Radiotherapy is a potential curative option for liver cancer; however, respiratory motion creates uncertainty in treatment delivery. Advances in imaging and registration techniques can provide information regarding changes in respiratory motion. Currently image registration is challenged by computation and manual intervention. A Navigator Channel (NC) technique was developed to overcome these limitations. A population motion model was generated to predict patient-specific motion, while a point motion detection technique was developed to calculate the patient-specific liver edge motion from images. An adaptation technique uses the relative difference between the population and patient calculated liver edge motion to determine the patient's liver volume motion. The NC technique was tested on patient 4D-CT images for initial validation to determine the accuracy. Accuracy was less than 0.10 mm in liver edge detection and approximately 0.25 cm in predicting patient-specific motion. This technique can be used to ensure accurate treatment delivery for liver radiotherapy.

Radiotherapy is a potential curative option for liver cancer; however, respiratory motion creates uncertainty in treatment delivery. Advances in imaging and registration techniques can provide information regarding changes in respiratory motion. Currently image registration is challenged by computation and manual intervention. A Navigator Channel (NC) technique was developed to overcome these limitations. A population motion model was generated to predict patient-specific motion, while a point motion detection technique was developed to calculate the patient-specific liver edge motion from images. An adaptation technique uses the relative difference between the population and patient calculated liver edge motion to determine the patient's liver volume motion. The NC technique was tested on patient 4D-CT images for initial validation to determine the accuracy. Accuracy was less than 0.10 mm in liver edge detection and approximately 0.25 cm in predicting patient-specific motion. This technique can be used to ensure accurate treatment delivery for liver radiotherapy.

Achieving realistic simulations of terrain vehicles in their work environment does not only require a careful model of the vehicle itself but the vehicle's interactions with the surroundings are equally important. For off-road ground vehicles the terrain will heavily affect the behaviour of the vehicle and thus puts great demands on the terrain model. The purpose of this project has been to develop and evaluate a deformable terrain model, meant to be used in real-time simulations with multi-body dynamics. The proposed approach is a modification of an existing elastoplastic model based on linear elasticity theory and a capped Drucker-Prager model, using it in an adaptive way. The original model can be seen as a system of rigid bodies connected by elastoplastic constraints, representing the terrain. This project investigates if it is possible to create dynamic bodies just when it is absolutely necessary, and store information about possible deformations in a grid. Two methods used for transferring information between the dynamic bodies and the grid have been evaluated; an interpolating approach and a discrete approach. The test results indicate that the interpolating approach is preferable, with better stability to an equal performance cost. However, stability problems still exist that have to be solved if the model should be useful in a commercial product.

This thesis deals with the design and experimental validation of Deformable Mirror Electronics (DME) for Extremely Large Telescope (ELT) Adaptive Optics (AO) applications. Modern ground based telescopes achieve their best possible imaging resolution through the application of AO. However, due to the fundamental diffraction of optical elements, the next generation of ELTs will employ primary mirrors of an increasingly large diameter as the final means of improving imaging resolution further. The corresponding increase in diameter and actuator count of the Deformable Mirrors (DMs) in these systems has led to the rapid development of high order DM technology. A significant challenge to operating these multi-thousand channel DMs is related to the DM Electronics (DME), which are required to be highly efficient so-as to operate within practical budgetary constraints. This thesis develops a DME reference design based on the requirements for the Thirty Meter Telescope’s next generation AO system, the Narrow Field Infrared Adaptive Optics System (NFIRAOS), which operates two DMs with a total of 7673 piezoelectric actuators. The basis of the DME is the DM actuator driver, which has been developed to be suitable for very high order reproduction by optimization of its size, power, cost and reliability. A complication is that the piezoelectric actuators in NFIRAOS DMs require high voltage drive signals of ±400 V to obtain the rated stroke and must be current limited to avoid damage. Candidate amplifiers are evaluated in simulation and hardware based on a combination of performance, physical and functional criteria; with the most suitable circuit chosen for a multi-channel prototype implementation and testing with a DM breadboard prototype. The development and optimization of an amplifier capable of meeting NFIRAOS performance criteria and budgetary constraints is demonstrated. / Graduate / 0544 / 0606

This study aims to improve flight simulation of flexible aircraft. More specifically, this thesis concentrates on comparing two flexible aircraft flight simulation models. Both modeling techniques considered use the same aircraft structural and aerodynamic data provided by the aircraft manufacturer. Simulation models were developed and tested using a number of control inputs in both longitudinal and lateral dimensions. Time history responses from the simulations were compared. The effect of increasing the flexibility of the aircraft model was also studied on both models. It was found that the two models produce very similar results for the original aircraft stiffness case. However, the lateral response of the two models diverges as the stiffness is lowered. A number of recommendations are made for further testing and research, based on the conclusions of the study.

This study aims to improve flight simulation of flexible aircraft. More specifically, this thesis concentrates on comparing two flexible aircraft flight simulation models. Both modeling techniques considered use the same aircraft structural and aerodynamic data provided by the aircraft manufacturer. Simulation models were developed and tested using a number of control inputs in both longitudinal and lateral dimensions. Time history responses from the simulations were compared. The effect of increasing the flexibility of the aircraft model was also studied on both models. It was found that the two models produce very similar results for the original aircraft stiffness case. However, the lateral response of the two models diverges as the stiffness is lowered. A number of recommendations are made for further testing and research, based on the conclusions of the study.

