Attitude Stabilization of a Quadrotor by Means of Event-Triggered Nonlinear Control

In this paper, a quaternion-based feedback is developed for event-triggered attitude stabilization of a quadrotor mini-helicopter. The feedback is derived from the universal formula for event-triggered stabilization of general nonlinear systems affine in the control. Event-triggered control is a resource-aware sampling strategy that updates the control value only when a certain condition is satisfied, which denotes event instants. Such a technique allows a reduction of the control computational cost and communications demand. The proposed feedback ensures asymptotic stability to the desired attitude. Real-time experiments are carried out in order to show the convergence of the quadrotor states to the desired attitude as well as robustness with respect to external disturbances. Results show that the proposed strategy can reduce by 80 % the number of control function calls and consequently reduce the communications of the embedded system without sacrificing performance of the whole system. To the best of the authors' knowledge, this is the first time that a nonlinear event-triggered controller is experimentally applied to the attitude stabilization of an unmanned aircraft system.