Methods for multimodal vibration suppression and energy harvesting using piezoelectric actuators

This paper presents a novel method for suppressing multimodal vibrations in structures by using the controlled harvesting and storage of vibration energy as electrical charge. Unlike a traditional semi-active system in which vibration energy is dissipated using a controlled variable dissipater, the proposed system harvests vibration energy for storage. The stored energy can then be recycled enabling the system to achieve a vibration reduction performance superior to that of a traditional semi-active system and approaching that of a fully active system. In the proposed method, an array of one or more precharged capacitors is employed to provide a selection of various voltages, which may be selected to approximate a desired control signal defined by an LQR multimodal vibration controller. The capacitors can apply a control voltage to the piezoelectric actuators and can also collect current generated by the actuators as the structure strains in vibration. Both a single capacitor system and a multi-capacitor system are considered and applied to a cantilevered beam. The response to impulse disturbances and random force disturbances are studied. The results are compared to a previously proposed energy harvesting based semi-active method. Advantages in both vibration suppression and energy harvesting performance over the previously proposed method are demonstrated. The multicapacitor method is found to be most effective due to its ability to apply sufficiently large control voltages while moderating large step inputs therefore reducing the excitation of higher frequency uncontrolled modes, which otherwise parasitically dissipate energy in the circuit resistance.