The Design and Application of a Vectored Thruster for a Negative Lift-Shaped AUV

Autonomous underwater vehicles (AUVs), as primary platforms, have significantly contributed to underwater surveys in scientific and military fields. Enhancing the maneuverability of autonomous underwater vehicles is crucial to their development. This study presents a novel vectored thruster and an optimized blade design approach to meet the design requirements of a specially shaped AUV. Determining the ideal blade characteristics involves selecting a maximum diameter of 0.18 m and configuring the number of blades to be four. Furthermore, the blades of the AUV were set to rotate at a speed of 1400 revolutions per minute (RPM). The kinematics of the thrust-vectoring mechanism was theoretically analyzed. A propulsive force test of the vectored thruster with ductless and ducted propellers was performed to evaluate its performance. A ductless propeller without an annular wing had a higher propulsive efficiency with a maximum thrust of 115 N. Open-loop control was applied to an AUV in a water tank, exhibiting a maximum velocity of 0.98 m/s and a pitch angle of 53 degrees. The maximum rate of heading angle was 14.26 degrees/s. The test results demonstrate that the specially designed thrust-vectoring mechanism notably enhances the effectiveness of AUVs at low forward speeds. In addition, tests conducted in offshore waters for depth and heading control validated the vectored thruster's capability to fulfill the AUV's motion control requirements.