A Vision-based Measurement System for Semi-Finished Cylindrical Geometries

This work describes a vision-based system for measuring the dimensions of a semi-finished cylinder in open forging, as a function of the rotation angle, in near real-time conditions. To evaluate the performance of the system, we designed a laboratory setup consisting of patterned cylinder at room temperature, with a diameter of approximately 70 mm that can rotate around a horizontal axis. A single camera observes the rotating cylinder and detects simultaneously the diameter and the rotation angle. Images were acquired with different resolutions, as well as at different distances from the cylinder. The tests have shown that, at a distance of 0.7 m from the measurand, the measurement systematic error in the diameter estimation is 0.22 mm with maximum resolution whereas uncertainty of the rotation angle was close to 5°.