Abstract
This paper studies four patterns for the maneuverability of robotic dolphins: turning with flapping flippers, turning with swing flippers, turning with head offset, and turning with head-flipper coordination. Turning maneuverability is one of the important evaluation indexes for the performance of underwater bionic robots, and existing literature has rarely theoretically or experimentally evaluated turning maneuverability for the latter two turning patterns. In this paper, we establish a dynamic model for the high maneuverability of underwater bionic robots and discuss the influence of motion design parameters, including the frequency of the pectoral fins and the offset angle of the head, on the turning maneuverability, focusing on the turning angular velocity and turning radius. To verify the effectiveness and control accuracy of the dynamic model, we develop a multidegree-of-freedom (multi-DOF) and high-maneuverability bionic robotic dolphin and test its maneuverability through experiments. Extensive experimental results demonstrate that the established dynamic model can successfully predict the turning maneuverability of robotic dolphins. In addition, the turning methods in this paper have better turning performance than some robotic fish. This paper provides a reference for the establishment of a maneuvering dynamics model for underwater bionic robots and a theoretical basis for the design of a turning maneuver control system.
Highlights
In recent decades, various autonomous underwater vehicles (AUVs) have been used to explore marine resources
We studied the relationship between motion parameters, including pectoral fin frequency and head offset angle, and turning performance based on the turning radius and turning angular velocity, which has certain guiding significance for the maneuverability control of underwater bionic robots
Robotic dolphins cannot rely on the caudal fin that produces the main propulsion to turn like a robotic fish, which greatly reduces the turning maneuverability of robotic dolphins
Summary
Various autonomous underwater vehicles (AUVs) have been used to explore marine resources. We studied the relationship between motion parameters, including pectoral fin frequency and head offset angle, and turning performance based on the turning radius and turning angular velocity, which has certain guiding significance for the maneuverability control of underwater bionic robots. FORCE ANALYSIS OF THE ROBOTIC DOLPHIN To build the dynamic model of the robotic dolphin, we need to analyze the external forces it experiences Such external forces mainly include the lift, drag, and fluid pressure caused by the caudal fin, the lift and drag caused by the pectoral fins, the resistance of the head and body, the gravity and buoyancy acting on the body, and the fluid inertia force. Similar to the caudal fin, the lift and drag acting on the robotic pectoral fins are expressed in body coordinates as: FLi = RkiFLiV i (24). The external forces and moments on the robotic dolphin in all directions and its moment are described as follows: Fx
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