The Research On Roll Measurement Based On Moiré Fringe

The pitch and yaw measurement technologies are ripe, roll measurement is researched in the dissertation. Moirre fringe generated by two gratings was put forward to measure the roll angle, it breaks through the routine application of moiréfringe. Two principle formulas were educed, one shows the roll angle can be gotten by the width change of moiréfringe, the other shows it can be gotten by the angle change of moiréfringe. The first is independent of measurement coordinates, the other is determined by the position of two gratings in coordinates, so a uniform formula was built which satisfies with any position in coordinates. And emulation validated the two formulas. Measurement precision and resolution were analyzed, some subdivision methods are introduced, and a new subdivision method was given for the paper.To get the width and angle of moiréfringe for roll measurement, moiréfringe image is processed. First, moiréfringe is processed in airspace and frequency domain. Airspace processing wiped off noise mainly by median filter. Frequency domain processing is that the image is transformed by fast Fourier transform, then proper filter was selected to wipe off noise. The next processing was binarizing and thinning, and then get the thinning of moiréfringe.Different from information acquirement in traditional measurement field, according to the measurement principle in the paper, two methods, the least square...