Alpha Uncertainty and Disturbance Based Robust Controller for Trajectory Tracking of Octocopter UAV

A robust controller for an octocopter is essential for flight stability. The presence of matched and unmatched disturbances can deteriorate a stable performance. This work proposes a robust controller for an octocopter to reject the matched and unmatched disturbances. The effects of fast varying external disturbances and parametric uncertainty on octocopter are considered matched disturbances and sensor measurement noise is modeled as unmatched disturbances. To alleviate the effects of disturbances an alpha uncertainty and disturbance estimator based integral sliding mode (ISMC-Alpha UDE) control law is proposed. The Lyapunov theory is used for stability analysis of the proposed ISMC-Alpha UDE control law. Comparative numerical simulations along with root mean square error (RMSE) analysis are presented to show the better performance of the proposed controller. The proposed controller offers reduced and smooth control efforts to achieve robust state tracking performance by mitigating the effects of matched and unmatched disturbances. The Monte Carlo simulations are performed to validate the efficacy of the proposed design.