Abstract

There are several problems with current electro-mechanical or biomechanical robotic fish. All servomotors emit detectable noises when they are operated. This is a major problem when designing a device that needs to remain undetectable, such as a submarine. The cost of hardware and electronics package that is associated with servo devices are generally very high. Another problem is the underwater reliability of sensitive electronics packages in a fresh or saltwater environment, where the possibility of leaking is a real threat. Finally the duplication of natural fish movement with servomotors is a very complex design.

This paper presents a novel design of a robotic fish actuated by shape memory alloy wires. This fish is constructed using an innovative composite skeleton and shape memory alloy wires for the muscle structure. The skeleton of the fish is designed to duplicate a natural fish like movement. Several working models of this type fish have been fabricated in the Smart Materials and Structures Laboratory at The University of Akron. An off-board electronic control package has been designed to actuate the SMA wires and maneuver the fish. The off-board electronic control package mainly consists of a programmable current amplifier and a real-time control system. Experimental results show that fish-like locomotion can be achieved.

By utilizing shape memory alloys instead of servomotors a robotic fish can become as undetectable as a living fish. Smart memory alloys are cheaper and more reliable than servomotors under harsh environmental conditions; the overall cost of the fish may be reduced. Since this fish can reproduce the natural mobility of a living fish without the noise of servomotors, this fish can be utilized in both the commercial fishing industry and the intelligence field.

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