Research On Motion Control Of Small UVMS

At present,with the increasing scarcity of land resources,the constant demand for natural resources in the development of human society,many countries have turned their attention to exploring and developing offshore resources,but given the special geography of the ocean,it also brings a certain danger to the exploitation of resources.Therefore,the Underwater Vehicle Manipulator System(hereinafter referred to as UVMS)is composed of an underwater robot equipped with an underwater manipulator,with its unique structure and the diversity of work,it has gradually become a hot spot of underwater mining resources.Since the UVMS is composed of the body ROV and the underwater manipulator,both have the characteristics of coupling,non-linearity and degrees of freedom redundancy.Therefore,the coordinated control of the two in the process of underwater operation is quite important,this is also one of the important difficulties in studying UVMS.The main research contents of this thesis are as follows:First of all,establish the relevant coordinate system of the body ROV,and analyze the force under water,the equation of its spatial motion is derived.The spatial motion is decoupled into horizontal motion and vertical motion,at the same time,according to the dynamic equations of the two planes,the mathematical models of the forward motion,advance and retreat motion and depth fixing motion of the body ROV were deduced.It lays a foundation for subsequent the body ROV motion control.Secondly,the mathematical modeling of 4-DOF underwater manipulator is carried out,the D-H coordinate system of underwater manipulator is constructed and its kinematics is analyzed.Then Newton-Euler method was used to derive the dynamics model.Establish the overall UVMS coordinate system,on this basis,the overall model of UVMS in the inertial coordinate system is deduced.This paper provides a mathematical model for the coordinated control of UVMS system.Thirdly,according to the motion control of the body ROV,the corresponding hardware system and software system are established.Using traditional PID control,fuzzy PID control and the proposed parallel fuzzy PID composite control,the mathematical models of the forward motion,advance and retreat motion and the fixed depth motion respectively,at the same time,compare the advantages and disadvantages of each control,the results show that the parallel fuzzy PID composite control can better control the motion of the body ROV.Finally,the underwater manipulator in UVMS is simulated,an adaptive control method based on RBF neural network for underwater manipulator based on model global approximation is proposed,the simulation experiment is carried out based on the model of two degrees of freedom underwater manipulator in vertical plane.The simulation results show that the control has good robustness.By constructing the overall dynamics model of UVMS,a two-loop integral sliding mode control is proposed to simulate the UVMS coordinated control.The results show the effectiveness of the control.