A stable adaptive attitude estimator on SO(3) for true-North seeking gyrocompass systems: Theory and preliminary simulation evaluation

Abstract

This paper reports a novel stable adaptive attitude estimator and preliminary simulation results of a true-North gyrocompass system employing the attitude adaptive identifier and a commercially available low-cost inertial measurement unit (IMU) comprising a 3-axis fiber optic gyroscope (FOG) with a 3-axis micro-electro-mechanical systems (MEMS) accelerometer. Optical North-seeking gyrocompass systems typically employ a microprocessor system to sample the low-level raw sensor values for angular-rate and linear-acceleration at a high sampling rate and estimate true-North heading, pitch, and roll. This paper reports the first adaptive attitude estimator on SO (3) which utilizes 3-axis angular-rate sensor data and 3-axis linear acceleration sensor data to estimate the instrument's 3-degrees of freedom (DOF) attitude (roll, pitch, and heading) without using magnetometry of the Earth's magnetic field. A stability proof and preliminary numerical simulation results are reported. The simulation results for a rotating IMU configuration are promising, and further experimental evaluation and extension of the algorithm for the case of a translating IMU configuration typically found on moving robotic vehicles are needed.