Adaptive control of hypersonic vehicles in presence of actuation uncertainties

The thesis develops a new class of adaptive controllers that guarantee global stability in presence of actuation uncertainties. Actuation uncertainties culminate to linear plants with a partially known input matrix B. Currently available multivariable adaptive controllers yield global stability only when the input matrix B is completely known. It is shown in this work that when additional information regarding the structure of B is available, this difficulty can be overcome using the proposed class of controllers. In addition, a nonlinear damping term is added to the adaptive law to further improve the stability characteristics. It is shown here that the adaptive controllers developed above are well suited for command tracking in hypersonic vehicles (HSV) in the presence of aerodynamic and center of gravity (CG) uncertainties. A model that accurately captures the effect of CG shifts on the longitudinal dynamics of the HSV is derived from first principles. Linearization of these nonlinear equations about an operating point indicate that a constant gain controller does not guarantee vehicle stability, thereby motivating the use of an adaptive controller. Performance improvements are shown using simulation studies carried out on a full scale nonlinear model of the HSV. It is shown that the tolerable CG shifts can be almost doubled by using an adaptive controller as compared to a linear controller while tracking reference commands in velocity and altitude.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2010

Author dc:creator

• Somanath, Amith

Advisor dc:contributor.advisor

• Anuradha Annaswamy.

• Aeronautics and Astronautics.

Statement dc:rights

• M.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.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/59699

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/59699