An analytical approach for better swimming efficiency of slender fish robots based on Lighthill´s model

In this initial work, we discuss the application of Lighthill´s small-amplitude elongated body theory (EBT) in improving the swimming efficiency. The prototype considered in the study is a slender fish model capable of performing various motion patterns. The mechanical design of the prototype, derivation of equations and the results are first discussed. We apply a body motion function with linear envelop to control the swimming of fish robot. We also study the influence of different combinations of amplitudes and frequencies on the swimming performance. The analysis shows that a high frequency with low amplitude mode is better at a given power consumption. Different definitions of swimming efficiency in robotic fishes are also discussed. By virtue of the current off-line based approach, a closed-loop swimming control method and an on-line swimming gait planning scheme are suggested.