A Study On Semi-active Vibration Control Of Flexible Structures Using Macro Fiber Composite Actuators

With the wide application of large flexible structures in the spacecraft, the vibration problem of them has got more and more attention and research. Piezoelectric macro fiber composites have the advantages of light weight, strong driving performance and great toughness,which are suitable for the vibration control of space structures. Synchronized switch damping semi-active vibration control system is simple, the vibration control effect is stable, and it’s easy integration, lightly, and reliability, which meet the space requirements for high reliability and lightweight. This paper proposed the use of synchronized switch damping semi-active vibration control method to control the vibration of the flexible structures based on piezoelectric macro fiber composites.Firstly, according to the unsymmetrical high voltage operating range-500V~+1500V of MFC, a non-symmetrical switch circuit is designed for semi-active control method based on synchronized switching damping principle of piezoelectric actuators. The control logic of the switches is introduced in detail and the switched voltages, which directly affect the control performance, are derived as functions of the vibration amplitude and the outputs of the voltage sources. The simulation of the control system using MATLAB/Simulink is carried out to verify the feasibility of non-symmetrical synchronized switch damping technology. By the same time, the influence of the voltage source and bypass capacitor on the actuator is investigated by the simulation analysis.Secondly, an unsymmetrical high voltage semi-active vibration control instrument is designed; and the voltage leakage problem of MFC in open circuit during the control process is analyzed in detail. The effect of the switch frequency and the parallel capacitance value on the amplification of the switch voltage is also analyzed by experimental results. By testing the integrated semi-active vibration control instrument, the non-symmetrical synchronized switch damping technology can be achieved, and the experimental results are compared with the simulation ones.Finally, experiments of vibration suppression of a flexible beam and a large flexible space structure are carried out, the experimental results show that the designed non-symmetrical high voltage semi-active vibration control instrument can not only control the vibration of the flexible beam at low voltage, but also can realize high voltage inverse for the vibration suppression of large flexible structure. Compared with the traditional synchronized switch damping technique, the proposed unsymmetrical SSD technique can improve the efficiency of the use of the piezoelectric element with asymmetrical operating voltage range like MFC.