Design and Control of a Single-Motor-Actuated Robotic Fish Capable of Fast Swimming and Maneuverability

This paper deals with a novel fast swimming robotic fish capable of high maneuverability and yet with less joints. On the basis of prior work on a single-motor-actuated miniature robotic fish, we mainly stress three aspects: mechanical design, motion analysis, and posture control to strike a tradeoff between speediness and maneuverability. Specifically, an improved mechanical structure endows the robot with large thrust and increased range of movements. Motion analysis offers useful guidance to parameter settings of steady swimming. Besides, sine-based functions responsible for generating traveling waves in conjunction with an analysis of parameter variation of oscillation amplitude of the fish tail serve the purpose to determine the posture of the robotic fish. Underwater tests on straight swimming and different turns demonstrate the effectiveness of the proposed methods and mechatronic designs. Remarkably, the robot attained a maximum swimming speed of 1.14 m/s (corresponding to 3.07 body lengths per second) in forward swimming, a turning rate of approximately 90°/s in normal turns, and a turning rate of approximately 63.8°/s in hybrid turns.