Johanna Nellen's research while affiliated with RWTH Aachen University and other places

Publications (11)

Chapter
In industrial model-based development (MBD) frameworks, requirements are typically specified informally using textual descriptions. To enable the application of formal methods, these specifications need to be formalized in the input languages of all formal tools that should be applied to analyse the models at different development levels. In this p...
Preprint
In industrial model-based development (MBD) frameworks, requirements are typically specified informally using textual descriptions. To enable the application of formal methods, these specifications need to be formalized in the input languages of all formal tools that should be applied to analyse the models at different development levels. In this p...
Chapter
The automotive industry makes increasing usage of Simulink-based software development. Typically, automotive Simulink designs are analyzed using non-formal test methods, which do not guarantee the absence of errors. In contrast, formal verification techniques aim at providing formal guarantees or counterexamples that the analyzed designs fulfill th...
Article
Full-text available
In this paper we propose an improvement for flowpipe-construction-based reachability analysis techniques for hybrid systems. Such methods apply iterative successor computations to pave the reachable region of the state space by state sets in an over-approximative manner. As the computational costs steeply increase with the dimension, in this work w...
Article
Full-text available
In this paper we address the safety analysis of chemical plants controlled by programmable logic controllers (PLCs). We consider a specification of the control program of the PLCs, extended with the specification of the dynamic plant behavior. The resulting hybrid models can be transformed to hybrid automata, for which advanced techniques for reach...
Conference Paper
Full-text available
Genetic algorithms have been applied to various optimization problems in the past. Our library GeneiAL implements a framework for genetic algorithms specially targeted to the area of hybrid electric vehicles. In a parallel hybrid electric vehicle (PHEV), an internal combustion engine and an electrical motor are coupled on the same axis in parallel....
Conference Paper
Abstract: Hybrid electric vehicles use control strategies to distribute the torque requested by the driver between the internal combustion engine and the electrical motor. Many different types of control strategies have been proposed, but in general it is impossible to determine which control strategy performs best if the future driving conditions...
Article
In this paper we address the safety analysis of chemical plants controlled by programmable logic controllers (PLCs). We consider sequential function charts (SFCs)for the programming of the PLCs, extended with the specification of the dynamic plant behavior. The resulting hybrid SFC models can be transformed to hybrid automata, opening the way to th...
Article
In this paper we address the safety analysis of chemical plants controlled by programmable logic controllers (PLCs). We consider sequential function charts (SFCs) for the programming of the PLCs, extended with the specification of the dynamic plant behavior. The resulting hybrid SFC models can be transformed to hybrid automata, opening the way to t...
Conference Paper
The last decade brought us a whole range of over-approximative algorithms for the reachability analysis of hybrid automata, a widely used modeling language for systems with combined discrete-continuous behavior. Besides theoretical results, there are also some tools available for proving safety in the continuous time domain. However, if a given set...
Conference Paper
Full-text available
Though there is an increasing need for computer scientists in our society, gifted young people with strong mathematical background, who would be well-suited for a study of computer science, often do not consider this choice because they have a wrong picture of computer science in mind. In this paper we present a new concept of collaborative learnin...

Citations

... This focus is also a weak point: It can not or not easily deal with memory allocation and many standard library headers usually not present in the targeted embedded code, making it unsuitable for a direct comparison on established SV-COMP benchmarks. Requirements can be specified directly using a pattern-based approach, see [21,22]. BTC EmbeddedValidator employs several back-end tools for verification: CBMC 7 , iSAT3, AutoFXP, SMIBMC, and VIS. ...
... We consider a decomposition in the continuous state space. Schupp et al. [12] performed such a decomposition by syntactic independence, which corresponds to dynamics with block-diagonal matrices (whereas our decomposition is generally applicable). ...
... Meanwhile, machine learning (ML) techniques have gained popularity for their ability to control complex tasks by deriving patterns or rules from a data-set or through experience [29,30]. These techniques have also been extended to automotive applications, for example, drive cycle prediction [31], drive cycle recognition [32], training the torque split controller from DP using supervised machine learning (SML) [33], reinforcement learning (RL) for power distribution between the battery and the capacitor [34], etc. In certain tasks, controllers trained using ML have outperformed the controllers based on classical control theory [35]. ...
... HEVs are equipped with an internal combustion engine and an electric motor and thus benefit from the advantages of the two systems, [2]. The (ICE) enables wider driving range and efficient when the requested torque is high, [3]. (EM) does not produce any pollutant emissions and efficient when torques and speeds are low, [3]. ...
... For small and medium models, Simulink Design Verifier can achieve high coverage, but for large models, Simulink may fail to generate test cases. In order to verify large systems, The counterexample-guided abstraction refinement (CEGAR) frameworks [25][26][27][28][29][30] have been proposed. Those techniques abstract hybrid system models into discrete finite state machines without dynamics or replace the complex system with a simpler one. ...
... Properties like persistence, stability, and optimality are crucial to human productivity. Thus, formal methods for chemical reactions are extensively studied [3,28,20,14,24]. ...
... The seminal CEGAR approach has been applied to different verification tasks for already given systems. Nellen et al. [9,10] used CEGAR to verify an already given programmable logic controller (PLC) against safety properties, proposing two approaches for that. Stursberg et al. [11] built on CEGAR for verification of a cruise control system using counterexample-guided search. ...