Design And Dynamics Simulation Of Autonomous Fishing Underwater Robot

China's seafood products are abundant in number and variety.It is an economically viable way to apply underwater robotics to the fishing of marine products.However,sea cucumbers are currently collected by manual fishing,which is inefficient.In view of the current shortage of sea cucumber fishing methods,this paper designs a robot for that.Based on the autonomous underwater robot as the carrier,the structural design to meet the requirements of the sea cucumber collection operation was carried out.From the structure,the fishing robot can be divided into collection mechanism,sorting mechanism and collection mechanism,which can complete the whole working process of collecting sea cucumber.The ANSYS Workbench finite element analysis software was used to analyze the underwater static pressure of the compressive cabin of the robot,and optimize the thickness.so as to reduce the thickness of the shell as much as possible under the premise of meeting the operation requirements.This can reduce the overall weight of the machine while reducing costs.Two coordinate systems are established for the underwater robot.The fixed coordinate system E-(?)-and the motion coordinate system O—xyz,the Getler equation are used to establish the kinematic equation of the six-degree-of-freedom of the underwater robot to analyze the motion of the machine.The inertia and viscous hydrodynamic coefficients are estimated.Based on the equation of motion and each coefficient,the motion model of vertical plane and horizontal plane is established.The PID controller is used to establish the control system.Given the appropriate values of KP?KI?and KD,the motion attitudes of the slanting angle,the pitch angle and the depth are given analysis.Finally,the influence of underwater environment on machine positioning is analyzed.The effects of filtering,image blur enhancement and edge contour detection are eliminated,so that the machine can be accurately positioned to achieve sea cucumber fishing in different positions with different motion postures.Since sea cucumbers are distributed in various areas of the breeding base,traversal path planning must be used to complete all fishing operations in the area where the machine is located.Firstly,a grid map is built to simulate the underwater real environment,and the obstacle avoidance function is completed by using the A*algorithm.The energy consumption and the navigation trajectory when encountering obstacles of the inner spiral algorithm and the field algorithm in path planning are compared.The inner spiral algorithm is selected to complete the global path planning.Finally,the inner spiral algorithm is combined with the A*algorithm.In this way the machine can find the nearest regional location where it can work when encountering obstacle to complete the underwater path planning.Due to the complexity,nonlinearity and fluid-solid coupling effect of underwater motion,this paper analyzes the fluid dynamics of the whole underwater robot based on ANSYS FLUENT.Establish a fluid enveloping domain to simulate the underwater environment and the turbulence model is selected.The movement of the robot during underwater fishing operations was analyzed by CFD(Computational Fluid Dynamics).The drag coefficient,velocity streamline and pressure cloud map during motion are obtained to facilitate analysis of the underwater motion of the robot.In this paper,the design and dynamics simulation of the autonomous underwater sea cucumber fishing robot is completed,which realizes the automation of sea cucumber fishing and improves the fishing efficiency which has great practical significance.