DEPTHX (DEep Phreatic THermal eXplorer) is a 4 degree-of-freedom autonomous underwater vehicle (AUV) designed to serve as an experimental platform for testing science autonomy and 3D SLAM (simultaneous localization and mapping) for the NASA Europa lander third stage “hydrobot”.
DEPTHX is an extraordinarily capable vehicle. It will maneuver, hover, and wall-track in full 3D. It contains redundant (survivable) thruster systems (4 horizontal, 2 vertical), dual power supplies, a sophisticated onboard navigation system, environmental sensing suite, and a 56 point 4-Pi steradian real-time mapping and obstacle avoidance system. It can be run on the surface using wireless WiFi. It can spool a thin single-mode optical fiber for either data uplink or tele-op control. And, most importantly, it can be programmed to autonomously (no tether) build and follow 3D maps, to explore and map unknown territory, and return home using it’s own maps, without any GPS aiding. It can be commanded to drive to a known position, acquire 3D geometry, measure environmental variables, and take liquid and solid samples. It can also be commanded to follow a programmed periodic pattern. The entire vehicle is service-rated to 1,000 meters ocean depth. The power sub-system provides 8 hours of cruising range. Nominal cruising velocity is 0.2 m/s, but this is an artificial constraint we have imposed for mapping and science missions in unknown territory (such as the unexplored Zacaton cenote). The vehicle is capable of 5X the power output used to obtain the 0.2 m/s cruise velocity. There are two available control modes: force and velocity feedback. In the velocity control mode the vehicle is extremely “stiff” and will hold position, elevation, and yaw angle very tightly, and it will stop on a dime. The current maximum geometry tracking range is approximately 250 to 300 meters (radius from the vehicle centroid).