Robust Trajectory Tracking Control for Small-Scale Unmanned Helicopters with Model Uncertainties

This paper addresses the trajectory tracking control problem for small-scale unmanned helicopters with model uncertainties. In particular, we propose a robust control scheme that is decomposed into a position and an attitude control modules, operating in a cascaded form, and does not depend on the explicit knowledge of the value of the model parameters. Exploiting the concepts and techniques of prescribed performance control, each module guarantees trajectory tracking with prescribed transient and steady-state response, despite the presence of external disturbances, such as wind gusts and ground effect phenomena. Additionally, a novel reformulation of the translational dynamics reveals a sufficient condition for closed-loop stability and allows us to extract the appropriate attitude commands straightforwardly. Moreover, the derived control algorithms are of low complexity and thus can be efficiently implemented on low-cost, aerial embedded systems of limited power and computational resources. Finally, the efficacy of the proposed control scheme is verified via extensive experimental studies using an autonomous small-scale helicopter.