## 2 Materials and Methods: The Design Approach
\begin{table}
\begin{tabular}{p{142.3 pt} p{142.3 pt}} \hline \multicolumn{1}{c}{**Step**} & \multicolumn{1}{c}{**Sub-Step**} \\ \hline _1.a. Concept_ & Formalization/conceptualization of a general idea about a system/subsystem \\ \hline _1.b. First Technical Synthesis_ & Interpretation of the goals in term of necessary technical requirements and constraints for the considered system/subsystem \\ \cline{2-3}  & Translation of the requirements and constraints into technical characteristics that the intended system/subsystem must have \\ \hline _1.c. First Creative Synthesis_ & Outline of the general features of the system (i.e., ex-novo design or identification of one or more technical systems/components already on the market which provide the technical features previously identified) \\ \cline{2-3}  & Plotting of the first conceptual schemes of the intended system/subsystem \\ \hline _1.d. Preliminary Analysis_ & Identification of strengths and weaknesses (i.e., advantages and disadvantages/critical states) of each solution, comparative evaluation of the various identified solutions and identification of the best solution \\ \cline{2-3}  & Preliminary study of the intended technical system/subsystem from the kinetic-dynamic point of view, aimed at performing a preliminary general dimensioning of the system/subsystem so that it can fulfil the desired minimum technical requirements \\ \hline _1.e. Second Technical Synthesis_ & Calculation of the overall dimensions of the considered system/subsystem, individual of any possible restrictions to its movements (minimum/maximum angles of rotation of the articulated links, minimum/maximum strokes of the translating organs) and prescription of the design loads which are to be used in the following design phases concerning the detail design of the mechanical structures, actuators, and sensors \\ \hline _1.f. Second Creative Synthesis_ & Preliminary design of the considered system/subsystem and of any of its parts \\ \cline{2-3}  & Description of technical solutions to be adopted in the subsequent detailed design phase \\ \hline \end{tabular}
\end{table} 
Table 1: Steps and sub-steps included in phase 1 of the general development process of technical systems (i.e., the ‘Conceptual and embodiment design’); many iterations of this sub-steps are possible before arriving to step 1.f and then going on with phase 2 (‘Detailed design’), typically: 1.b\(\rightarrow\)1.d, 1.b\(\rightarrow\)1.e (for each considered system/subsystem). Subsequently, as illustrated in Table 1, after the conceptualization of a general idea about the system (here: an innovative facility for testing moving and motionless vehicles on a slope; step 1.a), the minimum system requirements and the constraints to which the system is subjected have been defined and translated into technical specifications that the system should have (e.g., minimum dimensions, minimum achievable inclination-angle; step 1.b). In the following step 1.c, the system architecture has been designed (conceptual/CAD sketches of some subsystems) following certain criteria (e.g., regarding the actuators). During this phase, the creativity of the designer is essential but can be guided by one or more of the many approaches hitherto proposed in the literature [62], the most famous of which are based on the creation of components/blocks with proper interfaces of connection and on the study of relative interactions/movements/ways of operating [63,64]. Therefore, by reasoning on such schemes, some linear actuators were placed so that the desired movements (partial rotations of some machine components) take place in correspondence to the full extension of the actuators. All ideas in this phase have been initially accepted without considering the feasibility and the system dimensions, much resembling a brainstorming session for a group of people. Then, the operation of the system has been preliminary studied (step 1.d) with the aim of selecting the most interesting schemes/ideas, and further refinements to the design have been done (steps 1.e, 1.f).