Design and Implementation of a Controller for an Electrostatic MEMS Actuator and Sensor

An analog controller has been analyzed and built for an electrostatic micro-cantilever beam. The closed loop MEMS device can be used as both actuator and sensor. As an actuator it will have the advantage of large stable travel range up to 90% of the gap. As a sensor the beam is to be driven into chaotic motion which is very sensitive changes in the system parameters. Two versions of the controller have been analyzed and implemented, one for the actuator and one for the sensor. For the actuator, preliminary experiments show good matching with the model. As for the sensor, the dynamic behavior have been studied and the best operating regions have been determined

A real-time virtual-hand recognition system.

by Tsang Kwok Hang Elton.Thesis submitted in: December 1998.Thesis (M.Phil.)--Chinese University of Hong Kong, 1999.Includes bibliographical references (leaves 78-83).Abstract also in Chinese.Chapter 1 --- Introduction --- p.1Chapter 2 --- Virtual-hand Recognition --- p.5Chapter 2.1 --- Hand model --- p.6Chapter 2.1.1 --- Hand structure --- p.6Chapter 2.1.2 --- Motions of the hand joints --- p.8Chapter 2.2 --- Hand-tracking technologies --- p.9Chapter 2.2.1 --- Glove-based tracking --- p.10Chapter 2.2.2 --- Image-based tracking --- p.12Chapter 2.3 --- Problems in virtual-hand recognition --- p.13Chapter 2.3.1 --- Hand complexity --- p.13Chapter 2.3.2 --- Human variations --- p.13Chapter 2.3.3 --- Immature hand-tracking technologies --- p.14Chapter 2.3.4 --- Time-varying signal --- p.14Chapter 2.3.5 --- Efficiency --- p.14Chapter 3 --- Previous Work --- p.16Chapter 3.1 --- Posture and gesture recognition algorithms --- p.16Chapter 3.1.1 --- Template Matching --- p.17Chapter 3.1.2 --- Neural networks --- p.18Chapter 3.1.3 --- Statistical classification --- p.20Chapter 3.1.4 --- Discontinuity matching --- p.21Chapter 3.1.5 --- Model-based analysis --- p.23Chapter 3.1.6 --- Hidden Markov Models --- p.23Chapter 3.2 --- Hand-input systems --- p.24Chapter 3.2.1 --- Gesture languages --- p.25Chapter 3.2.2 --- 3D modeling --- p.25Chapter 3.2.3 --- Medical visualization --- p.26Chapter 4 --- Posture Recognition --- p.28Chapter 4.1 --- Fuzzy concepts --- p.28Chapter 4.1.1 --- Degree of membership --- p.29Chapter 4.1.2 --- Certainty factor --- p.30Chapter 4.1.3 --- Evidence combination --- p.30Chapter 4.2 --- Fuzzy posture recognition system --- p.31Chapter 4.2.1 --- Objectives --- p.32Chapter 4.2.2 --- System overview --- p.32Chapter 4.2.3 --- Input parameters --- p.33Chapter 4.2.4 --- Posture database --- p.36Chapter 4.2.5 --- Classifier --- p.37Chapter 4.2.6 --- Identifier --- p.40Chapter 5 --- Performance Evaluation --- p.42Chapter 5.1 --- Experiments --- p.42Chapter 5.1.1 --- Accuracy analysis --- p.43Chapter 5.1.2 --- Efficiency analysis --- p.46Chapter 5.2 --- Discussion --- p.48Chapter 5.2.1 --- Strengths and weaknesses --- p.48Chapter 5.2.2 --- Summary --- p.50Chapter 6 --- Posture Database Editor --- p.51Chapter 6.1 --- System architecture --- p.51Chapter 6.1.1 --- Hardware configuration --- p.51Chapter 6.1.2 --- Software tools --- p.53Chapter 6.2 --- User interface --- p.54Chapter 6.2.1 --- Menu bar --- p.55Chapter 6.2.2 --- Working frame and data frame --- p.56Chapter 6.2.3 --- Control panel --- p.56Chapter 7 --- An Application: 3D Virtual World Modeler --- p.59Chapter 7.1 --- System Design --- p.60Chapter 7.2 --- Common operations --- p.62Chapter 7.3 --- Virtual VRML Worlds --- p.65Chapter 8 --- Conclusion --- p.70Chapter 8.1 --- Summaries on previous work --- p.70Chapter 8.2 --- Contributions --- p.73Chapter 9 --- Future Work --- p.75Bibliography --- p.7

