This paper is concerned with large-angle attitude tracking control for quadrotors in the presence of time-varying inertia and external disturbances using a switched linear parameter-varying (LPV) system method. The attitude system of the quadrotor is divided into two parts, that is, the outer attitude-angle loop and inner angular-velocity loop. A feedback linearization controller is designed in the outer loop to generate the desired angular velocities. In the inner loop, the nonlinear quadrotor dynamics with time-varying inertia is approximated by a switched LPV system that consists of a series of LPV models. The persistent dwell time (PDT) switching logic is adopted to describe the fast and slow switches coexist among these LPV models. Then, both the continuous-time state-feedback and dynamic output-feedback controllers are designed, which ensure the globally uniformly asymptotically stability and 2 − ∞ external disturbance attenuation performance of the attitude tracking error system. Finally, the effectiveness of the proposed tracking control method of quadrotors is validated with an example.
K E Y W O R D S 2 − ∞ performance, persistent dwell time, quadrotor, switched linear parameter-varying systems
INTRODUCTIONIn recent years, the quadrotors have been broadly applied in surveillance, facilities inspection, and rescue missions because of their maneuverability and maintainability. [1][2][3] As the core part of the flight control system in quadrotors, the attitude controller determines the overall performance of quadrotors in various missions. 4 However, the attitude control system of quadrotors is characterized by nonlinearity and strong coupling, which is sensitive to external disturbances and model uncertainties. 5,6 Therefore, it is a challenge to design a satisfactory attitude tracking controller with fast response and high precision.