In this work, we propose a robust position control system
for the tilt-wing quadrotor aerial vehicle SUAVI (Sabanci
University Unmanned Aerial VehIcle (see Figure 1). Dryden
model is used to model wind gusts acting on the vehicle
and these disturbances are included in the dynamic model of
the vehicle. Thus, aerodynamic disturbances, which are not
considered in many studies, are integrated into the system
model. In order to estimate and compensate for the unknown
disturbances, a “disturbance observer” [11] is utilized. This
observer also takes into account the nonlinear terms in the
dynamics of the vehicle and treats them as disturbances.
As a result, a linear dynamical model with nominal parameters
has been obtained. Since the disturbance observer
provides robustness, only PID type controllers are employed
to achieve robust positioning. The proposed observer based
control approach is verified by simulations and experiments,
and its performance has been found quite satisfactory.