Abstract:
Underwater robotics applications require accurate velocity sensing to enable long-term dead reckoning navigation in the absence of GPS or visual features. Velocity is typically measured with a Doppler Velocity Log, which measures the Doppler frequency shift induced by the motion of the sensor along four beams, from which the sensor velocity can be recovered. We expand upon this idea with the proposed Doppler Velocity Imaging Sonar (DVIS) device: a 3D multibeam imaging sonar that measures Doppler velocity in addition to range. It consists of a single omnidirectional transmitter that ensonifies a large portion of the scene, and a 2D grid of receivers that collect echos. Digital beamforming techniques are applied to produce a 3D point cloud augmented with per-point Doppler velocity. We design and construct a proof of concept device and deploy it on an underwater vehicle for validation. The large number of Doppler velocity measurements should enable more accurate and robust vehicle velocity estimates in challenging underwater environments.

Committee:
Michael Kaess (advisor)
David Wettergreen
Easton Potokar