Real-time implementation of a decoupled and robust velocity controller for quadrotors

This paper presents a decoupled and robust velocity control strategy for a quadrotor involving parametric uncertainties, model uncertainties, coupling, and external disturbances. The quadrotor control system is divided into four subsystems. For each subsystem, a linear time-invariant robust controller is proposed, which uses its own state feedback and consists of a nominal controller and a robust compensator. The nominal controller is designed by PID control method to achieve the desired tracking for the nominal system, while the robust compensator is added to restrain the influence of the uncertainties. Tracking errors are guaranteed to converge into priorily set neighborhoods of the origin ultimately. Real-time experimental results on a quadrotor platform demonstrate that the horizontal velocity can be controlled effectively using the proposed control method.