Performance Evaluation of Controlled In-Motion Coarse Alignment Methods Applied to AUV Navigation

The initial alignment stage of Inertial Navigation Systems (INS) is a key factor for Autonomous Underwater Vehicles (AUVs) to achieve satisfactory navigation performance. Because the AUV alignment is usually conducted under marine environment conditions, the wave and wind disturbances impair the attainment of appropriate accuracy and convergence time requirements. Hence, this work presents a comparative performance evaluation of the well-known Attitude Decomposition-based Initial Alignment (ADIA) methods, for the specific case in which the AUV is under controlled motion conditions. As the main contribution of the work, we show that unaided ADIA approaches, which are self-alignment techniques, deliver a heading error of less than 1.0 degree for an in-motion alignment duration of 200 seconds. Results from experimental tests conducted with an Autonomous Surface Vehicle (ASV) in a straight-line maneuver confirm the outlined verifications.