Development of a shipyard simulator based on Petri nets

There are many restrictions on production in the factory. The most efficient production schedule should be planned taking these restrictions into account. Professional skill is necessary to plan the best schedule. A schedule planner has to deal with so much information during production planning that it is difficult to plan the best production schedule with a consideration of so many restrictions. In this study we introduced the use of Petri nets to support such production planning with a computer. Petri nets have been widely used to simulate production because of their capability of modeling concurrency, synchronization, and sequencing in discrete-event systems. This paper reports on implementing a simulation system for the shipyard. We had already implemented a production planning support system for a shipyard that is a part of the computer integrated manufacturing (CIM) system in shipbuilding. Based on this system, we implemented a shipyard simulator that can simulate the production activity in the shipyard. We therefore have defined a shipyard model. The production conditions can be changed, and the efficiency of a schedule can be evaluated. This paper discusses the effectiveness of using a factory simulator. Received for publication on Oct. 5, 1998; accepted on May 12, 1999