Reconfigurable LPV control design for Boeing 747-100/200 longitudinal axis

Presents the design of a reconfigurable linear parameter varying (LPV) controller for the Boeing 747-100/200 longitudinal axis in the up-and-away flight regime. The control objectives are to obtain decoupled flight-path angle and velocity command tracking and achieve good disturbance rejection characteristics during normal operation and in the presence of an elevator fault. The LPV controller is synthesized using a quasi-LPV model of the aircraft longitudinal axis based on the Jacobian linearization approach. The controller schedules on three parameters: flight altitude and velocity and a fault identification signal. During normal flight operations, the LPV controller uses the elevators and thrust for flight maneuvers. The stabilizer is used to trim the aircraft. Two elevator fault scenarios are contemplated-lock and float. The proposed control strategy is to use the stabilizer as the alternative longitudinal control surface. Simulation results with elevator faults present show that the reconfigured controller stabilizes the faulted system at the expense of a factor of a designed one-third reduction in the tracking responsiveness of the longitudinal axis and has good disturbance rejection properties.