Bugs and robots: Investigating the external reaction from clicking mechanics using simulation methods

The click beetle exhibits a unique morphological feature between its mesothorax and prothorax that enables it to rapidly convert stored elastic potential energy into kinetic energy. The beetle initiates this mechanism, or “click”, when lying on its ventral side, facilitating aerial movement without using its legs. In order to investigate the influence of this structure on the beetle's aerodynamic characteristics and the reaction forces when encountering the surrounding environment, we designed and employed a launching platform and beetle prototypes to control and manipulate relevant variables such as body mass, center of mass, spring elasticity, and elytra curvature.
Our experimental approach uses a prototype that simplifies the beetle’s morphology into two masses joined by a spring. These masses were 3D-printed and varied in their mass ratios and elytra curvature and connected through a thin strip of spring steel. These prototypes were launched into the air using the designed launching platform and their airborne trajectory was recorded under high-speed videography. We then used mathematical simulation to help us understand the system dynamics under different initial conditions and parameters.
The model simulation enabled a more detailed investigation into the forces exerted during the clicking motion of a click-beetle and its interaction with the environment. This study showed that beetle-related variables affect take-off angle, take-off velocity, and thus jumping capability. Our findings provide further insight into the design and fabrication of legless jumping robotic mechanisms.