Nonlinear controller design and implementation for altitude stabilization of quadrotor air vehicle

Flight control of unmanned aerial vehicle (UAVs) is an area that poses interesting problems for control researchers. Civil and military applications of autonomous flying vehicles have been steadily increasing over the last few years. Unmanned vehicles are important when it comes to performing a desired task in a dangerous and/or unaccessible environment. UAVs are highly nonlinear systems because of the aerodynamic parameters and model uncertainty. In this paper, an orientation controller structure is proposed for quad rotor aircraft. In order to achieve almost global asymptotic stabilization, a function like a Lyapunov function which is the most suitable for the system is chosen. Orientation analysis is performed based on a function which is similar to Lyapunov function and asymptotic convergence is proven by dynamic equations of the quad rotor aircraft. The proposed controller is implemented by numerical simulations on quad rotor aircraft and results are presented.