Towards Model-Aided Navigation of Underwater Vehicles

This paper reports the development and preliminary experimental evaluation of a model-aided inertial navigation system (INS) for underwater vehicles. The implemented navigation system exploits accurate knowledge of the vehicle dynamics through an experimentally validated mathematical model, relating the water-relative velocity of the vehicle to the forces and moments acting upon it. Together with online current estimation, the model output is integrated in the navigation system. The proposed approach is of practical interest both for underwater navigation when lacking disparate velocity measurements, typically from a Doppler velocity log (DVL), and for systems where the need for redundancy and integrity is important, e.g. during sensor dropouts or failures, or in case of emergency navigation. The presented results verify the concept that with merely an addition of software and no added instrumentation, it is possible to considerably improve the accuracy and robustness of an INS by utilizing the output from a kinetic vehicle model. To the best of our knowledge, this paper is the first report on the implementation and experimental evaluation of model-aided INS for underwater vehicle navigation.