Study on Model and Simulation of the Tilt Rotor Aircraft in Transition Mode

Abstract

In recent years, tilt rotor aircraft has been greatly developed because of its excellent performance. However, because of the complicacy in transition mode study on this aircraft is needed. In this paper a six degrees of freedom dynamic model of the tilt rotor aircraft was established, and PID controller was chosen when the aircraft in transition mode. Meanwhile, a defined S-function was used to solve the nonlinearity of the dynamic equations in real time and a simulation model is built in Matlab/Simulink. The results of simulation show the system is stable and provide a reference for analysis of tilt rotor aircraft dynamic and design of its flight control system. Introduction Tilt rotor aircraft, combined the vertical lift ability of helicopters and the speed of fixed-wing aircrafts, has been a great development in recent years [1]. And it also has a bright future in military and civilian application [2]. Researchers at home and abroad have made a great number of researches on the aircraft dynamic model [3-6]. However, most of them build the model using linearization techniques which make the result of simulation inaccurate because of the ignoring of high order element. In this paper, tilt rotor aircraft is a main research object, then its force and moment in the transition mode are analyzed. A six degree of freedom dynamic model of the aircraft is established by the Newton-Euler method. And a PID controller is used to make its attitude tend to stable quickly. In order to solve nonlinearity of the model, a defined S-function is used to express the state equations when the simulation model is established [7]. Dynamic model Firstly, the Euler angle need to be defined and a rotation matrix BE L as equation (1) presented [8]. BE c c c s s = s s c c s s s s c c s c c s c s s c s s s c c c L θ ψ θ ψ θ φ θ ψ φ ψ φ θ ψ φ ψ φ θ φ θ ψ φ ψ φ θ ψ φ ψ φ θ −     − +     + −   (1) where θ φ , andφ are yaw, roll and pitch angle, respectively. There are three phases of the tilt rotor during its flight phase. 1) Helicopter mode. In the Fig.1, the main features of this aircraft is a nacelle is located at the position which far from the wing root .When the angle between the nacelle and the body is 90, this aircraft is a helicopter rotor. 2) Fixed wing mode. The aircraft is similar to a fixed wing aircraft with four propellers when the rotor nacelle parallel with the body. 3) Transition mode. The process of flight between the helicopter mode and the fixed wing mode is called a transition mode. International Conference on Advances in Mechanical Engineering and Industrial Informatics (AMEII 2015) © 2015. The authors Published by Atlantis Press 1386 Fig.1 Tilt Rotor Aircraft Kinematics model. Using the equation (1) gives the aircraft translational kinematics equation: T BE x u y L v z w         =                (2) where , u v and w are the velocity of aircraft in the inertial frame. And the aircraft rotating kinematics equation can be given as follows: .