Research on Inner Circle of Micro Plastic Gear Based on Sub-Pixel Location

Due to the situation that gears’ defects are uncertain, the paper achieved the rough location of micro plastic gears’ inner circular contour by the method of determining-circle-with- three-points. The experiments showed that the running time by the new method is greatly reduced than that by the traditional Hough transform, and it can provide the primary dates for the sub-pixel location. Colligating the dimensionality reduction gray moment operator and the least square circle, the sub-pixel location of the inner circle centre was realized and the sub-pixel location precision was improved by applying the 3σ iteration algorithm. The results indicate that it can meet request on the automatic inspection of micro plastic gears.