Research On Longitudinal Attitude Control Technology Of Tilt Rotor During Transition

Tilt-rotor aircraft is a new type of aircraft, it combines the advantages of helicopters and aircraft, which Not only can take off and land vertically and hover in the air, but also fly forward fast, Therefore, tilt-rotor aircraft is the research focus of the aviation industry. The key of the control system design is to achieve a smooth transition between two flight modes.The design of flight control system with excellent performance need a mathematical model which can objectively reflect the aircraft motion. The tiltrotor aircraft model is improved in this article to enable it to run correctly.Through analyzing the flight characteristics of the tilt-rotor aircraft, The modeling of the tilt-rotor aircraft's wings, fuselage, horizontal tail, vertical tail and the rotor is respectively and separately established in this article. Then get the overall aerodynamic model and nonlinear equations of motion.The safety and efficacy of the tilt-rotor's flight is largely depends on its flight control system performance. In the transition mode, the aircraft speed keeps increasing, the changing of the aerodynamic layout exists, the stability is poor and the aircraft aerodynamic interference is serious, the mode switching needs to control. Therefore, the transition mode control system is the main difficulties of the tilt-rotor aircraft development. Tiltrotor aircraft mode of transition is mainly reflected in the vertical plane tilting nacelle systems, in the processing of the nacelle system, the aircraft's aerodynamic configuration change is mainly reflected in the vertical plane, so this paper studies the vertical Channel of the tilt rotor aircraft. In addition, the tiltrotor aircraft is hoped to keep the same height when it dump from helicopter mode to fixed-wing mode.Therefore, this paper mainly studies the Longitudinal channel operation principle, conversion program and flight control system design in transition mode.First, this article studies the manipulation and conversion program and designs corridors curve. Based on the nonlinear model, trim and linearization on operating point is finished. Then linear controllers are designed for the helicopter mode, transition mode and fixed-wing mode.This article designes the nacelle's speed scheme to track the corridor curves.Based on the three modes of imitation of nonlinear and robustness analysis verify the control programs, conversion programs, and control law are correct.Finally a three-dimensional visual simulation is finished.