Design And Kinematics Analysis Of Differential Drive Parallel Robot

In the field of aerospace,precision docking,secondary or three-mirror precision adjustment mechanism for large space telescope,fine surgical medical instruments,micro-electromechanical systems and many other aspects,the 6-DOF precision micro-motion attitude adjustment system has put forward higher demand.In addition,the high resolution micro pose adjustment system will also have a direct impact on the ultra-precision machining and integrated circuit manufacturing and other aspects,so it plays a very important role in modern advanced scientific research and production and industrial manufacturing,its technical indicators are also an important symbol of the level of national technology development.The combination of micro-positioning technology and robot technology forms a new type of micro-motion and posture adjustment robot,which has a broad application prospect.Parallel robots are often used as micromanipulators because of their high stiffness,compact structure and high motion accuracy.Their micro-motion accuracy in three-dimensional space can reach sub-micron or even nanometer.After studying several traditional design methods of 6-DOF parallel micro-motion pose adjusting robot,this paper proposes two innovative points for its design methods.The first innovative point is to realize micro-displacement motion by using servo motor to drive double helix pair differential transmission and positioning scheme,which not only improves the transmission accuracy of the mechanism but also reduces the cost of precise positioning platform.The second innovation is to replace the traditional rigid Hook hinge with a flexible Hook hinge to eliminate the hinge clearance,thus ensuring the precision of the fretting platform.In this paper,based on the structure of the biased flexible Hooke hinge and Gough-Stewart parallel robot,a 6-DOF parallel robot with 6-RR-RP-RR configuration is designed by using the differential transmission scheme.The main contents include structure design of parallel robot,flexibility modeling and performance analysis of offset flexible Hooke hinge,kinematics modeling and simulation of parallel platform,etc.Firstly,the structure design of the 6-DOF parallel micro-manipulator is carried out,including the transmission scheme design of the single-foot displacement driver and the structure design of the whole machine.Based on the double screw pair differential transmission design scheme for the design of the single foot displacement driver is proposed two reasonable schemes,and according to the two design methods of the single foot displacement driver platform configuration design,to determine the platform configuration parameters,to complete the design of the dynamic platform and static platform,on this basis to complete the two structural design of the whole machine platform.Finally,by comparing the advantages and disadvantages of the two design schemes to determine the final machine structure design scheme.Then the design of the flexible Hook hinge is carried out,the main content includes the flexibility modeling and performance analysis of the flexible hinge.Firstly,the hinge configuration,material,machining method and incision type were determined according to the motion accuracy and working conditions of flexure hinge.Secondly,based on the structure matrix method and the flexibility coordinate transformation method,the flexibility modeling of the Hooke hinge is introduced,and the finite element software is used to verify the correctness of the flexibility model.Furthermore,the influence of structural parameters of the flexible Hooke hinge on the performance of the hinge is analyzed by using the obtained flexibility expression,which provides a theoretical basis for the design of the hinge.Finally,the statics simulation of upper and lower flexible Hooke hinge is carried out to verify its strength under specific geometric parameters.Then the kinematic modeling and analysis of a 6-DOF parallel robot with flexible hinges are carried out,including kinematic analysis and simulation verification.Firstly,the flexible hinges of the rigid-flexible coupled parallel platform were regarded as rigid hinges by the pseudo-rigid-body model method.Then,the inverse kinematics of the rigid-flexible coupled parallel platform was modeled by using the D-H parameter method of the kinematics of the rigid six-degree-of-freedom parallel platform,and the inverse kinematics was solved by using the numerical iterative method.Secondly,the forward kinematics model of the platform is established and solved.Finally,multi-body dynamics simulation software and finite element simulation software are used to simulate the kinematics of the 6-DOF parallel platform to verify the effectiveness and correctness of the kinematics modeling.