This dissertation addresses the modeling, identification, and control of an automated planing vessel. To provide motion models for trajectory generation and to enable model-based control design for trajectory tracking, several experimentally identified models are compared over a wide range of speed and planing conditions for the Virginia Tech Ribcraft Unmanned Surface Vehicle. The modeling and identification objective is to determine a model which is sufficiently rich to enable effective model-based control design and trajectory optimization, sufficiently simple to allow parameter identification, and sufficiently general to describe a variety of hull forms and actuator configurations. Beginning with a 6 degree of freedom nonlinear dynamic model, several linear steering and speed models are obtained as well as a thruster model. The Ribcraft USV tracks trajectories generated with the selected maneuvering models by using a back- stepping trajectory controller. A PD cascade trajectory control law is also developed and the performance of the two controllers is compared using aggressive trajectories. The backstepping control law compares favorably to the PD cascade controller. The backstepping control law is then further modified to account for nonlinear sternward dynamics and for a constant or slowly varying fluid flow. / Ph. D.

京都大学 / 0048 / 新制・課程博士 / 博士(人間健康科学) / 甲第18912号 / 人健博第26号 / 新制||人健||2(附属図書館) / 31863 / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 市橋 則明, 教授 松田 秀一, 教授 木下 彩栄 / 学位規則第4条第1項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM

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[pt] O presente trabalho consiste num estudo experimental de laboratório, no qual procurou-se analisar o comportamento tensão-deformação-resistência de um solo residual jovem de biotita gnaisse na condição saturada. Foram realizados ensaios de compressão isotrópica e edométrico através dos quais foi definida a tensão de pré- adensamento do solo em estudo. Posteriormente foram realizados ensaios triaxiais de compressão e extensão seguindo diferentes trajetórias de tensão, com a utilização de instrumentação interna (ELETRONÍVEIS) para medição das deformações axiais. A utilização dos ELETRONÍVEIS possibilitou a identificação de uma superfície de escoamento no espaço de tensões de compressão e de extensão. Foi analisado o módulo secante de deformabilidade obtido com o uso do LSCDT e dos ELETRONÍVEIS a partir dos ensaios triaxiais. O estudo microestrutural do solo feito através de lâminas delgadas, analisadas ao microscópio óptico e eletrônico de varredura, possibilitou a verificação de cimentação entre os grãos do solo. Esta é causada pela cimentação do ferro liberado através da intemperização dos minerais de granada e biotita. / [en] The present work consists of experimental analysis to study the stress-strain-strenght behaviour of saturated young residual soil in laboratory. In a first moment isotropic compression and oedometric tests where made in order to define the overconsolidation stress of the studied soil. Further, compression and extension triaxial tests where made following diferent stress paths. The axial strain have been measured through internal instrumentation (Electrolevels).A yield surface could be observed, when the sample where submitted to compression and also to extension. The secant modulus of deformability, obtained through the use of LSCDT and electrolevels used in the triaxial tests, have been analised. A microstructural study of the soil have been made from thin sections of soil, analised on the scanning electronic microscope and optical microscope, where could be possible to observe link between grains. It was caused to iron originated from weathering of biotite and garnet minerals. / [es] EL presente trabajo consiste en un estudio experimental de laboratorio en el que se analiza el comportamiento tensión-deformación-resistencia de un suelo residual joven de bioptita gnaise en la condición saturada. Fueron realizados ensayos de compresión isotrópica y edométrico. A través de ellos, se definió la tensión de preadensamiento del suelo en estudio. Posteriormente se realizaron ensayos triaxiales de compresión y extensión utilizando diferentes trayectorias de tensión, con el empleo de instrumentación interna (electroníveles) para medir las deformaciones axiales. La utilización de los electroníveles hizo posible la identificación de una superfície de corriente en el espacio de tensiones de compresión y de extensión. Fue analizado el módulo secante de deformabilidad que se obtuvo con el uso del LSCDT y de los electroníveles a partir de los ensayos triaxiales. El estudio microextructural del suelo, realizado a través de láminas delgadas, analizadas al microscópio óptico y electrónico de barrido, posibilitó la verificación de cimentación entre los granos del suelo.Esta cimentación se debe a la cimentación del hierro liberado a través de la intemperización de los minerales de granada y bioptita.

This thesis aims to investigate the potential of a transfer orbit using successive aerocaptures at Saturn and Titan to establish a science orbit around Titan. Titan is an Earth-like moon with a dense atmosphere and organic compounds present. It has many similarities with Earth that are useful to study such as superrotation. Superrotation is when the atmosphere rotates faster than the body it surrounds. In order to study Titan, we need to establish an orbit around it. The Saturn system is distant from Earth, 8.5 Astronomical Units (AU) which makes it difficult to reach from a time and velocity point of view. We propose to use an aerocapture at Saturn to intercept Titan with lower relative velocity in order to perform an aerocapture at Titan. The analysis was performed in primarily MATLAB to simulate the orbits. The results of this showed that we can aerocapture a spacecraft at Saturn and arrive at Titan within roughly 4 to 8 km/s relative velocity regardless of the incoming hyperbolic excess velocity at the Saturn system. This can be improve upon by using intermediate transfer orbits, such as bi-elliptics, to arrive with even lower relative velocities to Titan of as low as 1 km/s. The drag acceleration experienced during the Saturn aerocapture had peak values of between 0.2 and 1.4 g's and acceleration over 50% of the peak is experienced between 6.8 and 8 minutes. This capture method has the potential to make Titan more easily accessible and allow for scientific study of a clear target for improving our understanding of Earth-like processes on other bodies in our solar system. / Master of Science / This thesis aims to investigate the potential of a transfer orbit using successive aerocaptures at Saturn and Titan to establish a science orbit around Titan. Aerocapturing is utilizing the atmosphere of a body to slow down a spacecraft. Titan is an Earth-like moon with a dense atmosphere and organic compounds present. It has many similarities with Earth that are useful to study such as superrotation. Superrotation is when the atmosphere of a body rotates faster than the body it surrounds. In order to study Titan, we need to establish an orbit around it. The Saturn system is distant from Earth, 8.5 Astronomical Units (AU) which makes it difficult to reach from a time and velocity point of view. It takes a large amount of time to get there so we attempt to get there faster by increasing velocity. This means we arrive at the Saturn system with a large amount of velocity that we need to counter-act in order to orbit. We propose to use an aerocapture at Saturn to intercept Titan with lower velocity in order to perform another aerocapture at Titan to slow into an orbit. The analysis was performed in primarily MATLAB to simulate the orbits. The results of this showed that we can aerocapture a spacecraft at Saturn and arrive at Titan within roughly 4 to 8 km/s regardless of the incoming velocity to the Saturn system. This can be improve upon by using intermediate transfer orbits, after capturing at Saturn, to arrive with even lower velocities at Titan of as low as 1 km/s. The drag acceleration experienced during the Saturn aerocapture had peak values of between 0.2 and 1.4 g's and acceleration over 50% of the peak is experienced between 6.8 and 8 minutes. This is relatively gentle for an aerocapture and means the spacecraft likely will not require significant structural support. This capture method has the potential to make Titan more easily accessible and allow for scientific study of a clear target for improving our understanding of Earth-like processes on other bodies in our solar system.

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