Multiple forces facilitate the aquatic acrobatics of grasshopper and bioinspired robot

Aquatic locomotion is challenging for land-dwelling creatures because of the high degree of fluidity with which the water yields to loads. For the first time, we surprisingly discovered that the Chinese rice grasshopper <i>Oxya chinensis</i><i>,</i> known for its terrestrial acrobatics, could swiftly launch itself off the water’s surface in around 25 milliseconds and seamlessly transition into flight. Biological observations showed that jumping grasshoppers use their front and middle legs to tilt up bodies first and then lift off by propelling the water towards the lower back with hind legs at angular speeds of up to 18°/ms, whereas the swimming grasshoppers swing their front and middle legs in nearly horizontal planes and move hind legs less violently (~ 8°/ms). Force measurement and model analysis indicated that the weight support could be achieved by hydrostatics which are proportionate to the mass of the grasshoppers, while the propulsions for motion are derived from the controlled limb-water interactions (i.e., the hydrodynamics). After learning the structural and behavioral strategies of the grasshoppers, a robot was created and was capable of swimming and jumping on the water surface like the insects, further demonstrating the effectiveness of decoupling the challenges of aquatic locomotion by the combined use of the static and dynamic hydro forces. This work not only uncovered the combined mechanisms responsible for facilitating aquatic acrobatics in this species but also laid a foundation for developing bioinspired robots that can locomote across multiple media.This data set contains three files, including the data of limb sequences(Time_data.xlsx), limbs kinetics(Limb_angles_and_speeds.xlsx) and the static force(Static_force.xlsx).<br>The former two were obtained from the insect videos directly while the last was obtained by immersing grasshoppers to water.<br>