A decision support system for synchronizing manufacturing in a multifacility production system
This thesis describes the design of a decision support system for planning sign production at the Ohio Department of Transportation. The process of maintaining Ohio's rural roadways with visible traffic signs can be viewed as a 2- stage geographically, distributed manufacturing process; the first stage being sign manufacture at a central facility, and the second stage being sign installation at one of twelve districts. A strategy utilizing state space representation is proposed for finding low cost sign production and installation plans that are feasible for both the central shop and the twelve districts. The continual production of signs is necessary because of the fact that signs out on the road are constantly deteriorating. When the reflectivity of a sign diminishes to a certain level (as set by ODOT), the sign must be replaced. Replacement of signs is carried out by roadway crews in each district. In addition to sign replacement, roadway crews are responsible for erecting detours, installing RPM's, and painting lines. Thus the capacity of the districts to replace signs is dependent on the demand for these other activities. The development of the DSS is part of a major software project for the Department of Transportation. The state of Ohio is currently in the process of upgrading its sign management system. This involves development of sign field inventory data bases in each district and a sign replacement candidate identification system. The latter is a group of models that queries the field inventory data base and determines whether a sign should be replaced. Its list of candidate signs becomes input to the DSS. The functions of the DSS are to plan the activities of the roadway crews in each district and to plan production at the sign shop. As with any manufacturing system, low inventories are maintained by synchronizing the two stages in the process. Signs are not produced unless they have been designated as replacements, and no replacements are planned unless the respective signs can be produced in time. In addition to inventory cost, labor cost is considered. The generation of sign installation and production plans is carried out by two subsystems in the DSS: the Roadway Crew Activity Planning System and the Production Planning System. Both systems contain algorithms that use search with a state space representation. In both algorithms, demons and constraint rules are used to maintain feasibility by pruning the search space of infeasible solutions. The ability to share results across the search space is made possible by an underlying truth maintenance system. Once the state space is completely generated, alternative contexts can be evaluated.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:decision support system synchronizing manufacturing multifacility production
Date of Publication:01/01/1989