Dynamic Analysis and Design of Spheroidal Underwater Robots for Precision Multidirectional Maneuvering

In this paper, we present an optimized body shape and thruster layout design for a class of jet-propelled underwater robots. Spheroidal robots with no rudders and appendages are highly maneuverable and capable of accessing complex underwater structures for inspection and surveillance. These robots are hydrodynamically unstable, but can make rapid turns and move in multiple directions. This paper describes a control-theoretical design methodology, examining the controllability of surge, sway, and yaw motion in relation to an aspect ratio of the body shape and the direction and location of each propulsion jet. A design with angled jets combined with a body aspect ratio of 1.2-1.8 is controllable and exhibits good performance. A prototype robot with an optimized body shape and jet arrangement has been built and tested. Experimental results illustrate the superb multiaxis maneuverability of this design.