Quaternion-Based Robust Attitude Control for Uncertain Robotic Quadrotors

A robust nonlinear attitude control method is proposed for uncertain robotic quadrotors. The proposed controller is developed based on a nonlinear model with the quaternion representation and subject to parameter uncertainties, nonlinearities, and external disturbances. A new state feedback controller is proposed to restrain the effects of nonlinearities and uncertainties on the closed-loop control system. These uncertainties are considered as input equivalent disturbances and their effects are guaranteed to be attenuated. Experimental results are given to show good steady-state and dynamic tracking performance of the closed-loop system by the proposed robust control method compared with other nonlinear control methods.