2. Christos G. Cassandras CODES Lab. - Boston University ELEVATOR DISPATCHING PASSENGER QUEUES COMPLEXITY: Huge state space, Movement constraints, non-stationary distributions, etc.

3. Christos G. Cassandras CODES Lab. - Boston University ELEVATOR DISPATCHING CONTINUED UPPEAK DISPATCHING CONTROL PROBLEM:

4. Christos G. Cassandras CODES Lab. - Boston University ELEVATOR DISPATCHING CONTINUED Can be shown that the optimal policy minimizing average waiting time is a threshold policy with thresholds that depend on passenger arrival rate service rate Ref: Pepyne and Cassandras, IEEE Trans. on CST, 1997 Ref: Pepyne and Cassandras, IEEE Trans. on CST, 1997 WHAT DOES THIS MEAN IN PRACTICE? Load one car at a time – call this car the “next car” to be dispatched Dispatch the “next car” when: number of passengers inside car  

5. Christos G. Cassandras CODES Lab. - Boston University ELEVATOR DISPATCHING CONTINUED Variation in over 12 5-min. intervals for 1 hour uppeak traffic ( courtesy P. Powell, OTIS Elevator ) PROBLEM: How to determine thresholds, one for each 5 min. interval of fixed traffic rate? How to automatically adjust them on line?