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 vibra tions excited by a parallel electric field is proposed. The vibrator o f a trapped-energy gyroscope is constructed using a partially polarize d 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 controll ing the resonant frequency of the vibrator by means of the electrode d imensions was identified from the measured impedance characteristics. Based on this method, the trapped-energy gyroscope on a 25-mm-square a nd 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 det ecting circuit is 72 dB. Although the edge of the vibrator is firmly a ttached to the base, the Q(m) of the resonance is over 900 because of the energy trapping effect. This trapped-energy gyroscope is useful fo r highly reliable applications such as a yawing sensor for the vehicle stability control systems.