Dead reckoning through the water column with an acoustic Doppler current profiler: Field experiences

Underwater vehicles currently rely on external acoustic tracking systems to estimate position when away from the surface or the seafloor. Many vehicles dead reckon near the seafloor using a Doppler velocity log. This paper presents a method for dead reckoning through the water column using over-lapping water profiles measured by a vehicle-mounted acoustic Doppler current profiler. Under mild assumptions, the vehicle can simultaneously estimate its own global velocity at the same time as identifying the ocean current profile. The estimation problem is solved using batch least squares, recursive least squares, or a simple online depth bin averaging scheme. We discuss challenges encountered in implementing the approach during three field deployments of the autonomous underwater vehicle Sentry, and provide estimates of the ocean current, the vehicle velocity, and integrated position.