Composite block backstepping trajectory tracking control for disturbed unmanned helicopters

In this paper, the position and yaw angle trajectory tracking control problem is studied for unmanned helicopters subject to both matched and mismatched disturbances. To achieve the trajectory tracking goal, a feedforward-feedback composite control scheme is proposed based on the combination of the generalized proportional integral observer and the block backstepping control techniques. The controller design process mainly consists of two stages. In the first stage, some generalized proportional integral observers are developed for the helicopter system to estimate the mismatched, matched disturbances and their (higher-order) derivatives. In the second stage, the composite controller is designed by integrating the block backstepping control method and the disturbance estimates together. The proposed composite scheme guarantees asymptotic tracking performances for the position and yaw angle of the helicopter to the desired trajectories even in the presence of fast time-varying disturbances. Numerical simulations demonstrate the effectiveness of the proposed composite control scheme. (C) 2018 Elsevier Masson SAS. All rights reserved.