Multiple forces facilitate the aquatic acrobatics of grasshopper and bioinspired robot

• 成果类型: Article
• 署名作者: Song, Yi; Wang, Huan; Dai, Zhendong; Ji, Aihong; Wu, Huaping; Gorb, Stanislav N.
• 署名单位: Zhejiang University of Technology; Nanjing University of Aeronautics & Astronautics; University of Kiel; Southeast University - China
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11179
• DOI: 10.1073/pnas.2313305121
• 发表日期: 2024-04-02
• 关键词: water-surface; locust jump; locomotion; walking; hydrodynamics; orthoptera; mechanics; DYNAMICS; araneae; motion

摘要

Aquatic locomotion is challenging for land-dwelling creatures because of the high degree of fluidity with which the water yields to loads. We surprisingly found that the Chinese rice grasshopper Oxya chinensis, known for its terrestrial acrobatics, could swiftly launch itself off the water's surface in around 25 ms 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 toward the lower back with hind legs at angular speeds of up to 18 degrees/ms, whereas the swimming grasshoppers swing their front and middle legs in nearly horizontal planes and move hind legs less violently (similar to 8 degrees/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.