An Application of Constraint Programming to Generating Detailed Operations Schedules for Steel Manufacturing

摘要

We present an overview of a system developed by IBM for generating short-term operations schedules for a large steel manufacturer. The problem addressed by the system was challenging due to the combination of detailed resource allocation and scheduling constraints and preferences, sequence dependent setup times, tight minimum and maximum inventory level constraints between processes, and constraints on the minimum and maximum levels of production by shift for each product group. We have developed a domain-specific decomposition based approach that uses mixed-integer programming to generate a high-level plan for production, and constraint programming to generate a schedule at fine level of time granularity taking into account detailed scheduling constraints and preferences. In this paper we give an overview of the problem domain and solution approach, and present a detailed description of the constraint programming part of the system. We also discuss the impact the system is having with the customer on their manufacturing operations.