Robust Flat Filtering Control of a Two Degrees of Freedom Helicopter Subject to Tail Rotor Disturbances

• Published in: International journal of applied mathematics and computer science Vol. 33; no. 4; pp. 521 - 535
• Main Authors: Sánchez-Meza, Victor-Gabriel, Lozano-Hernández, Yair, Gutiérrez-Frías, Octavio, Lozada-Castillo, Norma, Luviano-Juárez, Alberto
• Format: Journal Article
• Language: English
• Published: Zielona Góra Sciendo 01.12.2023; De Gruyter Poland
• Subjects: Control algorithms; Control systems; Controllers; Degrees of freedom; Design; Disturbances; Filtration; flat filtering control; Flatness; Free form; generalized proportional integral control; Helicopter tail rotors; Helicopters; Mathematical models; non-linear systems; Parameterization; Performance indices; Pitch (inclination); Prototypes; Robust control; tail rotor disturbance; Tail rotors; Tracking; two degrees of freedom helicopter; Unmanned aerial vehicles; Yaw
• ISSN: 1641-876X; 2083-8492
• DOI: 10.34768/amcs-2023-0038

This article deals with modelling and a flatness-based robust trajectory tracking scheme for a two degrees of freedom helicopter, which is subject to four types of tail rotor disturbances to validate the control scheme robustness. A mathematical model of the system, its differential flatness and a differential parametrization are obtained. The flat filtering control is designed for the system control with a partially known model, assuming the non-modelled dynamics and the external disturbances (specially the tail rotor ones) to be rejected by means of an extended state model (ultra-local model). Numerical and experimental assessments are carried out on a characterized prototype whose yaw angle ( ), given by the axis, is in free form, while the pitch angle ( ), which results from rotation about the axis, is mechanically restricted. The proposed controller performance is tested through a set of experiments in trajectory tracking tasks with different disturbances in the tail rotor, showing robust behaviour for the different disturbances. Besides, a comparison study against a widely used controller of LQR type is carried out, in which the proposed controller achieves better results, as illustrated by a performance index.