Automatic concentricity measurement by image processing

Responding to the market demand for high quality and production limited quantity and variety, the automation technology of flexible manufacturing system or computer manufacture system has been developed. During the automated manufacturing, the instability of product quality depends to some degree on different precision of machine tool, qualification of operators and manufacturing technology. In addition, the utilization of traditional manual measurement or off-line contact quality inspection reduce productivity. Therefore, the technology of non-contact on-line product quality inspection is becoming a very important research issue. This report focuses on the setup of non-contact automatic measurement of concentricity by applying personal computer and image processing technologies. LOG and zero-crossing method are used to complete image edge detection. Then curve-fitting is applied to generate the inner circle and outer circle of mechanical parts. Subsequently, the coordinate of edge points of the inner and outer circles, together with the least-square error method, will be applied to estimate the concentricity of the mechanical part waiting for inspection. Comparison of the result of experiment with the data measured by a FEDERAL high-precision roundest equipment indicates that the proposed system exhibits good repeatability and accuracy