{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T02:06:07Z","timestamp":1774922767348,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2025,12,17]],"date-time":"2025-12-17T00:00:00Z","timestamp":1765929600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Systems"],"abstract":"<jats:p>Model-Based Systems Engineering (MBSE) is employing systems analysis, design, and development on models of these systems, bringing together different viewpoints, with a step-by-step increase of detail. As such, it replaces traditional document-centric approaches with a methodology that uses structured domain models for information exchange and system representation throughout the engineering lifecycle. MBSE comprises different languages, each with distinct features and approaches. SysML is a widely used language in MBSE, and many tools exist for it. This paper is interested in the complexity of SysML models, as it may yield useful quantitative indicators to assess and predict the complexity of systems modeled in SysML, and, by extension, the complexity of their subsequent development. Two avenues are explored: objective structural metrics applied to the SysML model and assessment of the team experience. The proposed approach is implemented as a Java prototype. Although simpler models are easier to comprehend and modify, they may fail to capture the full scope of system functionality. Conversely, more complex models, though richer in detail, require greater development effort and pose challenges for maintenance and stakeholder communication. Technical and environmental factors are integrated into the complexity assessment to reflect real-world project conditions. A drone-based image acquisition system serves as a case study.<\/jats:p>","DOI":"10.3390\/systems13121128","type":"journal-article","created":{"date-parts":[[2025,12,17]],"date-time":"2025-12-17T15:53:46Z","timestamp":1765986826000},"page":"1128","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Measuring the Complexity of SysML Models"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-0123-1448","authenticated-orcid":false,"given":"Anoushka","family":"Bhatnager","sequence":"first","affiliation":[{"name":"F\u00e9d\u00e9ration ONERA ISAE-SUPAERO ENAC, Universit\u00e9 de Toulouse, 31400 Toulouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-6158-6562","authenticated-orcid":false,"given":"Lakshmi Bhargav","family":"Gullapalli","sequence":"additional","affiliation":[{"name":"F\u00e9d\u00e9ration ONERA ISAE-SUPAERO ENAC, Universit\u00e9 de Toulouse, 31400 Toulouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1404-0148","authenticated-orcid":false,"given":"Pierre","family":"de Saqui-Sannes","sequence":"additional","affiliation":[{"name":"F\u00e9d\u00e9ration ONERA ISAE-SUPAERO ENAC, Universit\u00e9 de Toulouse, 31400 Toulouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2339-4853","authenticated-orcid":false,"given":"Rob A.","family":"Vingerhoeds","sequence":"additional","affiliation":[{"name":"F\u00e9d\u00e9ration ONERA ISAE-SUPAERO ENAC, Universit\u00e9 de Toulouse, 31400 Toulouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,17]]},"reference":[{"key":"ref_1","unstructured":"OMG (2017). OMG Systems Modeling Language, Object Management Group. Available online: https:\/\/www.omg.org\/spec\/SysML\/1.5."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1007\/s10270-019-00735-y","article-title":"Thirteen Years of SysML: A Systematic mapping Study","volume":"19","author":"Wolny","year":"2020","journal-title":"Softw. Syst. Model."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Santos, T., and Soares, M. (2021). A Qualitative Study on SysML Based on Perceived Views from Industry Professionals. Computational Science and Its Applications, LNCS.","DOI":"10.1007\/978-3-030-87013-3_23"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"120936","DOI":"10.1109\/ACCESS.2022.3222387","article-title":"A Taxonomy of MBSE Approaches by Languages, Tools and Methods","volume":"10","author":"Vingerhoeds","year":"2022","journal-title":"IEEE Access"},{"key":"ref_5","unstructured":"Friedenthal, S., Moore, A., and Steiner, R. (2014). A Practical Guide to SysML: The Systems Modeling Language, Morgan Kaufmann."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Umeda, H., Takatsuki, S., Kobayashi, T., Ueda, Y., Wada, A., Komatsu, Y., Ishihama, N., and Iwata, T. (2022, January 24\u201326). System modeling process with SysML assuming the use of models. Proceedings of the 2022 IEEE International Symposium on Systems Engineering (ISSE), Vienna, Austria.","DOI":"10.1109\/ISSE54508.2022.10005553"},{"key":"ref_7","first-page":"284","article-title":"The role of Model-Based Systems Engineering (MBSE) in managing complex systems","volume":"6","author":"Pasek","year":"2015","journal-title":"Int. J. Syst. Syst. Eng."},{"key":"ref_8","unstructured":"Blanchard, B.S., and Fabrycky, W.J. (2011). System Engineering and Analysis, Prentice Hall."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Eppinger, S.D., and Browning, T.R. (2012). Design Structure Methods and Applications, MIT Press. Available online: https:\/\/www.researchgate.net\/publication\/371165639_Proceedings_2017_DSM_Conference.","DOI":"10.7551\/mitpress\/8896.001.0001"},{"key":"ref_10","unstructured":"Boehm, B.W. (1981). Software Engineering Economics, Prentice Hall."},{"key":"ref_11","unstructured":"Cohn, M. (2005). Agile Estimating and Planning, Prentice Hall."