Johanna Nellen


johanna.nellen at
+49 241 80 21244
Room 4227
Ahornstraße 55
D-52074 Aachen


I am a Postdoc at the research group Theory of Hybrid Systems headed by Prof. Dr. Erika Ábrahám. My research interests include the synthesis and verification of hybrid systems and their application in control engineering.

During my PhD I was granted a  scholarship in the DFG research training group AlgoSyn. I worked on the analysis of hybrid systems in the application area of plant control and on the synthesis of control strategies for hybrid electric vehicles.

Since June 2016, I work for a Ford – RWTH Aachen Alliance project on the verification of automotive Simulink models.

Research Projects

  • Ford – RWTH Aachen Alliance: Simulink Formal Verification, Ford Motor Company
    Project partners: Ford Motor Company (Germany/USA)
  • OASys (Online Algorithms for Optimal Control of Hybrid Propulsion Systems), DFG (German Research Foundation), Project-Id: AB 461/2-1
    Project partners: Chair of Computer Science 1, RWTH Aachen University, Institute of Automated Control, RWTH Aachen University

Teaching Assistance

I supervised students in seminars on “Satisfiability Checking”, “Hybrid Systems Verification”, “Algorithms and Tools for Verification” and “Real-Time Systems”. 
Moreover, I organized practical labs on “Control Strategies for Hybrid Vehicles” and “Explorative Search with Lego Mindstorms Robots”.

The following students finished their Bachelor/Master theses under my supervision:

  • Rebecca Haehn, “Learning control strategies for hybrid vehicles using neural networks”
  • Patricia Wessel, “Grid-based control strategy for hybrid vehicles”
  • Kai Driessen, “Modular verification for PLC controlled hybrid systems”
  • Kim Maren Haps, “Datatypes and tools for the analysis of hybrid systems”
  • Thomas Osterland, “Memory- and time-related action qualifiers in HSFCs”
  • Alin Ionascu, “Modeling and controler synthesis of hybrid propulsion systems using artificial intelligence”
  • Kai Driessen, “Counterexample-guided abstraction refinement for hybrid SFC verification”



