An Elastic Biomimetic Fish Tail and Its Undulation Fitting Method of Body Wave

This paper presents a novel wire-driven fish tail with two joints, using spring-steel-sheet to mimic fish spine, which makes the whole fish tail compliant and can simulate real fish better. This mechanism can also achieve C-shape and S-shape swing similar to natural fish tail. To predict the attitude of fish tail, kinematics model is established theoretically in this paper. The simulation experiments show that the maximum error between the amplitude predicted by the kinematics model and expected amplitude at the end of the fish tail is 5 mm, indicating the correctness of the proposed kinematics model. In order to solve the control coupling problem of servomotors, this paper further proposes a based-vision biomimetic undulation fitting method, which is both simple and efficient. Finally, the proposed method is verified by two groups of experiments involving forward motion and turn motion. Experimental results are in good agreement with the expected values. When the frequency is 0.1 Hz, the average errors of forward motion and turn motion are 0.59° and 0.7° respectively, which proves that the proposed method is reliable and effective.