In a prototype for monitoring hot steel wire different technologies are integrated to achieve a robust, flexibly configurable and scalable imaging system. It is designed as a distributed system with private network and Tuplespace communication implementable on a LINUX Server. Intelligent cameras grab and process the image data. For real time communication between the cameras and standard industrial I/O-modules (IEC-61131) MODBUS/TCP messaging is applied. A switch with integrated firewall makes services available to the supervisory control system. Results are available as XML-logfiles. The image processing defines the upper and lower edges of the material by minimum/maximum filtering of the y-gradient. Dual Grassmanian coordinates are used to fit two parallel lines to the edge points by singular value decomposition. This gives the distance between the lines and the confidence interval of each measurement simultaneously, whereas latter is used to reject poor data. Changes of the distance are analysed computing local central moments. Presently, 12 images per second are acquired. The application is able to detect spontaneous rotation of the wire around the axis of rolling directly at the rolling stands and treats also poor images (due to steam of cooling water). It indicates resulting defects, which may go undetected otherwise.
This paper presents a prototype system to monitor a hot glowing wire during the rolling process in quality relevant aspects. Therefore a measurement system based on image vision and a communication framework integrating distributed measurement nodes is introduced. As a technologically approach, machine vision is used to evaluate the wire quality parameters. Therefore an image processing algorithm, based on dual Grassmannian coordinates fitting parallel lines by singular value decomposition, is formulated. Furthermore a communication framework which implements anonymous tuplespace communication, a private network based on TCP/IP and a consequent Java implementation of all used components is presented. Additionally, industrial requirements such as realtime communication to IEC-61131 conform digital IO’s (Modbus TCP/IP protocol), the implementation of a watchdog pattern and the integration of multiple operating systems (LINUX, QNX and WINDOWS) are lined out. The deployment of such a framework to the real world problem statement of the wire rolling mill is presented.