Design and Fabrication of Piezoelectric Actuators with Self-Position-Sensing and Long-Stroke

• Main Authors: Yi-Bin Jiang, 江益賓
• Other Authors: Wang Yu-Jen
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/99bgk7

碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 106 === In this paper, a novel piezoelectric actuator with long-stroke and self-position-sensing is proposed. The driving range (DR) of the piezoelectric actuator has been defined as the in-phase range for driving edge in x- and y-components. To extend the stroke of a piezoelectric actuator, the in-phase range and amplitude of the driving edge were analyzed by utilizing finite element method under various dimensions of driving electrodes. Simulation results indicate that the dimensions of the long-stroke piezoelectric actuator, which is comprised of the selected driving electrode, is 44.2×8×1.5 mm^3 and its theoretical stroke is approximately 37.5 mm. Furthermore, the driving range is also acceptable by the varied dimensions of the long-stroke piezoelectric actuators half and twice of the originals. The driving electrodes were screen printed on a piezoelectric plate, and a clip fastener was clamped to the plate by its spring force, which was driven by sequential excitation. To drive the piezoelectric actuator at its resonance frequency, a driving circuit based on a phase-locked loop (PLL) was used and the piezoelectric actuator could be therefore maintained on its resonant mode at each sequential excitation states. To achieve the self-position-sensing function, a pair of comb-shaped electrodes were designed and integrated into the piezoelectric actuator as a capacitive position sensor. A capacitance readout integrated circuit (IC) was connected to a microcontroller unit (MCU) by using an inter-integrated circuit (I2C). A digital filter based on the Kalman filter was developed to process the capacitance signal in real time and implanted in a MCU, thereby suppressing the noise of the capacitance signal. According to the variations in the capacitance signal of comb-shaped capacitive sensor, a sinusoidal-prediction equation was used to modify the adaptive Kalman filter as the specifically adaptive Kalman filter (SAKF) for this system. In the experimental results, the SAKF reduced the standard deviation from 200 to 30, and suppressed the noise ratio of the capacitance signal approximately 30%.