| The wind tunnel test model, usually fixed on the support system by rear support during the test, is extremely easy to generate low frequency resonance coupled with the pressure of airflow pulsation. As a result, high magnitude vibration would be produced, which might reduce the data accuracy and even damage the instruments in a fatigue manner. When it comes to the vibration suppression using the conventional active vibration control, the time-delayed phenomenon caused by signal processing or data transmission can lead to the instability of the system. Therefore, considering the low-frequency characteristics of the model and the influence of the time delay appeared during the process of the signal acquisition, transmission and processing, it is quite necessary to research the active vibration control of the wind tunnel test model.A design method of controller with time-delayed acceleration feedback was developed to suppress the forced vibration of wind tunnel test model. Firstly, the mathematical model of the forced vibration was established through the model identification method based on the experiment data. Taking the time delay caused by the filter group delay in signal processing into consideration, the time-delayed system was then converted into equivalent delay-free system using the integral transformation method. Thirdly, the state-derivative pole placement method and Kalman filtering method based on the acceleration feedback were developed according to the different external excitation to estimate the system state and external excitation. Consequently, a controller for time-delayed acceleration feedback was designed based on the optimal control theory and Moore-Penrose theory. Finally, the numerical simulations and experiments are carried out to verify the ability of the controllers to suppress the forced vibrations. For the two different controllers, comparisons between them are given in terms of both simulation and experiment results. |
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