Analysis and experiments of a robot fish with a waving caudal fin with vertical phase differences

In this paper, motion of fishes with a caudal fin with vertical phase differences are analyzed to identify the effect of this kind of a caudal fin, some numerical model for this motion was made and some analyses have been investigated. To do this, torque and thrust from the fish motion were calculated based on the theoretical backgrounds from previous other researches. The results of a conventional caudal fin and the proposed fin were compared and it was found that fish with the proposed caudal fin can decrease the sum of torque exerted on the body maintaining the thrust force, which helps fish to save energy to propel and stare at something more stably under water. Some experiments were also performed and those were well accordance with theoretical analysis.