Product identity and its impact on discrete event observability

Sensing of the specific identity of products moving through the manufacturing supply chain is typically indirect. Usually, such information is inferred from local proximity data coupled with appropriate computer based tracking models which align this data to the last known point of identity recognition. So-called Automated Identification systems promise to address some of the limitations of these approaches by providing automated, ubiquitous, item level product identity information at any point in the supply chain. One interpretation of the impact of such a facility is in terms of the enhanced observability of the (discrete-event) state space which represents the production, storage, transportation and retail processes to which a product is subject during its life cycle. This paper examines this extended notion of observability and illustrates its impact on physical systems represented by such discrete event systems via a materials handling example. Practical implications for industrial control are also considered.