Design Of Full Mode Control Law For Unmanned Tiltrotor Aircraft And Research On Integrated Navigation Algorithm

The tiltrotor aircraft combines the advantages of helicopter and airplane,with the characteristics of helicopter air hovering and vertical takeoff and landing,as well as the high-speed flight performance of the airplane.However,the tilting of the nacelle causes aerodynamic shape chages,especially the strong coupling between channels and surface redundancy in transition flight mode,which brings great difficulties to design the flight control law.In this paper,the small unmanned tilting rotorcraft is taken as the research object,the design of flight control law and the development of integrated navigation algorithm based on low cost sensors are studied,aiming at achieving full-mode flight.Firstly,based on the mechanism modeling method,the aerodynamic and moment models of the tiltrotor aircraft components are established.According to the momentum theorem and the momentum moment theorem,the six-degree-of-freedom dynamic equations of the tilting rotorcraft are obtained,and the nonlinear flight dynamic mathematical model of tiltrotor aircraft is established,which provides a model basis for the design of full-mode flight control law.Secondly,the full-mode flight control law of an unmanned tiltrotor aircraft is designed.Aiming at the problem of control surface redundancy and channel coupling in the transition process of tiltrotor,the rudder distribution strategy and the control channel switching strategy of the aircraft in the transition mode are studied,and the attitude controller based on active disturbance rejection control is designed.According to the characteristics of flight control,the structure of the active disturbance rejection controller is optimized,the order of the extend state observer is reduced,and the differential output of the tracking differentiator is used as the attitude angular rate instruction to simplify the structure of the attitude controller.The accuracy,stability and robustness of the active disturbance rejection control are verified by simulation.Then,a low-cost integrated navigation algorithm of MEMS/GPS is designed.The main error sources of the MEMS sensors are analyzed.The fast calibration and compensation algorithms of gyroscopes,accelerometers and magnetometers are designed.The extended Kalman filter model of MEMS/GPS integrated navigation system is derived.On this basis,the software design and embedded implementation of the integrated navigation system are completed.Finally,the digital simulation of the full-mode flight control law of the unmanned tiltrotor aircraft is carried out,and the flight control simulation model of the tilt-rotor aircraft is built,the validity of the control system,the rationality of the rudder distribution and channel switch strategy are verified.The performance analysis of the integrated navigation system is completed,which shows the feasibility and effectiveness of the integrated navigation algorithm.