Vortex Interaction of Tripod Gait in Interfacial Locomotion of Semiaquatic Insects

Because of their small size, Microvelia can utilize surface tension to effortlessly traverse the water's surface. Employing an alternating tripod gait, a common gait pattern observed in insects like ants, Microvelia attains comparable speeds on land and water. To delve deeper into their locomotion on both terrains, we employ high-speed imaging techniques to analyze their biomechanics. We monitor their body, leg tarsi, and joints using DeepLabCut to gather data on speed, acceleration, stroke frequency, and other kinematic parameters. Additionally, we utilize particle image velocimetry (PIV) to visualize and quantify the wake generated when Microvelia move their middle and hind legs on the water's surface. Due to their legs' spatial and temporal dynamics, the hind legs step into and re-energize the vortices produced by the middle legs. Our research delves into the significance of vortex interactions in the hydrodynamics of water-walking by establishing correlations between leg speeds and the circulation of vortices generated by each leg's movement. This study can advance our understanding of biomechanics and interfacial fluid mechanics, potentially influencing the design of amphibious robots.