Vision system for on-line characterization of paper slurry

This paper presents a detailed description or a vision system that detects and localizes the nonuniformities that appear on the paper slurry (wood fib er and water mixture) at the wet end of a paper machine. Specifically, the system monitors the paper slurry as it exits the headbox and alerts the ope rators of any event (e.g., streaks) that disrupts the otherwise homogeneous background. These events affect crucial product properties such as formati on. A poor formation results in thick and thin spots on the sheet and impac ts its strength and printability. This paper describes the Vision system in terms of its hardware modules, as well as the image processing algorithms that it utilizes to perform its function. The system acquires intensity and topographic information from the scene. It uses texture-based features for the detection and facet-based descriptors for the localization of the nonu niformities. In addition to being tested in a laboratory environment, a pro totype of this system was constructed and deployed to a paper milt, where i ts performance was evaluated under realistic conditions, installed on a fou rdrinier paper machine, running at 480 m/min and producing linerboard mater ial, the vision system monitored about al m wide area and successfully dete cted and localized slurry streaks. (C) 2001 John Wiley & Sons, Inc.