Attitude stabilization of a four-rotor aerial robot

In this paper, we propose a quaternion-based feedback control scheme for exponential attitude stabilization of a four-rotor vertical take-off and landing (VTOL) aerial robot known as the quadrotor aircraft. The proposed controller is based upon the compensation of the Coriolis and gyroscopic torques and the use of a PD² feedback structure, where the proportional action is in terms of the quaternion vector and the two derivative actions are in terms of the airframe angular velocity and the quaternion velocity. We also show that the model-independent PD controller, where the proportional action is in terms of the quaternion vector and the derivative action is in terms of the airframe angular velocity, without compensation of the Coriolis and gyroscopic torques, provides asymptotic stability for our problem. Simulation results are also provided to show the effectiveness of the proposed controller.