Decentralized control of a material flow system enabled by an embedded computer vision system
In this study, a novel sensor/actuator network approach for scalable automated facility logistics systems is presented. The approach comprises (1) a new sensor combination (cameras and few RFID scanners) for distributed detection, localization and identification of parcels and bins and (2) a novel middleware approach based on a service oriented architecture tailored towards the utilization in sensor/actuator networks. The latter enables a more flexible deploying of automated facility logistics system, while the former presents a novel departure for the detection and tracking of bins and parcels in automated facility logistics systems: light barriers and bar code readers are substituted by low-cost cameras, local conveyor mounted embedded evaluation units and few RFID readers. By combining vision-based systems and RFID systems, this approach can compensate for the drawbacks of each respective system. By utilizing a state-of-the-art middleware for connecting all computer systems of an automated facility logistics system the costs for deployment and reconfiguring the system can be decreased. The paper describes image processing methods specific to the given problem to both track and read visual markers attached to parcels or bins, processing the data on an embedded system and communication/middleware aspects between different computer systems of an automated facility logistics system such as a database holding the loading and routing information of the conveyed objects as a service for the different visual sensor units. In addition, information from the RFID system is used to narrow the decision space for detection and identification. From an economic point of view this approach enables high density of identification while lowering hardware costs compared to state of the art applications and, due to decentralized control, minimizing the effort for (re-)configuration. These innovations will make automated material flow systems more cost-efficient.
Ten Hompel, M.