LinkJohanna Nellen, Thomas Rambow, Md Tawhid Bin Waez, Erika Abraham, Joost-Pieter Katoen. Formal Verification of Automotive Simulink Controller Models: Empirical Technical Challenges, Evaluation and Recommendations. Proc. of Formal Methods Symposium (FM 2018), Volume of LNCS, Springer, 2018.
DownloadLinkStefan Schupp, Johanna Nellen, Erika Abraham. Divide and Conquer: Variable Set Separation in Hybrid Systems Reachability Analysis. Proc. of the 15th Workshop on Quantitative Aspects of Programming Languages and Systems (QAPL'17), Volume 250 of EPTCS, pages 1–14, Open Publishing Association, 2017.
DownloadLinkJohanna Nellen. Analysis and Synthesis of Hybrid Systems in Control Engineering. Phd Thesis at RWTH Aachen University, 2016.
DOIJohanna Nellen, Kai Driessen, Martin R. Neuhäußer, Erika Abraham, Benedikt Wolters. Two CEGAR-Based Approaches for the Safety Verification of PLC-Controlled Plants. Information Systems Frontiers 18(5), pages 927–952, 2016.
DOISascha Geulen, Martina Josevski, Johanna Nellen, Janosch Fuchs, Lukas Netz, Benedikt Wolters, Dirk Abel, Erika Abraham, Walter Unger. Learning-based Control Strategies for Hybrid Electric Vehicles. Proc. of the 2015 IEEE Conf. on Control Applications (CCA'15), pages 1722–1728, IEEE, 2015.
Sascha Geulen, Martina Josevski, Johanna Nellen, Janosch Fuchs, Lukas Netz, Benedikt Wolters, Erika Abraham, Walter Unger, Dirk Abel. Online Lernen als Kontrollstrategie in Hybridfahrzeugen. Proc. of the 7th VDI/VDE Fachtagung AUTOREG: Auf dem Weg zum automatisierten Fahren, Volume 2233 of VDI-Berichte, pages 101–112, VDI Verlag, 2015.
DOILinkLinkJohanna Nellen, Erika Abraham, Benedikt Wolters. A CEGAR Tool for the Reachability Analysis of PLC-Controlled Plants using Hybrid Automata. In Thouraya Bouabana-Tebibel, Stuart H. Rubin editors, Formalisms for Reuse and Systems Integration, pages 55–78, Volume 346 of Advances in Intelligent Systems and Computing, 2015.
LinkJohanna Nellen, Benedikt Wolters, Lukas Netz, Sascha Geulen, Erika Abraham. A Genetic Algorithm based Control Strategy for the Energy Management Problem in PHEVs. Proc. of the 1st Global Conference on Artificial Intelligence (GCAI'15), Volume 36 of EPiC Series in Computer Science, pages 196–214, EasyChair, 2015.
DOIJohanna Nellen, Erika Abraham. A CEGAR Approach for the Reachability Analysis of PLC-Controlled Chemical Plants. Proc. of the 15th Int. Conf. on Information Reuse and Integration (IRI'14), pages 500–507, IEEE Computer Society Press, 2014.
DOILinkJohanna Nellen, Erika Abraham, Xin Chen, Pieter Collins. Counterexample Generation for Hybrid Automata. Proc. of the 2nd Int. Workshop on Formal Techniques for Safety-Critical Systems (FTSCS'13), Volume 419 of CCIS, pages 88–106, Springer, 2014.
DownloadLinkJohanna Nellen, Erika Abraham. Hybrid Sequential Function Charts. Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen (MBMV'12), Volume 68 of Schriftenreihe Forschungsergebnisse zur Informatik, pages 109–120, Verlag Dr. Kovač, 2012.
DOIDownloadLinkErika Abraham, Nadine Bergner, Philipp Brauner, Florian Corzilius, Nils Jansen, Thiemo Leonhardt, Ulrich Loup, Johanna Nellen, Ulrik Schroeder. On Collaboratively Conveying Computer Science to Pupils. Proc. of the 11th Koli Calling Int. Conf. on Computing Education Research (KOLI'11), pages 132–137, ACM, 2011.

Selected Talks

Johanna Nellen, Sascha Geulen. Learning-based Control Strategies for Hybrid Electric Vehicles, Talk at AlgoSyn Seminar, Aachen, Germany, 2015.
Johanna Nellen. A CEGAR Approach for the Reachability Analysis of PLC-Controlled Chemical Plants, Talk at 2nd IEEE International Workshop on Formal Methods Integration (FMi'14), 2014.
Ulrich Loup, Johanna Nellen. Judging Your Colleagues - Tutorial on Scientists’ Ratings, Talk at AlgoSyn tutorial, 2013.
Johanna Nellen. Counterexample generation for hybrid automata, Talk at 2nd International Workshop on Formal Techniques for Safety-Critical Systems (FTSCS'13), Queenstown, New Zealand, 2013.
Johanna Nellen. Verification of Chemical Plant Control, Talk at Gemeinsamer Workshop der Graduiertenkollegs I: GK 1651 SOAMED et al., 2012.
Ulrich Loup, Johanna Nellen. OASys: An Interdisciplinary DFG Project with Roots in AlgoSyn, Talk at AlgoSyn seminar, 2012.
Johanna Nellen. Hybrid Sequential Function Charts, Talk at MBMV, 2012.
Johanna Nellen. On Collaboratively Conveying Computer Science to Pupils, Talk at KOLI, 2011.
Johanna Nellen, Ulrich Loup, Jan Oliver Ringert, Wolfgang Thomas. Tutorial on Citation Metrics, Talk at AlgoSyn workshop, Dagstuhl, Germany, 2011.
Johanna Nellen. Confluence Analysis and Completion of Graph Grammars, Talk at the AlgoSyn Seminar, RWTH Aachen University, Germany, 2011.