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Applied Bionics and Biomechanics
Volume 9 (2012), Issue 3, Pages 333-345

Robotic Pectoral Fin Thrust Vectoring Using Weighted Gait Combinations

John S. Palmisano,1 Jason D. Geder,2 Ravi Ramamurti,2 William C. Sandberg,2,3 and Banahalli Ratna1

1Center for Biomolecular Science and Engineering at the Naval Research Laboratory in Washington, DC, USA
2Laboratory for Computational Physics and Fluid Dynamics at the Naval Research Laboratory in Washington, DC, USA
3Science Applications International Corp, Oration, Mclean, VA, USA

Copyright © 2012 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A method was devised to vector propulsion of a robotic pectoral fin by means of actively controlling fin surface curvature. Separate flapping fin gaits were designed to maximize thrust for each of three different thrust vectors: forward, reverse, and lift. By using weighted combinations of these three pre-determined main gaits, new intermediate hybrid gaits for any desired propulsion vector can be created with smooth transitioning between these gaits. This weighted gait combination (WGC) method is applicable to other difficult-to-model actuators. Both 3D unsteady computational fluid dynamics (CFD) and experimental results are presented.