Planning and operating sortation conveyor systems

• Applicants: Professor Dr. Nils Boysen; Professor Dr. Dirk Briskorn
• Subject Area: Traffic and Transport Systems, Intelligent and Automated Traffic ; Accounting and Finance ; Security and Dependability, Operating-, Communication- and Distributed Systems
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280446905

Sortation conveyor systems are at the very core of many crossdock terminals, operated e.g. by package delivery companies. In the scientifc literature the planning and operating of these kind of systems is mostly neglected. Literature is mainly concerned with analyzing the performance of predetermined systems or treat sortation systems as black boxes with predetermined behaviour. These approaches do not account for the opportunity to influence the system's performance by sophisticated coordination of flows of items through the system. The latter can be achieved on various planning levels.1. When planning the layout of a sortation system we can influence the positions of loading stations and, therefore, the travel distance between them. In multi-level sorter systems we can decide how many connections between two specific sorters to install and where to position them.2. When planning inbound streams and outbound streams, respectively, we can decide, e.g. the loading station used for the cargo delivered by a certain aircraft or the positions of containers to be loaded along the sortation conveyor. This influence travel distances of items and which transport streams partially overlap in their route.3. When scheduling and routing single items through the sorter system it has to be decided whether a certain items goes on the next free tray passing by (which means this tray is occupied when passing by the next couple of loading stations) or this tray is kept free for an item waiting at one of the next loading stations.The goal of this project is to close this reasearch gap. We will follow a bottom-up approach. First, we consider subproblems and develop efficient solution methods for them. Step by step we consider more integrated scheduling problems using the approaches developed for subproblems so far as building blocks. The final outcome is a method for integrated planning and scheduling, respectively, of sortation conveyor systems.The methodology used encompasses techniques from the fields of linear, integer, and mixed-integer programming, applied computer science (graph theory, e.g.), scheduling theorie, game theorie and computational complexity theory.

• DFG Programme: Research Grants