Research On Dynamics Analysis And Three-dimensional Obstacle Avoidance Control Of Bionic Robotic Fish Driven By Multiple Fins

With the growth of the "smart ocean" sector,tasks for seabed exploration are becoming more and more intricate,with an emphasis on ever-smaller spatial scales and ever-narrower maintenance space ranges.It is vitally necessary to develop an underwater mobility platform with more maneuverability and stronger autonomous motion capabilities for the constrained underwater environment.Bionic robotic fish is a new type of intelligent underwater robot with the advantages of high propulsion efficiency,high mobility,and concealment and it can perfectly satisfy the application requirements.Achieving accurate modeling and motion control for the robotic fish system to avoid obstacles will have significant theoretical implications for the creation of a new generation of intelligent underwater vehicles.The theoretical modeling and obstacle avoidance motion control of a three-joint tail and pectoral fins powered robotic fish system is investigated in this study by fusing theoretical modeling and simulation and comparing experimental and simulation findings.Here are the specifics:First of all,the research background and significance of this subject are described,and the domestic and foreign research status in all aspects of the bionic robot fish field are briefly surveyed.Also,the research content and research ideas of this paper are introduced in view of the key problems facing this field.Secondly,the robotic fish coordinate system is established,the variables are defined and the kinematics analysis of the whole fish and the flexible tail are carried out.The dynamics equation of the robotic fish is deduced and the force composition is analyzed.Each component’s external forces are analyzed,and the dynamic model is established.Then,the CFD numerical simulation is used to examine the hydrodynamic waterfront law of each component of the robotic fish body.The robotic fish prototype hydrodynamic observation experiment and MATLAB motion simulation are used to confirm the established model’s appropriate effectiveness and correctness.In addition,various kinds of path planning algorithms are briefly reviewed,and a new path planning algorithm which combines the bidirectional A*algorithm with the improved artificial potential field method is proposed to achieve the optimal path planning under the global map of robotic fish.Whereafter,the model predictive control method is briefly introduced.And the control model of the robotic fish is reconstructed.Based on the nonlinear model parameter estimation method and nonlinear model predictive control algorithm,the motion controller is designed to realize the 3D path tracking control of the robotic fish.Finally,the research achievements,innovations,and shortcomings of this paper are summarized,and the future research work is prospected.