Mathematical modeling and control of a tilt-rotor aircraft

TL;DR

This paper develops a comprehensive mathematical model and control strategy for large tilt-rotor aircraft, enabling smooth mode transitions between helicopter and fixed-wing flight with improved uncertainty handling.

Contribution

It introduces a novel dynamic model for large tilt-rotors and a switched logic control method with a finite-time observer for reliable mode transition control.

Findings

Effective modeling of large tilt-rotor dynamics

Finite-time observer accurately reconstructs unknown variables

Control strategy ensures stable mode transition

Abstract

This paper presents a novel model of large-size tilt-rotor aircraft, which can operate as a helicopter as well as being capable of transition to fixed-wing flight. Aerodynamics of the dynamic large-size tilt-rotors based on blade element method is analyzed during mode transition. For the large-size aircraft with turboshaft engines, the blade pitch angles of the rotors are regulated to vary according to the desired level of thrust, and the following expressions are formulated explicitly: rotor thrust and blade pitch angle, drag torque and blade pitch angle. A finite-time convergent observer based on Lyapunov function is developed to reconstruct the unknown variables and uncertainties during mode transitions. The merits of this design include the modeling of dynamic large-size tilt-rotor, ease of the uncertainties estimation during the tilting and the widely applications. Moreover, a switched logic controller based on the finite-time convergent observer is proposed to drive the aircraft to implement the mode transition with invariant flying height.