Nonlinear Attitude Control of a Spherical Underwater Vehicle.

Ramon Fernandez,Claudio Rossi,E R,Zorana Milosevic,Sergio Dominguez

doi:10.3390/s19061445

Abstract

In this work, we present the design, implementation, and testing of an attitude control system based on State Feedback Linearization (FL) of a prototype spherical underwater vehicle. The vehicle is characterized by a manifold design thruster configuration for both locomotion and maneuvering, as well as on a novel pendulum-based passive pitch control mechanism. First, the mechanical design and onboard electronics set up of the spherically shaped hull are introduced. Afterward, a high-fidelity dynamic model of the system is derived for a 6 degree-of-freedom (DOF) underwater vehicle, followed by several experiments that have been performed in a controlled environment to compare the performance of the proposed control method to that of a baseline Proportional-Integral-Derivative (PID) controller. Experimental results demonstrate that while both controllers were able to perform the specified maneuvers, the FL controller outperforms the PID in terms of precision and time response.

Highlights

Europe is coming under increased pressure due to its near-complete dependency on the import of mineral raw materials
The experimental tests were designed to compare the performance of the Feedback Linearization (FL) controller, presented in Section 4.1, with the PID controller previously implemented and tested in [23] for a regulation problem scenario [32]
This type of maneuver is key for the overall purpose of the UNEXMIN project, which involves data gathering from sensitive scientific instruments and a 3D mapping of the environment at specific locations inside the flooded mine tunnels which must not be corrupted by unstable control

Summary

Introduction

Europe is coming under increased pressure due to its near-complete dependency on the import of mineral raw materials. There are an estimated 30,000 inactive mining sites, a considerable number of which still contain raw materials, currently in critical demand [1]. Among these sought-after raw materials there are metallic and industrial minerals, construction materials, and base metals, such as cobalt, gallium, indium, and a range of rare earths necessary for IT appliances [2]. Once a mine is permanently closed, the dewatering systems cease to operate, and without the existence of any drainage, the tunnels become permanently submerged Most of these mine sites, presently submerged, are more than a century old, and the information available regarding the structural layout of the tunnels is limited and imprecise, if not totally lacking. The use of robotic platforms such as underwater vehicles to explore these sites and gather valuable geological and mineralogical

Methods

Findings

Discussion

Conclusion