Solving Integrated Scheduling Problem with Precedence Constraint and Machine-State-Related Setup Time based on Improved DE
Integrated Scheduling Problem (ISP) addresses a production mode for personalized and trial products with large differences in product structure and process parameters. ISP flexibly arranges operations according to BOM sequence. As long as the conditions are met, the operation can be processed or assembled without waiting for a unified production beat. Due to the influence of temperature, precision machines need to be warmed up after a period of inactivity in order to ensure machining accuracy. The warm-up time of a machine can be considered as a kind of preparation time related to the state of the machine. To solve the ISP considering precedence constraint (PC) between operations and machine-state-related setup time (MSRST), a mathematical model is developed to minimize the total tardiness. To deal with the PC, a differential update operator (DUO), which can ensure that the operations subject to the PC, is proposed. To satisfy the MSRST, a decoding method based on the machine idle signal strategy (MIS) is proposed. At last, the improved differential evolution (DE) algorithm based on DUO and MIS is designed to solve the problem. The operation research optimizer OR-Tools is used as the control algorithm. Experimental results show that the proposed algorithm is effective and feasible and that it can get similar results to the control algorithm in a very short time.