MULTILEVEL PRODUCTION CONTROL MODEL FOR FMS WITH DISTURBANCES.

A hierarchical flexible manufacturing system (FMS) is discussed. Three levels are considered--factory, section and machine--each level presenting a a different stochastic optimization problem. The machines are universal. The rates of demand and the due dates are pregiven deterministically. Each machine processes parts with several possible speeds which are subject to disturbances. On the machine level, the problem is to determine for each unit at every routine control point the speed to proceed with and the timing of the next control point. There are chance constraints for each unit of the machine and section levels; there should not be a shortage with a pregiven confidence probability. On the upper levels, the problem is to reassign the target amounts among various units or to relocate the resources whenever any of the units fail to meet the chance constraints. Because of the interconnected nature of the problem, a change in the parameters of one results in changes to the solutions of the others. However, the optimization problems as presented are nt cooridnated; this is pointed out as the next direction for the authors.