Electro-Quasistatic Analysis of an Electrostatic Induction Micromotor Using the Cell Method

An electro-quasistatic analysis of an induction micromotor has been realized by using the Cell Method. We employed the direct Finite Formulation (FF) of the electromagnetic laws, hence, avoiding a further discretization. The Cell Method (CM) is used for solving the field equations at the entire domain (2D space) of the micromotor. We have reformulated the field laws in a direct FF and analyzed physical quantities to make explicit the relationship between magnitudes and laws. We applied a primal-dual barycentric discretization of the 2D space. The electric potential has been calculated on each node of the primal mesh using CM. For verification purpose, an analytical electric potential equation is introduced as reference. In frequency domain, results demonstrate the error in calculating potential quantity is neglected (<3‰). In time domain, the potential value in transient state tends to the steady state value

Concept, modeling and experimental characterization of the modulated friction inertial drive (MFID) locomotion principle:application to mobile microrobots

A mobile microrobot is defined as a robot with a size ranging from 1 in3 down to 100 µm3 and a motion range of at least several times the robot's length. Mobile microrobots have a great potential for a wide range of mid-term and long-term applications such as minimally invasive surgery, inspection, surveillance, monitoring and interaction with the microscale world. A systematic study of the state of the art of locomotion for mobile microrobots shows that there is a need for efficient locomotion solutions for mobile microrobots featuring several degrees of freedom (DOF). This thesis proposes and studies a new locomotion concept based on stepping motion considering a decoupling of the two essential functions of a locomotion principle: slip generation and slip variation. The proposed "Modulated Friction Inertial Drive" (MFID) principle is defined as a stepping locomotion principle in which slip is generated by the inertial effect of a symmetric, axial vibration, while the slip variation is obtained from an active modulation of the friction force. The decoupling of slip generation and slip variation also has lead to the introduction of the concept of a combination of on-board and off-board actuation. This concept allows for an optimal trade-off between robot simplicity and power consumption on the one hand and on-board motion control on the other hand. The stepping motion of a MFID actuator is studied in detail by means of simulation of a numeric model and experimental characterization of a linear MFID actuator. The experimental setup is driven by piezoelectric actuators that vibrate in axial direction in order to generate slip and in perpendicular direction in order to vary the contact force. After identification of the friction parameters a good match between simulation and experimental results is achieved. MFID motion velocity has shown to depend sinusoidally on the phase shift between axial and perpendicular vibration. Motion velocity also increases linearly with increasing vibration amplitudes and driving frequency. Two parameters characterizing the MFID stepping behavior have been introduced. The step efficiency ηstep expresses the efficiency with which the actuator is capable of transforming the axial vibration in net motion. The force ratio qF evaluates the ease with which slip is generated by comparing the maximum inertial force in axial direction to the minimum friction force. The suitability of the MFID principle for mobile microrobot locomotion has been demonstrated by the development and characterization of three locomotion modules with between 2 and 3 DOF. The microrobot prototypes are driven by piezoelectric and electrostatic comb drive actuators and feature a characteristic body length between 20 mm and 10 mm. Characterization results include fast locomotion velocities up to 3 mm/s for typical driving voltages of some tens of volts and driving frequencies ranging from some tens of Hz up to some kHz. Moreover, motion resolutions in the nanometer range and very low power consumption of some tens of µW have been demonstrated. The advantage of the concept of a combination of on-board and off-board actuation has been demonstrated by the on-board simplicity of two of the three prototypes. The prototypes have also demonstrated the major advantage of the MFID principle: resonance operation has shown to reduce the power consumption, reduce the driving voltage and allow for simple driving electronics. Finally, with the fabrication of 2 × 2 mm2 locomotion modules with 2 DOF, a first step towards the development of mm-sized mobile microrobots with on-board motion control is made

Electropermanent magnetic connectors and actuators : devices and their application in programmable matter

