Design and analysis of piezoelectric transducer based resonant actuation systems

The objective of this research is to address some of the important design issues of the recently developed piezoelectric resonant actuation system (RAS) concept. The RAS is achieved through both mechanical and electrical tailoring. With mechanical tuning, the resonant frequencies of the actuation system (includes the piezoelectric actuator and the related mechanical and electrical elements for actuation) can be adjusted to the required actuation frequencies. This obviously will increase the authority of the actuation system. To further enhance controllability and robustness, the actuation resonant peak can be significantly broadened and flattened with electrical tailoring through the aid of an electric network of inductance, resistance, and negative capacitance. Therefore, one can achieve a high authority actuator without the negative effects of resonant systems. In this investigation, the RAS is analyzed and compared to an equivalent mechanical system to provide better physical understandings. Design guidelines of the RAS are derived in a dimensionless form, and the optimal values of the electrical components are explicitly determined. A method of implementing the actuator circuitry is proposed and realized via a digital signal processor (DSP) system. Performance of the resonant actuation system is analyzed and verified experimentally on a full-scale piezoelectric tube actuator for light class helicopter rotor control. The electric power consumption of the RAS is analyzed and discussed in terms of the power factor and apparent power. It is demonstrated that a piezoelectric resonant actuation system with proper tunings not only yields high authority with a broad frequency bandwidth but also is electrically efficient in terms of power consumption.