Design, Fabrication and Morphing Mechanism of Soft Fins and Arms of a Squid-like Aquatic-aerial Vehicle with Morphology Tradeoff.

Some animals have the ability to shuttle freely between water and air. These creatures have evolved special body structures to accommodate both underwater and airborne environments. Natural creatures have given us great inspiration to the variable structure design for aquatic-aerial multimodal vehicle. In this paper, we propose a new squid-like soft morphing fins according to the flying squid. This squid-like soft morphing fins can spread and fold for the adaptation of the aquatic-aerial multimodal locomotion. When the fin is spread, it can generate lift force for the aquatic-aerial vehicle. When the soft fin is folded, it can reduce the drag force during the underwater movement. An unique air cavity inside the fin was designed as actuator to bend the soft fin. The fabrication method of the soft fin was introduced. The bending performance of the soft fin was analyzed by FEA simulation and tested by several experiments. Then, morphology tradeoff strategy of aquatic-aerial vehicle with soft morphing fins was investigated by the wind and water tunnel. The results demonstrate the soft morphing fins have fast actuating response and good deformability, which verifies the soft fin can help the aquatic-aerial vehicle to realize multi-modal locomotion.