Flight control design for small-scale helicopter using disturbance- observer-based backstepping

A study adopts the disturbance-observer-based control scheme to enhance the flight control performance. This method is known as an active anti-disturbance strategy where the lumped disturbances from various sources are estimated by a disturbance observer (DO) and then incorporated into a nominal controller to compensate for their adverse effects. A preliminary study has demonstrated the disturbance rejection ability of this control strategy on a small-scale helicopter. The study proposes a novel disturbance-observer design that extends the scope of the classical one to a partial-state unmeasurable system.