Trapped energy gyroscopes using thickness shear vibrations in a partially polarized piezoelectric ceramic plate

A new type of gyroscope using energy trapping of thickness-shear vibrations excited by a parallel electric field is proposed. The vibrator of a trapped-energy gyroscope is constructed using a partially polarized piezoelectric ceramic plate and three electrodes on its surface, and the driving-detecting circuit includes the current detecting circuit. Prior to designing the trapped energy gyroscope, a method of controlling the resonant frequency of the vibrator by means of the electrode dimensions was identified from the measured impedance characteristics. Based on this method, the trapped-energy gyroscope on a 25-mm-square and 1.5-mm-thick PZT plate is constructed. The detection sensitivity of 2.8 mV/deg/s, which is proportional to the applied angular velocity, is obtained when the driving voltage is 2 Vp-p and the gain of the detecting circuit is 72 dB. Although the edge of the vibrator is firmly attached to the base, the Q(m) of the resonance is over 900 because of the energy trapping effect. This trapped-energy gyroscope is useful for highly reliable applications such as a yawing sensor for the vehicle stability control systems.