the cost effective one suiting mentioned purposes using only one single axis fiber optic gyro supported by an inertial MEMS based aiding system. We also proposed a calibration procedure and blended solution to provide both stable and reliable navigation data with accuracy better than 5 deg/h specified by the TSO-C5e.