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 199-206).Programmable matter is a digital material having computation, sensing, and actuation capabilities as continuous properties active over its whole extent. To make programmable matter economical to fabricate, we want to use electromagnetic direct drive, rather than clockwork, to actuate the particles. Previous attempts to fabricate small scale (below one centimeter) robotic systems with electromagnetic direct-drive have typically run into problems with insufficient force or torque, excessive power consumption and heat generation (for magnetic-drive systems), or high-voltage requirements, humidity sensitivity, and air breakdown. (for electrostatic-drive systems) The electropermanent magnet is a solid-state device whose external magnetic flux can be stably switched on and off by a discrete electrical pulse. Electropermanent magnets can provide low-power connection and actuation for programmable matter and other small-scale robotic systems. The first chapter covers the electropermanent magnet, its physics, scaling, fabrication, and our experimental device performance data. The second introduces the idea of electropermanent actuators, covers their fundamental limits and scaling, and shows prototype devices and performance measurements. The third chapter describes the smart pebbles system, which consists of 12-mm cubes that can form shapes by stochastic self-assembly and self-disassembly. The fourth chapter describes the millibot, a continuous chain of programmable matter which forms shapes by folding.by Ara Nerses Knaian.Ph.D

Design of a high-speed, meso-scale nanopositioners driven by electromagnetic actuators

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 218-230).The purpose of this thesis is to generate the design and fabrication knowledge that is required to engineer high-speed, six-axis, meso-scale nanopositioners that are driven by electromagnetic actuators. When compared to macro-scale nanopositioners, meso-scale nanopositioners enable a combination of greater bandwidth, improved thermal stability, portability, and capacity for massively parallel operation. Meso-scale nanopositioners are envisioned to impact emerging applications in data storage and nanomanufacturing, which will benefit from low-cost, portable, multi-axis nanopositioners that may position samples with nanometer-level precision at bandwidth of 100s of Hz and over a working envelope greater than 10x10x10 micrometers3 This thesis forms the foundation of design and fabrication knowledge required to engineer mesoscale systems to meet these needs.The design combines a planar silicon flexure bearing and unique moving-coil microactuators that employ millimeter-scale permanent magnets and stacked, planar-spiral micro-coils. The new moving-coil actuator outperforms previous coil designs as it enables orthogonal and linear force capability in two axes while minimizing parasitic forces. The system performance was modeled in the structural, thermal, electrical, and magnetic domains with analytical and finite-element techniques. A new method was created to model the three-dimensional permanent magnet fields of finite magnet arrays. The models were used to optimize the actuator coil and flexure geometry in order to achieve the desired motions, stiffness, and operating temperature, and to reduce thermal error motions.A new microfabrication process and design-for-manufacturing rules were generated to integrate multilayer actuator coils and silicon flexure bearings. The process combines electroplating for the copper coils, a silicon dioxide interlayer dielectric, and deep reactive-ion etching for the silicon flexures and alignment features.(cont.) Microfabrication experiments were used to formulate coil geometry design rules that minimized the delamination and cracking of the materials that comprise the coil structure. Experiments were also used to measure the previously-unreported breakdown strength of the unannealed, PECVD silicon dioxide interlayer dielectric. The results of this research were used to design and fabricate a meso-scale nanopositioner system. The nanopositioner was measured to have a range of motion of 10 micrometers in the lateral directions, a range of 2 micrometers in the out-of-plane direction, an angular range of 0.5 degrees, and a first mode resonant frequency at 900 Hz. Open-loop calibration has been shown to minimize parasitic in-plane motion to less than 100 nm over the range of motion.by Dariusz S. Golda.Ph.D

