Improvement of Static Characteristics of Force Sensor Using Piezoelectric Ceramics.
Hidetoshi Ohuchi, Tasuku Osada, Toshio KASAI · Journal of the Japan Society for Precision Engineering · 2001
This paper deals with a piezoelectric force sensor with static sensitivity and the improvement of the static characteristics. It is difficult for an electric-charge type force sensor to have static sensitivity because of the leak of the charge. On the other hand, the piezoelectric element has electrical resonance characteristics, and the resonance frequency is slightly shifted by the impedance change due to the applied stress. The voltage induced to the sensor element corresponds to the given load when it is oscillated with the fixed frequency near the resonance and with the alternating current of constant amplitude. It has been confirmed that the output stability is maintained and the drift is made negligible when the oscillation frequency is strictly fixed and that the hysteresis between the load and the sensor output is removed when the amplitude of current is kept constant by the feedback control. The force is applied directly on the sensor without converting the force into the deformation of elastic material. Then, the sensor can be made thin and it will be expected to be used in the wider application fields.