Decision-making algorithms in two-level complex operation system

A two-level manufacturing operation system composed of two interconnected subproblems, i.e. scheduling of independent, non-preemptive tasks on unrelated moving executors as well as motion control of a group of moving executors performing the tasks is investigated. As the performance index of the two-level system, the makespan is assumed. Three heuristic solution algorithms for the two-level system are presented. The first algorithm ensures the current modification of solutions for the scheduling subproblem during the decision procedure of the two-level system. In the second one, an iterative approach is applied, which consists in successive implementation of the solution algorithms for both subproblems. The third algorithm uses on-line procedure, which enables determination of the best solution in the current step of the decision procedure. Comparisons of the algorithms as well as a numerical example are also presented. D 2003 Elsevier B.V. All rights reserved.