Designing a Vertical / Horizontal AUV for Deep Ocean Sampling

Faculty and students at the URI Dept. of Ocean Engineering have conceived of a new class of AUV for deep sea profiling and sampling called a Mini Ocean Elevator (or MiniOE). The MiniOE is intended to operate as both a vertical and a horizontal AUV on the same mission, beginning its mission as a vertical profiler and then converting to a horizontal AUV for sampling prior to homing on an acoustic beacon at the surface. Such a vehicle has tremendous potential for ocean research while presenting unique challenges for stability and control. Horizontal AUVs typically achieve stability against roll and pitch through significant mass below the center of buoyancy along with tail fins. For a vertical vehicle this mass-ballast displacement must be in an orthogonal direction along the longitudinal axis to achieve stability in pitch and yaw, forsaking roll stability. Designing a cigar shaped AUV capable of both horizontal and vertical stability represents an unusual challenge. This paper describes the design work and testing involved in developing a stable vertical AUV that will later be equipped to convert itself to a stable horizontal AUV. This design effort used a balanced combination of physical experimentation and computer simulation to provide detailed information about how different configurations of an autonomous underwater vehicle (AUV) might affect its stability, and thus the controllability, while using conventional hardware and software resources.