Event-based recognition and source identification of transient tailbacks in manufacturing plants

Automated material handling systems in complex manufacturing plants oftentimes exhibit, possibly transient, tailback phenomena, which reduce a production line´s throughput. In order to identify origins and causes of observed tailbacks, historic event log data of loads passing certain waypoints has to be inspected. This paper introduces an approach to automatically carry out transient tailback recognition and cause identification. The approach is based on analysis of holding times and capacities of transport segments. As a result, complete lists of tailbacks and affected segments are provided. Each tailback consists of a reconstructed queue of loads waiting for preceding loads. For each tailback an initial cause event is determined. Additionally, identified tailbacks can be ranked by length or by impact on the transport delays. The developed demonstrator frees the user from time consuming visual inspection of log files by providing clearly represented complete tailback information instead.