Wei Bin Rong

Virtual Force Feedback-Based 3D Master/Slave Tele-Nanomanipulation in SEM

In this paper, we focus on the need for real time nanomanipulation, a 3D Master/Slave tele-nanomanipulation platform is studied with the haptic device (Omega3) as the master and the nanopositioner (Attocube) as the slave, working in scanning electron microscope (SEM). The 3D manipulation environment is developed with the help of VR technology. The platform is controlled by the enhanced virtual coupling (EVC) algorithm. The stability of the platform is discussed with Llewellyns stability criteria. Scale factors and enhancement factor of the control system are determined, according to the force applied on master and slave terminals. Performances of the platform are tested with the ZnO nanowire manipulation experiments. Experiment results show that the platform has good performance while guaranteeing stability on ZnO nanowires manipulation in SEM using the method presented in this paper.

Stability and Performance of Virtual Reality-Based Telenanomanipulation System in SEM

In this paper, a master/slave telenanomanipulation control system with force feedback is established with the micro-positioner (Attocube) working in scanning electron microscope (SEM) as the slave side and the haptic device (Omega3) as the master side. An improved virtual coupling (IVC) algorithm is introduced based on nanoscale virtual coupling (NSVC) by adding a proportional- plus-integral (PI) velocity controller in the haptic interface. The stability and performance of the established system are discussed. This method leads to an explicit design procedure for virtual coupling networks which give greatest performance while guaranteeing stability both on moving carbon nanowires in SEM and measuring force at the point of device-human contact.

Effects of Asperity Shape on the Adhesion Hysteresis Originated from Surface Roughness

Adhesion of solid surfaces plays a significant role in many technical fields especially at micro and nano scale. The effect of asperity shape on the adhesion hysteresis originated from surface roughness has been investigated theoretically in this paper. Based on the adhesive contact model of single asperities with axisymmetric power-law shapes, the roughness-induced adhesion hysteresis is modeled by assuming the asperity heights follow a Gaussian distribution on the rough surface. The analysis results show that the dissipation energy decreases dramatically when the surface becomes rougher for all the shape indices, and the shape index affects the adhesion hysteresis at different levels with the variance of surface roughness. A general parameter consisting of the shape index of asperities is proposed to characterize the adhesion hysteresis. These will be helpful to understand and control the adhesion hysteresis for solid-solid contact.

Design of a Micro-Nano Positioning Platform Based on Stick-Slip Driving

Micro-nanopositioning platform is a core component for micro-nanooperation. The static and dynamic characteristics of platform will determine its precision level. This paper presented a new 2-D micro-nanoplatform based on stick-slip driving. By using static structural module and modal analysis module of ANSYS software, the stress and natural frequency of pedestal were analyzed. The driving frequency of piezoelectric ceramic was selected far away from the natural frequency to avoid resonance. Dynamic performance of pedestal was also analyzed with ANSYS transient module. Simulation results show that the presented platform has excellent static and dynamic performance.

The Analyse on Stiffness Model of 3-PPSR Flexible Parallel Robot

In order to achieve greater workspace motion, it’s designed a high aspect ratio 3-PPSR flexible parallel robot, driven by a piezoelectric motor, connected by flexible hinges, which has the advantages of simple structure, non singular, seamless, high motion precision. Because of the stiffness of the system directly affecting the motion accuracy, load bearing performance, according to the characteristics of high aspect ratio flexible hinge, It’s established the mathematical model of flexible hinge through finite element method. Using method of integral stiffness, conbined coordination equation with force balance equation, the flexible stiffness model of system is obtained. Finally, through using Ansys, it’s confirmed the validity of the theoretical model by comparing of the theoretical stiffness model results with the finite element analysis of the model results, to provide a reliable guarantee for optimization and analysis of kinematics and dynamics of flexible parallel robot.

Microobjects Gripping with Controllable Menisci Based on Pressure Adjustment

Flexible and reliable gripping is a fundamental task in various micromanipulation and microassembly fields. Shape-controllable menisci based on pressure adjustment were proposed to pick up microobjects. Lifting force is provided by a controllable liquid bridge which is formed between the capillary tube and the microobject. The volume and the shape of the meniscus could be regulated dynamically by changing the pressure at the capillary nozzle orifice, thus the capillary force alters correspondingly. The pressure adjustment was realized by adjusting the height of the reservoir device precisely. Fluent software was used to simulate the fluid meniscus under different pressures. Experiments were performed to achieve controllable meniscus with different height difference of liquid level between the reservoir device and the capillary nozzle orifice, and microobjects griping operations were executed to verify the method.

Investigation on the Data Processing Method for High-Precision Alignment of PM Fibers

The extinction ratio is the characteristic parameter of polarization-maintaining (PM) fiber couplers. The detection accuracy of polarization angle is related to the extinction ratio, and affects the thin-diameter PM fiber coupler performances greatly. A series of image processing steps including median filtering, adaptive image morphology, and maximum variance threshold segmentation method are used to get the outline of optical fibers. The minimum squares method is used to get the maximum intensity of the light. The experimental data is processed using the Fourier filtering method and influences of the manufacturing error and random errors of fibers are reduced. By fitting the experiment data with cubic spine method, and its mean square error of fitting is 0.05458, then the polarization angle of the PM fiber is determined. Experiments show that this method can precisely determine the fast axis position of PM fibers, and it can achieve the high precision alignment of 80 um PM fibers.

Development of a Nanomanipualtion System for Handling Nanowires

A compact and versatile nanomanipulation platform and its dirve-control system are being developed. This nanomanipulation sytem is aimed to handle nanowires (NWs) and fabricate nanostructures by NWs in a Scanning Electron Microscope (SEM). The excellent performance of the compact manipulator developed with corase and fine positioning in one unit has been demonstrated, which shows that the resolution is 8 nm and the steps are from 50 nm to 0.8 μm. For the power supply of the manipulator, a three-output driver is designed with a high-power integrated operational amplifier based on a mixed approach of voltage control and current control. The planar push-and-lift handling of NWs is carried out by the use of two tips to demonstrate the capability of the nanomanipulation sytem inside SEM.

Influence of the Tabor Parameter on the Roughness-Induced Adhesion Hysteresis

Influence of the Tabor parameter on the roughness-induced adhesion hysteresis was investigated. To achieve this, the adhesive contact model of single asperities was considered by incorporating the Maugis-dugdale model and its corresponding extension firstly. Further more, the load-approach relationship of adhesive contact between a rough surface and a flat was analyzed. The dissipation energy during a load and unload cycle is derived for general values of the Tabor parameter. It was found that the adhesion hysteresis becomes weaker gradually with the increase of the adhesion parameter, and it becomes stronger with the decrease of the Tabor parameter at the same adhesion parameter. The adhesion hysteresis for a special case that rough surfaces with DMT(Deryagin-Muller-Toporov)-type asperities is also discussed.

Design of a SEM Compatible Slip-Stick Nano-Positioner with High Bearing Capacity

This paper presents a new structure of slip-stick positioner with a high bearing capacity, which is designed according to the requirement of nano-manipulation in the Scanning Electron Microscope (SEM). In addition, to analyze the performance of the slip-stick positioner, a dynamic model is developed in MATLAB/Simulink. The experimental results demonstrate the excellent performance of this positioner and especially its bearing capacity can be up to 400g.