Tracking Control System for Complex Shape of Welding Groove using Image Sensor

Abstract

This paper discusses an automatic weld-line tracking control system, in which a light sectioning technique by laser and image sensor is used for imaging the sectional pattern of joint groove and a microcomputer is used for image processing and producing the control output. The image processing method used here is applica-ble to various shapes of joint grooves, and even effective for the presence of pre-vious weld passes. Another feature of this system is that the picture pickup optical system is intentionally put out of focus; by processing this out-of-focus image, the detection resolution better than that determined from the number of image sensor elements has been successfully achieved. An automatic tracking controller based on this system has been applied to the large-diameter steel pipe production line of a steel mill, proving that it is practical and useful, and contributes to improvement of the weld quality and work efficiency.