Susanne Rösch

Challenges of Parallel Evolution in Production Automation Focusing on Requirements Specification and Fault Handling

Abstract Evaluating research approaches in production automation can be cost- and time-intensive. Motivated by this challenge, the role of a case study which is open to the research community is discussed at first and recent developments towards an open case study, the Pick & Place Unit (PPU), are presented. Based on evolution aspects not covered by the PPU case study until now, an extension on requirements, fault handling and parallel evolution are presented as an example. While carving out essential aspects of these topics, various challenges were identified that conclude this article.

Model-based testing of PLC software: test of plants' reliability by using fault injection on component level

Abstract In this paper, the current situation of how PLC software is tested in industry is analyzed and the challenges on new testing approaches are identified using real industry code and a survey conducted within industry. The different possible and most relevant faults that may occur and must be dealt with are identified and requirements for testing approaches concerning component failures are derived. Further on, an approach to generate tests for error handling routines, which test the reliability of plants by injecting the corresponding faults is presented. The test cases are generated from timing sequence diagrams in combination with failure mode and effects analysis. In order to inject the faults at relevant points during the execution of the control software, IEC 61131-3 code is analyzed for the derivation of the test cases.

Increasing agility in engineering and runtime of automated manufacturing systems

Modifications in product and system requirements as well as adaptations in lot sizes that cannot be foreseen in the initial planning period require rapid changes and, therefore, reconfigurable manufacturing systems. However, traditional automation technologies based on traditional procedural programming languages such as IEC 61131-3 often lack in flexibility. This paper presents two different approaches contributing to this field of research in order to enhance efficiency and flexibility in automation engineering, namely model-based engineering with automated code generation and dynamic orchestration of semantic web services. A combination of both approaches into an integrated concept are discussed, promising significantly increased flexibility and, by that, reconfigurability through ad-hoc code generation from models during deployment time.

Modularity and Architecture of PLC-based Software for Automated Production Systems: An analysis in industrial companies

Adaptive and flexible production systems require modular and reusable software especially considering their long-term life cycle of up to 50 years. SWMAT4aPS, an approach to measure Software Maturity for automated Production Systems is introduced. The approach identifies weaknesses and strengths of various companies’ solutions for modularity of software in the design of automated Production Systems (aPS). At first, a self-assessed questionnaire is used to evaluate a large number of companies concerning their software maturity. Secondly, we analyze PLC code, architectural levels, workflows and abilities to configure code automatically out of engineering information in four selected companies. In this paper, the questionnaire results from 16 German world-leading companies in machine and plant manufacturing and four case studies validating the results from the detailed analyses are introduced to prove the applicability of the approach and give a survey of the state of the art in industry.

Challenges for maintenance of PLC-software and its related hardware for automated production systems: Selected industrial Case Studies

The specific challenges for maintenance of software and its related hardware for the domain of automated Production Systems is discussed. Presenting four industrial case studies from renowned and world market leading German machine and plant manufacturing companies, these challenges and different solution approaches are introduced with a focus on software architectures to support modularity as a basis for maintaining long-living automated Production Systems. Additionally, most critical aspects hindering classical approaches from software engineering to be successful, e.g., modes of operation and fault handling, are discussed. In the last decades, research in the field of software engineering for automated Production Systems (aPS) has been focusing on developing domain specific model-driven engineering approaches supporting the development process, but mostly neglecting the operation, maintenance and re-engineering aspects. However, the success of model-driven engineering in aPS industry has been limited because the effort to introduce model-driven engineering and to change the entire existing legacy software is estimated as too high and the benefit as too low against the background of customer specific solutions expecting a low degree of reuse.

Supporting integrated development of closed-loop PLC control software for production systems

In this paper an approach to support the development process of closed-loop control software for Programmable Logic Controllers (PLC) is shown. To enhance the development process, a fast and reliable data transfer between different tools and models used during different design phases is realized by model transformation. A core model created using the Systems Modeling Language (SysML) and a corresponding model editor based on the Unified Modeling Language (UML) in combination with a newly realized model transformation from the SysML parametric diagram to the Simulink block diagram is used to integrate the information from different engineering tools and models involved during automation engineering design phases. Hence, a consistent process for the development of closed-loop control software is realized.

Model driven engineering of manufacturing execution systems using a formal specification

Industrial manufacturing processes are complex processes, where transparency of every process step is necessary to achieve a high level of quality and efficiency. In order to achieve this transparency, manufacturing execution systems (MES) are used. However, as these systems are very expensive, mainly due to individual programming effort, MES usage is oftentimes limited to larger companies. To ultimately reduce implementation costs for MES, the current research project AutoMES proposes a standardized, model-based approach to facilitate automatic generation of MES functions. This paper presents requirements on a suitable modeling language, as well as how these requirements are fulfilled by the modeling language used in the AutoMES project. The modeling language is an extension of the MES Modeling Language (MES-ML), a modeling language for the specification of MES. With the use of the extended MES-ML it is possible to generate a generic, machine-usable MES specification, suitable for code generation. To evaluate the proposed modeling language extensions, an industrial brewing process has been modeled and verified by MES engineers during the project AutoMES.

Applicability of Technical Debt as a Concept to Understand Obstacles for Evolution of Automated Production Systems

Automated production systems (aPS), a specific class of mechatronic systems, are complex, long living, software intensive, evolving systems designed according to customer request. Often, the evolution of such systems has to cope with imponderables and sudden disturbances of the systematic development or maintenance process. In software engineering, the concept of technical debt and, in more detail, architectural technical debt has been introduced recently to describe phenomena, which increase software development costs over time. This paper tries to adapt and apply the classification of technical debt and architectural technical debt to automated production systems, identifying similar dimensions but adding specific challenges, causes and their effects. Once the causes and effects are identified, management and recovery strategies coping with technical debt and architectural technical debt shall be developed in the future, thereby enlarging the strategies from software engineering. The adapted classification and adaptations are based on the experience of several industrial projects in aPS.

Technical debt in Automated Production Systems

The term technical debt borrowed from financial debt describes the long-term negative effects of sub-optimal solutions to achieve short-term benefits. It has been widely studied so far in pure software systems. However, there is a lack of studies on technical debt in technical systems, which contain mechanical, electrical and software parts. Automated Production Systems are such technical systems. In this position paper, we introduce technical debt for Automated Production Systems and give examples from the different disciplines. Based on that description, we outline future research directions on technical debt in this field.

Redeployment of control software during runtime for modular automation systems taking real-time and distributed I/O into consideration

Automation Systems have to deal with breakdowns of their components which potentially lead to drop-off in production and high follow-up costs. The current solution for this problem is the use of redundant hardware ensuring high availability but causing high costs. Starting from nowadays often used distributed automation systems, this paper proposes a software-based solution for high availability using automatic redeployment of control software during runtime avoiding high costs for redundant hardware. Existing approaches are enhanced concerning real-time and distributed I/O. The proposed solution replaces manual deployment and increases flexibility of automation systems.