Multiple Piezoelectric Transducers Research Articles

Assessment of Electrical Influence of Multiple Piezoelectric Transducers' Connection on Actual Satellite Vibration Suppression

We conduct comprehensive investigation of a semiactive vibration suppression method using piezoelectric transducers attached to structures. In our system, piezoelectric transducers are connected to an electric circuit composed of the diodes, an inductance, and a selective switch. Our method (SSDI) makes better use of counterelectromotive force to suppress the vibration, instead of simple dissipation of vibration energy. We use an actual artificial satellite to verify their high performance compared to conventional semi-active methods. As a consequence, we demonstrate that our semi-active switching method can suppress the vibration of the real artificial satellite to as much as 50% amplitude reduction. In our experiment, we reveal that the suppression performance depends on how multiple piezoelectric transducers are connected, namely, their series or parallel connection. We draw two major conclusions from theoretical analysis and experiment, for constructing effective semi-active controller using piezoelectric transducers. This paper clearly proves that the performance of the method is the connection (series or parallel) of multiple piezoelectric transducers and the their resistances dependent on frequency.

Experimental Implementation on Vibration Mode Control of a Moving 3-PRR Flexible Parallel Manipulator with Multiple PZT Transducers

This paper presents the experimental implementation of active vibration control applied to a moving 3-PRR parallel manipulator with three flexible links. The active vibration control is implemented using three piezoelectric (PZT) transducer pairs applied to one flexible intermediate link based on modal strain rate feedback (MSRF) control. A real-time active vibration control system is developed using two PCs with LabVIEW Real-Time. Modal analyses are conducted, and the results demonstrate that the vibration modes of the intermediate links are dynamically coupled and the vibration frequency components are complicated and closely spaced. Simplified and efficient modal filters are developed to extract modal coordinates in real time, and a second order compensator is used to filter amplified noises and unmodeled high frequency dynamics. A MSRF controller is then designed using an independent mode space control strategy, and is implemented experimentally with the first mode targeted for control. Experimental results demonstrate that the vibration amplitude of the first vibration mode of the intermediate link is significantly reduced using three PZT control pairs. The experimental results using one PZT control pair and two control pairs are provided to justify the use of three PZT control pairs.

A scalable micro-power converter for multi-source piezoelectric energy harvesting applications

This paper presents a conversion scheme based on active control for harvesting power from multiple piezoelectric transducers with higher efficiency than traditional passive approaches. The use of multiple sources is often mandatory for boosting up the available output power. The proposed approach guarantees that each source operates efficiently, especially in case of irregular vibrations and heterogeneous transducers. A prototype system was developed and validated in realistic conditions: three 0.5×12.7×31.8 mm3 Q220-A4-303YB transducers from Piezo Systems of different wear conditions loaded with 20g tip masses were stimulated with the vibrations recorded in a train passenger car at 100 km/h. The converter harvested up to 142 μW@0.22g-RMS and up to 90 μW@0.11g-RMS. With the latter vibrations the extra harvested power with respect to a standard passive electronic interface was at least 41%. The converter is modular and the number of sources can be easily increased.

Single-transducer dual-frequency ultrasound generation to enhance acoustic cavitation

Dual- or multiple-frequency ultrasound stimulation is capable of effectively enhancing the acoustic cavitation effect over single-frequency ultrasound. Potential application of this sonoreactor design has been widely proposed such as on sonoluminescence, sonochemistry enhancement, and transdermal drug release enhancement. All currently available sonoreactor designs employed multiple piezoelectric transducers for generating single-frequency ultrasonic waves separately and then these waves were mixed and interfered in solutions. The purpose of this research is to propose a novel design of generating dual-frequency ultrasonic waves with single piezoelectric elements, thereby enhancing acoustic cavitation. Macroscopic bubbles were detected optically, and they were quantified at either a single-frequency or for different frequency combinations for determining their efficiency for enhancing acoustic cavitation. Visible bubbles were optically detected and hydrogen peroxide was measured to quantify acoustic cavitation. Test water samples with different gas concentrations and different power levels were used to determine the efficacy of enhancing acoustic cavitation of this design. The spectrum obtained from the backscattered signals was also recorded and examined to confirm the occurrence of stable cavitation. The results confirmed that single-element dual-frequency ultrasound stimulation can enhance acoustic cavitation. Under certain testing conditions, the generation of bubbles can be enhanced up to a level of five times higher than the generation of bubbles in single-frequency stimulation, and can increase the hydrogen peroxide production up to an increase of one fold. This design may serve as a useful alternative for future sonoreactor design owing to its simplicity to produce dual- or multiple-frequency ultrasound.

