Modem control methods have often been advocated by academics as able to solve fairly complex
control engineering design problems in the aircraft industry. However, evidence suggests
that practicei s still gearedt owardsu sing classicalt echniques,e ven on the most modem fighter
aircraft which are open-loop unstable. This thesis stems from a need to understand the reasons
for this. Modem methods are examined in order to determine their strengths and weaknesses
when applied to industrial problems.
As a representative situation, a modem control method, eigenstructure assignment, is examined.
One objective of the research described in the thesis is to improve the application oriented
aspects of the methodology of eigenstructure assignment. The purpose of this is that
every facet of the method can then be explained in terminology that is familiar to the aircraft
Furthermore, the theory is developed such that it is compatible with easily understandable controller
structures and control design strategies, to provide a control system with good performance
and robustness characteristics. The design of a robust controller for a civil aircraft model
developed by the GARTEUR (Group for Aeronautical Research and Technology in Europe)
demonstrates the utility of eigenstructure assignment and culminates in suggestions as to when
and where the method has its greatest strengths and weaknesses.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.