Floyd-IROS2006 - 1 A Novel Water Running Robot Inspired by...

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Unformatted text preview: 1 A Novel Water Running Robot Inspired by Basilisk Lizards Steven Floyd, Terence Keegan, John Palmisano, and Metin Sitti NanoRobotics Laboratory, Department of Mechanical Engineering, Carnegie Mellon University, PA 15213, USA Abstract This paper introduces a novel robot which can run on the surface of water in a manner similar to basilisk lizards. Previous studies on the lizards themselves have characterized their method of propulsion and their means of staying afloat. By slapping and stroking their feet into the water, the lizard effects a momentum transfer which provides both forward thrust and lift. The design of a biomimetic robot utilizing similar principles is discussed, modeled, and prototyped. Functionally, the robot uses a pair of identical four bar mechanisms, with a 180 o phase shift to achieve bipedal locomotion on the waters surface. Computational and experimental results are presented and reviewed with the focus being a maximization of the lift to power ratio. After optimization, two legged models can experimentally provide 12-15 g/W of lift while four legged models can provide 50 g/W of lift. This work opens the door for bipedal and quadrupedal robots to become ambulatory over both land and water, and represents a first step toward studies in amphibious stride patterns; step motions equally conducive to propulsion on water and land. Index Terms Biomimetics, legged robots, basilisk lizard, walk- ing on water. I. INTRODUCTION Small, lightweight animals have a large variety of floatation mechanisms open to them. There are spiders and insects which float using surface tension, and propel themselves using menis- cus in the water and marangoni flows. Larger animals have fewer options. Lizards, aquatic birds, and marine mammals, with their larger bulk and higher mass, utilize buoyancy, viscous drag and momentum transfer [1]. The basilisk lizard ( Basiliscus sp.) is capable of running across the surface of water at approximately 1.5 m/s, and a stepping rate of 5-10 Hz (per leg). Four factors influence the lizards ability to stay afloat: a) body mass, b) characteristic length, c) running speed, and d) shape of the foot. All of these variables are inter-related, and the morphological relations to the lizards water running have been characterized in [2][4], [6], [7]. Biomimetic robots are those machines which emulate some aspect of a living system. In this case, the ability to run over water is what our robot attempts to duplicate. This robot em- ploys momentum transfer for both lift and propulsion, instead of surface tension, which other water walking robots employ [8], [9]. The goal is not to copy nature, but to understand the principles of operation, and use or improve on them for use in our own creations....
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This note was uploaded on 08/03/2010 for the course MECHANIC 65921 taught by Professor Jons during the Spring '10 term at Tampa.

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Floyd-IROS2006 - 1 A Novel Water Running Robot Inspired by...

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