Study On Angle Measurement About In-plane Rotation Motion In MEMS

Micro-Electro Mechanical System (MEMS) develops rapidly and steps intoindustry in recent years. In MEMS industrialization course, many researchdepartments attach much more importance to MEMS testing technique. MEMSdynamic testing technique has obviously significant place in MEMS R&D andindustrialization.The MEMS testing technique of estimating the relative translation of two imageshas full developed at present, while the problem of estimating the relative rotation, onthe contrary, has received far less attention. There are some ways, which have lowresolution. We do much research about the method based on phase correlation andRadon transform, the method based on edge detection and Hough transform and themethod based on the invariability of center of mass of a fixed region, and ultimatelyget the conclusion that the method based on phase correlation and Radon transform isnot suitable for angle measurement of MEMS, while other two method are realize themeasurement of relative rotation with high resolution. The main contents of this papercan be summarized as follows:1. By studying on phase correlation and Radon transform, we propose a methodto obtain the angle of rotation by researching a peak of phase correlation function.MEMS images are transformed from Cartesian coordinate (space (x, y)) to polarcoordinate (space ( ?, ?)) via Radon transform. Thus the rotation for the image inspace (x, y) is converted to the translation in the space ( ?, ?). Finally theparameters of translation are obtained using the traditional 2D phase correlation.2. Take deep research of angle measurement method based on Hough transformand edge detection and get conclusion whether this method is suitable for MEMStesting. Edges will be extracted by using edge detector. Meanwhile, the edges will bepitched in sub pixel by interpolation. Hough transform can accurately get theparameters of the edges, and display feature points obviously. By compare referenceimage and input image, the rotate angle will be obtained.3. An improved rotation measurement method based on the invariability of centerof mass of a fixed region is put forward for better calculation precision. Given thespecial structures of MEMS which are left behind fabrication, we get several regionswhich have unattached object and smooth background. Filtering the noise and background, calculate the center of mass of respective regions, then the rotate angelwill be obtained by observing the changes about center of mass of given regions.4. Experiment about all this three method and analyze the measurement error.Propose approaches to decrease error to get high resolution.