Abstract
In recent years, precision positioning devices containing piezoelectric elements (PZT) with displacement amplitude mechanisms have been used in various fields. Numerous positioning devices have been developed thus far, however, the aim of these was to increase the displacement amplitude. We have developed highly precision positioning devices that use PZT and lever mechanisms. In contrast to existing devices, our devices are characterized by high speed positioning owing to a high resonance frequency. However, because this device uses the elastic deformation of a hinge structure, the resonance peak is considerably high. Therefore, we attached a damper composed of a viscoelastic material (VEM) and a restriction plate. As a result, the resonance peak became very low, but the gain property was reduced by several decibels in the low frequency range and this was a factor of the overshoot in the detailed analysis conducted in our previous study. Moreover, we proposed the modeling of a gain reduction area by the high-order phase lag elements, however, the modeling error was large, occasionally, because of the slope of the gain characteristic. In this research, we propose a method to model the gain reduction part using fractional-order transfer functions and demonstrate the effectiveness of the model by control experiments. Consequently, it will be possible the highly precision positioning to improve the transient response.
