Studies on Hydrodynamic Propulsion of a Biomimetic Tuna

Current unmanned undersea vehicles (UUVs) are almost exclusively propeller driven designs, which must inherently be optimized for a particular speed, sacrificing low speed manoeuvrability for cruising efficiency. Recently, biomimetic approaches to underwater vehicle propulsion have illuminated the exciting possibilities for performance improvements made possible by emulating fish motion. In particular, a number of test vehicles indicate that the carangiform swimming mode employed by highly developed species of fish, such as the Bluefin tuna, offers both a more efficient propulsion mechanism than propellers, in addition to the ability to perform quick manoeuvring. This book chapter presents studies on the propulsion efficiency of a biomimetic tuna at the University of Victoria. Two prototypes have been designed and implemented experimentally. The first prototype consists of a biomimetic tuna that employs shape memory alloy wires to affect shape induced propulsion. The second prototype propulsion model consists of four joints that are rotated using servomotors. Issues related to the mechanism, systems and energy are discussed. The performance and the lessons learned related to the two design philosophies are presented and discussed.