A hierarchical controller for miniature VTOL UAVs: Design and stability analysis using singular perturbation theory

This paper presents the design and the stability analysis of a hierarchical controller for unmanned aerial vehicles (UAV), using singular perturbation theory. Position and attitude control laws are successively designed by considering a time-scale separation between the translational dynamics and the orientation dynamics of a six degrees of freedom vertical take-off and landing (VTOL) UAV model. For the design of the position controller, we consider the case where the linear velocity of the vehicle is not measured. A partial state feedback control law is proposed, based on the introduction of a virtual state into the translational dynamics of the system. Results from simulation and from experiments on a miniature quadrirotor UAV are provided to illustrate the performance of the proposed control scheme.

► Design and stability analysis of a hierarchical controller for UAVs are presented.
► It is assumed that no measurements of the linear velocity of the vehicle are available.
► A time-scale separation is achieved for control design.
► Closed-loop stability is analyzed by the singular perturbation theory.
► Simulation and experimental results illustrate the efficiency of the control scheme.