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Dynamics and control of flexible airframe is studied in th- is
dissertation. Both the classical and H∞ control algorithms are
applied for the flight controller design. The performance of
the basic 2-loop and the synthetic 3-loop classical control
sys- tems are discussed and compared. A method for control gain
dete- rmination to obtain the desired crossover frequency is
developed. It is shown that the synthetic 3-loop control system
is more re- liable in the sense that it provides realizable
feedback gain with good tracking performance. However, the
performance of the classical control system can be
significantly degraded by the a- irframe flexibility. In
addition to the classical control technique, H∞ control is
applied to deal with the airframe flexibility. Due to its loop
shaping property, H∞ control can provide better tracking
perfor- mance and stability robustness as compared with the
classical co- ntrol system. Furthermore, H∞ controller can be
applied with sa- tisfactory tracking performance and stability
requirements at di- fferent flight conditions without any gain
tuning. The performan- ce and stability robustness of H∞
control system is also valid- ated under the presence of model
uncertainties. Especially, the order of H∞ controller can be
reduced from ten orders to three orders while the classical
controller is three-orders. Flight controller of airframe
flexibility design by H∞ control is expe- cted to be very
promising.
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