Abstract
This paper is concerned with robust control of a quad-rotor aerial vehicle attitudes (pitch, roll, yaw). Attitudes of the quad-rotor vehicle is affected by various sources of disturbances such as wind and ground effect. In this paper, we propose a new disturbance observer so that these disturbances are estimated and compensated by the disturbance observer. It is shown by simulations that the proposed disturbance observer effectively compensates disturbances.