Yipeng Wu

Novel Approach of Self-Sensing Actuation for Active Vibration Control

In a self-sensing actuator, the same piezoelectric element functions as both a sensor and an actuator. Due to their advantages of reducing the number of needed piezoelectric elements and true collocation of sensors and actuators, self-sensing actuators have attracted the attention of many researchers and many studies have been reported. Since the actuator signal and the sensor signal are mixed together in a self-sensing actuator, usually a bridge circuit is used to separate the two signals. It has been found that the two signals cannot be separate ideally, because the bridge is difficult to balance and the actuator signal is much larger than the sensor signal. In this study, the influence of the local strain on the output signal of a piezoelectric sensor is investigated numerically and experimentally. In order to delete the influence of local strain on performance of the self-sensing actuator, a new method using neural network is proposed to identify the strain of global vibration. The identified signal is used as feedback signal for an adaptive control system and the effectiveness in suppressing the beam vibration is verified in the experiment.

A new figure of merit for wideband vibration energy harvesters

The performance evaluation method is a very important part in the field of vibration energy harvesting. It provides the ability to compare and rate different vibration energy harvesters (VEHs). Considering the lack of a well-recognized tool, this article proposed a new systematic figure of merit for the appraisement of wideband VEHs. Extensive investigations are first performed for some classic figures for linear VEHs. With the common fundamental information obtained, the proposed figure integrates four essential factors: the revised energy harvester effectiveness, the mechanical quality factor, the normalized bandwidth and the effective mass density. Special considerations are devoted to the properties of wideband VEHs about the operation range and the average power in this domain which are related to the performance target of stable power output. Afterward, this new figure is applied to some literature VEHs and demonstrated to present good evaluations of wideband VEHs. Moreover, it exhibits the ability to point out the improvement information of the concerned VEHs further developments.

A frequency up-converting harvester based on internal resonance in 2-DOF nonlinear systems

This paper reports the design and experimental testing of a novel frequency up- converting piezoelectric energy harvester. The harvester is firstly approximated as a 2-degree- of-freedom cubic nonlinear system instead of the general Duffing systems. A 1:3 internal resonance innovatively applied in the frequency up-conversion approach is thoroughly investigated. Finally, the theoretical dynamic model confirmed by the experimental results clearly shows the effect of the frequency up-conversion.