Configuration Synthesis And Dynamic Modeling Of Spherical Parallel Vector Thruster For Underwater Robot

As a developed branch of propulsion technology in the fields of aviation and aerospace,thrust vectoring technology with single manipulator and multidimensional attitude is a novel thrust vectoring method in the field of autonomous underwater vehicle.In order to complete both the rotational transmission and attitude adjustment in this paper,the innovative designs for vector thruster on the basis of some novel limited-DOF parallel mechanisms and space gear train are proposed based on screw theory.The main contents of this paper are as follows:Firstly,the demand of vector driving function of underwater robot is analyzed in this paper and 8 kinds of branch kinematic chains which can be used to synthesize vector propulsion mechanism are induced,after which the combination of 8 kinds of branch chains are given respectively.A comprehensive and systematic solution of the parallel vector thruster type synthesis problem with two directions of deflection is given,and the design method of three kinds of parallel vector thruster is put forward.A feasible configuration scheme is analyzed,and the corresponding force constraint and motion characteristics are induced.The design examples of three kinds of parallel vector thrusters are given respectively.Secondly,a 3-DOF RRR-RR-RU spherical parallel vector thruster is designed by constructing over-constrained parallel mechanism.The topological model of the spherical parallel vector thruster is constructed based on screw theory,and the positive and inverse solutions of the mechanism are calculated after the motion characteristics of the mechanism are analyzed.The Jacobian matrix of the mechanism is deduced by vector algebra based on the closed-chain constraint equations.The speed and acceleration model of the mechanism are established by using the decoupling method of the feature structure,and the kinematic characteristics of the workspace and dexterity of the mechanism are analyzed.Finally,the dynamic modeling of RRR-RR-RU spherical parallel vector thruster of underwater robot is put forward,and the influence of the working environment is analyzed in combination with hydrodynamics,which improves the screw theory method in the dynamic modeling of underwater robots.Combined with examples,the simulation analysis of MATLAB and ADAMS is carried out to verify the correctness and feasibility of the design principle.The research of this paper has certain practical value and wide application prospect for the advantages of multi-branched vector thruster in stability and control.