Design of a bioinspired cownose ray robot

Fish swimming is a promising source of inspiration for novel and efficient propulsion mechanisms for autonomous underwater vehicles, as fishes swim with excellent energy efficiency and high maneuverability. Among the locomotion strategies of aquatic animals, the swimming mode of batoids is one of the most interesting, as these fishes swim with high energy efficiency, and they are capable of performing maneuvers with great agility. These advantages are mainly due to the fin geometry and the kinematics of their movement. The fish develops a traveling wave from the leading edge to the trailing edge of the fin, the amplitude of which increases towards the tip of the fin. This wave pushes the water backward, giving the fish a forward thrust due to momentum conservation. The motion of the fin of a cownose ray has been studied, and a biomimetic swimming robot inspired by the cownose ray has been designed and realized. Each fin is made of silicone sheets, and it is moved by three mechanisms whose kinematics replicate the fin deformation. Each mechanism is driven by an independent servomotor, creating a traveling wave on the fin whose frequency, wavelength, and amplitude can be modulated. The motors, battery, and electronics are housed in the central body of the robot, which is rigid. This paper describes the robot's design and construction.