Gain-Scheduled Lateral Control of the F-14 Aircraft During Powered Approach Landing

Abstract

The design of a linear fractional transformation gain-scheduled controller, scheduled on angle of attack, for the F-14 aircraftlateral-directionalaxisis presented.Thecontrolleris designed forthe powered approach e ight phase, during which the angleof attack and corresponding airspeed varies from 2 deg and 182 kn to 14 deg and 126 kn. A linearfractional modelof the lateral dynamics is constructed based on four linearized models that correspond to 2, 6, 10.5, and 14 deg angle of attack. Using parameter-dependentfunctions, a controller is designed that dependsin a linear fractional manner on angle of attack and delivers uniform handling quality over angle-of-attack variations that lie between 2 ‐14 deg. The resulting controller performs well when implemented in a nonlinear simulation model of the F-14 aircraft. Nomenclature p = roll rate r = yaw rate v = lateral velocity yac = lateral acceleration a = angle of attack b = sideslip angle d dsp = differential spoiler dee ection d dstab = differential stabilizer dee ection d lstk = lateral stick input d rud = rudder dee ection d rudp = rudder pedal input u = bank angle