Active control of V/STOL aircraft
Vertical/Short Take-Off arid Landing (V/STOL) fighter aircraft are characterised by increased control complexity caused by the extra degree ol freedom. This can result in a high pilot workload which may be alleviated with the careful application of active flight control. However, the advent of control configured vehicles demands that the controller design must be part of a fully integrated and iterative aircraft design; hence it must allow the two-way flow of design information. In this thesis a suitable controller design method is developed to solve this two-fold problem. The method is based upon a singular perturbation analysis which is used to expose the underlying dynamics of a closed-loop state-space system. developments are described which allow high-order, dynamically complex parasitics, such as actuators, to be included in the design. Furthermore, the method gives the designer insight into the problem allowing tuning and engineering trade-offs to be performed intelligently with a two-way flow of design information. The end result is a robust high-gain multivariable controller. In order fully to develop arid analyse the method it has been applied to a representative non-linear time-varying aircraft simulation model. This LS supplied by the Royal Aerospace Establishment, Bedford. The necessary slate-space matrices are otitairted by lirLearisirig the model at several different flight cases. This occurs over a wide flight envelope, from hover to 300 Kts, and consequently the multivariable control laws are implemented using gain scheduling. Finally, task tailored control and handling qualities requirements are derived for a V/STOL aircraft in the form of a design brief. This design brief is then fulfilled by designing a controller which alleviates pilot workload during transitions from jet-borne to fully wing-borne flight (and vice versa).