@misc{HerrmannDilefeld, author = {Herrmann, Frank and Dilefeld, Maximilian}, title = {Improving the scheduling of AGV and AMR using simulation}, series = {OR23, International Conference on Operations Research, August 29 to September 1, 2023, Hamburg}, journal = {OR23, International Conference on Operations Research, August 29 to September 1, 2023, Hamburg}, abstract = {Automated Guided Vehicles (AGV) and intelligent Autonomous Mobile Robots (AMR) are an important tool for designing a flexible Industry 4.0 shopfloor. Both types of Mobile Robots are usually deployed with a Fleet Management software to manage (transport) orders and vehicles together with other superordinate control systems. The planning tasks in the superordinate control system used by both AGVs and AMRs can be divided into Material Flow Management, Job Management, Vehicle Dispatching and Job Processing. Requests for supply and removal of material is issued by the stations and has to be combined to transport jobs. Alternatively, more complex system often user external Material Flow Controllers (e.g. MES). Jobs are collected in a queue and their execution order is determined. Vehicles which can execute the next job have to be identified and the best one is selected. Jobs are split into smaller tasks which are sent to the Mobile Robot and executed. For AGVs navigation functions are mostly integrated into the Fleet Manager as part of the Job Processing, while AMRs perform lower-level navigation functions directly on the vehicle and use the superordinate control system for implementing restrictions and traffic control functions. A need for further research and development was identified especially for decision-making algorithms within the Fleet Management. The goal is to compare existing and develop new strategies to solve the different planning problems. For the individual planning tasks different techniques have been discussed and used in research and practice. However, there is no universal best solution and different options must be compared in the context of the specific use case.}, language = {en} } @misc{HerrmannSchoenClausetal., author = {Herrmann, Frank and Schoen, Maximilian and Claus, Thorsten and Dai, Chenghao}, title = {Aggregate Production Planning under Risk of Disruption}, series = {OR 2024, International Conference on Operations Research 2024, September 3-6, 2024, Munich}, journal = {OR 2024, International Conference on Operations Research 2024, September 3-6, 2024, Munich}, abstract = {In recent years, large scale disruptions to global supply chains, like the Covid pandemic, a ship blocking the Suez canal or sanctions against Russia, have caused production to slow down or even to stand still, causing shortages and massive losses for affected businesses. Even if only specific companies were originally affected, shortages and delays rippled along the supply network. The established approach to deal with disruptions is to utilize safety stock and capacity to compensate for fluctuations in uncertain quantities like customer demand. This approach is tried and tested for small fluctuations. To address larger disruptions, like the above given, very high safety stock and capacity would be needed, which would lead to unnecessarily high costs. Resilience has often been viewed as an expensive capability that drives costs. Recent studies however advocate for the development of lean resilience concepts, creating new capabilities, which enable resilience and can deal with large fluctuations, reimagining resilience from the perspectives of efficiency and value creation. This contribution identifies gaps in current research and establishes structural deficits of approaches discussed in the literature regarding supply chains. Firstly, the need for rigorous, quantitative definitions of resilience and relevant disruptions is justified. Then, a stochastic model for aggregate production planning that includes capabilities to compensate for such large fluctuations along several dimensions is proposed. Lastly, this model is then applied to a case study pertaining to a realistic supply chain under the risk of large scale disruptions and the results of this approach are evaluated.}, language = {en} } @misc{Herrmann, author = {Herrmann, Frank}, title = {Scheduling of a real world filter production with lot-size 1}, series = {SIMUL 2020: The Twelfth International Conference on Advances in System Simulation, 18.-22.10.2020 in Porto, Portugal}, journal = {SIMUL 2020: The Twelfth International Conference on Advances in System Simulation, 18.-22.10.2020 in Porto, Portugal}, editor = {Herrmann, Frank and Parra, Lorena and Popescu, Manuela}, publisher = {IARIA XPS Press}, address = {Wilmington, DE, USA}, isbn = {978-1-61208-831-0}, pages = {1 -- 6}, abstract = {In industrial practice, a travelling crane on the ceiling of a factory hall transports products in process from one station to the next one in a production line. Due to space restrictions, there is no buffer between the stations. The production line at Fiedler Andritz, Regensburg in Germany, can be seen as an example of such a problem class. Such restrictions reduce the set of feasible schedules even more than the no-buffer restrictions discussed in the literature in the case of limited storage. Since this scheduling problem is integrated in the usual hierarchical planning, the tardiness is minimised. Due to the high number of jobs as well as the goal of a simple algorithm, scheduling is always done by priority rules at the company site. The standard approach of using the net processing time causes poor results. A simulation of the processing time is suggested. In addition, several very relevant priority rules from the literature are modified by this simulated processing and significantly better results are obtained. Keywords-Simulation of processing time; scheduling, flowshop; no-buffer (blocking); no-wait; priority rules; real world application; filter production}, language = {en} } @article{LoshajHerrmann, author = {Loshaj, Albion and Herrmann, Frank}, title = {Entwicklung einer systemgest{\"u}tzten Stellplatzorganisation f{\"u}r die Werksversandstellen unter Ber{\"u}cksichtigung von variablen M{\"a}rkten}, series = {Anwendungen und Konzepte der Wirtschaftsinformatik}, journal = {Anwendungen und Konzepte der Wirtschaftsinformatik}, number = {6}, publisher = {AKWI}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-1848}, pages = {53 -- 65}, abstract = {Die Gestaltung der Distributionsfl{\"a}chen der Werksversandstellen bei der BMW Group resultiert aus unterschiedlichen und meist werksspezifischen Gegebenheiten. Im Zuge eines Referenzprojektes sollen einheitliche Standards und Vorgehensweisen f{\"u}r die Entwicklung einer Stellplatzorganisation untersucht und festgelegt werden. Im Rahmen dieses Projekts wird analysiert, worauf bei einer Lagergestaltung im Allgemeinen zu achten ist und wie diese Kriterien im Falle der Werksversandstellen im Speziellen umgesetzt werden k{\"o}nnen. Zus{\"a}tzlich behandelt dieses Projekt auch die computerunterst{\"u}tzte Betrachtung der Lager- bzw. Stellplatzverwaltung.}, subject = {Distributionslogistik}, language = {de} }