Active control of V/STOL aircraft

Vertical/Short Take-Off arid Landing (V/STOL) fighter aircraft arecharacterised by increased control complexity caused by the extra degreeol freedom. This can result in a high pilot workload which may bealleviated with the careful application of active flight control.However, the advent of control configured vehicles demands that thecontroller design must be part of a fully integrated and iterativeaircraft design; hence it must allow the two-way flow of designinformation.In this thesis a suitable controller (leSign method is developed to solvethis two-fold problem.The method is based upon a singular perturbation analysis which is usedto expose the underlying dynamics of a closed-loop state-space system.developments are described which allow high-order, dynamicallycomplex parasitics, such as actuators, to be included in the design.}urtherrnore, the method gives the designer insight into the problemallowing tuning and engineering trade-offs to be performed intelligentlywith a two-way flow of design information. The end result is a robusthigh-gain multivariable controller.In order fully to develop arid analyse the method it has been applied toa representative non-linear time-varying aircraft simulation model. ThisLS supplied by the Royal Aerospace Establishment, Bedford. The necessary slate-space matrices are otitairted by lirLearisirig the model at severaldifferertt flight cases. This occurs over a wide flight envelope, fromhover to 300 Kts, and consequently the multivariable control laws areimplemented using gain scheduling.Finally, task tailored control and handling qualities requirements arederived for a V/STOL aircraft in the form of a design brief. This designbrief is then fulfilled by designing a controller which alleviates pilotworkload during transitions from jet-borne to fully wing-borne flight(and vice versa)