Exploring the timescale limitations of RoboClam : a biologically inspired burrowing robot

Abstract

The Atlantic razor clam (Ensis directus) burrows into soil by contracting its valves in a pattern that fluidizes the particles around it. In this way, it uses an order of magnitude less energy to dig to its burrowing depth than would be expected if it were moving through static soil. This technology is a mechanically simple solution to reduce energy requirements in applications such as anchoring and underwater pipe installation. RoboClam is a robot that imitates the movements of Ensis and has achieved localized fluidization in environments similar to that of the animal. This paper tests the theoretical timescale limits for running RoboClam while still achieving the soil fluidization that Ensis achieves. Needle valves were used on the robot's pneumatic control system to vary its expansion and contraction times in a series of tests, then each test was analyzed to determine to what extent soil fluidization occurred. It was found that the theoretical minimum contraction time is an appropriate boundary and the theoretical maximum contraction time is a loose boundary on tests that will result in soil fluidization. However, these conclusions came from a limited number of tests, so further testing is necessary to confirm these results.