{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T10:49:47Z","timestamp":1791629387929,"version":"4.3.4"},"reference-count":40,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T00:00:00Z","timestamp":1790726400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T00:00:00Z","timestamp":1790726400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"FCT, Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UID\/00066\/2025"],"award-info":[{"award-number":["UID\/00066\/2025"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"award":["UID\/00066\/2025"],"award-info":[{"award-number":["UID\/00066\/2025"]}],"id":[{"id":"https:\/\/ror.org\/00snfqn58","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Funda\u00e7\u00e3o Santander Portugal","award":["IPEX2025\/INUV-LIGHT_ISEL"],"award-info":[{"award-number":["IPEX2025\/INUV-LIGHT_ISEL"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Congestion at shared intersections can limit the scalability of Automated Guided Vehicle (AGV) fleets in high-density warehouses. This study evaluates a Deep Q-Network (DQN) controller for adaptive intersection management in a SUMO-based warehouse model with five crossings, including the shared central crossing CP1. After one 200-episode training run, the DQN was evaluated in three seeded 6200 s simulations per demand scenario. Against a study-specific cyclic fixed-time controller at 250, 350, and 400 AGVs\/h, the DQN achieved unweighted mean reductions of 62.9% in signal queue, 59.1% in average waiting time, and 18.0% in AGVs waiting to load, while loading\/unloading occupancy changed by less than 1%. A matched 750 AGVs\/h stress test showed that the benefit did not persist after saturation: at CP1, the mean signal queue increased from 13.15 to 30.68 AGVs and the mean number waiting to load from 9.64 to 15.93 AGVs. Sustained CP1 congestion began between 350 and 400 AGVs\/h for the tested layout. Retained test outputs quantify test-level dispersion, but the single training run cannot estimate training variability. These results quantify the DQN traffic-control policy under ideal availability of SUMO state information and do not validate a VLC system. VLC is presented separately as a proposed future implementation layer; communication delay, packet loss, occlusion, and other physical-channel effects were not modelled.<\/jats:p>","DOI":"10.3390\/s26196212","type":"journal-article","created":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T13:01:19Z","timestamp":1790773279000},"page":"6212","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["DQN-Based Adaptive Intersection Control for Warehouse AGVs in SUMO with a Proposed VLC Architecture"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4167-2052","authenticated-orcid":false,"given":"Paula","family":"Louro","sequence":"first","affiliation":[{"name":"Instituto Superior de Engenharia de Lisboa (ISEL), Universidade Polit\u00e9cnica de Lisboa, R. Conselheiro Em\u00eddio Navarro, 1959-007 Lisboa, Portugal"},{"name":"Instituto de Desenvolvimento de Novas Tecnologias-Center of Technology and Systems-Laborat\u00f3rio Associado de Sistemas Inteligentes (UNINOVA\u2013CTS-LASI), Universidade NOVA de Lisboa, Quinta da Torre, Monte da Caparica, 2829-516 Caparica, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-4267-0389","authenticated-orcid":false,"given":"Gon\u00e7alo","family":"Galv\u00e3o","sequence":"additional","affiliation":[{"name":"Instituto Superior de Engenharia de Lisboa (ISEL), Universidade Polit\u00e9cnica de Lisboa, R. Conselheiro Em\u00eddio Navarro, 1959-007 Lisboa, Portugal"},{"name":"Instituto de Desenvolvimento de Novas Tecnologias-Center of Technology and Systems-Laborat\u00f3rio Associado de Sistemas Inteligentes (UNINOVA\u2013CTS-LASI), Universidade NOVA de Lisboa, Quinta da Torre, Monte da Caparica, 2829-516 Caparica, Portugal"},{"name":"NOVA School of Science and Technology, Universidade NOVA de Lisboa, Quinta da Torre, Monte da Caparica, 2829-516 Caparica, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susana","family":"Amaral","sequence":"additional","affiliation":[{"name":"Instituto