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"533","DOI":"10.1002\/cplx.21767","article-title":"A general framework for measuring system complexity","volume":"21","author":"Efatmaneshnik","year":"2016","journal-title":"Complexity"},{"key":"ref_13","unstructured":"Gullapalli, L.B., Bhatnager, A., de Saqui-Sannes, P., and Vingerhoeds, R. (2024, January 23\u201325). Quantitative Assessment of Complexity in SysML Models. Proceedings of the Modelling and Simulation 2024, ESM 2024, San Sebastian, Spain."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Flood, R.L. (1990). Liberating Systems Theory. Contemporary Systems Thinking, Plenum Press.","DOI":"10.1007\/978-1-4899-2477-3"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Van de Poel, I. (2009). Values in engineering design. Handbook of the Philosophy of Science. Volume 9: Philosophy of Technology and Engineering Sciences, Elsevier.","DOI":"10.1016\/B978-0-444-51667-1.50040-9"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1145\/606666.606681","article-title":"The Complexity of Formal Specifications\u2014Assessments by alpha-Metric","volume":"34","author":"Kokol","year":"1999","journal-title":"SIGPLAN Not."},{"key":"ref_17","unstructured":"yat Cheung, T., Ren, S., and Mak, W.M. (1994, January 22\u201325). A tool for assessing the quality of distributed software designs. Proceedings of the Proceedings Software Education Conference (SRIG-ET\u201994), Dunedin, New Zealand."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/S0164-1212(97)00008-3","article-title":"On measuring the complexity of an estelle specification","volume":"40","author":"Huang","year":"1998","journal-title":"J. Syst. Softw."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Masmali, O., and Badreddin, O. (2020, January 11\u201314). Comprehensive Model-Driven Complexity Metrics for Software Systems. Proceedings of the 2020 IEEE 20th International Conference on Software Quality, Reliability and Security Companion (QRS-C), Macau, China.","DOI":"10.1109\/QRS-C51114.2020.00115"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2209","DOI":"10.1016\/j.ins.2010.01.026","article-title":"The impact of structural complexity on the understandability of UML statechart diagrams","volume":"180","author":"Maes","year":"2010","journal-title":"Inf. Sci."},{"key":"ref_21","unstructured":"Davis, A. (1993). Software Engineering and Analysis, Pearson."},{"key":"ref_22","unstructured":"Parsons-Hann, H., and Liu, K. (2005, January 25\u201328). Measuring Requirements Complexity to Increase the Probability of Project Success. Proceedings of the Seventh International Conference on Enterprise Information Systems\u2014Volume 3: ICEIS, Miami, FL, USA."},{"key":"ref_23","first-page":"100","article-title":"Estimating Project Effort Based on Skill Levels","volume":"8","author":"Wrigley","year":"1987","journal-title":"J. Proj. Manag."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"276","DOI":"10.4236\/jsea.2015.86028","article-title":"Impact of Modification Made in Re-UCP on Software Effort Estimation","volume":"8","author":"Kirmani","year":"2015","journal-title":"J. Softw. Eng. Appl."},{"key":"ref_25","unstructured":"Kusumoto, S., Matukawa, F., Inoue, K., Hanabusa, S., and Maegawa, Y. (2002, January 19\u201325). Estimating effort by use case points: Method, tool and case study. Proceedings of the 24th International Conference on Software Engineering, Orlando, FL, USA."},{"key":"ref_26","first-page":"18","article-title":"Project Estimation With Use Case Points","volume":"19","author":"Clemmons","year":"2006","journal-title":"CrossTalk J. Def. Softw. Eng."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1007\/s00163-017-0260-9","article-title":"Pareto-optimization of complex system architecture for structural complexity and modularity","volume":"29","author":"Sinha","year":"2018","journal-title":"Res. Eng. Des."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Lopez, V., and Thomas, L. (2022). Metric for Structural Complexity Assessment of Space Systems Modeled Using the System Modeling Language. Aerospace, 9.","DOI":"10.3390\/aerospace9100612"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Lankford, J. (2003, January 8\u201315). Measuring system and software architecture complexity. Proceedings of the IEEE Aerospace Conference Proceedings (Cat. No.03TH8652), Big Sky, MT, USA.","DOI":"10.1109\/AERO.2003.1235569"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Dalvi, A.S., and El-Mounayri, H. (2021, January 1\u20135). Integrated System Architecture Development Framework And Complexity Assessment. Proceedings of the ASME 2021 International Mechanical Engineering Congress and Exposition, Virtual, Online.","DOI":"10.1115\/IMECE2021-67515"},{"key":"ref_31","unstructured":"Friedenthal, S. (2024). SysML v2 Basics: Transition from SysML v1 to SysML v2, OMG MBSE Wiki."},{"key":"ref_32","unstructured":"OMG (2023). SysML v2 Beta Specifications, Object Management Group (OMG)."}],"container-title":["Systems"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-8954\/13\/12\/1128\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,17]],"date-time":"2025-12-17T16:06:32Z","timestamp":1765987592000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-8954\/13\/12\/1128"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,17]]},"references-count":32,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2025,12]]}},"alternative-id":["systems13121128"],"URL":"https:\/\/doi.org\/10.3390\/systems13121128","relation":{},"ISSN":["2079-8954"],"issn-type":[{"value":"2079-8954","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,17]]}}}