Robotics: Science and Systems XVII

Droplet: Towards Autonomous Underwater Assembly of Modular Structures

Samuel E Lensgraf, Amy Sniffen, Zachary Zitzewitz, Evan Honnold, Jennifer Jain, Weifu Wang, Alberto Quattrini Li, Devin Balkcom


This paper presents a first low-cost autonomous robotic system for underwater assembly of mortarless structures. The long-term goal is to enable the construction of large-scale underwater structures; such as retaining walls and artificial reefs. The approach follows the principle of co-design; the 2-DOF manipulator and blocks are designed to complement the localization and control strategies. The blocks and gripper are designed with a connector geometry that removes error during pickup of blocks and drop assembly. This error correction feature allows a simplification of localization and control; which are based on fiducial markers on custom platforms. We developed the proposed system on a low-cost heavily modified BlueROV2 autonomous vehicle — which we call Droplet — with a two-degree of freedom hand that can open and close a gripper and rotate over the yaw. We performed extensive experiments in the pool to evaluate each component and the system as a whole. Results showed a 100% success rate in dropping blocks in the presence of some localization and control errors and the assembly of several different 3D structures composed of up to eight blocks.



    AUTHOR    = {Samuel E Lensgraf AND Amy Sniffen AND Zachary Zitzewitz AND Evan Honnold AND Jennifer Jain AND Weifu Wang AND Alberto Quattrini Li AND Devin Balkcom}, 
    TITLE     = {{Droplet: Towards Autonomous Underwater Assembly of Modular Structures}}, 
    BOOKTITLE = {Proceedings of Robotics: Science and Systems}, 
    YEAR      = {2021}, 
    ADDRESS   = {Virtual}, 
    MONTH     = {July}, 
    DOI       = {10.15607/RSS.2021.XVII.054}