## 2 State of the Art
### Technology Roadmapping  
Technology roadmapping, or the technology roadmap (TRM) approach, is one of the many known methodologies available to support technology management and planning, enabling activities concerning technology innovation to be systematically carried out and communicated within the organization. The TRM approach immediately attracted the growing attention of both academic and industrial communities and it spread rapidly within companies, industries and even governments [23; 24; 25]. A technology roadmap can be described as a \"time-based chart, comprising a number of layers that typically include both commercial and technological perspectives\", depicting a set of structured relationships between markets, products and technologies over the time [26]. Moreover, a TRM is a document that results from the technology roadmapping process [23]. The definition and the objectives of the TRM tool may be different according to the different organizational purposes that it can address. A company often chooses the definition that better suits its objectives. A TRM is most widely utilized as an alignment tool for planning decisions or as a tool for technological foresight. Its timeframe usually varies from 3 to 5 years. To understand the focus of a TRM, it is necessary to clarify the importance of technology management. Taking into account different definitions of technology present in the literature, [26] define technology as applied knowledge embodied within a physical artifact. Managing technologies involves both the hard part, linked to science and engineering, and the soft part, linked to the processes that enable its effective application. Only the perfect balance between these two aspects could ensure the stream of products and services to the market. Technology roadmapping is a \"flexible technique (\(\ldots\)) to support strategic and long-range planning (\(\ldots\)) providing a structured (and often graphical) means for exploring and communicating the relationships between evolving and developing markets, products and technologies over time\" [26]. While it might be easy to describe the technology roadmapping process using what is available in literature, the process of building a TRM in practical terms is surely more difficult. Therefore, several authors decided to develop methods to facilitate the implementation of this process (e.g., the 'fast-start' approach named 'T-Plan', developed by [27]. Nevertheless, before starting to build a TRM, a clear overview of all the technologies that are under control of a certain function or organization is mandatory and it is functional to create a map of said technologies. The T-plan approach proposes a series of activities to achieve a TRM:  
1. Initially, after building the roadmapping team, a planning phase allows the participants to define the scope, the boundaries and the purpose of the process. Moreover, in this planning phase, the outcomes of the literature research are presented. Subsequently, with the support of a facilitator, the participants are involved in a brainstorm session aiming at identifying possible technologies likely to be developed over the following five years. 3. In the third phase, the TRM tool is charted (using computer-based tools) as a two-dimensional technology roadmap, consisting of a timeline and one layer on the vertical axis, reporting the identified technology clusters. 4. Finally, the TRM is presented to the participants, in order to be validated and stored, and follow-up activities are identified and scheduled. Prompted by the interest arising from this first implementation, a review was carried out in order to improve the outcome and to add a second layer, introducing a market perspective. This is due to the fact that said preliminary TRM focused only on technological aspects. Moving from these considerations and following a step-by-step approach, the second attempt to develop a TRM tool was carried out, again following an approach that resembled the T-plan.