The Stereoscopic Width Gauge DigiScan XD500, designed for installation above the strip in cold rolling mills and processing lines, is state-of-the-art technology for measuring the width and centerline of cold strips or plates.
The stereoscopic arrangement permits high on-line accuracy despite material hop, tilt, lateral movement, and thickness variation.
DELTA Stereoscopic Width Gauge employs an advanced digital edge detection process that captures the digitized camera data. Software routines running on the high-speed embedded processor perform sub-pixel edge determination in two-dimensional space.
The camera data is filtered using a high-speed Infinite Impulse Response (IIR) digital filter. Sub-pixel edge locations are then determined based on the second derivative of the pixel data.
With two sub-pixel edges from each camera, the true width of the material is calculated using geometric triangulation. These trigonometric functions allow very accurate width measurement in spite of the influences of material pass line variations, thickness variations and flutter.
The gauge has an integrated Web server and the connection to the gauge with any Web browser, from a PC or a tablet, gives an access to gauge measurement data and configuration parameters. Remote access is possible for diagnostic assistance.
The DigiScan XD500 with built in Ethernet connection, integrated digital inputs / outputs and analogue outputs, has a very flexible communication architecture and can easily be connected into any automation system.
Two-dimensional calibration is performed prior to delivery by placing a calibration fixture at several positions. Calibration is accomplished by collecting camera pixel data at these referenced positions and then the stereo optical parameters are estimated.
The width gauge is delivered calibrated in our factory. The installation’s position is not critical as the stereoscopic cameras will compensate for any variation in the distance between the strip and the gauge.
Verification of accuracy and standardization
The DigiScan XD500 can be supplied with an active verification fixture, including a certified mask with 10 slots plus red LED simulating different strip widths. If the accuracy does not comply with the specification, a standardization can be made and the correction coefficients will be computed based on the measurements of the mask.
The verification is executed in a few seconds. All data are logged and can easily been retrieved from the web browser.