Research On Coordinated Propulsion And Mechanism Analysis Of Robotic Fish With Multi-degree Of Freedom

As an important research direction in the field of biomimetic intelligent robot,underwater vehicles are being widely concerned by the scientific community and the engineering community because of its potential application prospect in the fields of water quality monitoring,water environment measurement,underwater ecosystem observation and military reconnaissance,and lots of achievements are produced in the study of body and/or caudal fin propulsion mode and median and/or paired fins.With the obvious advantages in the promotion efficiency and mobility,the MPF propulsion mode has gradually become a hot research.In this thesis,we study the swimming mechanism of biomimetic robotic fish with coordinated propulsion and the main contents are as follows:(1)A collaborative propulsion robotic fish with 2-DOF(degree of freedom)pectoral fins and three-joint flexible body was designed.Based on cod as the bionic object,the pectoral fin mechanism of the bionic robotic fish use MPF mode to achieve flapping,swaying,the composite motion of them,separately;the flexible body with three-joint and tail fin use BCF propulsion mode to realize the swing motion in the horizontal plane.The head of robotic fish is designed to the sealed plastic shell,the flexible body is wrapped with waterproof plastic skin and Atmel128 microcontroller is chose as the master chip for control system.(2)Based on the analysis of the basic behavior of the bionic robot fish,including straight swim and turning,the hydrodynamic model of the robot fish with collaborative propulsion is established.Firstly,based on the biomechanical research results,the kinematic model of the 2 DOF pectoral fins and the kinematic model of the flexible body / tail fin fitting Lighthill curve are given respectively.Secondly,based on the micro-element method,the hydrodynamic model of the pectoral fin movement is established.The hydrodynamic model of the flexible body / caudal fin was established through the three-dimensional wave plate.In Coordinated Propulsion mode,the hydrodynamic model of the whole biomimetic robotic fish is presented,which can achieve straight swim and turning,finally.(3)On the basis of hydrodynamic model,the straight swim mode and turning mode of the robotic fish are determined through numerical analysis and experimental verification.Firstly,the relationship between the basic kinematics parameters such as the swing,the cycle,the initial angle,the phase difference and the straight travel speed,the turning speed is analyzed by numerical simulation,and five kinds of straight swim modes and three kinds of turning modes are preliminarily determined.Secondly,we verified the simulation results through the physical experiments,and optimized the parameters,and finally,the straight swim mode and turning modes of the biomimetic robotic fish are determined.The simulation and experimental results show that the robotic fish can achieve more abundant swimming behavior,and the proposed method is consistent with the experimental results,therefore providing the theoretical and technical support for the application in the real field.