A microfabricated Electro Quasi Static induction turbine-generator

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.Includes bibliographical references (p. [263]-268).An ElectroQuasiStatic (EQS) induction machine has been fabricated and has generated net electric power. A maximum power output of 192 [mu]W at 235 krpm has been measured under driven excitation of the six phases. Self excited operation was also demonstrated. Under self-excitation, no external drive electronics are required and sufficient power was produced to dimly light four LED's on two of the six phases. This is believed to be the first demonstration of both power generation and self-excited operation of an EQS induction machine of any scale reported in the open literature. The generator comprises 5 silicon layers, fusion bonded together, and annealed at 700⁰C. The turbine rotor, 4 mm in diameter, is supported on gas bearings. The thrust bearings are formed by a shallow etch of 1.5 [mu]m to define the thrust bearing gap. Thrust bearing pressurization is through 10 [mu]m diameter nozzles, etched 100 [mu]m deep. The journal bearing is a precision, ... wide, 300 [mu]m deep annular trench around the periphery of the turbine disk. The generator airgap is 3 [mu]m. The inner radius of the generator is 1.011 mm, and the outer radius 1.87mm. The machine has ].31 poles for each of the 6 phases, for a total of 786 stator electrodes. Precise microfabrication and aligned, full-wafer fusion bonding enabled turbine generator devices to be operated at rotational speeds as high as 850 krpm. A detailed state-space model of the EQS machine and its external parasitics is presented. The external stray capacitances, and their unbalance, play a critical role in the performance of the device. A method for estimating the strays experimentally is discussed.(cont.) This estimated, updated model made it possible to use computer optimization techniques to find the optimal drive conditions for the device to generate maximum power. Carrier depletion in the moderately doped polysilicon rotor conductor film prevented the generator from producing power at higher voltages, and limited the maximum machine terminal voltage under self-excitation to approximately 30 Vp-p.by Jasper Lodewyk Steyn.Ph.D

Microgénérateurs à aimants permanents entraînés par des\ud microturbines à air ou des micromachines à gaz chaud

L'énergie nécessaire au fonctionnement des systèmes électroniques est en train de surpasser les capacités des batteries actuelles. Par conséquent, l'application des technologies MEMS pour la conception de nouvelles sources de puissance à haute performance est très attractive. Cette thèse considère la fabrication de microgénérateurs entraînés par gaz froid ou chaud.\ud Tout d'abord, nous avons développé des microgénérateurs à aimants permanents compatibles avec le fonctionnement de micromachines à combustion. Dans le contexte de la réduction des systèmes électroniques, la miniaturisation de ces dispositifs a été étudiée. Ensuite, ces microsystèmes été intégrés avec des microturbines, en polymère pour une utilisation au gaz froid (air comprimé), et en silicium pour un fonctionnement avec une micromachine à combustion. Finalement, un dispositif convertissant une source d'hydrogène en énergie électrique a été conçu. Il comprend un générateur électrique et un moteur connu sous le nom de pulsejet et réalisé par des techniques de microfabrication.\ud ----------------------------------------------------------\ud ------------------------------------------------The constant miniaturization of electronic systems has driven the development of new generations of ultra-compact power sources that could surpass the performance of conventional batteries. MEMS-based heat-engine-driven devices are very attractive in such small power systems. The focus of this research is to develop electromagnetic microsystems capable of generating electrical power, and driven by either cold or hot gases.\ud First, rotary permanent-magnet microgenerators are developed for watt-level applications and compatibility with heat engines. Further miniaturization of such devices is also presented. Next, small-scale fluidic packages are coupled with these microgenerators. Polymer-based microturbines are engineered for air-driven micropower sources, and silicon-based gas-bearing microgenerators are developed for compatibility with micro heat engines. Finally, a fuel-driven power generator is presented, and consists of a MEMS-fabricated pulsejet and its electrical generator. The device, powered by a source of hydrogen fuel, demonstrates chemical-to-electrical power conversion.\u

Aeronautical engineering: A continuing bibliography with indexes (supplement 301)

This bibliography lists 1291 reports, articles, and other documents introduced into the NASA scientific and technical information system in Feb. 1994. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics