Effect of flapping orientation on caudal fin propelled bio-inspired underwater robots

Aquatic animals and mammals in nature, in particular, the Body and/or Caudal Fin (BCF) swimmers swim either by flapping their fins in the sideways direction or the dorso-ventral direction. Not much literature is available on the effects of the performance of these robots based on the choice of its flapping orientation. In this research, it is found that dorso-ventral flapping could lead to better self-stabilizing effects and lesser energy consumption compared to sideways flapping. It is also found that the choice of dorso-ventral flapping offers the possibility of controlling the body’s oscillation amplitude while flapping. This is an appealing advantage for underwater surveying robots carrying cameras and sensors as controlled body oscillations could yield better results from its payloads. The main body of results is obtained with simulations for underwater vehicle dynamics with the coefficients of the REMUS underwater vehicle, while stability analysis for a generalised case is also presented.