Research On Two-dimensional Airfoil Active Flutter Suppression System With Structural Nonlinearity And Time-delay

In recent years,the method for flutter active suppression by controlling the output of wing's control surface angle,has become a kind of actual engineering technology that is expected to be applied in the aircraft industry. However,the past studies of wing flutter active control technology often neglected the time delay of control system and structural nonlinear factors of wing's model. In this paper,the dynamic influence of the wing flutter control system with time-delay and control surface free play nonlinear factors was studied by using three degrees of freedom two dimensional wing's model as the research object. The main research work as follows:Firstly,the hardware design of the active control system is accomplished based on the DSP processor,the ultrasonic motor as the actuator and each sensor,then the wind tunnel experiment platform has been built. The experimental tests and mathematical modeling of the ultrasonic motor are completed. At the same time,the PID motion control algorithm is designed,which realizes the accurate motion tracking control effect. Besides,the serial communication interface is designed,which is convenient for users to monitor the states of system.Secondly,the dynamic state equation of the wing section is established based on the theory of Theodorsen,and the flutter velocity of the wing aeroelastic model is obtained by using the root locus method. The H_? controller and ? controller are designed based on the robust control theory and constitute the wing flutter active control system with pneumatic elastic system of two-dimensional wing,and numerical simulations and wind tunnel experiments are performed under the condition of different wind speed. The simulation and experimental results show that the designed robust controller has good control effect on the wing's flutter.Thirdly,aiming at the time delay problem in control loop,this thesis introduced the group delay of digital filters in the output feedback signal to study the size of time delay factor effects on the wing flutter H_? and ? control system. And numerical simulations and wind tunnel experiments are also performed to compare the stability of robust controller.Finally,a three degree of freedom dynamic elastic model of the wing with control surface free-play nonlinearity is established and it also has been described in the form of the state equation. Through the structural design of the wing control surface,the control panel can produce different gap values in order to study the dynamic effects of the different size of control surface free play in the wing's model. Wind tunnel experiments show that the control surface free-play nonlinearity makes the wing flutter control system has a limit cycle oscillation,and it's also in line with the simulation results.