Design and Fabrication of a Magnetic Manipulator with Five Degrees of Freedom

Magnetic manipulation has the potential to recast the medical field both from an operational and drug delivery point of view as it can provide wireless controlled navigation over surgical devices and drug containers inside a human body. The accuracy and precision of controlled navigation will provide access to delicate organs and decrease the rehabilitation time. The advantages of achieving such a task have absorbed engineers' and researchers' attention and effort in the electromagnetic, imaging, mechanical, and robotic fields to implement the principles and make a functional magnetic manipulator. The main idea behind magnetic manipulators is to regulate electrical currents fed to the coils to precisely position and orient an agent- also known as a robot or a magnetic tool- inside a working space. The presented system in this research is formed with nine coils, also known as electromagnets, placed normal to the spherical volume. The radius of this space is directly correlated with the dimensions and the number of coils, which can be utilized to parameterize the spatial constraints. Extending the number of coils forming a spherical volume, also known as spherical workspace, has led to developing a unique geometrical constraint to optimize the coil placement. The determination of the constraints resulted in a specific outer diameter for each coil. In order to design a coil that produces the maximum axial force with the least power combustion with a given outer radius, Fabry Factor equation and Finite Element Method (FEM) were adopted. Fabry Factor relates the dimensions of the coils to each other such that the power consumption is minimized. Therefore, various iron-core coils were simulated using this method, and then the axial force of each coil at the furthest operational point in the working space was measured using FEM. The optimization result led to a cylindrical iron-core coil with an inner diameter of 20.5 mm, an outer diameter of 66 mm, and a length of 124 mm. The FEM results in 3D for a complex system is mostly associated with errors between actual and simulated values of the magnetic field, around 17 percent less than the actual values in this project. In order to eliminate this error, the magnetic field of the manufactured coil had been predicted using Artificial Intelligence (AI) techniques for experimental purposes. Regression models of Artificial Neural Network (ANN), a hybrid method called Artificial Neural Network with Simulated Annealing (ANN/SA), and Gene Expression Programming (GEP) had been built individually. ANN/SA has shown outstanding performance with an R-squared equal to 0.99 and root mean square error of 0.0028; hence, it has been used in the actuation process for magnetic field prediction. Finally, to indicate the functionality of the system, a simple 1D PI actuation logic with = 3.25 and =0.01 using a laser sensor had been successfully investigated. It first predicts the magnetic field using ANN/SA at the agent's current position provided by the laser sensor; then, regulates the current flowing through each coil till the agent settles at the final destination

Progettazione, sviluppo e test per il microassemblaggio di microcomponenti

In questa tesi viene studiata una stazione di microlavorazione composta da un microgripper, un microavvitatore ed un micromanipolatore per realizzare un collegamento tra due oggetti di materiale plastico utilizzando una micro-rosetta ed una micro-vite autofilettante. Lo studio si articola in tre parti. La prima parte consiste nella progettazione e realizzazione di un dispositivo capace di rilevare la forza di contatto durante le operazioni di pick and place, installato su un microgripper precedentemente realizzato presso il Dipartimento di Ingegneria Meccanica e Nucleare. La seconda parte della tesi ha previsto la progettazione e la realizzazione di un avvitatore azionato da un attuatore piezoelettrico. Lo spostamento generato dall’attuatore comprime una molla progettata e realizzata sulle specifiche fornite da questa tesi al fine di trasformare l'azione lineare dell'attuatore in una coppia torcente capace d’avvitare micro-viti. L'ultimo elemento studiato riguarda un innovativo manipolatore capace di afferrare micro-oggetti dalle svariate dimensioni e geometrie. L'afferraggio sfrutta le forze capillari generate da una gocci d’acqua, ed il rilascio dei micro-oggeti invece è basato sulle doti di idrofilia ed idrofobia di un particolare tessuto realizzato dall'università danese "DTU" che costituisce il fulcro del manipolatore. Tutti i componenti sono stati realizzati presso i laboratori del Dipartimento di Ingegneria Meccanica dell'Università di Pisa. Ad eccezione dell'avvitatore per il quale non è stato possibile reperire un generatore sufficientemente potente per farlo azionare, sono stati testati sperimentalmente tutti i componenti ottenendo ottimi risultati. __________________________________________________ In this thesis we studied a micro station composed by a micro-gripper, a micro-screwdriver and a micromanipulator for making a link between two objects of plastic materials using a micro-washer and a micro-screw. The study is composed of three parts. The first part is about the design and implementation of a device able to detect the contact force during the pick and place operations. The device was installed in a micro-gripper previously realized by the Department of Mechanical and nuclear Engineering. In the second part of the thesis it was designed and completed a screwdriver driven by a piezoelectric actuator. The movement generated by the actuator compresses a spring, which was designed and built thanks to the specifications provided by this thesis, in order to transform the linear action of the actuator in a torque able to screw micro-screws. The last studied element is an innovative manipulator able to grip micro-objects with a variety of sizes and geometries. This grip exploits capillary forces generated by a drop of water, and the release of micro-objects is based on the qualities of hydrophilic and hydrophobic properties of a particular material ,made by the Danish University "DTU", that constitutes the core of the manipulator. All components have been manufactured in the laboratories of the Department of Mechanical Engineering of the University of Pisa. All components were tested with good results, with the exception of the screwdriver, because it was not possible to find a generator powerful enough to operate it

