Parallel Coupled Micro-Macro Actuators

This thesis presents a new actuator system consisting of a micro-actuator and a macro-actuator coupled in parallel via a compliant transmission. The system is called the Parallel Coupled Micro-Macro Actuator, or PaCMMA. In this system, the micro-actuator is capable of high bandwidth force control due to its low mass and direct-drive connection to the output shaft. The compliant transmission of the macro-actuator reduces the impedance (stiffness) at the output shaft and increases the dynamic range of force. Performance improvement over single actuator systems was expected in force control, impedance control, force distortion and reduction of transient impact forces. A set of quantitative measures is proposed and the actuator system is evaluated against them: Force Control Bandwidth, Position Bandwidth, Dynamic Range, Impact Force, Impedance ("Backdriveability'"), Force Distortion and Force Performance Space. Several theoretical performance limits are derived from the saturation limits of the system. A control law is proposed and control system performance is compared to the theoretical limits. A prototype testbed was built using permanenent magnet motors and an experimental comparison was performed between this actuator concept and two single actuator systems. The following performance was observed: Force bandwidth of 56Hz, Torque Dynamic Range of 800:1, Peak Torque of 1040mNm, Minimum Torque of 1.3mNm. Peak Impact Force was reduced by an order of magnitude. Distortion at small amplitudes was reduced substantially. Backdriven impedance was reduced by 2-3 orders of magnitude. This actuator system shows promise for manipulator design as well as psychophysical tests of human performance.

Design and Development of 3-DOF Modular Micro Parallel Kinematic Manipulator

This paper presents the research and development of a 3-legged micro Parallel Kinematic Manipulator (PKM) for positioning in micro-machining and assembly operations. The structural characteristics associated with parallel manipulators are evaluated and the PKMs with translational and rotational movements are identified. Based on these identifications, a hybrid 3-UPU (Universal Joint-Prismatic Joint-Universal Joint) parallel manipulator is designed and fabricated. The principles of the operation and modeling of this micro PKM is largely similar to a normal size Stewart Platform (SP). A modular design methodology is introduced for the construction of this micro PKM. Calibration results of this hybrid 3-UPU PKM are discussed in this paper.

Investigation of aspect ratio of hole drilling from micro to nanoscale via focused ion beam fine milling

Holes with different sizes from microscale to nanoscale were directly fabricated by focused ion beam (FIB) milling in this paper. Maximum aspect ratio of the fabricated holes can be 5:1 for the hole with large size with pure FIB milling, 10:1 for gas assistant etching, and 1:1 for the hole with size below 100 nm. A phenomenon of volume swell at the boundary of the hole was observed. The reason maybe due to the dose dependence of the effective sputter yield in low intensity Gaussian beam tail regions and redeposition. Different materials were used to investigate variation of the aspect ratio. The results show that for some special material, such as Ni-Be, the corresponding aspect ratio can reach 13.8:1 with Cl₂ assistant etching, but only 0.09:1 for Si(100) with single scan of the FIB.

Micro-layered-photolithography for Micro-Fabrication and Micro-Molding

A novel process based on the principle of layered photolithography has been proposed and tested for making real three-dimensional micro-structures. An experimental setup was designed and built for doing experiments on this micro-fabrication process. An ultraviolet (UV) excimer laser at the wavelength of 248 nm was used as the light source and a single piece of photo-mask carrying a series of two dimensional (2D) patterns sliced from a three dimensional (3D) micro-part was employed for the photolithography process. The experiments were conducted on the solidification of liquid photopolymer from single layer to multiple layers. The single-layer photolithography experiments showed that certain photopolymers could be applied for the 3D micro-fabrication, and solid layers with sharp shapes could be formed from the liquid polymer identified. By using a unique alignment technique, multiple layers of photolithography was successfully realized for a micro-gear with features at 60 microns. Electroforming was also conducted for converting the photopolymer master to a metal cavity of the micro-gear, which proved that the process is feasible for micro-molding.

Process Variability in Micro-Embossing

A promising technique for the large-scale manufacture of micro-fluidic devices and photonic devices is hot embossing of polymers such as PMMA. Micro-embossing is a deformation process where the workpiece material is heated to permit easier material flow and then forced over a planar patterned tool. While there has been considerable, attention paid to process feasibility very little effort has been put into production issues such as process capability and eventual process control. In this paper, we present initial studies aimed at identifying the origins and magnitude of variability for embossing features at the micron scale in PMMA. Test parts with features ranging from 3.5- 630 µm wide and 0.9 µm deep were formed. Measurements at this scale proved very difficult, and only atomic force microscopy was able to provide resolution sufficient to identify process variations. It was found that standard deviations of widths at the 3-4 µm scale were on the order of 0.5 µm leading to a coefficient of variation as high as 13%. Clearly, the transition from test to manufacturing for this process will require understanding the causes of this variation and devising control methods to minimize its magnitude over all types of parts.

