Experimental Validation of Quaternion Based Integral Backstepping Design for Attitude Tracking

This paper presents two backstepping control design for Unmanned Aerial Vehicle (UAV) attitude tracking subject to uncertainties and external disturbances. We first propose an extension to attitude tracking control design using quaternion based backstepping procedure from attitude stabilization. Next, we develop an original integral backstepping control law for UAV attitude tracking. The proposed control includes an integral term that improves tracking performances and provides better disturbance rejection. The obtained control law contains a proportional, a derivative and an integral terms so that it is a PID like nonlinear controller. Both quaternion based controllers allow passing through singularities usually caused by Euler angles representation. Global asymptotic stability of the closed loop system is proved for both controllers via systematic constructive Lyapunov functions. Simulations results with Matlab-Simulink for stabilization, tracking, robustness tests and singularities avoidance are given for each controller. Finally, experimental results are validated in real-time on the Quanser 3 degree of freedom (DOF) Hover test bench and show the efficiency of the integral backstepping controller and the quaternion superior performances.