  This paper applies the UAV to the inspection of water diversion pipelines in
hydropower stations. The diversion pipeline is an enclosed space, so the
airflow disturbance caused by the rotation of the UAV blades and the strong air
convection from the chimney effect have a great impact on the flight control of
the UAV. Although the traditional linear control PID flight control algorithm
has been widely used and can meet the requirements of general flight tasks, it
cannot guarantee the stability of the system over a wide range. The inspection
of a diversion line in an enclosed space requires high system stability and
robustness of the UAV controller. In this paper, a hybrid stabilised adaptive
backstepping control method is proposed. Firstly, a multi-rotor UAV model is
analysed and transformed into a strict feedback form with external
disturbances; then adaptive techniques are used to estimate the airflow
disturbances caused by the blades, and the attitude and position tracking
controllers are designed by combining backstepping control and PID control
respectively; finally, the asymptotic stability of the system is ensured by
constructing a Lyapunov function. The experimental data show that the flight
controller designed in this paper has good robustness and tracking performance,
and can better resist the disturbance caused by airflow disturbance in confined
space.
