Reduction of Complexity of Manufacturing Systems through the Creation of Time-Dependent Periodic Complexity from Time-Dependent Combinatorial Complexity

Abstract

System integration requires that several subsystems, often made by different manufacturers, be assembled together seamlessly so that the overall system achieves the functional requirements (FRs) of the system. It must be done without compromising the independence of FRs. One of the FRs is the throughput rate of the integrated system. The integration process can be rather challenging when the subsystems are not exactly compatible with each other and when the modules that make up each subsystem have random variations in process times. This paper deals with the scheduling problem when two or more subsystems that have many independent modules for different processes with different fluctuating cycle times must be integrated. Such a situation may lead to a time-dependent combinatorial complexity that has an increasing number of combinations and thus, increasing uncertainty as a function of time. The performance of such a system can be improved by recognizing that the original problem is a timedependent combinatorial complexity problem, which can be transformed into a time-dependent periodic complexity problem through re-initialization at the beginning of each period. A “period” begins when the same key function re-initiates the subsystem, and its duration may vary if the process times of the modules have random variations. This approach to scheduling can be used to integrate many different kinds of systems such as factories with individual machines, manufacturing systems, supply-chain management systems for large retailers, and any system with two or more subsystems.