Li Ning Sun

Design of Tactile Sensor for Measuring Orthocenter Deviation and Friction in Wafer Transmission Process

In order to raise position accuracy and stability in wafer transmission process, a tactile sensing system which can measure both deviation of wafer to manipulator and friction acting on wafer simultaneously is introduced. Analysis on kinetic model abstracted from sensing system is made, and following algorithms are applied: micro displacement is calculated through pressure values acting on different sensing units, and meanwhile friction is calculated from relative velocity between permanent magnet and inductance. Through simulation, indicators of sensing unit are established. This sensing system has the capacity of detecting deviation ranging 0-5 mm with resolution 0.05 mm and measure friction ranging 0-0.64 N. The results indicate that this sensing system meets the requirements in orthocenter deviation and friction measurement in wafer transmission process.

A Novel Micro-Dissection Method Using Ultrasonic Vibration for Molecular Analysis

Molecular techniques are transforming our understanding of cellular function and disease. However, accurate molecular analysis methods will be limited if the input DNA, RNA, or protein is not derived from pure population of cells or is contaminated by the wrong cells. A novel Ultrasonic Vibration Microdissection (UVM) method was proposed to procure pure population of targeted cells from tissue sections for subsequent analysis. The principle of the Ultrasonic Vibration Cutting is analyzed, and a novel microknife is designed. A multilayer piezoelectric actuator is used to actuate a sharp needle vibrating with high frequency and low amplitude (Approx. 16–50 kHz, and 0-3μm) to cut the tissue. Contrast experiment was done to test the feasibility of UVM method. Experimental results show that the embedded tissue can be quickly and precisely cut with the ultrasonic vibration micro-dissection method.

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.

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.

Dynamic Modeling of Continuum Flexible Leg System for Micro Robot

The micro robot that based on resonant principle can get high speed and high precision. However its leg is usually a flexible continuum with complex shapes, and its dynamic modeling is a key problem during researching this kind of robot. A method combining finite element with modal coordinates is presented, and is used to build Finite Degree Of Freedom (FDOF) model of Multi Rigid Bodies (MRD) for flexible leg of micro robot. Modal analysis of continuum model and FDOF model of MRD for flexible leg is conducted in ANSYS and ADAMS software environment respectively. Analysis results show that the two model have similar lower nature frequency and vibration modes, which verified the correctness of the FDOF model and its establish method. Based on FDOF model, the equivalent drive model of piezoelectric bimorph and system dynamic model of micro robot are build, which provides a theoretical basis for dynamic analysis of the micro robot.

A Robot-Assisted Surgery Positioning Method for Artificial Cervical Disc Replacement

Robotic–assisted surgery is a new trend in medicine. To overcome problems in artificial cervical disc replacement surgery, a robot-assisted surgery system which consists of an active 6-UPS parallel robot and its control system, a surgical planning system and an optical tracking system was developed to replace the cumbersome mechanical positioning device. A positioning method for robot-assisted cervical disc replacement surgery will be studied. Firstly, the robot-assisted surgery system is described. Secondly, the coordinate transformation method for robot-assisted surgery positioning is given. Then, a preoperative position and pose planning method is given. Finally, a robot-assisted surgery positioning by using the method in this paper is carried out. The result shows that the robot-assisted surgery positioning method in this paper is an effective method for artificial cervical disc replacement surgery.

Design of a Topology Nano-Positioning Stage

Nano-positioning technology has been widely used in many fields, such as microelectronics, optical engineering, and micro-technology equipment and manufacture. This paper presents a one-dimensional positioning system, adopting a PZT piezoelectric ceramic nano-positioning stage designed by multi-objective topological optimal synthesis. In order to obtain better performance, wedge-shaped structure has been applied as a precise pretension for the piezoelectric ceramic. Through finite element simulation and experimental verification, better static performance and smaller kinetic coupling are achieved, with up to 10 μm stroke displacement output and 5 nm resolution. This stage provides a novel, flexible, and efficient way in the design and optimization of the nano-positioning system.

Design of a Rudder Actuator Electric Loading Test System

Rudder actuator loading test system is the torque load simulation device of flight vehicles. An electric loading scheme of a PWM drive torque motor is proposed in this paper. Then the box-shaped structure of the loading system is designed, the performance of the loading system is improved for the high machining and assembly shaft system precision by adopting this structure.

Study on MEMS Microgripper Integrated Vacuum Tool

This paper presents a hybrid type of microelectromechanical systems (MEMS) microgripper integrated with an electrostatic mechanism and vacuum technology. Vacuum tools are integrated in this microgripper in order to achieve a reliable and accurate manipulation of microobjects. The microgripper is fabricated by a surface and bulk micromachining technology. The pick and release micromanipulation of microobjects is accomplished by electrostatic driving force caused by comb structure and an auxiliary air pressure force from air pump. The performance of this new hybrid type of microgripper is experimentally demonstrated through the manipulation of 100–200μm polystyrene balls. Experimental results show that this microgripper can successfully fulfill the pick and release micromanipulation.