Dead Reckoning of Dynamically Positioned Ships ©ISTOCKPHOTO.COM/TRYAGING Using an Efficient Recurrent Neural Network By Robert Skulstad, Guoyuan Li, Thor I. Fossen, Bjørnar Vik, and Houxiang Zhang W hen a ship experiences a loss of position reference systems, its navigation system typically enters a mode known as dead reckoning (DR) to maintain an estimate of its position. Commercial systems perform this task using a state estimator that includes mathematical model knowledge. Such a model is nontrivial to derive and needs tuning if the vessel's dynamic properties change. To this end, we propose using machine learning to estimate the horizontal velocity of the vessel without the help of position, velocity, or acceleration Digital Object Identifier 10.1109/MRA.2019.2918125 Date of publication: 12 August 2019 1070-9932/19©2019IEEE SEPTEMBER 2019 * IEEE ROBOTICS & AUTOMATION MAGAZINE * 39http://www.ISTOCKPHOTO.COM/TRYAGING