Optical EngineeringDynamic characterization of a microgyroscope by digital image spectrum correlation
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In order to have an efficient design methodology and achieve high-performance inertial instruments, it is important to analyze the dynamic characteristics of micromechanical vibratory gyroscopes. In this paper, a novel optical method based on a high-speed CMOS camera and digital image spectrum correlation is developed to measure the motion of the sensitive elements. Unlike digital image correlation (DIC) in the spatial domain, correlation in the spectral domain gives direct access to the whole image under translational motion, which retains all the advantages of DIC and provides an expanded range of measurement. In addition, the proposed method is much faster in computation and capable of calculating dynamic temporal serial images in real time. The proposed method is employed to obtain the displacement of temporal series images and to extract dynamical parameters such as resonant frequency and quality factor at atmospheric pressure. During dynamic testing, the discrete wavelet transform is employed to eliminate the low-frequency components, and the continuous wavelet transform (CWT) for identification of the frequency and damping ratio. Experimental results show that the proposed method is a direct inspection tool and a practical alternative to the conventional electrical measurements of micromechanical vibratory gyroscopes.