Computer vision assisted measurement of the displacements of a bimorph piezoelectric cantilever beam

A computer vision assisted displacement measurement technique is proposed in this study. A sharp micro-marker is used as the marker of the bimorph piezoelectric actuator (PZT-5H). The micrometer actuation of the PZT-5H is monitored by a high resolution stereomicroscope. The micro-marker actuation is recorded as the driving voltage increases. Post image processing of the captures are conducted by MATLAB. The extracted vertex pixel values of the micro-marker from the captures are used to represent the PZT-5H actuation. The driving voltages are varied from 0 to 190 V which induce maximum displacements of 300 μm (1029 pixels). The proposed system can resolve a minimum displacement of 248 nm (1 pixel). Voltage to displacement linearity and repeatability are investigated. The PZT-5H chip has good linearity with driving voltages between 10 and 90 V. Future applications of this measurement technique are discussed.