Active Authority Enhancement of Piezoelectric Actuator Design via Mechanical Resonance and Electrical Tailoring

In this research, a new approach is proposed to enhance the authority of piezoelectric actuators without the trade off between force and stroke. Through mechanical tailoring, the resonance frequencies of the actuator system can be tuned to the required actuation frequencies. This obviously will increase the authority (both stroke and force) of the actuator. However, resonant actuators could be hard to control and non-robust, due to its narrow operating bandwidth. This issue can be resolved through electric circuit tailoring. With the aid of a network of inductance, resistance, and negative capacitance, the actuation resonance peak can be significantly broadened and flattened. In this case, one can achieve a high authority actuator without the negative effects of resonance problems. The electrical networks can also achieve a fail-safe system due to its passive shunting characteristic. The proposed concept is evaluated and compared on three types of PZT actuators (benders, stacks and tubes) for trailing edge flap control of rotorcraft blades. Promising results are demonstrated, showing that the treatment can indeed create a high authority and robust actuator that satisfies the performance requirements of the example system.