Measurement of the vibration of a quartz pendulous reed based on multiple structuring elements and parameter mapping

There are stringent requirements for highly accurate measurement of the parameters of quartz pendulous reeds (QRP) in civilian fields and national defense technology. In order to meet them, a novel non-contact measuring method that uses visual images for acquiring QPR circularity parameters was proposed. The method can carry out automated optical measurements. The QRP images are obtained by a vision system, then the circular edges of the QPR are fully extracted using multiple structuring elements-based generalized morphological edge detection, diminishing the influence of noise in the images. In subpixel image processing, an algorithm for edge detection was proposed to locate the subpixel edges of the circular curve, and the circular edge location was identified by setting the mapping between the edge point and the parameters of the circle where the edge point lies in the image. Then, the estimation of the parameters for QPR based on a set of edge-point data was addressed by defining an error function and minimizing it. To achieve the desired degree of accuracy, a new error function was introduced. Experimental results showed that the algorithm is very accurate and stable, and the measuring accuracy is better than 0.03 pixels. The proposed method is very effective in detecting QRP parameters for real-time online measurements.