Abstract:
A nonlinear dynamic inversion (NDI) controller and a sliding mode controller are
developed for large civil transport Boeing 747 in this thesis. Furthermore adaptive
control theory is applied on both NDI controller and SMC controller to improve the
performance. Nonlinear dynamic inversion is an advanced control method which
is able to directly handle nonlinear system with less gain schedule and provides
inherent decoupled property. The system is linearized as a pure integrator by inner
loop feedback, whilst the desired control law is fulfilled by the outer loop linear
controller. However, the NDI controller is considerably sensitive to uncertainty due
to the incomplete cancellation. SMC, a well known nonlinear robust control method,
is utilized to endow the controller with more robustness. The results show that SMC
controllers perform better than NDI controllers, but are still not perfect. Finally, a
parameter on-line estimation adaptive scheme is applied to improve NDI controller
meanwhile a disturbance observer is designed in addition to SMC controller. It is
drawn from assessments that the disturbance observer based SMC controller achieves
the best performance for all flight points: fast rising-up speed, little overshoot, short
settle time and very small steady state error.
In addition, the classical and modern linear control theories as well as nonlinear
control methods are reviewed. Moreover, some flying and handling quality criteria
are also given as literature review.
