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dc.contributor.authorKraus, R.en_US
dc.contributor.authorCliff, E.en_US
dc.contributor.authorWoolsey, C.en_US
dc.contributor.authorLuby, J.en_US
dc.date.accessioned2013-04-25T20:55:52Z
dc.date.available2013-04-25T20:55:52Z
dc.date.issued2008
dc.identifier.urihttp://hdl.handle.net/10919/19357
dc.description18 p.
dc.description.abstractAn undersea glider is a winged autonomous undersea vehicle which modulates its buoyancy to rise or sink and moves its center of mass to control pitch and roll attitude. By properly phasing buoyancy and pitch control, an undersea glider rectifies the vertical motion caused by changes in buoyancy into forward motion caused by the lift force on the fixed wing. The characteristic "porpoising" motion is useful in oceanographic surveys and the propulsion method is extremely efficient - undersea gliders routinely operate for months without human intervention. Glider efficiency could be improved even further by addressing the phenomenon of "stall" (loss of lift) when a glider transitions from downward to upward flight. Because the stall phenomenon occurs asymmetrically over the vehicle's wing, it can cause directional errors which must be corrected at a corresponding energetic cost. This paper describes the formulation of a point mass model and its dynamic equations of motion. An optimal control formulation was designed using angle of attack and buoyancy as controls to investigate control scheduling methods for avoiding stall in a symmetric pull-up. The calculations were repeated using three different numerical solution techniques for comparison of the methodologies and results. The model was updated to include longitudinal rigid body dynamics and changed the control to the rate of change of the longitudinal center of gravity location. This model allowed for the inclusion of added mass effects due to fluid displacement.
dc.format.mimetypeapplication/pdfen_US
dc.languageEnglish
dc.publisherVirginia Center for Autonomous Systems
dc.relation.ispartofseriesVaCAS
dc.rightsCopyright, Virginia Polytechnic Institute and State University
dc.subjectUndersea glidersen_US
dc.subjectBuoyancyen_US
dc.subjectStallingen_US
dc.subjectGlider efficiencyen_US
dc.titleOptimal Control of an Undersea Glider in a Symmetric Pull-upen_US
dc.title.alternativeVaCAS-2008-03
dc.typeTechnical reporten_US
dc.identifier.urlhttp://www.unmanned.vt.edu/discovery/reports/VaCAS_2008_03.pdf
dc.date.accessed2013-04-25
dc.type.dcmitypeTexten_US


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