USV Navigation Geometry for Surface Current Inference

A novel method to infer the surface current vector and propulsive speed of a Liquid Robotics Wave Glider, based on GPS-derived speed over ground recorded for three or more unique transects, is presented. The method follows directly from the characteristics of the Wave Glider’s navigation system. Error of the inference solution is explored, based on the known geometry of Wave glider transects, considering a noisy measurement of speed over ground. Experimental results are given following a one-week deployment off of the Southern California coast. Surface current estimates are compared to control observations from a mooring-mounted, downward looking Acoustic Doppler Current Profiler and High-Frequency Radar. Finally, an application of this method is showcased through implementation as an autonomous behavior that may be used to provide real-time environmental awareness and to predict the feasibility and completion times of future planned paths.