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dc.contributor.advisorNergis Mavalvala.en_US
dc.contributor.authorShapiro, Brett N. (Brett Noah)en_US
dc.contributor.otherMassachusetts Institute of Technology. Dept. of Mechanical Engineering.en_US
dc.date.accessioned2008-09-03T15:18:15Z
dc.date.available2008-09-03T15:18:15Z
dc.date.copyright2007en_US
dc.date.issued2007en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/42310
dc.descriptionThesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.en_US
dc.descriptionIncludes bibliographical references (leaves 124-126).en_US
dc.description.abstractGravitational waves are predicted to exist by Einstein's General Theory of Relativity. These waves are distortions of space-time which until now have remained outside the realm of possible detection, due to their incredibly weak interactions. Now, due to newly built highly sensitive observatories, such as the Laser Interferometer Gravitational Wave Observatory (LIGO), these detections are now believed to be possible and may occur in the very near future. The research discussed here is on an active control system for the quadruple pendulum, from which the mirrors of the LIGO interferometer are suspended. This pendulum is a chain of four masses used to provide seismic isolation of the mirrors at the level of 10-19 m Hz-1/2 at 10 Hz. Because the pendulum is so quiet above 10 Hz, the sensor noise used in the active control is not trivial. Thus, the purpose of this research is to optimize a control scheme that has high gain at the resonant frequencies of the pendulum to provide damping while at the same time rolling the gain off to virtually zero at the limit of the gravitational wave detection band less than half a decade away. This requirement is very difficult to achieve with classical control design techniques. The alternative method explored here is a type of modal control with state estimation where incomplete sensor information is reconstructed and mathematically decomposed into modal responses. The modal responses can be thought of as simple single degree of freedom oscillators that are very easy to control. In this way, a few highly complicated controllers are traded for a larger collection of reasonably simple ones that are easy to design for each mode. Damping vs. noise injection can then be optimized by tailoring the control gain on each mode.en_US
dc.description.statementofresponsibilityby Brett N. Shapiro.en_US
dc.format.extent126 leavesen_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectMechanical Engineering.en_US
dc.titleModal control with state estimation for advanced LIGO quadruple suspensionsen_US
dc.typeThesisen_US
dc.description.degreeS.M.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Mechanical Engineering
dc.identifier.oclc232550601en_US


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