Abstract:
One of the attractive and challenging design problems is the Unmanned Air Vehicle (UAV) where the
flight control system is designed to achieve robust stability and acceptable performance across
specified flight envelope in the presence of uncertainties. Therefore, this paper is devoted to design
adequate automatic flight control systems in order to stabilize the attitudes and natural modes of a
flying fixed wing (Aerosonde) UAV under exogenous disturbances. Toward this objective, a nonlinear
mathematical model for the underlying aircraft is developed and linearized yielding a state-space
model. This linear model is then decoupled into two smaller models associated to the longitudinal and
lateral motions of the aircraft. The natural modes for both motions are analyzed by initializing the
system matrix with the real parts of eigenvector corresponding to each mode. Classical PID tuning
techniques have been utilized with the longitudinal model to design flight control systems that achieve
the performance requirements; including good tracking and the rejection of disturbances.