A Bioinspired Robot Growing like Plant Roots

Abstract

Plants are usually considered static organisms, but they can perform a wide range of movements that can be a source of inspiration for robots. The roots’ growing motion is the most noteworthy since they are excellent diggers that can move in unstructured environments and navigate past barriers. Furthermore, root growth has a high energy efficiency since it penetrates the soil at its tip, adding new material without displacing the already grown portion, minimizing the energy dissipation due to friction and lowering the inertia. A robot inspired by the growth of roots could be used in search and rescue or environmental monitoring. The design of a soft robot inspired by root growth is presented in this article. The robot body consists of a cylindrical plastic membrane folded inside itself. The robot body is inflated, and its tip is everted, expanding its length as air is blown from the base. Velcro straps are placed on the membrane’s exterior surface to keep it folded. The head is positioned inside the tip, which houses the mechanism that controls the growth direction. It consists of housing for two balloons that are selectively inflated, and their expansion applies pressure on the exterior surface, opening the Velcro straps and determining the growth direction. The robot was constructed, and a kinematic model of its motion in the plane was created and compared with experimental data. The error in predicting the turning angle is only 5%, and the resulting predicted position differs on average by 55 mm on a total length of 850 mm.