Rhinoceros beetles effortlessly deploy and retract their wings without using their muscles, according to international researchers, who say the discovery of how this is achieved could help with the development of microrobots that can operate in limited or cluttered spaces. The team found that the delicate membranous hindwings of the beetles are released in a spring-like fashion by their hardened forewings – known as elytra – and a flapping motion then brings the hindwings into a raised flight position. They then created microrobots that mimic the beetle wings’ passive deployment, which were able to successfully take off and maintain flight.
Journal/conference: Nature
Link to research (DOI): 10.1038/s41586-024-07755-9
Organisation/s: Ecole Polytechnique Fédérale de Lausanne, Switzerland
Funder: This project was partially funded by the Swiss National Science
Foundation through the NCCR Robotics programme, and by the Korean government (MSIT)
(No. 2022R1A4A101888411) through the National Research Foundation of Korea (NRF).
Media release
From: Springer Nature
Biomechanics: Beetle wing mechanisms inspire robot design *IMAGES*  An analysis of how rhinoceros beetles deploy and retract their hindwings shows that the process is passive, requiring no muscular activity. The findings, reported in Nature this week, could help improve the design of flying micromachines.Among all flying insects, beetles demonstrate the most complex wing mechanisms, involving two sets of wings: a pair of hardened forewings called elytra and a set of delicate membranous hindwings. Although extensive research exists on the origami-like folds of their wings, little is known about how they deploy and retract their hindwings. Previous research theorizes that thoracic muscles drive a beetle’s hindwing base movement, but experimental evidence to support this theory is lacking.Hoang-Vu Phan and colleagues combine the use of high-speed cameras and a dynamically similar flying robot to address this research gap. The authors observe that rhinoceros beetles use passive mechanisms, including their elytra, when deploying and retracting their wings. Deployment is a two-phase process in which elevation of the elytra partially releases their hindwings in a spring-like fashion, then a flapping motion brings the hindwings into a raised flight position. They also find the beetles use their elytra to lower their hindwings into a resting position passively.Inspired by their observations, the authors make microrobots that mimic beetle wings’ passive deployment and retraction. They find the bots successfully take off and maintain flight. Their findings suggest that transferring the beetle’s passive hindwing processes to a flapping robot design could help to improve the capabilities of small robots that need to operate in limited or cluttered spaces.