Research On 3D Modeling And Motion Control Of Underwater Snake Robot Based On Vector Thruster

With the advancement of science and technology and the development of society,the development of marine energy has gradually attracted the attention of the world.However,due to the complexity and uncertainty of the underwater environment,underwater detection and operation are difficult and costly,and many times require divers to perform underwater operations,which poses a high risk.As a bionic robot,the snake robot has high flexibility and can detect and operate in a narrow space or under complex working conditions.The problem with the snake-like robot is that the model is complex and difficult to control.Especially in the underwater environment,various fluid forces and unpredictable factors increase the underwater snake-like robot.It is important in the establishment of dynamic equations and the design of the control system.difficult.In order for the underwater snake-like robot to effectively complete its tasks underwater,it is necessary to establish a correct and effective dynamic model of the underwater snake-like robot in three-dimensional space,and to design a corresponding fast and stable controller.The research content of this paper is as follows:(1)Through the modular design of the driving system of the underwater snake robot,it is divided into a main propulsion system containing a vector thruster,an auxiliary propulsion system that provides horizontal and vertical thrust,and a connection system containing orthogonal joints.By distributing and arranging the drives of the underwater snake-like robot,the over-driving system of the underwater snake-like robot is realized.Subsequently,the structural design of the vector thruster in the main propulsion system,including the design of the propeller using the flexible shaft as the main drive shaft,the matching and selection of the motor,the design of gears and the selection of sealing methods.(2)The establishment of mathematical models of underwater snake-like robots including kinematics equations,hydrodynamic equations and dynamic equations.According to the DH coordinate method,the kinematic equations of the underwater snake-like robot in three-dimensional space are listed.According to the Morrison formula,the hydrodynamic model of the snake-like robot when navigating underwater is listed.Finally,the snake shape is listed according to the Newton-Euler formula.The dynamic equation of the robot in the underwater three-dimensional space,and the established dynamic equation is simulated in Matlab.Through the analysis of the simulation results,the correctness of the dynamic model of the underwater snake-like robot is proved.(3)Construct an RBF neural network variable structure controller according to the established model,and set an expected snake-like robot motion trajectory,and according to the established kinematics equations,solve the expected tracking of the centroid of each section of the snake-like robot The desired change curve of the trajectory and the joint angle.According to the constructed controller,a simulation platform was built in Matlab and Simulink,and the underwater snake-shaped robot was simulated in the trajectory through the designed controller.The result converged to the desired trajectory,which proved the stability of the designed controller Sex and effectiveness.