Research On Fusion Propulsion Mechanism And Control Of Pectoral Fin Fluctuating And Swing On Bionic Robotic Fish

Compared with the traditional underwater robots with the propeller propulsion,the bionic robot fish based on the pectoral fin fluctuating propulsion in the MPF mode has the advantages of high efficiency,stability,maneuverability and controllability.For the reason that,it has good application prospects in resource exploration,underwater archaeology,water quality monitoring,military investigation and biological observation.However,for the pectoral fin fluctuating propulsion mode,it shows that the propulsive force is small,and the swimming speed is low.Therefore,in order to improve the defect of pectoral fin fluctuating propulsion mode,the caudal fin swing propulsion strategy in BCF mode is introduced,then a bionic robot fish with pectoral fin fluctuating and swing fusion propulsion mode is designed based on stingray in the thesis.Firstly,the body structure and pectoral fin movement characteristics of the stingray,as well as the movement characteristics of caudal fin in BCF model fish,are analyzed in the thesis.According to the result,the kinematics and hydrodynamic model of the pectoral fin fluctuating and swing fusion propulsion mode are established.Then based on the principle of morphological and functional bionics,the mechanical structure and control system of bionic robot fish are designed.Secondly,based on the study of the dynamic characteristics of a single Hopf oscillator,the Hopf oscillator model is improved to establish the coupling mechanism between multiple Hopf oscillators.Then a central bionic nerve Center Pattern Generator network topology model is constructed by 20 modified Hopf oscillators.And it is verified by the MATLAB/Simulink simulation that the network topology model can output coupling state signal stably,which control the motion of the machine fins to realize the linear parade,maneuvering,accelerating swimming and smooth switching between the swimming modes in the fusion propulsion mode.In addition,the algorithm is implemented on STM32 microcontroller.Finally,propulsion and motion performance test of the bionic robotic fish are carried out under the pectoral fin wave and swing fusion propulsion mechanism.The propulsion test included the force and the speed test.The propulsion performance test results show that the maximum thrust generated by the fusion propulsion mode is 2.8N,which is 1.52 times higher than that of the pectoral fin wave propulsion mode;the maximum speed is 121mm/s,which is 1.2 times higher than that of the pectoral fin wave propulsion.In addition,the results of the motion performance test show that the central CPG network topology model established by the improved Hopf nonlinear oscillator can effectively control the motion of the pectoral fin to achieve the various swimming modes and smooth switching between the swimming modes in the fusion propulsion mode.In addition,the motion performance test verified that the fusion propulsion mode retains the outstanding mobility,stability and controllability that show in the pectoral fin fluctuation propulsion mode.