Design And Analysis Of Precise Assembly Platform Of Giant Laser Facility

With the exhaustion of energy sources,humans have accelerated the research of nuclear fusion.The Giant laser facility proposed by China has a major mission that accompolishing nuclear fusion of inertial confinement.The key part of the Giant laser facility is the precise assembly of a large number of optical modules.This paper designs a kind of adjustment platform of 6-DOF.Because the parallel mechanisms have the characteristics of high precision,high specific stiffness,fast response speed,and high load capacity,the platform contains of two kinds of Lower-mobility parallel mechanism(3-PSS+PS adjustment unit and 4-PP adjustment unit).The main contents of this paper are as follows.This paper analyzes the demand and function of 's assembly of Giant laser facility.Based on this,it proposes a new type of parallel mechanism including 3-PSS+PS adjustment unit and 4-PP adjustment unit.For the two kinds of Lower-mobility parallel mechanism,it analyzes their structure principle.And the calculation of the degree of freedom of the two kinds of adjustment unit based on the spiral theory provides a basis for kinematic analysis of the platform.According to the closed vector method,the inverse solution of the position of the 3-PSS+PS adjustment unit is solved.For the solution of the positive solution of the position,the Newton-Raphson method is used and the results that meet the project's requirements are obtained by iterative calculation.For the 4-PP adjustment unit,analytical method is used to solve its positive and inverse solutions of the position.The mathematical models of velocity and acceleration of 3-PSS+PS adjusting unit and 4-PP adjusting unit are deduced by differential method.The displacement,velocity and acceleration of 3-PSS+PS adjusting unit and 4-PP adjusting unit are simulated by Adams and Matlab software.The simulation and solution about kinematics verify the correctness of the kinematic model.It provides methods and theoretical basis for solving the engineering problems of kinematics of parallel/ hybrid mechanism.Based on the mechanical parameters of the 3-PSS+PS and 4-PP adjustment units,the inequality equations of their workspace constraints are established respectively,and their workspaces are solved by the numerical search method-integral method.The reachable workspace maps of 1-DOF,2-DOF and 3-DOF for 3-PSS+PS adjustment unit were established.At the same time,its reachable workspace's solution of 4-DOF was given and it's verified that the coupling motion of 4-DOF can still meet the needs of the project;for 4-PP adjustment unit,its reachable workspace was solved when the 3-PSS+PS adjustment unit is at initial position and the actual working condition of assembly of the optical modules.Based on the key workspace volume of the the 3-PSS+PS adjustment unit and 4-PP adjustment unit,the structural parameters are optimized,which provided the theoretical basis for the parameter optimization of the parallel/ hybrid mechanism.Velocity vector—spiral theory method and differential method were used to solve jacobian matrixs of the velocity of 3-PSS+PS and 4-PP adjustment units respectively,and the singularity and dexterity of the two units were solved based on the velocity Jacobian matrixs.The inverse kinematic singularity,positive kinematic singularity and hybrid singularity of the 3-PSS+PS adjustment unit were obtained by Jacobian matrix method,while the 4-PP adjustment unit had no singularity in its workspace.According to the jacobian matrix about the velocity,the paper establishes the analysis of their dexterity.For the 3-PSS+PS adjustment unit,a method of solving dexterity based on the assembly process of optical modules is proposed.The paper obtains the dexterity of the unit in the entire assembly process;for the 4-PP adjustment unit,the global dexterity of the unit is one and reaches the optimal value.Therefore,a parameter optimization method based on the global dexterity of the mechanism is proposed.The structural parameters of the 3-PSS+PS adjustment unit are optimized,so that its global dexterity can be optimized.