## 3 Application of the Design Approach to the Definition of the Innovative Test Rig
### Design of the General System ('Test Rig')
#### 3.2.4 Proposal of an Actuation Mechanism (\(\rightarrow\) Step 1.d)
If necessary, another primary actuator (#2) can be placed at the middle of the support frame. Axonometric views of a concept-platform, inclined only (**AX1**) or inclined and angled (**AX2**). Hydraulic cylinders are represented in dark blue. The trajectories have a radius ranging from 2500 to 6500 mm. In the lower half-plane, the turntable is also visible in light blue (see following paragraph). Figure 18: Kinematic schemes (left) and basic implementation schemes (right) of the mechanisms for generating the overall inclination of the platform (**I.a**, **I.b**) and for generating the angle between the semi-platforms (**A.a**, **A.b**) in their initial position (**I.a**, **A.a**) or angled (**I.b**, **A.b**); with regards to their frames of reference, the black and white circles are hinges whose positions are fixed over time. points of the secondary actuators. Unfortunately, by doing so the 'tiltable' structure will be partly cantilevered with respect to the position of the connection points of the primary actuators;
2. (AS2.) Juxtaposition of two equal jacks, in a series-parallel configuration (only if the global length is far from buckling), possibly in combination with the previous solution;
3. (AS3.) Creation of a kinematic mechanism (with one dof) that multiplies the elongation of a single actuator to obtain the complete lifting of the platform. The creation of a concave articulated quadrangle is proposed as the best solution in this case. The dimensions of the folded components and their possible interference with the secondary actuators must be considered in the design of the modified structure. Particular consideration should be awarded to the coupling points and to the dome height. Figure 20: _Cont._  
Also, in this case, as previously done for the solutions concerning the global inclination mechanism, it is possible to synoptically evaluate the advantages and disadvantages of the proposed solutions to increase the maximum inclination reachable by the support plane (Table 3). Considering the illustrated advantages and disadvantages, the preferable solution is to shift the coupling points of the primary actuators toward the inclination hinges. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Subsystem** & **Solution** & **Pros** & **Cons** \\ \hline \multirow{6}{*}{_System making use of hydraulic jacks to generate thrust force_} & \multirow{2}{*}{Shifting of the coupling points of the primary actuators toward the inclination hinges} & Solution very simple to implement in the design of this test rig: the total number of components does not increase & Positioning limited by the need not to interfere with the circular paths of the vehicles under test and with the coupling points of the secondary actuators \\ \cline{2-3}  & & Absence of interference of the connection points with the circular paths of the vehicles under test and with the coupling points of the secondary actuators \\ \cline{2-3}  & & Absence of interference of the connection points with the circular paths of the vehicles under test and with the coupling points of the secondary actuators; limited increase of the total number of components & Need to double the hydraulic jacks; need to design the coupling component; need to verify the absence of buckling phenomenon \\ \cline{2-3}  & & & Significant increase of the total number of components and of the complexity of the facility; dimensions of the components limited by the need not to interfere with the coupling points of the secondary actuators \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Advantages (’pros’) and disadvantages (‘cons’) of the solutions proposed to realize a mechanism to perform the global static stability tests; scheme references are the same as in Figures 21-23.