Nonlinear disturbance rejection control for quadrotor attitude via finite-time state observer

In this article, to improve disturbance rejection characteristics and implement fast-tracking of angles, a nonlinear disturbance rejection control for quadrotor attitude via finite-time state observer is studied with an inner-outer loop control framework. In the inner loop system, a finite-time nonlinear disturbance observer (FTNDO) and a controller with robust control law are employed to estimate and compensate the disturbances, respectively. The finite-time technology is used to improve the convergence rate of the system. Additionally, a composite nonlinear feedback controller (CNFC) is devised for the outer loop to improve transient performance. The stability of both loops is analyzed individually, and the effectiveness of the proposed approach is verified through numerical simulations and platform experiments.