Wong Kwok Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 88-93). / Abstracts in English and Chinese. / LIST OF FIGURES --- p.VI / LIST OF TABLES --- p.IX / ACKNOWLEDGEMENTS --- p.X / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Literature review on self-sensing purely active system --- p.3 / Chapter 1.3 --- Literature review on active constrained layer treatment --- p.5 / Chapter 1.4 --- Introduction to enhanced active constrained layer treatment --- p.8 / Chapter 1.5 --- Objectives of this research --- p.10 / Chapter 1.6 --- Thesis outline --- p.11 / Chapter CHAPTER 2 --- CONTROL LAW IMPLEMENTATION --- p.12 / Chapter 2.1 --- Electrical equivalent model of piezoelectric material --- p.12 / Chapter 2.2 --- Bridge circuit --- p.14 / Chapter 2.2.1 --- Strain rate sensing bridge circuit --- p.14 / Chapter 2.2.2 --- Strain sensing bridge circuit --- p.17 / Chapter 2.3 --- Control laws implementation --- p.19 / Chapter 2.3.1 --- Strain rate feedback control --- p.19 / Chapter 2.3.2 --- Positive position feedback (PPF) control --- p.21 / Chapter 2.3.3 --- Modified strain rate feedback control --- p.25 / Chapter CHAPTER 3 --- EXPERIMENTAL STUDIES --- p.28 / Chapter 3.1 --- Experimental setup --- p.28 / Chapter 3.2 --- Test of actuating ability --- p.30 / Chapter 3.3 --- Test of sensing ability --- p.32 / Chapter 3.4 --- Open loop response --- p.34 / Chapter 3.5 --- Closed loop response --- p.36 / Chapter 3.6 --- Chapter summary --- p.52 / Chapter CHAPTER 4 --- SYSTEM MODELING AND SIMULATION --- p.53 / Chapter 4.1 --- Literature review on finite element method --- p.53 / Chapter 4.1.1 --- Element stiffness matrix through potential energy --- p.57 / Chapter 4.1.2 --- Element mass matrix through kinetic energy --- p.58 / Chapter 4.2 --- System modeling --- p.59 / Chapter 4.2.1 --- Stiffness and mass matrices of beam layer --- p.63 / Chapter 4.2.2 --- Stiffness and mass matrices of piezoelectric layer --- p.64 / Chapter 4.2.3 --- Stiffness and mass matrices of VEM layer --- p.67 / Chapter 4.2.4 --- Stiffness and mass matrices of beam edge elements --- p.71 / Chapter 4.3 --- Simulation --- p.76 / Chapter 4.4 --- Chapter summary --- p.83 / Chapter CHAPTER 5 --- SUMMARY AND FUTURE WORK --- p.84 / Chapter 5.1 --- Summary --- p.84 / Chapter 5.2 --- Future Work --- p.87 / BIBLIOGRAPHY --- p.88

Law Wai Wing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 64-66). / Abstracts in English and Chinese. / 摘要 --- p.i / ABSTRACT --- p.ii / ACKNOWLEDGEMENTS --- p.iii / CONTENTS --- p.iv / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.ix / Chapter 1 --- INTRODUCTION / Chapter 1.1 --- Background --- p.1 / Chapter 1.1.1 --- Piezoelectric Materials --- p.1 / Chapter 1.1.2 --- Self-sensing Actuation --- p.2 / Chapter 1.2 --- Literature Review --- p.3 / Chapter 1.3 --- Motivation --- p.5 / Chapter 1.4 --- Thesis Organization --- p.6 / Chapter 2 --- STRUCTURE MODELING AND FORMULATION / Chapter 2.1 --- Overview of Piezoelectricity --- p.7 / Chapter 2.2 --- Modeling of the Smart Structure --- p.8 / Chapter 2.2.1 --- Electromechanical Conversion --- p.8 / Chapter 2.2.2 --- Model Derivation Using Hamilton's Principle --- p.10 / Chapter 2.3 --- Discretization of Equation of Motion --- p.15 / Chapter 2.4 --- Sensing Model of the Piezoelectric Sensor --- p.20 / Chapter 2.4.1 --- Strain Sensing Model --- p.21 / Chapter 2.4.2 --- Strain Rate Sensing Model --- p.23 / Chapter 2.5 --- Model Validation --- p.25 / Chapter 3 --- CONTROL OF SMART STRUCTURE / Chapter 3.1 --- Strain Rate Feedback Control --- p.27 / Chapter 3.2 --- Positive Position Feedback Control --- p.31 / Chapter 3.3 --- Unbalanced Bridge Effect on Closed Loop Stability --- p.36 / Chapter 3.4 --- Self-Compensation of Capacitance Variation --- p.39 / Chapter 4 --- EXPERIMENTAL STUDIES / Chapter 4.1 --- Experiment Setup --- p.47 / Chapter 4.2 --- Experiment Results --- p.48 / Chapter 4.2.1 --- Open Loop Response --- p.48 / Chapter 4.2.2 --- Closed Loop Response with Balanced Bridge --- p.49 / Chapter 4.2.3 --- Closed Loop Response with Unbalanced Bridge --- p.51 / Chapter 4.2.4 --- Closed Loop Response upon Sudden Change in Bridge Parameter --- p.53 / Chapter 4.2.5 --- Closed Loop Response upon Temperature Variation --- p.57 / Chapter 4.2.6 --- Frequency Response --- p.58 / Chapter 5 --- SUMMARY / Chapter 5.1 --- Conclusion --- p.51 / Chapter 5.2 --- Future Work --- p.62 / BIBLIOGRAPHY --- p.63

