Simulation and modeling of a soft grounding system for an AUV

Abstract

Energy storage is very limited in AUV's. To assist with energy management, data gathering missions have been proposed where the vehicle should sit on the bottom and gather acoustic/video/chemical data over extended periods of time. In this grounding scenario while thrusters may be used, they are less desirable because of their high energy consumption and restricted use close to the ocean floor. The purpose of this work is to study a low cost, simple soft grounding capability for a submersible vehicle using controllable ballast. The ballast system based on the NPS Phoenix AUV is designed to control weight addition into or out of two ballast tanks. The developed control law adjusts the pump flow rate keeping the pitch angle and depth rate within the limits. Results for a soft grounding operation have been obtained using simulation.