Measurement Of Shaft Diameters Based On The Vision Technology Of Point-array Structured Light

Traditional approaches of measuring shaft diameters focus on contact measurement,such as using a vernier caliper or micrometer caliper, which are difficult to achieve on-linemeasurement. Non-contact measurement method by machine vision makes it possible toachieve online measurement. Therefore, application of machine vision measurement tech-nology is paid great attentionin in many fields.Aiming at the shafts, this paper uses point-array structured light technology instructured light vision, and research on a method of diameter measurement.The followingrelated research work will be completed:(1) According to the linear and nonlinear models of camera imaging, this paper usesZhengyou Zhang’s calibration’s method based on plane and introduces two tangentialdistortion model and also changes the solving order of the pixel coordinate to the globalcoordinate. The calibration accuracy of the camera internal and external parameters will beimproved.(2) The two-dimensional Ostu method is used for the threshold segmentation of faculaein the image preprocessing. Faculae’s positions are extracted accurately by a fast faculacentroid extraction algorithm.(3) The lattice structure of lights are located in a light plane, the plane is calibrated inthe camera coordinate system. And then the calibrated camera model is used to calculate thespatial coordinates of the faculae. Finally, equation of the plane is fitted by the Least Squaresmethod.(4) Shaft diameters’ measurement model is proposed based on characteristics of thelattice structure of light and rotation properties of the shaft. This model overcomes thelimitations of multi-camera vision which is used for measuring shaft diameters, avoiding the complexity of multiple camera parameters’ calibration and making the operations moreconvenient.(5) Finally, using the available equipments to build an experimental measurementplatform, Feasibility and accuracy of the method proposed in this paper are verified bycomparison. And the relevant factors affecting the measurement accuracy of the model areanalyzed.