We present the design, analysis and construction of a biologicallyinspired tactile sensor. The sensor can measure normal and lateralforces, conform to the surfaces with which it comes in contact andincrease the friction of the surface for a good grasp.The sensor is built using a simple process and the applied forcesare read using standard electronics. These features make thesensors ideal for mass production.We are motivated to build tactile sensors that are useful forrobotic manipulation given that the current ones do not have thefeatures that we consider necessary. The sensors presented in thispaper have been designed to deal with these issues. They have beendesigned and implemented in the fingers of the humanoid robotObrero.

This thesis aims to model the uniaxial deformation of a class of materials consisting of microscopic spherical shells embedded in a rubber matrix. These shells are assumed to buckle as the stress on the material increases. To motivate the analysis we consider the paradigm problem of the debonding of a distribution of cylindrical inclusions in an elastic material undergoing antiplane shear, with bonded and debonded inclusions playing the role of unbuckled and buckled shells respectively. We begin the modelling of the microsphere-containing material by considering the buckling of an isolated embedded shell inclusion with a uniaxial stress field at infinity, using Koiter's theory of shallow shells. The resulting energy functional is solved as an eigenvalue problem by the Rayleigh-Ritz method. Subsequently, we analyse the buckling criterion asymptotically in the limit as the thickness ratio tends to zero by analogy with the WKB analysis of a beam on a variable-stiffness substrate. To model the shell after buckling we consider the simplified case of an embedded shell with a crack around its equator. The system is solved by expressing the displacements in the shell and matrix as series of Love stress functions, with the resulting infinite system of equations solved numerically with the aid of a convergence acceleration method. Finally we consider a composite material consisting of a homogenised dilute distribution of buckled and unbuckled shells, with the proportion of each type of shell dependent on the stress applied to the material, according to an asymptotic formula relating the size of the inclusions and the critical buckling stress that was obtained previously.

Thesis (M.Sc.Eng.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / This thesis presents an integrated driver for deformable mirror array based on the architecture proposed in Horenstein, et al's "Ultra-low power multiplexed electronic driver for high resolution deformable mirror systems." The integrated driver consists of numerous high voltage (HV) analog switches connecting the deformable mirror cells, on demand by low-voltage digital control signals, to the HV analog signal line, and a HV power amplifier used to drive the HV analog signal line. The reduction of power consumption is essential in both HV power amplifier and analog switch designs for utilization of deformable mirror systems in space-based applications. In addition to low power design, this work also focuses on the analysis and design of multi-stage amplifier capable to drive large load capacitor, and HV analog switch robust to analog signal noise during OFF state. The specific research contributions of this work include (1) A feed-forward stage in combination with a class B output stage is proposed in the HV multi-stage power amplifier structure to improve the large-signal performance when driving large capacitive load. (2) A low voltage level-shifter and a voltage clamp are added in conventional HV analog switch to reduce the interference from the noisy analog signal line. / 2031-01-01

Actualmente, muchos investigadores están desarrollando robots capaces de desplazarse por el interior de espacios confinados, como por ejemplo los In-pipe robots, capaces de trasladarse por el interior de ductos. Existen siete tipos de robots consolidados en esta área: Pig, Wheel, Caterpillar, Wall-press, Walking, Inch worm y Screw [1]. Usualmente un sistema de ductos está compuesto por complejos obstaculos que dificultan la navegación como variaciones de diámetros, codos y uniones tipo T. Estas últimas presentan un particular desafío dado que ningún sistema robótico ha demostrado la capacidad de sobrepasarlas cuando se presentan en ciertas posiciones. El objetivo de este trabajo es diseñar y construir un prototipo de una nueva categoría de robot de inspección de ductos consistente en un Robot Deformable Octaédrico con una estructura compuesta principalmente por actuadores lineales. Al ser un octaedro, todos los lados del robot son triangulares, que al estar compuestos por actuadores lineales, pueden deformarse. De esta forma el robot puede adaptarse a los distintos escenarios, en particular a los complejos componentes de una red de tuberías, en un rango mayor de diámetros interiores. Esta estructura se puede adaptar y navegar por espacios confinados inaccesibles para la mayoría de los sistemas robóticos existentes. Tiene 6 puntos de apoyo que ejercen presión en la superficie interna del ducto, los cuales pueden funcionar de forma independiente como dos triángulos inscritos en la superficie cerrada. Cada triángulo permite mantener estable al robot al interior del espacio cerrado sin necesidad de que el otro ejerza presión alguna. Para el desarrollo de este robot, se trabajó inicialmente con ODE (Open Dynamic Engine), una librería de software para simular la dinámica de cuerpos rígidos articulados, que permitió probar el diseño básico del robot. El robot se simuló en los distintos escenarios posibles y se estudió su estructura deformable. Inicialmente se construyó un prototipo hidráulico para estudiar el comportamiento cinemático de la estructura. Se finalizó con otro prototipo, con actuadores lineales eléctricos diseñados exclusivamente para el uso en robots deformables, con el cual se probaron las deformaciones principales necesarias para producir los movimientos básicos que permiten navegar por una red de tuberías. Con el software existente, el prototipo eléctrico puede navegar en tuberías cuyo diámetro interior va desde 35 a 48 cm, a una velocidad en línea recta de 0.5 cm/seg utilizando movimiento peristáltico. La capacidad mecánica permite aumentar el diámetro máximo a 67 cm y se estima que su velocidad seria de 1 cm/seg. Gracias a su geometría octaédrica, el prototipo es capaz de avanzar hacia cualquier dirección en forma análoga, permitiendo así superar una unión tipo T con salida superior.