Modeling and Control of a Telescopic Quadrotor Using Disturbance Observer Based Control

Morphing multirotors are characterized by the capability to modify their shape during the flight, in order to negotiate narrow gaps without the need for miniaturization, thus preserving flight time and payload. In this paper, we propose a mathematical model for a morphing quadrotor characterized by telescopic arms: as extendable arms move, the center of mass position changes, as well as the inertia of the vehicle. Then, we address the tracking control problem of the telescopic quadrotor under external additive disturbances (e.g., wind), following the disturbance observer based control approach. The control scheme consists in an inner/outer loop structure, where both loops interact with a nonlinear disturbance observer. Closed loop performances are analyzed and the control scheme is validated through a realistic numerical simulation.