The Inertio-Elastic Planar Entry Flow of Low-Viscosity Elastic Fluids in Micro-fabricated Geometries

The non-Newtonian flow of dilute aqueous polyethylene oxide (PEO) solutions through microfabricated planar abrupt contraction-expansions is investigated. The contraction geometries are fabricated from a high-resolution chrome mask and cross-linked PDMS gels using the tools of soft-lithography. The small length scales and high deformation rates in the contraction throat lead to significant extensional flow effects even with dilute polymer solutions having time constants on the order of milliseconds. The dimensionless extra pressure drop across the contraction increases by more than 200% and is accompanied by significant upstream vortex growth. Streak photography and videomicroscopy using epifluorescent particles shows that the flow ultimately becomes unstable and three-dimensional. The moderate Reynolds numbers (0.03 ≤ Re ≤ 44) associated with these high Deborah number (0 ≤ De ≤ 600) microfluidic flows results in the exploration of new regions of the Re-De parameter space in which the effects of both elasticity and inertia can be observed. Understanding such interactions will be increasingly important in microfluidic applications involving complex fluids and can best be interpreted in terms of the elasticity number, El = De/Re, which is independent of the flow kinematics and depends only on the fluid rheology and the characteristic size of the device.

El parque natural de Redes (Asturias) : un paseo por el valle del río Alba.

Resumen basado en la publicación

Caminando Asturias : ruta 3 : Parque Natural de Redes (Foces de Lla??mo)

Caminando Asturias es una acci??n enmarcada en el Programa de Actividades Complementarias y Extraescolares que promueve la Consejer??a de Educaci??n y Ciencia de Asturias. Est?? orientado a promover actividades de car??cter formativo y convivencial, fomentando la pr??ctica de los mejores valores humanos que siempre se dan en pleno medio natural, las relaciones sociales y de compa??erismo, al tiempo que contribuye a una adecuada educaci??n medioambiental. En este sentido, trata de potenciar el estudio y disfrute de los recursos naturales, como un elemento que contribuye a la Formaci??n Integral de los alumnos. As?? mismo, se pretende fomentar las pr??cticas de educaci??n no formal, ni reglada, vertebradas a trav??s de las actividades extraescolares y complementarias. Por ??ltimo, como objetivo b??sico se busca fomentar y facilitar la participaci??n de las familias en las actividades de los centros docentes. El programa se dirige a alumnos de los colegios p??blicos e institutos de ense??anza secundaria, a sus familias y a sus profesores, y va preferentemente dirigido a alumnos y alumnas matriculados en el tercer ciclo de Primaria (quinto y sexto) y de la ESO (primero a cuarto). Este d??ptico recoge la informaci??n, itinerario y mapa de la ruta Foces de Lla??mo o Ruta del Alba, que discurre en el Parque Natural de Redes.

Creación de Modelos Digitales de Elevaciones a partir de diferentes métodos de interpolación para la determinación de redes de drenaje

The Digital Elevations Models represent an elemtary space information for the study of the relief forms. The obtaining of models of great resolution implies a greater precision and therefore a greater apporach to the reality of the terrestrial morphology. (...)

Diseño de redes neuronales artificiales en neurociencias.

Resumen tomado de la publicación

Redes de apoyo social y adaptaci??n de los menores en acogimiento residencial

Resumen tomado de la publicaci??n. Resumen tambi??n en ingl??s

Redes transnacionales y emergencia de la diplomacia indígena : un estudio a partir del caso Colombiano

Este libro busca analizar, de una manera novedosa, las luchas jurídicas de los Pueblos Indígenas desde las trayectorias sociales de sus protagonistas, utilizando el método etnográfico aplicado a la disciplina de las Relaciones Internacionales, dando cuenta, sin embargo, de procesos estructurales. De esta manera, aporta elementos teóricos y metodológicos para el estudio de la dimensión “transnacional” de las problemáticas globales, desde un tema aparentemente encasillado en perspectivas nacionales o locales. Su público principal son los organismos internacionales, las organizaciones sociales y la comunidad académica nacional e internacional de internacionalistas, antropólogos sociales, politólogos, sociólogos y juristas, y en general estudiosos del tema de los derechos humanos, los Pueblos Indígenas y la globalización jurídica.

Validación Modelo Proceso Analítico de Redes (PAR)

El presente trabajo comprobará la validez del modelo de selección de mercados, llamado, Proceso Analítico de Redes, PAR. Esto con el objetivo de dar una propuesta alternativa a los modelos de selección que ya conocemos.

Evoluci??n de los estudios sobre autismo en Espa??a : publicaciones y redes de coautor??a entre 1974 y 2007

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Incidencia del poder no violento de las redes transnacionales en la defensa de los derechos humanos. Caso de estudio: Shirin Ebadi, Premio Nobel de Paz

Mientras la atención de la comunidad internacional se ha centrado en el programa nuclear de la República Islámica de Irán, los informes muestran gran deterioro de los derechos humanos al interior del país, por el cual, el Estado no ha rendido cuentas.