Project of a 6 Degrees of Freedom Remotely Operated Vehicle propulsion system with azimuthal thrusters

The control of underwater vehicles is a challenging task even in the era of highly efficient computing technology. Its difficulties consist of the properties of the underwater environment such as high nonlinearity, drag and disturbances and the expected vehicle performance, which should be able to fulfill its tasks precisely, safely and possibly quickly. Additionally, the miniaturization, availability and lowering costs of electronics created new possible applications for underwater vehicles. While in the case of a work-class Remotely Operated Vehicles (ROVs) the power efficiency and consumption is not the most significant aspect, it is very considerable in the case of smaller robots with limited power source. Nevertheless, the standard principles of actuating an ROV remained roughly unchanged over the years. Most units which are designed to move independently in all 6 Degrees of Freedom are equipped with a set of 8 thrusters which are fixed to the frame and provide no thrust vectoring, resulting in forces partially cancelling each other out. Due to the fact that the thrusters consume the majority of the energy supplied to the vehicle, this causes losses in efficiency. Widely used Open-loop control systems could also be an issue in which an experienced operator is needed in order to maneuver the vessel. The scope of this work is to propose and test an alternative solution with azimuthal thrusters, which could provide the same mobility in 6 DoF with reduced overall number of thrusters and thus improved power efficiency as well as better control based on closed-loop system with position feedback.