Design and Yaw Control of a TwoMotorActuated Biomimetic Robotic Fish This paper addresses the design and control of a novel tunainspired robotic fish able to realize both fast swimming and high maneuverability. A twostage transmission mechanism is proposed, aiming at reducing the volume and mass of caudal peduncle. Benefited by it, both volumes and mass of moving parts can be reduced to allow higher swing frequency. At the same time, two joints driven by two motors ensure the flexibility of steering. The robotic fish achieves a maximum speed up to 1.65 body lengths per second (BLs) and a minimum turning radius less than 0.35 body lengths (BL), based on the openloop control designed by Central Pattern Generator (CPG) method. Furthermore, a yaw control is proposed to maintain course angle at high swimming speed, and simulation in Automatic Dynamic Analysis of Mechanical Systems (ADAMS) software reveals the effectiveness. The results show that the proposed yaw control method can regulate the fluctuation of anterior body to desired range but without compensation of sideways drift.

Design of a Robotic Fish Based on a Passive Flexible Mechanism In recent years, along with the rapid development of manufacturing, control, sensing and other technologies, biomimetic robotic fish has played an increasingly important role in marine exploration, underwater rescue, water quality monitoring and other fields. This paper designed a robotic fish based on a passive flexible mechanism to realize the fishlike propulsion function. The motion simulation of the designed transmission mechanism was carried out to get the actual curve of the structure. Through the analysis of the force of the fishtail, the preliminary selection scheme of the elastic joints based on the passive flexible mechanism was obtained. Finally, this paper built a robotic fish based on a passive flexible mechanism, which could achieve the motion frequency adjustable from 0.5 to 9 Hz, and the maximum swimming speed reaching 1.05 BLs (BL, body length). This design scheme provided a new reference for the design of the biomimetic robotic fish and had certain practical significance.