Structure Design And Dynamic Analysis Of A Parallel Micromanipulator Driven By LUMs

In recent decades,along with the continuous development of the micro-electromechanical system and its wide application in various fields,the development of the micro-manipulation technology is also very rapid.Micromanipulator is the core component of the micro-manipulation technology,thus its design and research are getting more and more attention.How to meet the demands of hign-precision,hign-velocity,large operating space,large output force and other key elements simultaneously has always been the difficulties of the study on micromanipulators.Aiming at the above problem,take the advantage of the quick response,hign control accuracy,large motion stroke,large propulsive force and other advantages of the linear ultrasonic motors(LUMs),this thesis constructs a new space parallel micromanipulator driven by LUMs.The kinematic modeling analysis,the rigid-flexible coupling dynamic model,the simulation analysis,the vibration control of the fingers,the study on mechanical drift existing in the mechanism are all conducted.The experimental results indicate that the micromanipulator can be used for gripping and moving the micro-objects with the diameter of several microns to hundreds of microns such as the biological cells.This research will contribute to promoting the development of the micro/nano technology,the biotechnology as well as the medical science in China.The main research contents of the thesis are presented as follows:1.According to the design object of hign-precision,hign-velocity,large operating space and large output force,a new 3-DOF parallel micromanipulator with two fingers is constructed.Utilizing the LUMs as the actuator,adopting the space parallel structure cooperating the universal flexible hinges make the whole mechanism possess the advantage of no gap and zero friction,and support the micromanipulator acquire not only high motion precision,but also faster running velocity,greater output force and larger operating space.2.An ordinary kinematic model of the rigid parallel micromanipulator is established utilizing the vector chain method and space coordinate transformation.The kinematic relationship between the input component and output component is derived.In order to get the more accurate kinematic relationship between the input and output of the micromanipulator,the kinematic model of the flexible parallel micromanipulator is established based on the hypothesis that the two end planes of the flexible hinge are always parallel.Combing the flexibility analysis of the flexible hinge,the workspace of the micromanipulator is calculated.Then,the displacement error of the hypothesis is analyzed.The maximum relative error of the end-effector is calculated as 0.65%.3.The rigid-flexible coupling dynamic model of the micromanipulator is established.According to the principle of enegy equivalence,the micromanipulator is divided into three symmetrical kinematic chains and one movable platform subsystem.Their kinetic energy and potential energy are calculated respectively.Adopting Lagrange method,the dynamic equation of the micromanipulator is formulated.Then,the dynamic simulation analysis is carried out by using ADAMS software and the dynamic properties of the actuator,the end-effector and the flexible hinge are obtained.4.For the vibration problem of the finger end,the dynamic model of the finger vibration is established.Through analyzing the main factors influcing the vibration rule,a parameter optimization model to restrain the finger vibration is put forward and the optimization model is solved by using interior penalty function method united with Newton method.Using the Ansys software,the transient dynamic simulation of the fingers is conducted.Through experimental measurement,the vibration amplitude of the postoptimality finger-end is reduced by 84.7%.5.The mechanism analysis and experimental research on the mechanical drift phenomenon of the end-effector is proposed.Firstly,the mechanical model of the flexible clamped LUMs stator is established.The model analysis indicates that the tangential stiffness of the stator is the main factor influencing the mechanical drift of the output.Tests on the clamping components with different stiffness are carried out.According to the analytical results,a new type of LUM stator which one side hinge fixed whie one side spring clamped is designed to restrain mechanical drift.Then,for the mechanical drift arised on the mechanism,experimental study on the drift time,drift measure on subsection trajectory is developed.Lastly,a method of avoiding operate at both ends of the trajectory for reducing the mechanical drift is presented.6.Combined with a 2-DOF motion platform,the experimental evaluated system of the micromanipulator is constructed.The constituted macro/micro dual drive device can quickly locate the operational objects.The fundamental characteristics tests of the micromanipulator are conducted,including the vibration optimization performance test of the fingers,the determination of the workspace and the displacement resolution of the end-effector,the relationship between the input and output displacement.The experimental results indicates that the maximum workspace of the micromanipulator is 2.332 mm × 2.109 mm × 20 mm while the displacement resolution is 100 nm.The designed micromanipulator is able to grip and move the tiny objects of different materials and sizes.