Structural Design And Analysis Of Underwater Grasping Manipulator

Artificially cultured sea cucumbers have become one of the channels for people to eat sea cucumbers,but the sampling and capture method of artificially cultured sea cucumbers is still manual harvesting.The artificial harvesting method is limited by the physical condition of the human body and the underwater environment,resulting in high risk and low efficiency of artificial harvesting.Therefore,based on the risks of manual harvesting,this paper deeply studies the domestic and foreign status quo of existing robotic arms,and designs an underwater grasping manipulator with a two-part structure of an underwater light-weight electric manipulator and a polyhedral folding end effector.It greatly reduces the risk of manual harvesting and improves the operation efficiency.The main research contents of this paper are as follows:(1)Lightweight underwater electric mechanical arm is designed with waterproof steering gear.Firstly,the overall structural design of the underwater manipulator is analyzed to realize the design of the underwater electric manipulator and the establishment of the 3D model;secondly,the screw theory and the D-H method are used to compare and solve the forward kinematics of the manipulator to verify the consistency of the forward kinematics solutions;Finally,the inverse kinematics of the manipulator is solved and analyzed by the inverse transformation analytical method,and the workspace of the manipulator is solved and analyzed based on the Monte Carlo method.(2)On the basis of the forward and inverse kinematics analysis,the simulation analysis of the joint space trajectory planning of the underwater manipulator through the path points is further carried out.Firstly,the two planning algorithms of joint space trajectory planning and Cartesian space trajectory planning are studied and analyzed;secondly,the motion effect of quintic interpolation joint space trajectory planning with path points is compared and verified,which is better than cubic interpolation joint space trajectory planning;finally,polyhedron folding and grasping is studied.The manipulator grabs the motion trajectory of the end pose point,taking the flat state as an example,to simulate and analyze the feasibility of the joint space phased 3-5-3 polynomial trajectory planning scheme for the underwater manipulator to assist the grasping operation of the path point.(3)The end effector of the underwater grasping manipulator is designed based on the polyhedral folding and unfolding structure.Firstly,the structural design requirements and polyhedral structure configuration of the end effector are analyzed;secondly,it is proposed to use the plane-symmetric Bricard structure as the external transmission mechanism,and the degrees of freedom and kinematics are analyzed;then the virtual prototype of the end effector is used.Modeling,motion simulation and physical production to verify the feasibility and reliability of the end effector,and further simulate and analyze the motion trajectory of the end effector to obtain the envelope range of its motion trajectory;Finally,simplify the single-branch end model and conduct D-H modeling,using the Monte Carlo method to obtain the singlebranch motion envelope space.(4)Design and analysis of the control system of the underwater grasping manipulator.Firstly,through the analysis of the overall architecture design scheme of the control system,the hardware of the control system is selected and designed to complete the overall connection of the hardware objects;secondly,through the development of the software control program,the upper computer of the PC-side web control interface is designed and studied;Finally,through the experimental verification,the test realizes the remote online real-time control of the underwater grasping operation function.