Modelling of product-service systems (PSS) based on the PDD approach

Abstract

To achieve a sustainable competitive advantage, it is necessary to minimise the development time of new products. At the same time, any new product must be a rather optimal compromise between fulfilment of the customers' and/or users' requirements, economical efficiency and ecological awareness. To deal with these — partially conflicting — requirements, it seems to be necessary to allow a new perspective onto the product development process. On the one hand, a continuous methodology is necessary that guides the designer through the development process, beginning with (often fuzzy) requirements and supporting him/her right through to the final description of the solution. On the other hand such a methodology is closely linked to a suitable approach to modelling the product itself, and also in this respect extended or new concepts are required. An integrated view on material and non-material components of products ('products' in the traditional meaning of the word and 'services') seems to be very promising. Such a holistic perception has been made in an implicit way for a long time, but an explicit and systematic consideration is rather new. In recent publications, the term Product-Service System (PSS) has been established for this type of integrated business; where the traditional separation between material and service components is given up and both are considered as potential means to fulfil customers' needs [1, 3, 6, 10, 11]. Considering material components and services of a product ('product' in an extended sense) fully integrated and on equal terms, it can not be determined in advance which requirements will be fulfilled by services and which requirements will be fulfilled by material components. In some cases certain properties of a product can only be achieved by services that complement or even replace the material component. Although the importance of PSSs in today's marketplace is undisputed, there is no clear approach to develop them in a systematic way. The main problem of applying traditional design methodologies like VDI 2221 [9] to the development of PSSs is their strong orientation on functional, physical and building structures of a product. This orientation may match material products, but does not fit PSSs, the purpose and behaviour of which can hardly be displayed in the categories mentioned. A result-oriented approach seems to be necessary. In the field of business engineering, there do exist some models to describe services and some — still very conceptual — approaches to how to develop them. The goal of a joint research project of the Institute of Engineering Design/CAD (LKT) and the Institute of Information Systems (IWi), both of Saarland University, is to develop a consistent methodology for developing PSSs. The initial point for this consideration is the concept of Property-Driven Design/Development (PDD), a new product development theory and methodology developed by LKT originally to describe material products and to lead through development processes for them.The following paper will briefly introduce the basics of the PDD concept. Requirements for applying the PDD approach to PSSs will be covered, and a new approach to capturing integrated product models of PSSs will be shown. Furthermore, we want to give some outlooks, mainly with regard to the question how to describe (integrated) development processes of PSSs.