Design and testing of innovative thrusters and their integration in the design of a reconfigurable underwater vehicle

Nowadays, Unmanned Underwater Vehicles (UUVs) are increasingly used in underwater operations (e.g. exploration, monitoring, maintenance), because they make safe working under the water. Since their use is growing, it is extremely important to ensure better maneuverability and lower power consumption to improve the performances of this kind of vehicles. The work carried out in the last three years at the Mechatronics and Dynamic Modelling Laboratory (MDM Lab) of the Department of Industrial Engineering of University of Florence (UNIFI DIEF), focused exactly on these problematics. More in details, the study presented below concerned both an in-depth analysis of current commercial and research UUVs, with the aim to define the specifications and the design of a new type of underwater vehicle, and the study of commercial low cost motors, with the purpose of improving their performance thus the one of the mobile robots they are mounted on. In the introduction a short summary of the UUVs history is reported and all the vehicle of UNIFI DIEF are presented. In the first chapter, instead, a deep analysis of the state of art of underwater vehicles is reported. This study has been divided into AUVs (Autonomous Underwater Vehicles), ROVs (Remotely Operated Vehicle) and Gliders features, taking into account especially their propulsion systems. In addition, based on also the study of the state of art, the conceptual design of an innovative vehicle capable of changing its shape and its thrusters layout is synthetized. In the following chapter (chapter 2), the design of the innovative vehicle is described, in order to verify the feasibility of the vehicle itself exploiting current technology and to estimate its performances and the budget required for its realization. In chapter 3, a low cost commercial thruster is presented. With these thrusters all the vehicles of UNIFI DIEF have been equipped; for this reason, the third chapter reports a deep experimental study to define the relation between thruster parameters and the input command. This study has been very important because it allows improving the thruster parameters estimation and consequently the control performances. In addition, in this third chapter the new vehicle designed by UNIFI DIEF with the collaboration of MDM Team s.r.l. (an University of Florence Spin Off) and named ZENO is presented. In chapter 4, it is shown how the thruster studied in the previous chapter has been upgraded and hardware modifications have been made. More in details, in this chapter it is explained how a Hall effect sensor has been integrated in the thruster in order to measure the rotor speed. In addition, it is shown how a low cost closed loop control system has been implemented for the thruster previously described and the results obtained on dedicated test rig are given. Finally, in the conclusion the results obtained are summarized, highlighting how the designed innovative vehicle is feasible and has the performances required by its hypothetical application. In addition, it is summarized how the studied thrusters have improved the UNIFI DIEF vehicles performances.