Wind disturbance rejection in position control of unmanned helicopter by nonlinear damping

Abstract

This paper presents a new design of a Lyapunov-redesigned control system for large horizontal wind disturbance rejection on a small-scale unmanned autonomous helicopter (UAH). In this paper, the wind disturbance cannot be treated as small perturbations around the equilibrium state any more. Instead, wind disturbances are considered as force/moment disturbances in the state equation. The force/moment caused by the wind can be estimated by the experimental data obtained in the wind tunnel. The whole control system consists of a nominal system controller and a wind disturbance controller. The nominal system controller is designed with back-stepping algorithm while the wind disturbance controller is designed with nonlinear damping algorithm. The nonlinear damping is introduced to ensure that the whole system has a uniformly bounded solution under uncertain large horizontal wind disturbances. Both longitudinal and lateral wind disturbances are considered in the simulation. The simulation results show the wind disturbances are well rejected and the proposed method can be effective for the position control of UAH in windy environment.