Adaptive Second-order Sliding Mode Control of UAVs for Civil Applications

摘要

Quadcopters, as unmanned aerial vehicles (UAVs), have great potential incivil applications such as surveying, building monitoring, and infrastructurecondition assessment. Quadcopters, however, are relatively sensitive to noisesand disturbances so that their performance may be quickly downgraded in thecase of inadequate control, system uncertainties and/or external disturbances.In this study, we deal with the quadrotor low-level control by proposing arobust scheme named the adaptive second-order quasi-continuous sliding modecontrol (adaptive 2-QCSM). The ultimate objective is for robust attitudecontrol of the UAV in monitoring and inspection of built infrastructure. First,the mathematical model of the quadcopter is derived considering nonlinearity,strong coupling, uncertain dynamics and external disturbances. The controldesign includes the selection of the sliding manifold and the development ofquasi-continuous second-order sliding mode controller with an adaptive gain.Stability of the overall control system is analysed by using a global Lyapunovfunction for convergence of both the sliding dynamics and adaptation scheme.Extensive simulations have been carried out for evaluation. Results show thatthe proposed controller can achieve robustness against disturbances orparameter variations and has better tracking performance in comparison withexperimental responses of a UAV in a real-time monitoring task.