Centerline-based measuring method for endpoints of tube

For the problem of high-accurate measurement for the endpoints in tube system, a centerline-based measuring method was proposed. The principle of machine vision was utilized to extract the centerline of a tube from its image taken from a camera, and the endpoints were located with assistance of the extracted centerline. A stereo-vision reconstruction method was used for spatial coordinate calculation of endpoints and the relative position of two points was further calculated. Experimental results showed that the maximum absolute deviation between measured values and tube's true value was 0.136 mm, and the maximum relative deviation among the measured values was 0.306 mm. The easy-computation and high efficiency of this method were proved as well, which enhanced the measurement accuracy effectively.