OPTIMAL-CONTROL OF POLLING MODELS FOR TRANSPORTATION APPLICATIONS

We formulate and analyze a dynamic scheduling problem for a class of t ransportation systems in a Markov Decision Process (MDP) framework. A transportation system is represented by a polling model consisting of a number of stations and a server with switch-over costs and constrain ts on its movement (the model we have analyzed is intended to emulate key features of an elevator system). Customers request service in orde r to be transported by the server from various arrival stations to a c ommon destination station. The objective is to minimize a cost criteri on that incorporates waiting costs at the arrival stations. Two versio ns of the basic problem are considered and structural properties of th e optimal policy in each case are derived. It is shown that optimal sc heduling policies are characterized by switching functions dependent o n state information consisting of queue lengths formed at the arrival stations.