Superior de Engenharia de Lisboa (ISEL), Universidade Polit\u00e9cnica de Lisboa, R. Conselheiro Em\u00eddio Navarro, 1959-007 Lisboa, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1150-9895","authenticated-orcid":false,"given":"Manuela","family":"Vieira","sequence":"additional","affiliation":[{"name":"Instituto Superior de Engenharia de Lisboa (ISEL), Universidade Polit\u00e9cnica de Lisboa, R. Conselheiro Em\u00eddio Navarro, 1959-007 Lisboa, Portugal"},{"name":"Instituto de Desenvolvimento de Novas Tecnologias-Center of Technology and Systems-Laborat\u00f3rio Associado de Sistemas Inteligentes (UNINOVA\u2013CTS-LASI), Universidade NOVA de Lisboa, Quinta da Torre, Monte da Caparica, 2829-516 Caparica, Portugal"},{"name":"NOVA School of Science and Technology, Universidade NOVA de Lisboa, Quinta da Torre, Monte da Caparica, 2829-516 Caparica, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1385-3646","authenticated-orcid":false,"given":"Manuel A.","family":"Vieira","sequence":"additional","affiliation":[{"name":"Instituto Superior de Engenharia de Lisboa (ISEL), Universidade Polit\u00e9cnica de Lisboa, R. Conselheiro Em\u00eddio Navarro, 1959-007 Lisboa, Portugal"},{"name":"Instituto de Desenvolvimento de Novas Tecnologias-Center of Technology and Systems-Laborat\u00f3rio Associado de Sistemas Inteligentes (UNINOVA\u2013CTS-LASI), Universidade NOVA de Lisboa, Quinta da Torre, Monte da Caparica, 2829-516 Caparica, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,30]]},"reference":[{"key":"ref_1","first-page":"552","article-title":"A review of controller approach for autonomous guided vehicle system","volume":"20","author":"Gul","year":"2020","journal-title":"Indones. J. Electr. Eng. Comput. Sci."},{"key":"ref_2","unstructured":"U\u00e7ar, A., and \u00c7elik, M. (2017). Automated Guided Vehicles (AGVs): A review. 2017 International Conference on Computer Science and Engineering (UBMK), IEEE."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1483","DOI":"10.1007\/s10845-021-01893-x","article-title":"Automated guided vehicles position control: A systematic literature review","volume":"34","author":"Reis","year":"2023","journal-title":"J. Intell. Manuf."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"405","DOI":"10.1016\/j.ejor.2021.01.019","article-title":"Planning and Control of Autonomous Mobile Robots for In-tralogistics: Literature Review and Research Agenda","volume":"294","author":"Fragapane","year":"2021","journal-title":"Eur. J. Oper. Res."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1016\/j.jmsy.2019.12.002","article-title":"Automated Guided Vehicle Systems, State-of-the-Art Control Algorithms and Techniques","volume":"54","author":"Versteyhe","year":"2020","journal-title":"J. Manuf. Syst."},{"key":"ref_6","first-page":"1","article-title":"A Review of Design and Control of Automated Guided Vehicle Systems","volume":"171","year":"2006","journal-title":"Eur. J. Oper. Res."},{"key":"ref_7","first-page":"18","article-title":"Overview of Current Indoor Positioning Systems","volume":"35","author":"Mautz","year":"2009","journal-title":"Geod. Cartogr."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1963","DOI":"10.1109\/COMST.2018.2806558","article-title":"A Survey of Positioning Systems Using Visible LED Lights","volume":"20","author":"Zhuang","year":"2018","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2681","DOI":"10.1109\/COMST.2017.2706940","article-title":"Current Challenges for Visible Light Communications Usage in Vehicle Applications: A Survey","volume":"19","author":"Dimian","year":"2017","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"9819","DOI":"10.1109\/ACCESS.2018.2792419","article-title":"A Comparative Survey of Optical Wireless Technologies: Architectures and Applications","volume":"6","author":"Chowdhury","year":"2018","journal-title":"IEEE Access"},{"key":"ref_11","first-page":"60","article-title":"Indoor Visible Light Communications: Challenges and