Design and performance analysis of a compact dual-motor underwater vector propulsion system

Vector propulsion systems enhance the limited three-dimensional motion capabilities of conventional systems at low speeds. However, their requirement for multiple prime movers increases the underwater robot's power capacity, impacts its size and mass and compromises long endurance capabilities. To solve this problem, a compact dual-motor underwater vector propulsion system is proposed in this paper. It employs a nozzle, adjustable in a two-dimensional plane, to produce an adjusting force, and a propeller, perpendicular to this plane, for main thrust, achieving three-dimensional motion. The innovation lies in a dual-shaft motor with each shaft featuring a one-way bearing. The synchronized direction of rotation of the two one-way bearings is opposite. This configuration enables the motor to drive the propeller during forward rotation and the nozzle during reverse rotation, achieving a two-in-one drive motor and reducing prime movers. Additionally, using nozzles for attitude regulation overcomes the limitation of conventional propulsion systems. An analytical model defines mechanical output characteristics. Computational fluid dynamics analyze hydrodynamic characteristics. The prototype's underwater experiments confirm its ability to generate main thrust and a two-dimensional planar adjusting force, enabling three-dimensional motion.