| The Quad Tilt Rotor(QTR)is a new configuration aircraft with heavy lift VTOL and high speed forward flight.According to the shape characteristics of Quad Tilt Rotor,flight dynamics model of the quad tilt rotor aircraft was developed,a set of applicable manipulation strategy was proposed,and the problem of redundant manipulation was solved.First of all,the rotor aerodynamic model was established by using the blade element theory,the wing aerodynamic model was established based on the wing slipstream and free stream theory,the aerodynamic model of the fuselage and the vertical fin calculated by CFD was established,and combined with the case of gravity center changed by the forward tilt of the nacelle,the 6DOF nonlinear flight dynamics model of QTR was established.According to the configuration of Quad Tilt Rotor,three manipulation strategies were proposed for different flight modes,and the simulation model was built based on the MATLAB/Simulink environment.The control methods used for each channel in different modes were determined by the trim of whole envelope and the analysis of control efficiency at various speeds.Control inputs were combined by implying the minimum control energy principle.The coefficients of each control inputs were given,and the problem of redundant manipulation was solved.Taking the minimum power for the aircraft as the objective function,the pitch angle corresponding to the minimum power at different speeds was determined.Finally adding the boundary restriction condition to trim,compare and analyze two tilting strategies of synchronous/asynchronous tilting in the transition mode.Selecting the synchronous tilting strategy as the tilting strategy of the QTR.Finally,based on the small disturbance hypothesis,QTR's state matrixes were obtained by linearization for analyzing its stability and control.Stability and control contain the nonlinear responses of the QTR and coupling of each channel.Ultimately,the feasibility of manipulation strategies was verified. |
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