Application of an off-the-shelf Fiber Optic Gyroscope based Inertial Measurement Unit for attitude and heading estimation

The ability to estimate attitude (pitch, roll) and heading (yaw) in reference to the North-East-Down frame is of great importance for localization applications. Determining true north proves to be especially challenging. This paper presents a fast and simple north-seeking method by utilizing earth's rotation measured by a three-axis Inertial Measurement Unit (IMU) based on Fiber Optic Gyroscopes (FOG) and Micro-Electro-Mechanical Systems (MEMS) accelerometers. Assuming a non-moving IMU, its measured accelerations and angular velocities are solely evoked by earth's gravitation and angular speed. To increase accuracy, a static multi-position calibration scheme is introduced. Sensor bias is estimated under the assumption that the magnitude of accelerometer and gyroscope data equals earth's gravitation and angular speed. Precision and accuracy of the gyrocompass is experimentally evaluated and prove to be a promising alternative in comparison to expensive commercially available Attitude and Heading Reference Systems (AHRS).