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dc.contributor.authorSchuch, Eric Matthewen
dc.date.accessioned2011-08-06T16:02:46Zen
dc.date.available2011-08-06T16:02:46Zen
dc.date.issued2004-07-16en
dc.identifier.otheretd-07312004-204213en
dc.identifier.urihttp://hdl.handle.net/10919/10053en
dc.description.abstractSampling small scale ocean turbulence is one of the most important problems in oceanography. The turbulence can be near the noise level of current microscale profiling techniques and these techniques do not provide spatially and temporally dense measurements and can be labor intensive. A 5 beam acoustic Doppler current profiler (VADCP) can more accurately measure three components of fluid velocity in a column. By towing such a device in a sensor platform, called a towfish, one may measure turbulent mixing in a vertical swath of the ocean. If the towfish attitude is not precisely regulated, however, the turbulence measurements can be irreversibly corrupted. A two-part tow that includes a depressor weight between the towing vessel and the towfish can provide some degree of disturbance rejection. Passive devices alone, however, can not meet the performance requirements for measuring ocean turbulence. This thesis presents a design for a two-stage towing system which will be used to measure ocean turbulence. The focus is on the towfish, which includes independently actuated stern planes for pitch and roll disturbance rejection. The thesis also describes design and analysis of an active control system to precisely regulate the pitch and roll attitude of a streamlined towfish. A three dimensional numerical model is presented and a PID controller is developed to provide active attitude stabilization. The effect of random depressor motions on the towfish dynamics is assessed for both the uncontrolled and the feedback-controlled case. The numerical investigation also considers variations in parameters such as tether length and CG location.en
dc.format.mediumETDen
dc.publisherVirginia Techen
dc.relation.haspartSchuchThesis2004Rev5.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectSimulationen
dc.subjectTowfishen
dc.subjectPIDen
dc.subjectTethered Vehiclesen
dc.subjectUnderwater Vehiclesen
dc.subjectTowed Vehiclesen
dc.titleTowfish Design, Simulation and Controlen
dc.typeThesisen
dc.contributor.departmentAerospace and Ocean Engineeringen
dc.description.degreeMaster of Scienceen
thesis.degree.nameMaster of Scienceen
thesis.degree.levelmastersen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.disciplineAerospace and Ocean Engineeringen
dc.contributor.committeechairWoolsey, Craig A.en
dc.contributor.committeememberNeu, Wayne L.en
dc.contributor.committeememberCliff, Eugene M.en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-07312004-204213en
dc.date.sdate2004-07-31en
dc.date.rdate2004-08-09en
dc.date.adate2004-08-09en


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