Patent attributes
A method for determining a node based penalty for use in a path finding algorithm for an automated material handling system (AMHS) is described. The AMHS includes a track interconnecting a plurality of nodes, and on which a plurality of material transport vehicles (MTVs) move. In particular, each of the nodes and MTVs provide queue-blocking data that is stored in a queue-blocking database along with a time tag indicating the time the data was collected. The AMHS retrieves data from the queue-blocking database that has a time tag within a predetermined time window and determines a queue blocking metric for each node in the material transport system. The queue blocking time is converted from to a node based penalty that is the additional distance that an MTV would travel while blocked. Thus, the node based penalty distance is added to the physical distance between a pair of nodes to provide a distance metric indicative of the current traffic conditions. The AMHS receives a source node and a destination node from a material control system and determines all possible routes between the two nodes. The distance metric for each route is computed and the AMHS selects the route having the shortest distance metric.
