Study On Rapid Motion Mechanism And Control Of Bionic Tuna Based On Electromagnetic Drive

Fish,as a vertebrate widely found in nature,has unparalleled advantages of traditional underwater robots,such as fast swimming,high mobility,great efficiency,and long cruising time.Many researchers have explored its swimming theory.By uses tuna as a bionic object,this study designed a bionic tuna based on electromagnetic drive.After analyzed the disadvantages of existing bionic fish-driven structures and the advantages of electromagnetic drives,we designed a kind of bionic tuna based on electromagnetic drive to explore the swimming characteristics of tuna fish under high frequency swing.In this study,it analyzed the kinematics and control methods of bionic fish,and completed the fish wave curve simulation of bionic tuna.By fitting the bionic tuna and the wave curve of the fish body,it was verified that the articular bionic fish conforms to the tuna swimming mode under a small swing.After comparison of existing CPG control models and analyzed the characteristics of fish swimming in the tuna model,we chose the CPG model based on Hopf oscillator as the control method of bionic tuna.Then,we analyzed the resistance to the bionic tuna swimming and used Adams to simulate the resistance to the underwater swing and used the results as a reference for the design of the electromagnetic drive joints.Secondly,the study proposesed the overall design goals of bionic tuna.And by reference to the characteristics of the fish's swing attitude in the tuna mode,the electromagnetic driving joints of the bionic tuna were designed.After calculated the joint drive capability with Ansys Maxwell electromagnetic simulation software,we proposed two types of joint driving methods for bionic fish.Then we completed the mechanical structure design of the bionic tuna fish body,tail fin and pectoral fin and designed drive system and host computer to acquisit data by labview.Then,the study compared the advantages and disadvantages of existing bionic fish dynamics,and used the Kane method to establish the underwater dynamic model of bionic tuna.Combines the CPG control method based on Hopf oscillator,we obtained the swimming rules of bionic tuna by Matlab simulation.We analyzed the control laws of bionic tuna during each phase of rapid turning under wat`er.and completed the dynamic simulation of fast turning of the bionic tuna through the bionic joint of Matlab/Simulink and Adams,which verified the correctness of the control model.Based on the characteristics of electromagnetically driven joint swing,a closed-loop control method of joint swing based on Fourier transform is proposed.The swing characteristics of electromagnetically driven joints are separated by Fourier transform:frequency,amplitude and zero offset control.Combined with the CPG control strategy to achieve closed-loop control of the swing characteristics.After a single joint test experiment,this method can improve the stability and accuracy of joint swing.Finally,we established an electromagnetically driven bionic tuna prototype and the corresponding experimental platform.By measuring the movement attitude of the bionic fish prototype and comparing the fish wave curve,the correctness of its kinematic model was verified and the bionic tuna at different frequencies and phases was obtained.Through experiments,the head and tail swing laws of bionic tuna under different frequencies and phase are also obtained.At last,the law of the underwater swing frequency and swimming performance of the prototype is verified by the underwater test.