A Novel Approach for Trajectory Tracking Control of an Under-Actuated Quad-Rotor UAV

Dear Editor, This letter presents a novel Udwadia-Kalaba (U-K) approach for the trajectory tracking control of a quad-rotor unmanned aerial vehicle (UAV). Compared to conventional control approaches, the desired trajectories are treated as trajectory tracking constraints in this approach. Neither making any approximation or linearization of the nonlinear system nor imposing any a priori structure on the nature of the nonlinear controller, this approach provides closed-form non-linear control. The control inputs satisfying the desired trajectory requirements can be obtained explicitly and in compact closed form by solving U-K equation. The theoretical analysis and MATLAB simulation results verify the validity and efficiency of this approach. The real-time servo constraint force is solved and the quad-rotor UAV satisfies the designed trajectory precisely.