Benjamin Kormann’s research while affiliated with Technical University of Munich and other places

The need for increasing flexibility of industrial automation system products leads to the trend of shifting functional behavior from hardware solutions to software components. This trend causes an increasing complexity of software components and the need for comprehensive and automated testing approaches to ensure a required (high) quality level. Nevertheless, key tasks in software testing include identifying appropriate test cases that typically require a high effort for (a) test case generation/construction and (b) test case modification in case of requirements changes. Semi-automated derivation of test cases based on models, like UML, can support test case generation. In this paper we introduce an automated test case generation approach for industrial automation applications where the test cases are specified by UML state chart diagrams. In addition we present a prototype application of the presented approach for a sorting machine. Major results showed that state charts (a) support efficient test case generation and (b) enable automated generation of test cases and code for industrial automation systems.

Zusammenfassung Die zunehmende Entwicklungskomplexität von Steuerungsprogrammen erfordert neue Methoden sowie einen automatisierten Testansatz, um ein gefordertes Qualitätsmaß effizient nachweisen zu können. In diesem Beitrag wird ein modellbasierter Ansatz zur Testfallerstellung mit UML-Sequenzdiagrammen (UML-SD) und eine universelle Testsystemarchitektur vorgestellt. Für die Generierung ausführbarer Testfälle aus Modellen erfolgt eine semantische Adaption von UML-SD an die zyklische Ausführungslogik. Anhand eines Beispiels wird die aufwandsarme Erstellung, Ausführung und Auswertung von Testfällen gezeigt.

Current production plants are highly customizable and flexible in their processes. This flexibility is mainly realized by software. Standards like IEC 61508 for functional safety demand intensive testing efforts to ensure a certain level of integrity. The uncertainty about system behavior, especially in fault situations, complicates reliability testing. We propose a concept that integrates fault models into SysML system models for model based development. The introduced fault models can be designed in two granularity levels, starting with coarse information at early development phases up to precise mathematical relations. The concept is applied to a component (rotary switch) of a laboratory plant, which connects three conveyor bands where friction deviation can occur during rotary movement. Such models can build the foundation for test generation in reliability testing.

Current production plants are highly customizable and flexible in their processes. This flexibility is mainly realized by software. It causes an increasing complexity of control software components and the need of new methods for comprehensive and automated testing approaches to ensure a requested level of quality at high efficiency. A survey among mechanical engineering companies of the industries aerospace, automotive and machine/plant automation was conducted. Aspects of requirements engineering, testing, simulation, processes, tools, etc. were addressed to reveal research demands of PLC (Programmable Logic Controller) control software development in machine/plant automation. A system architecture embedding UML sequence diagrams for testing is proposed. We further contribute transformation rules of semantically adapted UML sequence diagrams to the cyclic execution logic of PLCs for reactive systems. The approach can be applied to any IEC 61131-3 programming language of the automation control software. A prototypical realization shows proof of concept and reveals the potential for future work.

The need for increasing flexibility of industrial automation system products leads to the trend to shift functional behavior from hardware solutions to software components. This trend causes an increasing complexity of software components and the need for comprehensive and automated testing approaches to ensure a requested quality level. Nevertheless, a key task in software testing is to identify appropriate test cases typically requiring high effort for test case generation and rework effort for adapting test cases in case of requirements changes. Semi-automated derivation of test cases based on models, like UML, can support test case generation. In this paper we introduce an automated test case generation approach for industrial automation applications which are specified by UML state chart diagrams. In addition we present a prototype application of the presented approach for a sorting machine. Major results showed that state charts (a) can support efficient test case generation and (b) enable automated code generation of test cases and code for the industrial automation domain.

The development of PLC control software in machine and plant automation is facing increasing challenges, since more and more functionality and safety aspects are in the control software's responsibility. Reliability and robustness of reactive systems in long-term operation is being influenced by physical conditions. These aspects must be considered at an early development stage in order to reduce development costs and fulfill quality requirements at the same time. We propose an automatic test case generation approach to verify the system behavior in erroneous situations using fault injection, simulating component (device) defects during runtime. We focus on the generation of a reduced set of meaningful test cases to be executed in a simulated environment to increase reliability. The applicability is demonstrated on a laboratory plant.

An increasing number of functionality in today’s machine and plant automation is being shifted from pure mechanics or electronics into software. Therefore the system behavior must be checked for compliance with the demanded software functionality by software tests. The precondition for test case execution is a start state, the system has to take in. In order to evaluate the testability of a system, it must be verified whether the test case triggering system state is reachable. We propose a transformation approach of the control software model and the corresponding environment model (physics) to timed automata for model checking to exploit the power of the query language Timed Computation Tree Logic for start state reachability analysis. The applicability is demonstrated on a laboratory plant.

Our goal is to increase efficiency and quality in automation engineering in machine and plant manufacturing industry by supporting modularity and reuse. This article proofs that object-oriented model-based design can beneficially be applied in industry and that the code automatically derived from the UML model can be implemented on industrial PLCs without additional effort. We had to solve the formal mapping from UML models to IEC 61131-3 program code in order to use an object-oriented approach with Unified Modeling Language (UML) as modeling notation integrated into a classical Programmable Logic Controller (PLC) programming environment (IEC 61131-3).

This paper defines an adaptation of UML-statecharts which can be used as a visual programming language for PLCs. Those PLC-statecharts combine the advantages of UML-statecharts with a strict formal basis and dedicated features for PLC-programming. Finally an empirical study on PLC-statecharts is briefly presented.