Task Scheduling for Multiunit Parallel Test Using Mixed-Integer Linear Programming

Parallel test is an efficient approach for improving test efficiency in the aerospace field. To meet the challenges of implementing multiunit parallel test in practical projects, this paper presented a mixed-integer linear programming (MILP) model for solving the task scheduling problem. A novel sequence-based iterative (SBI) method is proposed to solve the model in reasonable time. The SBI method is composed of an implied sequence finding procedure (ISF) and a sequence-based iterative optimization (SBIO) procedure. The first procedure can reduce the search space by fixing free sequence variables according to the original test flowcharts, and the second procedure can solve the model iteratively in a reasonable amount of time. In addition, two indexes, namely, speed rate and average resource utilization rate, are introduced to evaluate the proposed methods comprehensively. Computational results indicate that the proposed method performs well in real-world test examples, especially for larger examples that cannot be solved by the full-space method. Furthermore, it is proved that the essence of the parallel test is trading space for time.