Robotic mechanism for soil penetration inspired by plant root

Abstract

In this paper we propose a soil penetration robotic system inspired by low friction penetration strategies in plant roots. Growth of cells at the root tip deforms soil, while sloughing cells in the cap create an interface between root and soil to reduce root-soil friction during penetration. A simple prototype, inspired by these root features and based on a tubular shaft and a soft continuum skin, was developed. The skin is kept inside the shaft and slips out and slides on its external body. This outward movement of the skin opens the soil in front of the tip and helps the system to penetrate. The skin covering the external body of shaft imitates the role of sloughing cells and provides low-friction interface between soil and shaft. Interaction between the external skin and soil gives to the system self-anchorage capabilities for the penetration.The performances of our robotic system were characterized during penetration in granular soils. The skin-soil interaction was found to be fundamental for 1) displacing the soil in front of the tip and 2) preventing backward movements of the robot by anchoring the posterior body to the soil. In order to exploit these effects some artificial hairs were added along the skin.The increased hair density (0.012 hairs/mm2) resulted in higher penetration depth of robot (about 30%).

Why the seahorse tail is square

“…Such applications for the seahorseinspired technology would be able to take advantage of a large body of kinematics and actuation work that has been developed for similar long, slender "continuum" structures inspired by organisms such as snakes and worms (26)(27)(28)(29)(30), squids and octopuses (tentacles) (31,32), elephants (trunks) (33), and plants (tendrils and roots) (34,35). The combination of articulated rigid plates and elastic deformability observed in a seahorse tail ( Fig.…”

A Soft, Steerable Continuum Robot That Grows via Tip Extension

“…Evaluating the static equilibrium equations (Eqs. 13,14) with the new arc-space parameters and stiffnesses, we get:…”

“…Rearrangement of the kinematic model equations (Eqs. 7,13,14) results in an equation that predicts the growing robot backbone curvature as a function of sPAM pressure:…”

“…of growth was described by Mishima et al [11] in 2003, without steering. Rösch et al and Sadeghi et al [12], [13] also developed devices that moved using tip eversion, with tip eversion driven by a motor rather than air pressure. Those devices were developed to penetrate granular material [14], [15].…”

Plants as Model in Biomimetics and Biorobotics: New Perspectives

“…An important aspect of growth regards the sloughing of cells from the tip, and to this regard a simple but effective artificial method was investigated (Sadeghi et al, 2013). A soft and flexible tubular skin was stored inside a rigid shaft so that it could traverse the hole to the external surface of the shaft.…”