Design of a biologically-inspired underwater burrowing robot with on-board actuation

Abstract

The Atlantic razor clam (Ensis directus) burrows by contracting its valves, fluidizing the surrounding soil and reducing burrowing drag. Moving through a fluidized, rather than static, soil requires energy that scales linearly with depth, rather than depth squared. In addition to providing an advantage for the animal, localized fluidization may provide significant value to engineering applications such as vehicle anchoring and underwater pipe installation. This thesis presents the design of RoboClam 2, a self-actuated, radially expanding burrowing mechanism that utilizes E. directus burrowing methods. The device is sized to be a platform for an anchoring system for autonomous underwater vehicles. The scaling relationships necessary for the creation of this internally actuated burrowing robot are presented. These relationships allow for designing devices of different sizes for other applications, and describe optimal sizing and power needs for various size subsea burrowing systems. RoboClam 2 is a proof of concept iteration of a digging mechanism that utilizes localized fluidization. It will be used for testing digging parameters in a laboratory setting and validating the theory presented.