Design and characteristics evaluation of a novel spherical underwater robot

This paper depicts the structural design of a novel water-jet-based spherical underwater robot. The propulsion system is made up of four water-jet thrusters and 8 steering servo motors which can adjust the polydirectional shift of thrusters nozzle to achieve 4-degrees-of-freedom (4-DOF) motion. Every two thrusters nozzles formed an angle of 90 degree in one plane. A bilayer structure was adopted for the control system to obtain data from various sensors, meanwhile control the outputs of ports after calculation processing. The primary side whose core is TMS320f28335 processor was employed for the data collection and disposing calculation. And made the Atmega2560 processor as the main chip of the subordinate side to control the propulsion system. The Micron Data Modem is integrated into the electrical design, which can realize the data transmission and communication between multi-SURs in future. Based on the theoretical analysis and calculation, a series of underwater experiments were carried out to test the performance of the novel spherical underwater robot; these experiments included surgesway motion test, yaw motion test, heave motion test, and anti-interference test. A FSMC controller was employed to control the direction of the vectored water-jet thrusters for underwater motion. The experimental results demonstrated that the novel spherical underwater robot could realize underwater motion rapidly and accurately. The performance of the novel SUR is more nimbler and flexible than the previous SUR-II we developed.