prospects","volume":"7091","author":"Zeng","year":"2008","journal-title":"Proc. SPIE"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"2047","DOI":"10.1109\/COMST.2015.2476474","article-title":"Visible Light Communication, Networking and Sensing: Potential and Challenges","volume":"17","author":"Parth","year":"2015","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1063","DOI":"10.1109\/JPROC.2018.2823500","article-title":"Localization via Visible Light Systems","volume":"106","author":"Keskin","year":"2018","journal-title":"Proc. IEEE"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1109\/COMST.2020.3034224","article-title":"Vehicular Visible Light Communications: A Survey","volume":"23","author":"Memedi","year":"2021","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_15","first-page":"483","article-title":"Visible Light Communication for Intelligent Transportation Systems: A Review of the Latest Technologies","volume":"8","author":"Shaaban","year":"2021","journal-title":"J. Traffic Transp. Eng. Engl. Ed."},{"key":"ref_16","unstructured":"Vieira, M., Louro, P., Vieira, M.A., Fernandes, M., Costa, J., and Fantoni, A. (2011). Use of a-SiC:H Photodiodes in Optical Communica-tions Applications. Advances in Photodiodes, IntechOpen."},{"key":"ref_17","first-page":"100305","article-title":"Measurement-based VLC channel characterization for I2V communications in a real urban scenario","volume":"28","author":"Caputo","year":"2021","journal-title":"Veh. Commun."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"780","DOI":"10.1016\/j.matpr.2016.02.009","article-title":"Transmission of Signals Using White LEDs for VLC Applications","volume":"3","author":"Louro","year":"2016","journal-title":"Mater. Today Proc."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Yang, W., Liu, H., and Cheng, G. (2024). Modeling and Performance Study of Vehicle-to-Infrastructure Visible Light Communication System for Mountain Roads. Sensors, 24.","DOI":"10.3390\/s24175541"},{"key":"ref_20","unstructured":"Behrisch, M., Bieker, L., Erdmann, J., and Krajzewicz, D. (2011, January 23\u201329). SUMO\u2014Simulation of Urban MObility: An Overview. Proceedings of the Third International Conference on Advances in System Simulation (SIMUL 2011), Barcelona, Spain."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Lopez, P.A., Wiessner, E., Behrisch, M., Bieker-Walz, L., Erdmann, J., Fl\u00f6tter\u00f6d, Y.-P., Hilbrich, R., L\u00fccken, L., Rummel, J., and Wagner, P. (2018, January 4\u20137). Microscopic Traffic Simulation Using SUMO. Proceedings of the 2018 21st International Conference on Intel-ligent Transportation Systems (ITSC), Maui, HI, USA.","DOI":"10.1109\/ITSC.2018.8569938"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1243","DOI":"10.1109\/TVT.2018.2890726","article-title":"A Deep Reinforcement Learning Network for Traffic Light Cycle Control","volume":"68","author":"Liang","year":"2019","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1624","DOI":"10.1109\/TITS.2011.2158001","article-title":"Data-driven intelligent transportation systems: A survey","volume":"12","author":"Zhang","year":"2011","journal-title":"IEEE Trans. Intell. Transp. Syst."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1016\/j.procs.2018.04.008","article-title":"Evaluating Reinforcement Learning State Representations for Adaptive Traffic Signal Control","volume":"130","author":"Genders","year":"2018","journal-title":"Procedia Comput. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"012011","DOI":"10.1088\/1742-6596\/421\/1\/012011","article-title":"Photodetector with integrated optical thin film filters","volume":"421","author":"Vieira","year":"2013","journal-title":"J. Phys. Conf. Ser."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Michailidis, P., Michailidis, I., Lazaridis, C.R., and Kosmatopoulos, E. (2025). Traffic Signal Control via Reinforcement Learning: A Review on Applications and Innovations. Infrastructures, 10.","DOI":"10.3390\/infrastructures10050114"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1109\/TITS.2020.3008612","article-title":"Deep Reinforcement Learning for Intelligent Transportation Systems: A Survey","volume":"23","author":"Haydari","year":"2022","journal-title":"IEEE Trans. Intell. Transp. Syst."