Caudal Fin Locomotion And Design Of Control System For Robotic Fish

Autonomous underwater vehicles can mimic locomotion of aquatic animals-fishes that utilize oscillating foils as their propulsive elements. There are overwhelming advantages for them in speed, maneuverability, and noise over conventional man-made propeller. This paper presents an overview of the swimming mechanisms and the caudal fin locomotion employed by fish. A practical method is brought forward that use the track of the caudal fin oscillating to study the locomotion of the robotic fish. And this paper mimic the BCF (Body and/or Caudal Fin) propulsive fish with a three-link robotic fish model(OuceFish- I )for oscillating foil propulsion, and then describes the design (hardware and software) of it in detail. Furthermore, this paper describes the experimental results of the robotic fish. All the work above establishes the base for the future work of the robotic fish.The paper is structured as follows: In the first section, the contemporary development of robotic fish technology is reviewed comprehensively and a brief introduction to the main work of this paper is given.The second section describes the morphological features and the swimming mechanisms of fish and explains the reason why this paper chooses BCF propulsive fishes as the model. And explain the correlative parameters and the mechanics of the caudal fin locomotion.The equation of the robotic fish caudal fin locomotion is deduced in the third section. The robotic fish model selected in this paper which consider an idealized BCF propulsive fish model that consists of only three links: the rigid body in the foreside; the high aspect ratio caudal fin; the caudal peduncle which connects the caudal fin and the body. Based on the strategy, this paper gives the equation of caudal oscillating track when the robotic fish swimming forward with a certain speed by using two-link caudal fin.The forth and the fifth section present a practically real-time maneuvering control strategy with a MCU(68HC908MR8) for the robotic fish that uses the two-link oscillating foil as a propulsor. One robotic fish (OuceFish- I )is designed and accomplished.The sixth section gives the experimental results in the quasi-steady flow around the caudal fin and mimic the forward swimming using the caudal fin as the propulsor. And then review the speed and track of the robotic fish swimming when locomotion parameters are set in the experiment condition.Finally, the seventh section summarizes the contributions of the paper and offers some comments on the future research work.