Optimal Seafloor Mapping Technologies

The primary objective of this proposal is to implement an autonomous swath bathymetry survey capability aboard an unmanned undersea vehicle (UUV) using a hybrid sonar that combines the high spatial resolution of a focused multibeam echo sounder in a sector spanning +/-30 deg about nadir with the long range mapping capabilities of a bathymetric sidescan sonar for a total swath angle of up to 160 deg (swath width roughly 11 times the UUV's altitude above the bottom). This represents a better than twofold improvement in swath bathymetry coverage (hence survey efficiency) over existing solutions that rely on a multibeam sonar system alone, and it fills the near-nadir data gap typical of systems that rely on a bathymetric sidescan sonar alone. In addition, high-resolution acoustic backscatter imagery is obtained concurrently with the bathymetry, thus alleviating the need for a separate imaging survey. In both sonars, dynamic focusing will help constrain the vertical uncertainty associated with each sounding. Likewise, high across-track data density for each ping will provide the redundancy necessary to constrain horizontal uncertainties and resolve navigation offsets. For each ping, the achieved swath coverage will be defined at the across-track limits where sounding uncertainty exceeds a prescribed threshold.