Design And Motion Optimization Of Underwater Bionic Robot Based On CPG

With the continuous development of science and technology,the global exploration and development in the marine field has been intensified,and the research technology of underwater robotics has been developed rapidly.At present,the common underwater robots include manned submersible powered by propellers,autonomous underwater vehicles(AUV),remotely operated vehicles(ROV),bionic fish robots with tail oscillation propulsion,and the underwater bionic octopus robot with tail propulsion,etc.In view of the limitations of these robots,the influence of their own driving methods and external currents in the process of motion can lead to poor stability,complex motion contro l,and single motion.This paper aims to develop an underwater bionic robot with good stability and diverse motion by comparing the motion propulsion methods of underwater bionic robots through investigating the relevant research on underwater bionic robots at home and abroad.First,an underwater bionic robot is designed,which includes a body part with a control board and attitude and depth sensors,a front part with ultrasonic sensors,a foot rudder drive part,a tail rudder drive part,and a passive webbing part.The dynamics modeling analysis was performed for the foot drive part of the robot to understand the oscillation mode of the passive webbing under the tiller drive and the propulsion force and other performance parameters,and to determine the motion mode in conjunction with the robot body.Second,to ensure the stability of the robot in underwater motion,a control model based on Central Pattern Generators(CPG)is developed to reduce the influence of its own motion on the stability of the robot when gait switching is performed.Through the simulation model,the influence of different parameters on the output signal is analyzed,and the coupling model is built to determine the basic gait state by combining the servo properties and the number of servos,while the tail servo and the attitude sensor form a PID closed-loop feedback control to instantly correct the robot motion attitude and further improve the robot stability.In order to understand the robot’s attitude in underwater motion and to faci litate control and adjustment,a wireless module was built for communication,while ultrasonic underwater sensors,attitude sensors IMU,and depth sensors were used to obtain information about the distance to underwater obstacles,the depth it was at,and its own attitude.Based on the use of sensors,servos and other components and the size of the robot body,the electrical control hardware system is designed and a C#-based host computer is built for parsing,transmitting data and controlling the robot mot ion.Finally,in order to further verify the correctness of the design model building,as well as to better determine the CPG model parameters to achieve the maximum propulsion rate of the robot.The experimental platform was built to collect the force of the webbing under the CPG model drive in real time through the pressure sensor,to analyze the data,to complete the determination of the oscillation parameters,and to adjust the control parameters.A physical prototype was built to perform seal testing,buoyancy adjustment,and PID parameter adjustment to complete the basic gait movements of the robot,such as forwarding,turning,and diving,and to verify the robot’s ability to avoid obstacles with instant feedback and correction adjustment when encountering obstacles with the cooperation of sensors.Through the above experiments,it is verified that the developed underwater bionic robot based on CPG basically meets the design requirements and lays the foundation for the development of this kind of bionic robot products.