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"208016","DOI":"10.1109\/ACCESS.2020.3034141","article-title":"Deep Reinforcement Learning for Traffic Signal Control: A Review","volume":"8","author":"Rasheed","year":"2020","journal-title":"IEEE Access"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"40797","DOI":"10.1109\/ACCESS.2019.2907618","article-title":"Cooperative Deep Q-Learning with Q-Value Transfer for Multi-Intersection Signal Control","volume":"7","author":"Ge","year":"2019","journal-title":"IEEE Access"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"13677","DOI":"10.1007\/s10489-022-04105-y","article-title":"A Review of Cooperative Multi-Agent Deep Reinforcement Learning","volume":"53","author":"Oroojlooy","year":"2023","journal-title":"Appl. Intell."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3133","DOI":"10.1109\/COMST.2019.2916583","article-title":"Applications of Deep Reinforcement Learning in Communications and Networking: A Survey","volume":"21","author":"Luong","year":"2019","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Al Hasnawi, R., Marghescu, I., and Rusu-Casandra, A. (2024, January 3\u20134). Reliability and Capacity Evaluation for Vehicle-to-Vehicle VLC. Proceedings of the 2024 International Conference on Communications (COMM), Bucharest, Romania.","DOI":"10.1109\/COMM62355.2024.10741390"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Chen, H.-C., Li, S.-A., Chang, T.-H., Feng, H.-M., and Chen, Y.-C. (2024). Hybrid Centralized Training and Decentralized Execution Reinforcement Learning in Multi-Agent Path-Finding Simulations. Appl. Sci., 14.","DOI":"10.3390\/app14103960"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"100478","DOI":"10.1109\/ACCESS.2022.3206537","article-title":"MARL-Based Cooperative Multi-AGV Control in Warehouse Systems","volume":"10","author":"Choi","year":"2022","journal-title":"IEEE Access"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Ye, X., Deng, Z., Shi, Y., and Shen, W. (2023). Toward Energy-Efficient Routing of Multiple AGVs with Multi-Agent Reinforcement Learning. Sensors, 23.","DOI":"10.3390\/s23125615"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Yu, C., Liao, W., and Zu, L. (2024). Dynamic Scheduling Optimization Method for Multi-AGV-Based Intelligent Warehouse Considering Bidirectional Channel. Systems, 12.","DOI":"10.3390\/systems12010009"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Liu, Y., and Li, J. (2024). Runtime Verification-Based Safe MARL for Optimized Safety Policy Generation for Multi-Robot Systems. Big Data Cogn. Comput., 8.","DOI":"10.3390\/bdcc8050049"},{"key":"ref_38","first-page":"241","article-title":"Adaptive Traffic Control Using Cooperative Communication Through Visible Light","volume":"5","author":"Louro","year":"2024","journal-title":"SN Comput. Sci."},{"key":"ref_39","unstructured":"Berghmans, F., Zergioti, I., and Chiavaioli, F. (2026). Visible light communication for adaptive AGV fleet coordination. Optical Sensing and Detection IX, SPIE."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Louro, P., Galv\u00e3o, G., Vieira, M., and Vieira, M.A. (2026, January 19\u201322). Advanced Signal Processing and Visible Light Communication for AGV Coordination in Automated Warehouses. Proceedings of the 30th Light-Emitting Devices, Materials, and Applications Conference, SPIE Photonics West, San Francisco, CA, USA.","DOI":"10.1117\/12.3079720"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/19\/6212\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T10:13:23Z","timestamp":1791627203000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/19\/6212"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,30]]},"references-count":40,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2026,10]]}},"alternative-id":["s26196212"],"URL":"https:\/\/doi.org\/10.3390\/s26196212","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,30]]}}}