Research On The Energy-fuzzy Based Active Vibration Control Of A Cantilever-like Structure Excited By Aerodynamic Loads

The system of the aircraft and the support structure has a low stiffness in the direction of the pitching.In the wind tunnel experiment,especially at the large angle of attack and the transonic speed,the low frequency large vibration is easily produced,which seriously affects the measurement of the aerodynamic load of the model.This paper describes the development of a fuzzy adaptive PD controller for the active vibration control of a cantilever-like structure which is excited by aerodynamic loads.The vibration energy and the excitation power are selected as the reference condition of the process and are utilized on-line to determine the parameters of the PD controller via fuzzy rules and reasoning.An experimental system is designed and established,and verification experiments are conducted under both subsonic(0.6 Ma)and transonic(0.8 Ma)conditions.The results demonstrate that the proposed controller has a better performance and adaptiveness in comparison with the traditional fixed gain PD controller.(1)First of all,the overall vibration energy stored in the system(both the model and the supporting structure)is estimated by acceleration signal,which is able to characterize the current vibration intensity.Due to the restriction of testing environment,the vibration of the system can only be measured by an acceleration sensor installed inside of the model.The vibration energy stored in the system,in the form of kinetic energy and potential energy,is accumulated when the system is stimulated by the aerodynamic load.Kinetic energy includes that of the model and that of the sting,and potential energy includes elastic energy stored in the sting and gravitational potential energy of the model.By describing and analyzing the motion state during the system's vibration.A system vibration energy estimation method based on model acceleration signal is proposed,which provides reference input for fuzzy adaptive controller.(2)And then,the excitation power of aerodynamic loads is estimated which is able to evaluate the trend of the structural vibration.To estimate the average exciting power of aerodynamic loads,we need to remove the energy change contributed by the output control force from the variance of vibration energy,and thus the average output power model of the damper need to be built.The excitation power of aerodynamic loads is another reference input of the fuzzy logic controller.(3)And finally,the estimations of vibration energy and the excitation power are fuzzified so that they could be processed by a fuzzy controller which determines the parameters of a PD controller.From the perspective of energy,the proposed control strategy takes the vibration intensity and excitation strength into account,which makes the algorithm and active vibration control system possess better adaptability to the change of experimental environment.(4)The energy fuzzy adaptive PD controller and vibration reduction system are tested by wind tunnel experiment.In order to verify the feasibility and effect of proposed system and controller,verification experiments are carried out in the both subsonic and transonic wind tunnel condition.The active vibration control ability is better than the PD controller,and the RMS of vibration is reduced by more than 10% under all working conditions.