A Performance Predictive Model for Steady Swimming of a Fish Robot

Swimming performance is one of the primary concerns and applications to the underwater robots, such as thrust force relating to swimming velocity. As fish's swimming involves the kinematics of its own body and the hydrodynamic interaction with the surrounding fluid, it is difficult to formulate a precise mathematical model by purely analytical approaches. In order to avoid tedious parameter studies in evaluating its performance, this paper proposes a semi-empirical method to model the steady-state swimming performance of a BCF (body and/or caudal fin) biomimetic robotic robot. By using a dimensional analysis method, the semi-empirical model for predicting the thrust force generated by a BCF-oscillating swimming mode is derived. Thereafter, the swimming velocity prediction model is established based on the predictive thrust model together with the use of fundamental theory on drag force and the regression analysis on the experimental data. The model shows a reasonable prediction capability as the resultant predicted results are in good agreement with experiment data. Therefore, the proposed modeling method can be used for a quick prediction of the swimming performance in terms of thrust and velocity. The proposed methodology can be extended to other types of fish robots in real environment, by including changes to relevant parameters.