Abstract:
This thesis considers the problem of designing gain scheduled flight control system
(FCS) for large transport aircraft that satisfy handling qualities criteria. The goal is
to design a set of local Linear Time Invariant (LTI) controllers to cover the wide non-
linear aircraft operation flight envelope from the viewpoint of the handling qualities
assessment. The global gain scheduler is then designed that interpolates between
the gains of the local controllers in order to transfer smoothly between different
equilibrium points, and more importantly to satisfy the handling qualities over the
entire flight envelope. The mathematical model of the Boeing 747-100/200 aircraft
is selected for the purpose of the flight controller design and handling qualities as-
sessment.
In order to achieve an attitude hold characteristic, and also improve the dynamic
tracking behavior of the aircraft, longitudinal pitch Rate Command-Attitude Hold
(RCAH) controllers are designed as the local flight controllers at the specific equilib-
rium points in the flight envelope by means of a state space pole placement design
procedure.
The handling qualities assessment of the aircraft is presented, based on which the
scheduler is designed. A number of existing criteria are employed to assess the han-
dling qualities of the aircraft, including the Control Anticipation Parameter (CAP),
Neal and Smith, and C∗ criteria. The gain scheduled flight controller is found to
have satisfactory handling qualities.
The global gain scheduler is designed by interpolating the gains of the local flight
controllers in order to transfer smoothly between different equilibrium points, and
more importantly to satisfy the handling qualities over the flight envelope.
The main contribution of this research is the combination of the gain scheduling
technique based on the local controller design approach and handling qualities as-
sessment. The controllers are designed based at a number of operating points and
the interpolation between them (scheduling) takes place through the scheduling
scheme functions. The aircraft augmented with gain-scheduled controller performs
satisfactorily and meets the requirement of handling qualities. Moreover, the per-
formance using the gain-scheduled controller is considerably improved compared to
the performance using the fixed one.