This thesis designed and realized a two-degree of freedom wrist and two finger manipulator that completes the six-degree of freedom Sensitive Manipulation Platform, the arm of which was previously developed. This platform extends the previous research in the field of robotics by covering not only the end effector with deformable tactile sensors, but also the links of the arm. Having tactile sensors on the arm will improve the dynamic model of the system during contact with its environment and will allow research in contact navigation to be explored. This type of research is intended for developing algorithms for exploring dynamic environments. Unlike traditional robots that focus on collision avoidance, this platform is designed to seek out contact and use it to gather important information about its surroundings. This small desktop platform was designed to have similar proportions and properties to a small human arm. These properties include compliant joints and tactile sensitivity along the lengths of the arms. The primary applications for the completed platform will be research in contact navigation and manipulation in dynamic environments. However, there are countless potential applications for a compliant arm with increased tactile feedback, including prosthetics and domestic robotics. This thesis covers the details behind the design, analysis, and evaluation of the two degrees of the Wrist and two two-link fingers, with particular attention being given to the integration of series elastics actuators, the decoupling of the fingers from the wrist, and the incorporation of tactile sensors in both the forearm motor module and fingers.

Among the MEMS field, the design and simulation of piezoelectric micro-actuators are difficult as compared to thermal micro-actuators and electrostatic micro-actuators. The main reason of the piezo-electric material coupling effect is difficult to calculate. However the piezo-electric material has several advantages and characteristics for designing micro-actuators. Moreover, the design is usually done by the experimental or try-and-error method which is not so effective. It should be noted that there is not a simple method already developed for the design and simulation of the piezo-electric micro-actuators. In this research we proposed to use the software of ANSYS for the simulation of piezo-electric micro-pump. Simulation of force output of piezo-micro-pump can use ANSYS software to establish the simulation system of piezo-micro-pump. The micro-pump will have different resonance frequency, back-pressure and fluid due to piezo-electric characteristic. In this study, the author used a square, rectangle and circle geometric shape to simulate the result, each geometric shape has four different kinds of size. As a result, there are twelve groups of different simulation results. We are able to using the chart to present and explain the relation between resonance frequency and displacement.

Therapeutic operation risk has been reduced by the use of micro-robots, allowing highly invasive surgery to be replaced by low invasive surgery (LIS), which provides an effective tool even in previously inaccessible parts of the human body. LIS techniques help delivering drugs effectively via micro-carriers. The micro-carriers are divided into two groups: tethered devices, which are supported by internally supplied propulsion mechanism, and untethered devices. Remote actuation is the critical issue in micro-device navigation, especially through blood vessels. To achieve remote control within the cardiovascular system, magnetic propulsion offers an advantage over other proposed actuation methods. In the literature, most research has focused on micro-device structural design, while there is a lack of research into design and analysis of combined structure and control. As the main part, integrating the principle of electromagnetic induced force by feedback control design will lead to the desired automatic movement. An actuator configuration should thus first be designed to initiate the desired force. The design is basically defining the type and placement of a set of coils to achieve an operational goal. In this project, the magnetic actuation is initiated by a combination of four electromagnets and two sets of uniform coils. Preliminary studies on 2D navigation of a ferromagnetic particle are used to show the effect of actuator structure on controller performance. Accordingly, the performance of the four electromagnets combination is compared to the proposed augmented structure with uniform coils. The simulation results show the improved efficiency of the augmented structure. In more general cases, the arrangement and number of electromagnets are unknown and should be defined. An optimization method is suggested to find these variables when the working space is maximized. Finally, the problem of robust output regulation of the electromagnetic system driven by a linear exosystem, is also addressed in this project. The exosystem is assumed to be neutrally stable with unknown frequencies. The parallel connection of two controllers, a robust stabilizer and an internal model-based controller, is presented to eliminate the output error. In the latter one, an adaptation is used to tune the internal model frequencies such that a steady-state control is produced to maintain the output-zeroing condition. The robust regulation with a local domain of convergence is achieved for a special class of decomposable MIMO nonlinear minimum-phase system. The simulation results show the effectiveness and robustness of this method for the electromagnetic system when two different paths are considered.

