Peter Hehenberger

Design, modelling, simulation and integration of cyber physical systems

Presentation of a systematic classification of systems and new CPS paradigms.Analyses of literature conducted across a range of different perspectives.A systematic review of CPS-design literature was carried out, with an emphasis on the design, modelling, simulation and integration of CPS.An architectural and behavioural paradigm for CPS.Compilation of different viewpoints referring to applications at different levels of granularity. The main drivers for the development and evolution of Cyber Physical Systems (CPS) are the reduction of development costs and time along with the enhancement of the designed products. The aim of this survey paper is to provide an overview of different types of system and the associated transition process from mechatronics to CPS and cloud-based (IoT) systems. It will further consider the requirement that methodologies for CPS-design should be part of a multi-disciplinary development process within which designers should focus not only on the separate physical and computational components, but also on their integration and interaction. Challenges related to CPS-design are therefore considered in the paper from the perspectives of the physical processes, computation and integration respectively. Illustrative case studies are selected from different system levels starting with the description of the overlaying concept of Cyber Physical Production Systems (CPPSs). The analysis and evaluation of the specific properties of a sub-system using a condition monitoring system, important for the maintenance purposes, is then given for a wind turbine.

CONSISTENCY CHECKING OF MECHATRONIC DESIGN MODELS

During all phases of the design process there is a need to build models. Hierarchical models are very important tools for complex activities such as engineering design. In engineering of high performance products, mathematical modeling and simulation, i.e. experimenting with computer-based models, is an increasingly important technique for solving problems, evaluating solutions and making decisions. However, large design models may contain thousands of model elements. Designers easily get overwhelmed maintaining the correctness of such design models over time. Not only is it hard to detect new errors when the model changes but it is also hard to keep track of known errors. In the software engineering community this problem is known as a consistency problem and errors in models are known as inconsistencies. This paper presents an approach for consistency checking of mechatronic design models.

Perspectives on hierarchical modeling in mechatronic design

Hierarchical modeling helps to describe product models and data from different viewpoints that, representing the different disciplines involved in the design process of mechatronic systems. This paper gives an overview of hierarchical modeling techniques. This includes the investigation of systems, which requires handling different issues that address very specific views of the system (system aspects) and come from various disciplines. Also the model granularity which describes the extent to which an object or model is broken down into smaller elements it an important aspect. The different phases of the product life cycle require models with different objectives and levels of detail. Some models are needed mainly in specific phases of the product life cycle, which are discussed in detail in the paper. Especially in the conceptual design phase some design-characteristic aspects such as hierarchy of parameters, modularity of the design should be analyzed, because in this phase the largest part of the later resulting product costs is predetermined or even fixed. As a consequence, the scope for design is limited to merely small changes in the subsequent design phases. Therefore the interaction between the design phases and the related models plays an important role the development process of mechatronic systems.

Hierarchical Structuring of Mechatronic Design Models

Abstract Synergies and integration in design set a mechatronic system apart from a traditional, multi-disciplinary system. On the other hand, the increased complexity of mechatronic systems, resulting from the benificial interaction of components from various domains, requests the use of an appropriate design methodology in order to recognize the functionality and performance of a solution already at an early stage of the mechatronic design process and to shorten development time. The mechatronic pillar model outlined in this paper deals with a systematic approach of modeling mechatronic systems by establishing an appropriate model hierarchy. This helps to keep the overview over such systems and to make the interactions, interdependencies and interfaces more transparent.

DesignSpace: an infrastructure for multi-user/multi-tool engineering

The engineering and maintenance of large (software) systems is an inherently collaborative process that involves diverse engineering teams, heterogeneous development artifacts, and different engineering tools. While teams have to collaborate continuously and their artifacts are often related, the tools they use are nearly always independent, single-user applications. These tools range from programming to modeling tools and cover a wide range of engineering disciplines. However, relations among the artifacts across these tools often remain undocumented and are handled in an adhoc manner. Keeping these artifacts in sync continues to be a key engineering challenge. In this paper, we present our vision of the DesignSpace, a novel engineering infrastructure for integrating diverse development artifacts and their relations. The DesignSpace supports distributed collaboration, a wide range of tools and development, maintenance, and evolution services including incremental consistency checking and transformation.

