High-Velocity, Pressure-Driven Eversion for Rapid Vine Robots

‘‘Vine robots” are thin-walled, tubular, pneumatic soft robots that lengthen at their tips to navigate constrained and complex environments. Previous studies have already explored the mechanics of vine robot bodies and investigated applications for which the device is well-suited. However, these studies almost exclusively focus on eversion rates in the quasi-static regime, overlooking other potential applications of high-speed vine robots in medical devices, projectile launchers, or for informing biology. To better understand this rapid behavior, we present a dynamic growth model for high-velocity vine robot body extension with a payload mass and verify the model experimentally. To the best of the authors’ knowledge, this is the first instance of vine robots utilized for projectile launching. We find three key results: i) vine robot bodies experience rate-dependent damping that is scale-dependent and monotonically increases with increasing wall thickness; ii) steady-state velocity, or the upper limit of speed in terms of growth velocity, monotonically increases with isometric scaling; and iii) energy efficiency increases with decreasing wall thickness. These findings are used to inform the preliminary design of a large-scale, drug delivery device proof-of-concept, as well as design the fastest–on–record vine, capable of 60 m/s eversion. Our work provides a basic understanding of the dynamic movement of vine robots and opens the door to new areas of application.