Water Referenced Doppler Velocity Aiding for AUV Navigation

Water relative Doppler velocity aiding is an alternative that can be used in high-end inertial navigation systems for autonomous underwater vehicles in operations where bottom relative measurements are not available. The paper starts with reviewing how the water relative velocity measurements should be integrated in the navigation system, before presenting results from experiments with a HUGIN AUV. The extent to how a sea current forecast model could be used to counter the effect of the unknown sea current, which is the main error source when there measurements are used, is investigated. The experimental results demonstrate that qualitative information about the sea current can be utilized in the navigation system, and that in this particular experiment, the position drift over an 8 hour submerged operation can be reduced from 12 % of traveled distance when no velocity measurements are used, to 3 % when using water relative Doppler velocity measurements.