Multi-input multi-output (MIMO) control system design is much more difficult than single-input single
output (SISO) design due to the combination of cross-coupling and uncertainty. An investigation is
undertaken into both the classical Quantitative Feedback Theory (QFT) and modern H-infinity frequency
domain design methods. These design tools are applied to a bank-to-turn (BTT) missile plant at multiple
operating points for a gain scheduled implementation. A new method is presented that exploits both
QFT and H-infinity design methods. It is shown that this method gives insight into the H-infinity design
and provides a classical approach to tuning the final H-infinity controller. The use of “true” inversionfree
design equations, unlike the theory that appears in current literature, is shown to provide less
conservative bounds at frequencies near and beyond the gain cross-over frequency. All of the
techniques investigated and presented are applied to the BTT missile to show their application to a
practical problem. It was found that the H-infinity design method was able to produce satisfactory
controllers at high angles of attack where there were no QFT solutions found. Although an H-infinity
controller was produced for all operating points except the last, the controllers were found to be of very
high-order, contain very poorly damped second order terms and generally more conservative, as
opposed to the QFT designs. An investigation into simultaneous stabilization of multiple plants using Hinfinity
is also presented. Although a solution to this was not found, a strongly justified case to entice
further investigation is presented. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/7861 |
| Date | January 2011 |
| Creators | Reddi, Yashren. |
| Contributors | Boje, Edward Sidney. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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