Performance evaluation of coarse alignment methods for autonomous underwater vehicles in mooring conditions

• Published in: Ocean engineering 2023-08, Vol.282, p.114991, Article 114991
• Main Authors: Frutuoso, Adriano, Silva, Felipe O., de Barros, Ettore A.
• Format: Article
• Language: English
• Subjects: ADIA methods comparison; AUV; Coarse alignment
• ISSN: 0029-8018
• DOI: 10.1016/j.oceaneng.2023.114991

The coarse alignment stage of inertial navigation systems (INS) is a step of paramount importance, specially for vehicles that employ the latter as a reference navigation solution, as is the case of autonomous underwater vehicles (AUVs). For such class of vehicles, the alignment has encumbrances that goes beyond those usually reported for terrestrial and aerial systems, as AUVs generally align at non benign environments (e.g., under swaying and mooring conditions) and have limited auxiliary navigation sensors. This work, hence, proposes a comparative analysis of the most representative coarse alignment methods applied to AUVs in mooring condition. The alignment approach herein explored, throughout its optimized and non-optimized versions, is the attitude decomposition-based initial alignment (ADIA) method, and the proposed comparison procedure tests different types of observation vectors resolved in the frames of interest. Experimental tests are conducted, which are based on kinematic data collected from an unmanned marine vehicle representing the typical swaying and attitude oscillations of AUVs in the mooring state, i.e., when subject to wave induced disturbances. Results lead to practical conclusions that can be applied to the AUV initial attitude estimation and are related to autonomy, accuracy and precision of the methods, as well as to their convergence rate and computational effort. •Coarse alignment methods applied to autonomous underwater vehicles are presented.•Those methods can be applied even when the vehicle is on the sea surface.•The methods belong to the attitude decomposition-based initial alignment approach.•Optimized and non-optimized versions were considered in this study.•Results were based on experimental tests.