Force Sensing and Control in Micromanipulation

Ph.DDOCTOR OF PHILOSOPH

Mikrosystembasierte Zellkultivierung und Zellmanipulation zur Applikation mechanischer Reize auf Zellen

Die übergeordnete Fragestellung der vorliegenden Arbeit ist biomedizinischer Art und seit mehr als 150 Jahren anhängig: Wie verhalten sich Zellen unter definierter Belastung? In vivo ist die Beobachtung zellulärer Prozesse bisher nicht ohne invasive Methoden möglich. Das verlangt nach einer Lösung in vitro, welche die natürlichen Bedingungen adäquat nachahmt und gleichzeitig optimale Bedingungen für die Beobachtung und Beeinflussung der Prozesse bietet. Dass sich dafür Mikrosysteme mit einer angepassten Peripherie eignen, wird in dieser Arbeit nachgewiesen.The motivating question underlying this work is generated by life sciences, pending for more than 150 years: How do cells behave under defined load? In vivo it is not possible to monitor subsiding cellular processes without the use of invasive methods. This demands for a solution in vitro, which mimics natural conditions adequately and offers optimized conditions for observation and manipulation at the same time. For this purpose BioMEMS (Bio Micro Electro Mechanical Systems) for cell are suitable. By means of analysis of state of the art for conventional macro and for micro system based cell cultivation and manipulation, requirements from cells and from users of such systems are defined. A micro system with a cultivation camber, tube connectors, an integrated scaffold, an optical and a mechanical access and other components forms the backbone of the entire system. It is completed by peripheral modules for supply of cells under adequate environmental conditions, observation of cells and processes and manipulation of cells and technical components. This configuration is explained in detail by exemplary realizations. Cell cultivation outside an incubator is feasible, securing biocompatibility. Considerations of the application of stimuli on cells are founded on this newly developed infrastructure. Existing macroscopic and microscopic methods may be adapted to the system, realizations are suggested. The performance of the entire system is discussed with reference to results of technical and biological tests. As result of the documented developmental process now a system exists, which after integration of cell-specific loading methods can be used by life scientists conduce to answer questions on cellular behavior.Zusätzliche Dateien: - Tabelle 5: Mikrozellkultivierungssysteme - Anhang A5: Literatur Zelldetektio

Magnetic Driven Two-Finger Micro-Hand with Soft Magnetic End-Effector for Force-Controlled Stable Manipulation in Microscale

In recent years, micromanipulators have provided the ability to interact with micro-objects in industrial and biomedical fields. However, traditional manipulators still encounter challenges in gaining the force feedback at the micro-scale. In this paper, we present a micronewton force-controlled two-finger microhand with a soft magnetic end-effector for stable grasping. In this system, a homemade electromagnet was used as the driving device to execute micro-objects manipulation. There were two soft end-effectors with diameters of 300 μm. One was a fixed end-effector that was only made of hydrogel, and the other one was a magnetic end-effector that contained a uniform mixture of polydimethylsiloxane (PDMS) and paramagnetic particles. The magnetic force on the soft magnetic end-effector was calibrated using an atomic force microscopy (AFM) probe. The performance tests demonstrated that the magnetically driven soft microhand had a grasping range of 0–260 μm, which allowed a clamping force with a resolution of 0.48 μN. The stable grasping capability of the magnetically driven soft microhand was validated by grasping different sized microbeads, transport under different velocities, and assembly of microbeads. The proposed system enables force-controlled manipulation, and we believe it has great potential in biological and industrial micromanipulation

MRI-compatible Micromanipulator Design and Implementation and MRI-compatibility Tests

Abstract — In this paper, we present a magnetic resonance imaging (MRI)-compatible micromanipulator, which can be employed to provide medical and biological scientists with the ability to concurrently manipulate and observe micron-scale objects inside an MRI gantry. The micromanipulator formed a two-finger micro hand, and it could handle a micron-scale object using a chopstick motion. For performing operations inside the MRI gantry in a manner such that the MRI is not disturbed, the system was designed to be nonmagnetic and electromagnetically compatible with the MRI. The micromanipulator was implemented with piezoelectric transducers (PZT) as actuators for micro-motion, strain gauges as sensors for closed-loop control, and a flexure parallel mechanism made of acrylic plastic. Its compatibility with a 2-Tesla MRI was preliminarily tested by checking if the MRI obtained with the micromanipulator were similar to those obtained without the micromanipulator. The tests concluded that the micromanipulator caused no distortion but small artifacts on the MRI. The signal-to-noise ratio (SNR) of the MRI significantly deteriorated mainly due to the wiring of the micromanipulator. The MRI caused noise of the order of ones of volts in the strain amplifier. I