The Flight Control And Vibration Suppression Of Flexible Unmanned Aerial Vehicle

The unmanned aerial vehicle(UAV)with flexible wings can produce structure deformation under the normal flight,which may cause the coupling of low frequency vibration and rigid body movement.The coupling has serious effects in reliability and security of the aircraft.It is necessary to analyze the effect of coupling dynamics between flexible structure and the aircraft rigid body and stability problems of the flexible UAV.Therefore,aiming at the unmeasurable flexible modes,the flexible modal vibration and model parameter perturbation during cruise flight,this paper addresses the control problems between climbing and fixed high flight for a flexible UAV,study on the related issues.The main works are as follows:Firstly,Trim the original complete UAV model at different trimming angle of attack,trimming elevator and trimming airspeed within the flight envelope and produce a series of design points for standard linear model of the unmanned aerial vehicle in the process of climbing and fixed high flight.To test the step response performance of airspeed and altitude,the augmented tracking model was built based on the original object system,through integrating the tracking error.Secondly,without considering the model parameter perturbation,for some design point,two different methods,the LQR fixed point tracking control theory and the state regulators method,are considered for the control design of the unmanned aerial vehicle through the augmented tracking model,then the simulation was carried on the two control schemes,the results show that the designed controller can not only guarantee the stability and tracking performance index of the flexible unmanned aerial vehicle,but also suppress the vibration of the flexible modes in a better level.Finally,the whole process flight control of flexible unmanned aerial vehicle was researched.In order to use the least control law such that the system satisfies the requirements of the specified performance index in all design point,a common Lyapunov function of all the design points should be constructed.Furthermore,for the uncertainty problem caused by the model parameters,a flexible modes observer based controller is first designed for the nominal system to guarantee the stability and the expected performance index,then the disturbance observer is constructed to estimate the influence of the parameter perturbation which is compensated by the feedforward.The simulation results show that the proposed method can guarantee the performance index of the UAV in flight process,and it has good robustness to the model parameter perturbation.