Underwater robots have been promoted a significant interest in monitoring the marine environment. In some complex situation, robots sometimes need to keep moving fast, sometimes need to keep low speed and low noise. To address this issue, a novel spherical underwater robot (SUR IV) with hybrid propulsion devices including vectored water-jet and propeller thrusters is proposed in this paper. The diversity of the movement modes is also proposed for the different targets as remote or hover and general or silent. To analyze the hydrodynamic characteristics of the hybrid thruster, the computational fluid dynamics simulation is calculated in ANSYS CFX by using the multi-reference frame method. The simulation results show the interaction between the propeller and water-jet thruster. The thrust experiment to evaluate the performance of the improved hybrid thruster is also conducted. The maximum thrust of the hybrid thruster is increased 2.27 times than before. In addition, a noise comparison experiment is conducted to verify the low noise of the water-jet thruster. Finally, the 3 DoF motions which include the surge, heave and yaw for the SUR IV were carried out in the swimming pool. The improvement of the overall robot is assessed by the experimental results.

中文翻译：

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具有混合推进装置的高度稳定，高效的球形水下机器人

水下机器人已引起人们对监视海洋环境的极大兴趣。在某些复杂的情况下，机器人有时需要保持快速运动，有时需要保持低速和低噪音。为了解决这个问题，本文提出了一种新型的球形水下机器人（SUR IV），该机器人具有混合推进装置，包括矢量水射流和螺旋桨推进器。还针对不同的目标（如远程或悬停以及常规或无声）提出了运动模式的多样性。为了分析混合动力推进器的流体动力学特性，使用多参考框架方法在ANSYS CFX中计算了流体动力学仿真。仿真结果表明了螺旋桨与喷水推进器之间的相互作用。还进行了推力实验，以评估改进型混合动力推进器的性能。混合动力推进器的最大推力比以前增加了2.27倍。另外，进行了噪声比较实验以验证喷水推进器的低噪声。最后，在游泳池中进行了3个自由度运动，包括SUR IV的喘振，起伏和偏航。实验结果评估了整个机器人的性能。