Magnetic contact-less speed measurement sensor for steel industries

Speed measurement in steel production is a common task for multiple purposes: fine control, strip coiler control, elongation. Nowadays, the most common method for this is the use of encoders in the rolls, but in some lines there is excessive sliding and new methods are required. Laser sensors offer high accuracy (around 0.1%) in the 1000 m/minute range, but their cost is quite high (over $10000). In this paper we explain a complete speed measurement system, using standard components, for steel lines, with a cost lower than $300, a range up to 800 m/minute and accuracy of about 0.4%.