Meta-Model of PLM for Design of Systems of Systems

Mechatronic System Design involves close examination and further development of design methods, design processes, models and tools. The current trend in mechatronics involves networked mechatronic systems, or cyber physical systems (CPS), which can also be considered as a sub-part of Systems of Systems (SoS). Therefore data models for the description of the product lifecycle of SoS are necessary on the base of existing meta-models for single (mechatronic) systems. The paper shows a meta-model of PLM for the design of SoS and discusses the influence of the IT-architecture in supporting the PLM interoperability.

Variability and consistency in mechatronic design

Mechatronic products combine hardware and software; and today, much of software engineering is directly or indirectly involved to support mechatronic design. Due to the high level of standardization, especially among its hardware, the design of mechatronic products is strongly characterized by integrating standardized components and thus seems an ideal environment for product line engineering techniques, which allow dealing with the variability of reusable components if fully definable a priori. However, while many aspects of mechatronic design are standardized, there is also the need for the continuous construction of new components. However, today, it is difficult to seamlessly integrate the reuse of standardized components with the development of new components. This article presents a model-based approach for integrating component variants with user-defined components to better support the mechatronic design process. We present a combination of existing approaches addressing certain needs of the mechatronic design domain, for example, the integration of components is ensured through incremental consistency checking. Our approach is illustrated using the example of a basic articulated robot.

Reduced-order modelling of self-excited, time-periodic systems using the method of Proper Orthogonal Decomposition and the Floquet theory

The mathematical models of dynamical systems become more and more complex, and hence, numerical investigations are a time-consuming process. This is particularly disadvantageous if a repeated evaluation is needed, as is the case in the field of model-based design, for example, where system parameters are subject of variation. Therefore, there exists a necessity for providing compact models which allow for a fast numerical evaluation. Nonetheless, reduced models should reflect at least the principle of system dynamics of the original model. In this contribution, the reduction of dynamical systems with time-periodic coefficients, termed as parametrically excited systems, subjected to self-excitation is addressed. For certain frequencies of the time-periodic coefficients, referred to as parametric antiresonance frequencies, vibration suppression is achieved, as it is known from the literature. It is shown in this article that by using the method of Proper Orthogonal Decomposition (POD) excitation at a parametric antiresonance frequency results in a concentration of the main system dynamics in a subspace of the original solution space. The POD method allows to identify this subspace accurately and to set up reduced models which approximate the stability behaviour of the original model in the vicinity of the antiresonance frequency in a satisfying manner. For the sake of comparison, modally reduced models are established as well.

Improving mechatronical engineering: An artifact-assessment-based approach

Industrial engineering as a specialization of systems engineering inherently has mechatronic character. The seamless integration of engineering activities across engineering disciplines and throughout the overall engineering life cycle is a key element for achieving optimal technical as well as economic results and has to be supported by adequate engineering concepts and models. In this paper we present a criteria catalog for the qualitative evaluation of engineering artifacts created in or for engineering projects or contained in mechatronic product catalogs. The criteria catalog forms the basis for an assessment-based approach for evaluating mechatronic objects with the main purposes of providing the basis for characterizing, comparing, and improving them and furthermore for identifying directions for engineering improvements.

Understanding the relationship of information in mechatronic design modeling

Understand the information flow during engineering processes of mechatronic systems is an important point for competitive mechatronic engineering. The paper gives an overview about product models used in mechatronic design and analyzes also the flow of information through tools. Furthermore, there is also the need for considering model consistency because if objects and models are independently created and maintained by the various disciplines then correctness is no longer guaranteed. The same is true for objects or models that are transferred from one discipline to another, from one abstraction level to another, or from one design phase to the next one --- if such objects or models are subsequently modified on both ends just as proposed in simultaneous engineering.