2関節イルカ形水中推進機構の動力学解析 : 第5報, 第2関節がばね支持のモデルの解析

抄録

In this paper, we describes a numerical study of dynamics and efficiency of a two-joint bending propulsion mechanism that is composed of a streamlined body and a caudal fin. First, we extended our analysical model to a model in which the second joint was supported by a spring instead of an actuator by use of an iterative calculation method. Second, we discussed the characteristics of the caudal fin motion and the propulsive efficiency with regard to the variation of the spring constant of the second joint in comparison with the forced motion model so far. It was found that the motion of sufficiently high propulsive efficiency can be attained by spring model with wide variety of spring constant. Finally, we investigated the robustness of the thrust with regard to the temporal variation of the propulsive speed both for the forced motion model so far and for the spring model. It was found that, when the temporal propulsive speed becomes large, the thrust keeps being positive in the spring model although the thrust suddenly decreased to a negative value in the forced motion model. This tendency is especially preferable in the case of propulsion in the ocean.