The “W-Modell” – A Systems Engineering based Approach to Active Systems Development

Prof. Dr.-Ing. Reiner Anderl
Dipl.-Ing. Roland Nattermann
Dr.-Ing. Dipl.-Wirtsch.-Ing. Thomas Rollmann

Department of Computer Integrated Design
Fachgebiet Datenverarbeitung in der Konstruktion (DiK)
Technische Universität Darmstadt
Petersenstr. 30
64287 Darmstadt
E-mail: {anderl, nattermann, rollmann}@dik.tu-darmstadt.de
Phone: +49(0)6151/16-6001
www.dik.tu-darmstadt.de

The development of active systems is characterized by the integration of electronic components into mechanical structures. The behavior of the overall system, based on a framework of internal and external conditions, is influenced by the targeted use of intelligent control circuits.

Mechatronic systems are defined by the functional and/or spatial integration of actuators, sensors and information processing into existing mechanical structures. Adaptronic systems are to be considered as a further development of mechatronic systems and are characterized by the fully structurally and spatially integrated electronic components [1]. This high level of integration gives rise to high demands on product development methodology and requires a tight integration of the various technical disciplines during the development process of active systems.
For the development of mechatronic systems a procedure in accordance with the “V-Modell” of VDI guideline 2206 is applied. The “V-Modell” describes the development of mechatronic systems based on a systematic analysis of needs and requirements as well as an allocation of tasks between the individual disciplines [2]. The detailed design is then performed in parallel and self-dependently in the various involved disciplines. Furthermore, following completion of the development activities, the results of the various disciplines will be integrated to subsystems and systems, and verified to assure compliance with the requirements originally specified.

It appears, however, that this approach often leads to problems in the integration phase [3]. Due to self-dependence development, the discipline-specific components meet their specific requirements but cannot easily be integrated to comprehensive systems. This is generally due to an inadequate consideration of the dependencies between the interdependence of disciplines and components and the lack of communication between the disciplines during the development process.

The problems during the integration result in a high number of iterations in which the discipline-specific solutions subsequently are adapted, integrated and analyzed again. The problems are even more challenging if cross-enterprise development has to be performed.

The further development of mechatronic to adaptronic products therefore requires not only profound developments in the field of mechanics, electronics, information technology (IT), and material sciences, but also necessitates a change in paradigm and hence substantiates the need to adapt and enhance the methods of modern virtual product development in this multidisciplinary field of engineering.

The future methods of product development not only need to control the development processes and manage data from all disciplines, but must also offer the possibility to compare the results of disciplines involved. This requires pushing up the event of synergistic integration to -earlier stages of the virtual product development process.

To take the structural integration of mechatronic and adaptronic systems and the high degree of crosslinking of the various disciplines in the system development into consideration, the Department of Computer Integrated Design of TU Darmstadt proposes the “W-Modell” as a new methodological approach for the development of active systems. The “W-Modell” principally is based on the well-known “V-Modell”, but also includes several essential methodical innovations, which address current and future challenges in the development of active systems.

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Figure 1: A new approach to active systems development – the “W-Modell”, cf. [4]

At the beginning and at the end of the development process, the suggested procedures and activities of the “W-Modell” and the “V-Modell” are identical.  In both approaches, the development process starts with an analysis of requirements and a sharing of development tasks amongst the participating disciplines. The development process concludes in both approaches with an integration and analysis of discipline-specific solutions to systems. The advancement of the “W-Modell” in comparison to the “V-Modell” becomes obvious in particular during the development of discipline-specific components, which in the “W-Modell” are not independent of each other [4].
Instead, the development processes are conducted in mutual dependence on the basis of an integration of digital models of discipline-specific solutions for virtual verification of the interdisciplinary interim and final development results. Thereby new methods of analysis and simulation play a significant role.

The “W-Modell” also provides a new data management methodology. Hence, the “W-Modell” presumes the use of a dedicated data management system, which provides not only a central management of the data-sets of all disciplines and control of all development activities, but is also able to analyze and synchronize the discipline-specific data across disciplines. Thus, the data management system is able to monitor the condition and behavior of the system to be developed at any stage of the product development process, and to ensure the compatibility of the discipline-specific components and subsystems [5].

Therefore the principles of system engineering are applied in the “W-Modell”. The data management methodology uses a formal system model which, among other things, maps the system elements, properties and parameters. This allows analyzing the dependencies between the disciplines and cross-disciplinary mapping of discipline-specific results and changes. The use of the data management system in conjunction with a global system model also offers the possibility to evaluate changes of the systems to be developed on the basis of external conditions or findings from real tests and prototype testing.

As a result of the data management system, it is possible to ensure that the system being developed not only fulfills the requirements in every stage of development process, but also improves the integration of the discipline-specific solutions to subsystems and systems.

Literature
[1] Bös, J; Bein, T; Hanselka, H.: LOEWE-Zentrum AdRIA: First results and future plans, In: Proceedings of the Forum Acusticum 2011, S. 647–652. Aalborg, Denmark, 2011.

[2] Verein Deutscher Ingenieure (VDI), 2004, VDI 2206, Design methodology for mechatronic systems, Beuth, Berlin, Germany

[3] ProSTEP iViP Association, 2009, Mechatronic Process Integration (MPI), Final Report, ProSTEP iViP Documentation, Darmstadt, Germany

[4] Nattermann, R.; Anderl, R.: Approach for a Data-Management-System and a Proceeding-Model for the Development of Adaptronic Systems, In: Proceedings for the ASME International Mechanical Engineering Congress & Exposition (IMECE), Vancouver, 2010

[5] Nattermann, R.; Anderl, R.: Simulation Data Management Approach for Developing Adaptronic Systems – The W-Model Methodology, In: Proceedings of the WASET 2011 International Conference in Software and Data Engineering (ICSDE), Bangkok, 2011

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