60 likes | 377 Views
Elevator Group Control Problem – Stochastic and Dynamic Vehicle Routing Problem. Janne Sorsa, janne.sorsa@kone.com Supervisors: Prof. Harri Ehtamo (HUT) Dr. Marja-Liisa Siikonen (KONE). Background. EGCP: Integer programming based methods not found in literature
E N D
Elevator Group Control Problem – Stochastic and Dynamic Vehicle Routing Problem Janne Sorsa, janne.sorsa@kone.com Supervisors: Prof. Harri Ehtamo (HUT) Dr. Marja-Liisa Siikonen (KONE)
Background • EGCP: • Integer programming based methods not found in literature • Multi-deck control methods not available in literature • Contribution: Complete formulation and solution method ready for implementation for multi-deck elevators • SVRP: • Modeling framework and terminology • Typically optimal policies solved with heuristics • Contribution: practical way to solve SVRP to optimality for an on-line optimization
Modeling and Analysis • Formulate VRP as • Generalized Assignment Problem as Integer Programming Problem • Traveling Salesman Problem for an elevator as stochastic optimal control problem • Solve GAP with Genetic Algorihm • Solve TSP as a Certainty Equivalent Controller (CEC) • Simulation of several case studies: • Measure computation time • Compare service level to other algorithms
Results • Method realized for on-line optimization • Linear growth of computation time with respect to problem size • Optimization based method beats heuristics in passenger service level • Objective affects directly to the corresponding service level statistic • Objective of optimization not straightforward for double-deck elevators
Conclusions and the way forward • Practical approach, which works in reality! • Future research: • Pickup and Delivery Problem formulation (partly done by Ruokokoski, 2007) • Integer Programming solution • Theoretical properties (lower bounds for WT etc à la Bertsimas and van Ryzin) • Effect and reliability of forecasting accuracy (HUT 2008?)
References • Closs, 1970. The Computer Control of Passenger Traffic in Large Lift Systems. PhD Thesis • Google Scholar: 7 • Scopus: 4 • Bertsimas, van Ryzin, 1991. A stochastic and dynamic vehicle routing problem in the Euclidean plane • Google Scholar: 117 • Scopus: 49 (Transp. Sc., EJOR, OR)