Stability Analysis of a Multirotor UAV with Robust Backstepping Controller

In this paper, the stability analysis of an hexarotor micro-aerial vehicle for outdoor applications using IMU sensors is presented. The dynamic model of the hexarotor was expressed using the Newton-Euler laws jointly with a full state robust backstepping controller, not only when it is hovering, but also when it is taking-off, or landing, or flying to perform a task. The experimental hexarotor is equipped with an IMU/sonar sensors, which appropriately provides measurements of attitude and altitude. For the performance of the robust controller, sensors were modeled as real measurements with unknown bias and white noise. The bounded attitude/altitude controller were derived on the robust practical stability that deals with convergence and stability into a ball of the state space with non-null radius, under some assumptions. The Lyapunov analysis technique was used to prove the stability of the closed-loop system, compute bounds on control gains and guaranteeing desired bounds on attitude dynamics tracking errors in the presence of measurement disturbances.