RTWARP system
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RTWARP system configuration
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Slab before RTWARP
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Slab after RTWARP

Real-time hot slab warping control system (RTWARP) is a real-time video processing system working in hazardous steel plant environments. RTWARP controls the roughing mill to flatten the slab warp that causes serious impair of the roll and even stopping the steel production.

RTWARP detects and measures the curvature of the slab end in real time and controls the milling speed in real time. The RTWARP project was funded by POSCO for 3 years with $1.5 million budget. I joined RTWARP at its 2nd year (1994) as the main hardware and software engineer to developed the next generation RTWARP to enhances its performance and stabilize the system. RTWARP won several major awards and also copied to other steel plants successfully.


The slab warping caused by the slab upside and downside rolling mismatching factors causes equipment damage, lowered productivity by dummy passes and also defected slab quality problems. To come up with the innovative solutions, POSCO, POSTECH and RIST constitutes the joined project team in the end of 1992.

The team performed the extensive computer simulations and operating data analysis and found out the main causes. We also developed the advanced control method to flatten the slab by atypical up and down roll speed control. Based on these analysis result, we designed the innovative on-line slab warping control system. The first system run on December 1994 at POSCO 2nd thick-plate milling plant and installed the second RTWARP system in 1995 at POSCO 3rd thick-plate milling plant.


The RTWARP system works just 10 feet away from the slab heated over 1800 F (1000 C). Also to reduce the friction heat, the water cooler is applied that puts the slab in the vapor. Thus we needed the extremely stable computer vision system working in the hazardous environment where a human can not stand on without protection. Also in 1994 the personal computing power was not sufficient for real-time processing and we need some heterogeneous programming that utilizes the full power of the graphic board and the CPU both to catch up the fast moving slab over 20 meter/sec (66 feet /sec).


After applying RTWARP in the production line, the average warping of a slab reduced by 64% and the average thick error reduced by 45%.