Assisted localization methods for automated handling processes in the material flow based on electronic marks
Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics
Final Report Abstract
Project ASEM focuses on automation in the field of logistics. The widespread use of RFID (radio frequency identification) in supply chain management over the last decades, mainly for object tracking and identification, provided the impetus for an amount of novel RFID-based applications. From SCM (supply chain management) systems, to tool sharing and RFID-assisted guidance systems for AGVs (automated guided vehicle), the Institute of Transport and Automation Technology furthermore demonstrated an RFID-based positioning system for cardboard boxes which enabled their automated handling with the aid of respective manipulators. The results include the papers titled “Package localization in a warehouse environment by means of RFID” and “RFID-Assisted Detection and Handling of Packages” which set the standards for such applications. Therein, methods were presented for positioning HF (high frequency) tags with a positioning accuracy in the order of under 2 centimeters. Furthermore, a complete automated positioning and handling process of cardboard packages based on HF RFID tags was shown, thereby demonstrating the use of RFID tags as qualified robot sensors. The whole concept was based on an RFID-assisted cognitive manipulator i.e. a robot in position of identifying the content and calculating the position of packages equipped with RFID tags. The advances during the final year of project ASEM over the previous results reflect upon the enhancement of the processing velocity, upon an optimized positioning accuracy, and upon lower processing costs. Based on the principles of the previously developed tracking system, a new one was conceived and constructed. Contrary to the previous one, the new tracking system was not integrated into the gripping system, thus making the positioning and the handling process independent from one another, which was essential in decreasing the time consumption. The new tracking system was designed so as to be integrated inside the conveyor system employed for the transportation of the packages. After studying the operation of common commercial conveyor systems, we presented methods for integrating miniaturized HF RFID readers in roller based, as well as belt based conveyor systems and concluded upon optimal positions for the antennas. In continuation we selected a belt based conveyor and developed a “plug and play” tracking system with the possibility of integration into the majority of all commercial linear belt conveyors. Regarding the time needed to process one package, the new system allows positioning algorithms to run while the package is still in motion, thus eliminating completely the need to halt the material flow. The tracking system calculates with the aid of two RIFD tags the position of a vector, which executes a translation on top of the conveyor system. Additionally, it acquires data stored from inside the memory of the RFID tags regarding the content and the weight, as well as the geometrical properties of each package. With the aid of this information, when the package reaches the working envelope of the manipulator it can be effectively grabbed and stored or further processed. In terms of positioning accuracy we demonstrated a more literate way to interpret the data acquired from the tracking system while remaining in the area of 1-2 centimeters in accuracy and optimized as much as possible compared to the previous process. In terms of lowering the total cost we eliminated the extra antenna, employed for the acquisition of stored data and more important we decreased the necessary amount of the tags from 3 to 2. Though the price of one tag does not exceed 60-80 cents, it represents 2-20% of the total packaging cost and in large warehouses it can sum up to millions. In terms of implementing new technologies, part which mainly focused on developing and applying a tracking system operating in the UHF (ultra high frequency) band by employing commercial equipment, the results based on state-of-the art devices presented that this case is not possible without extra modification and customization. Though the herein presented results for the HF band are conclusive and leave little possibilities for improvement, the results from the experiments with UHF RFID devices present the possibility for vast improvement and the fulfillment of the original objective of a tracking system operating in real time. The concept herein is to develop an antenna array system with an electronically steered beam (beamforming). Common practice in radar systems is to adjust the phase and/or the amplitude of the signal radiated from each array element, thus aiming the beam in a specific direction. The systems and the results in general deriving from this project find application in logistics automation and supply chain management. They can be employed in warehouse environments where the level of automation plays an important role in the overall efficiency. They can help to seriously reduce processing time e.g. in palletizing and depalletizing of diverse-sized cardboard boxes and decrease warehouse processing costs. The results regarding the positioning of RFID tags can furthermore find application in a wider spectrum of applications including asset tracking, mobile robot localization-mapping and process control.
Publications
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Package Localization in a Warehouse Environment by Means of RFID. at-automatisierungstechnik. Oldenbourg Verlag, München, 7/2010 - ISSN 0178-2312
A. Bouzakis, L. Overmeyer
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RFID-Assisted Detection and Handling of Packages. ROMANSY 18 Robot Design, Dynamics and Control - CISM Courses and Lectures, vol. 524. Springer Wien New York, 2010 - ISBN 978-3-7091-0276-3
A. Bouzakis, L. Overmeyer
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RFID-assistierte Stückguterfassung und -handling anhand eines kognitiven Robotersystems. 6. Fachkolloquium der Wissenschaftlichen Gesellschaft für Technische Logistik e.V. (WGTL), S. 83-93: PZH Produktionstechnisches Zentrum GmbH, 2010. – ISBN 978-3-941416- 71-0
A. Bouzakis, S. Weigelt, L. Overmeyer
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Package Positioning and Handling with the aid of an integrated RFID Module for Belt Conveyors. 4th International Conference on Manufacturing Engineering (CIRP Sponsored), 3-5 October 2011. Pages 529-537– ISBN 978-960-98780-4-3
A. Bouzakis, L. Overmeyer
