Unit Quaternion Based Attitude Control of An Aerial Manipulator

Abstract This paper considers an aerial manipulator consisting of a quadcopter and a 2-DoF manipulator. The attitude of the quadcopter, represented by unit quaternion, is expected to track a given time-varying reference. In the modeling of the attitude dynamics of the quadcopter, both the external disturbances and the torque generated by the gravity force of the manipulator are taken into consideration. It turns out that the torque generated by the gravity force of the manipulator can be linearly parameterized and thus the attitude control problem of the quadcopter could be converted into a standard stabilization problem, which can be addressed by the internal model control. The system performance is examined by a numerical example.