Design and motion characteristics analysis of underwater biomimetic jellyfish based on shape memory alloy springs

Jellyfish has attracted much attention in the field of bionic robots because of its unique body structure and swimming mode. Inspired by the moon jellyfish, the shape memory alloy (SMA) spring is used as the driving material, and the influence law of the spring force with the change of related parameters is studied for underwater robot development in the present study. The design of the full-length walking tentacles and half-length turning tentacles of the bionic jellyfish is conducted, with the design parameters and motion characteristics being analyzed through experiments and numerical simulations. The results show that under the conditions of output voltage of 12 V DC and control signal frequency of 0.91 Hz, the biomimetic jellyfish can swim straight at a maximum speed of 39 mm/s (0.33 BL/s), the maximum turning speed can reach 14/s, and the minimum turning radius is 104.1 mm. The research results provide a foundation for the future development of bionic underwater soft robots.