Schedule guidance system for slab extraction sequence from furnace in hot rolling process

This paper describes a development of a schedule guidance system for a slab extraction sequence from the furnace. To improve productivity, it is necessary to optimize not only the extraction sequence but also a selection of the cooling facility. This scheduling problem is a multi-mode resource constraint project scheduling problem (multi-mode RCPSP) since it includes resource constraints and alternative processes that differ in a process time and occupied resources. The system is required to solve this problem in a short time in order to quickly redisplay a modified schedule, in which the difference between the actual and predicted process time due to an operational disturbance has been resolved. Moreover, the derived schedule from the system is expected to outperform the human operator´s result in the point of productivity and have high maintainability to respond flexibly to changes in operational constraints. We investigated some methods to solve this problem. As a result, we applied constraint programming (CP) which can solve this problem in realistic time and find semi-optimal solution.