To provision material at a manual workstation, gravity roller conveyers with totes containing the material are widely used. But gravity roller conveyors are inflexible; if another product variant has to be assembled, the totes have to be rearranged manually which consumes time and comes at high costs due to the manual work force needed.

We want to develop a system which consists of a grid of rectangular conveyors which can convey into the four cardinal directions. Usually, most conveyors in this system are occupied by a tote, only few are empty. Therefore, most totes cannot be accessed directly. Instead, one or several empty cells have to navigate through the system to retrieve a tote. This is done in a manner similar to the 15-puzzle, a children’s game. For that reason we call this system a puzzle-based system. 

If we want to assemble a different product or product variant, the system has to be reconfigured: the totes containing the parts necessary to assemble that product variant have to travel to the front in order to enable the worker to pick the contained parts. Since picking is not possible during the reconfiguration of the system, our main objective is to minimize the number of moves needed to reach the desired configuration. This is also one of the main research questions within this project. Furthermore, we want to build a scalable and flexible system. We achieve this by using a modular and decentralized control: each conveying module has its own controller and modules communicate with each other in order to move the carried totes.