Chirp estimation in phase-shifting interferometry

We propose a new approach for estimating the phase in the presence of a nonlinear response of a phase-shifting device: a piezoelectric transducer (PZT). The method is complemented well by the high resolution and the maximum likelihood estimation techniques in the estimation of the phase step and the nonlinear coefficient. The advantage of the proposed method is that it can be extended to the extraction of multiple phases in configurations involving multiple PZTs in the presence of nonlinearity. Symmetricity in the phase steps is not required in this method. Hence hysteresis of the PZT does not have any influence on the accuracy of the phase estimation. The effectiveness of the method is shown by experimental results.

Resolution-enhanced Fourier transform method for the estimation of multiple phases in interferometry

A phase shifting method based on high-resolution frequency estimation and Fourier transform technique is introduced. This method, also referred to as the eigenvector method, draws on the complementary strengths of both these methods. The salient feature of the method lies in its ability to handle nonsinusoidal wave-forms, multiple piezoelectric transducers, and arbitrary phase steps in an optical configuration. The method does not need the addition of carrier fringes to separate the spectral contents in the intensity fringes. The proposed concept thus overcomes the limitations of methods based on Fourier transform techniques. The robustness of the proposed method is studied in the presence of noise.

Parametric loudspeaker with improved phase characteristics

A parametric loudspeaker which uses multiple piezoelectric bimorph transducers (62). These multiple piezoelectric bimorphs (62) have a resonant frequency which varies from unit to unit. The phase response at and near the resonant frequency changes at a very high rate with slight changes in frequency. The associated modulator electronics have a primary carrier frequency that is optimized for maximum parametric output. This is achieved by aligning the carrier frequency with the flattest portions of the phase curve for maximum phase coordination among the multiple devices.

Energy-Recycling Semi-Active Method for Vibration Suppression with Piezoelectric Transducers

*A novel energy-recycling method is studied that enables effective semi-active vibration suppression with piezoelectric transducers embedded or bonded to a structure. In this method, the energy converted from the mechanical energy of a vibrating structure is collected in the capacitor of a piezoelectric transducer as an electric charge, and to suppress vibration, rather than dissipate the energy, the polarity of the charge is changed according to the state of vibration. With this method, no energy is supplied to the total system of the structure and transducers with shunt circuit, which means that the system is stable. A simple electric circuit and a control law for multiple-degree-offreedom systems with multiple piezoelectric transducers are proposed for this method based on energy recycling. Numerical simulation of vibration suppression of a truss structure shows that this method is more effective in suppressing vibration than both a semi-active method without energy-recycling and that based on the use of an optimally tuned passive system. A preliminary experiment with a truss structure also shows that this method can effectively suppress vibration in an actual structure. However, there was some discrepancy in the experimental results compared to the results of the numerical simulation performed assuming ideal linear characteristics of the piezoelectric transducers estimated from a static test. Nomenclature

Dynamics and Stability of Wideband Vibration Absorbers with Multiple Piezoelectric Transducers

This paper is concerned with the problem of dynamics and stability of piezoelectric laminate structures, in which several piezoelectric elements are shunted by a multi-input impedance. The problem is shown to be equivalent to a multivariable feedback control problem. A parameterization of stabilizing admittance transfer function matrices is given, and a specific class of controllers capable of reducing structural vibrations and guaranteeing closed loop stability is introduced. Experimental results are presented, demonstrating the effectiveness of the proposed methodology.