Bionic jellyfish robot achieving enhanced steering maneuverability through asymmetric tentacles

With the rapid advancement of the marine industry, bionic robots have become increasingly important to underwater scientific research and engineering applications. As representative invertebrate zooplankton, jellyfish exhibit an efficient jet propulsion swimming mode that enables them to adapt to complex and ever-changing marine environments. This paper proposes a lightweight and energy-efficient bionic jellyfish robot capable of achieving high-efficiency spatial swimming and steering via asymmetric tentacles. Forward propulsion is achieved through a reciprocating cylindrical cam that swings six tentacles coated with a thick silicone membrane. Spatial steering is realized through an eccentric disc cam, which adjusts the circumferential asymmetry of the six tentacles. A compact controller based on STM32F4 is designed to receive commands wirelessly and generate the required control signals to drive three motors. Fluid simulation, integrated with a theoretical model, was performed to analyze the jet propulsion force of the jellyfish robot. The 287-g robot prototype measures 110 mm in diameter and 159 mm in height in its contraction state. It was tested under various swimming modes to verify its steering capability in three-dimensional space. Experimental results demonstrate that the bionic jellyfish robot achieves a maximum average swimming speed of 7.5 cm/s, corresponding to 0.47 body lengths per second (BL/s), placing its swimming efficiency among the best of existing bionic jellyfish robots. Furthermore, it exhibits remarkable maneuverability, with a maximum steering angle of 200° and a maximum steering velocity of 22.7°/s. The proposed robot holds significant potential for applications in underwater signal relays, environmental monitoring, and geological investigations.