Closed-loop precise turning control for a BCF-mode robotic fish

This paper deals with a novel closed-loop maneuvering control method to enhance the turning precision and turning response speed of a robotic fish propelled via the body and/or caudal fin (BCF) mode. Although the BCF propulsion is favorable for the cases requiring greater thrust and accelerations, its maneuverability can be compensated by effective turning control. In our method, the turning maneuver is divided into three phases: the bending, holding, and unbending phases. After much consideration on turning details, the functions of each phase and the basic control laws are further identified. Results of experiments on in-situ direction tracking and direction maintaining verify the effectiveness of the proposed turning control.