Abstract This paper reports about a precision positioning XY stage utilizing flexure hinges and piezoelectric actuators. XY stage was designed with the aim of reducing the stress-concentration of flexure hinges and the low interference between two actuating axes. Utilized the expression of matrix to figure out the properties of the bellow-type flexure hinges, and proved these by mathematical software. Experiments demonstrated that the stage actuated by a stairstep driving signal with maximum displacement 1.3£gm and interference 50nm along X axis; along Y axis with maximum displacement 0.8£gm and interference 11nm. The stage actuated by a ramp signal with maximum displacement 1.2£gm and interference 45nm along X axis; along Y axis with maximum displacement 0.9£gm and interference 35nm. The finite element method (FEM) was used to analyse the stress-concentration of the stage. and the simulated results were compared with the experiments. Referred to the testing results, the target object could be moved in the aimed position accurately.

The objective of this dissertation is to analytically model a parallel plate electrostatic actuator operating in a liquid electrolyte and experimentally verify the analysis. The model assumes the system remains in thermodynamic equilibrium during actuation, which enables the ion mass balance equations and Guass’ Law to be combined into the Poisson-Boltzmann equation. The governing equations also include the linear momentum equation including the following forces: the electric force, the osmotic force, the spring force, the viscous damping force, and the van der Waals force. Equations are also derived for the energy stored in the actuator. The analytical results emphasize the stored energy at mechanical equilibrium and the voltage versus electrode separation behavior including the instability. The analytical results predict that the system may not be a good actuator because the displacement has a very limited stable range, although the actuator would be suitable for bistable applications. The experiment consisted of a fixed flat gold electrode and a movable gold electrode consisting of a gold sphere several micrometers in diameter mounted on the end of an Atomic Force Microscope (AFM) cantilever, which serves as the spring. The electrodes were separated by approximately 100nm of 1mM NaCl aqueous solution. The analytical results were not verified by the experiment. Relative to the analysis, the experiments did not show distinct critical points, and the experiments showed less electrode separation for a given applied electric potential. The experiments did show points at which the electrode separation versus electric potential rapidly changed slope, which may be instability points. It is suggested that this phenomenon may be due to coalesced gas bubbles on hydrophobic regions of the electrode surfaces, which are not included in the model. Although clean gold surfaces are hydrophilic, gold surfaces may become hydrophobic due to impurities.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 130-134).

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2004. / Includes bibliographical references (p. 51-54).

 There are two concentrations in this project. One is to explore the possibility to construct negative acoustic impedance by electronic techniques, and the other is to see whether such method can be utilized to build effective sound absorber using electromagnetic actuator (here we adopt the moving-coil loudspeaker as sample) with a shunt circuit. Our study begins with analytical analysis, and the result shows that it is impossible to gain independent control of basic acoustic impedance components (mass, stiffness and damping) by simple circuits. Two alternative designs are put forward as a compromise. One is the series circuit with NIC to simulate the negative acoustic impedance, and another is the series-parallel circuit with NIC. Theoretical prediction shows that we can indeed obtain broadband negative mass and local negative stiffness by these two types of circuits, and that we can achieve broadband noise control with simple electronic shunt circuits despite fact that completely independent control over each parameter is not possible. We argue that these conclusions represent significant technological and economic advantage worthy of further development. All analytical results are validated by experiments with satisfactory agreement. The sample loudspeaker with shunt circuit is tested with acoustic impedance tube. The rig consists of a DC powered op-amp circuit and a loudspeaker. An efficient Matlab code controls the excitation sound generation and data acquisition with AD/DA cards. Two typical and most interesting results are summarized here. In the first, a series type circuit with NIC is used to construct negative equivalent mass and local (banded in frequency domain) negative stiffness. We experimentally demonstrated that it is rather easy to reduce original mass of the loudspeaker to half of its original value and it could be reduced to almost zero. This is evidenced by a very flat sound absorption coefficient curve from 100 Hz to 1000 Hz. The second circuit is a series-parallel circuit. It’s an improved design from the first type. This type of circuit can, to a certain extent, decouple the stiffness and mass controls. The results show that we can reduce mass globally (in the frequency domain) and stiffness at low frequencies. The original mass of the sample loudspeaker is almost eliminated and the stiffness at low frequencies is reduced too. In terms of the spectrum of sound absorption coefficient, it manifests itself through a broadband absorption with prominent improvement in the low frequency region. Finally, potential applications for our designs are discussed. A tunable low frequency resonance absorber is designed. Prediction results point out that, by choosing the right parameters of the circuit, we can achieve 100% absorption at any given low frequency. Thin absorber is another potential application. With the same dimension, the performance of a thin absorber is much better than that of the standard sound absorption construction. A 90% noise absorption from 300Hz-600Hz and 50% absorption from 250Hz-1000Hz is achieved by our new design. The dimension can be further reduced in theory. Finally, a broad-band absorber with 50% or more absorption over 80Hz-1000Hz is demonstrated. / published_or_final_version / Mechanical Engineering / Master / Master of Philosophy