Power efficient dynamic station keeping control of a flat-fish type autonomous underwater vehicle through design modifications of thruster configuration

Abstract

In many underwater missions, it is necessary for the autonomous underwater vehicle (AUV) to be stationed at a particular position and orientation to carry out tasks like inspection, opening/closing of valves, or repair of underwater installations. The ability of an AUV to maintain its position and orientation dynamically is termed as dynamic station keeping. Being a free-floating device, dynamic station keeping is not natural to most of the AUVs. This becomes more complex when the vehicle is underactuated and is not neutrally buoyant. In this paper, the problem of dynamic station keeping of an underactuated flat-fish type AUV is analysed and a new method of station keeping is proposed with an addition of dedicated thrusters. Effect of introduction of additional thrusters on tracking performance has been analysed and a modular configuration (using retractable thrusters) is proposed to reduce its influence on tracking control. The effects of underwater current magnitudes and angle of incidences on the station keeping performance are also analyzed. A comparative analysis on power consumption during station keeping is presented to prove the effectiveness of the proposed modular configuration.