Results from MBARI´s integrated mapping system

The Monterey Bay Aquarium Research Institute (MBARI) has developed an autonomous underwater vehicle (AUV) for deep ocean seafloor mapping. The MBARI Mapping AUV is a 21" diameter, torpedo-shaped Dorado class vehicle equipped with a 200 kHz multibeam sonar, 110 kHz and 410 kHz chirp sidescan sonars, and a 2-16 kHz sweep chirp sub bottom profiler. The multibeam sonar incorporates a circular receive array conformal to the vehicle hull, providing 1 degree × 1 degree beam resolution over a 150 degree swath. Navigation and attitude data are provided by an inertial navigation system integrating a laser ring gyro, accelerometers, and a 300 kHz Doppler velocity log (DVL). The vehicle is tracked during missions using an ultra-short baseline navigation system. The vehicle will also include acoustic modem and long-baseline navigation capabilities. A central cylindrical pressure housing contains all of the mapping sonar electronics. The main vehicle control and acoustic communications electronics are housed in a separate pressure housing in the vehicle tail section. Propulsion and steering are provided by a tailcone including an articulating propeller. Li-ion or Li-polymer battery packs allow for a 12 hour mission duration. The assembled package is rated to 6000 m depth. The mapping payload is also designed for ROV mounting, enabling low altitude (< 20 m) high precision missions in topographically challenging sites. The Mapping AUV has now been operated in both autonomous and ROV modes in and around the upper Monterey Canyon, successfully collecting high-resolution multibeam bathymetry and subbottom profile data. Near bottom surveys of the canyon axis achieve bathymetric coverage with a lateral resolution of 1 m and a vertical precision of 0.3 m. The subbottom profiler images subsurface structure to depths of 60 m in soft sediments.