Decoupled Trajectory Tracking Controllers Design for Multirotors

A controller design method is proposed to control quadrotors with six degrees of freedom. The vehicle system is divided into four subsystems: the longitudinal, lateral, yaw, and height subsystems. A linear and decoupled nominal model is obtained for each subsystem, while coupling and nonlinear dynamics, parametric perturbations, and external disturbances are considered as uncertainties. For each subsystem, a decoupled robust controller is proposed. Although there exist couplings between each channel, the output tracking errors of the four subsystems are proven to ultimately converge into a-priori set neighborhood of the origin. Real-time implementation results of the decoupled controller are given to demonstrate its viability.