Implementing 3-D high maneuvers with a novel biomimetic robotic fish

This paper is devoted to the exploration of three-dimensional (3-D) maneuvers using a free-swimming fishlike robot. For the sake of a better maneuverability, an Esox lucius robotic fish consisting of a yawing head, two degrees of freedom pectoral mechanism and multilink body joints together with a caudal fin is developed. With full consideration of both mechanical configuration and propulsive principles of the robotic fish, detailed analysis and viable approaches to perform serval high maneuvers involving rotational maneuvers and translational maneuvers are presented. Based on the feedback of turning angles measured by an onboard six-axis gyroscope, the robotic fish achieves various agile and swift motions. Specifically, according to the C-start of Esox lucius, a flexible and wide-range yaw turn up to 360◦ is attained. Under the propulsive forces and moments from pectoral fins with symmetric or asymmetric pitching and heaving attack angles, the robotic fish can agilely flip in a pitch style and roll a 360◦ rotation around the swimming direction. Moreover, two types of backward swimming separately employing pectoral fins and body undulation are also accomplished. The experimental results verify the remarkable maneuverability of the developed robotic fish and the effectiveness of approaches presented for the maneuver control.