Development of a dual-shaft propeller thruster equipped with rotational speed sensor for UVMS control

Abstract

Majority of underwater robots utilize single propeller thrusters for navigation. A disadvantage of using a single-shaft propeller thruster is that the thrust force generated from a single propeller for reverse and forward thrust is asymmetric due to the disturbed flow caused by the thruster's body which may reduce thruster efficiency. Moreover, measurement procedures to precisely calculate propeller's rotation speed were also not available. To address these problems, this paper proposes a dual-shaft magnetic coupling-driven propeller thruster for underwater robot, equipped with sensors for measuring propeller's rotational speed. Numerical studies and experimental results on the position and orientation control of the proposed thruster are presented. Detail comparison of the rotational speed, thrust force and duty ratio between numerical calculation and actual experimental measurement results show the effectiveness of the proposed thruster. This paper also demonstrated that by using the proposed thruster, the control performance of an underwater robot can be improved significantly compared to commercially available thruster. The ability to determine propeller rotation directions is also a major advantage of this work.