Preliminary study of cooperative navigation of underwater vehicles without a DVL utilizing range and range-rate observations

This paper reports a preliminary study of a method for combined underwater communication and navigation of underwater vehicles (cooperative navigation) equipped with an acoustic modem, attitude, and depth sensors, but lacking a Doppler velocity log (DVL), and a surface vehicle equipped with an acoustic modem and GPS. Few previously reported studies have utilized acoustic range rate in addition to acoustic range for the general navigation of underwater vehicles. This paper reports an observation model for range-rate measurements and preliminary anecdotal simulation studies for cooperative navigation of one underwater vehicle client with one surface vehicle server employing both range and range-rate observations to estimate the vehicle states with a delayed-state extended Kalman filter in the absence of DVL velocity observations. The preliminary studies suggest that the addition of range-rate measurements may offer advantages over the case of range-only observations in a limited set of circumstances, such as poor range-observation accuracy. The present study is preliminary, however, and directions for future study are suggested.