## 3 Results and Discussion
### Possible Operative Modes of the Test Rig  
The rotating platform (also called \"turntable\") can be used in two operating modes: \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Test Scenario** & **Pure Lateral Inclination** & **Pure Frontal Inclination** & **Generic Inclination** \\  & & & **(Realistic Situation)** \\ \hline Characteristic angles of the vehicle in the frame of reference of the test system (support plane inclination, vehicle longitudinal axis direction) & (\(\alpha\), \(\pm 90^{\circ}\)) & (\(\alpha\), \(0^{\circ}/\pm 180^{\circ}\)) & (\(\alpha\), \(\beta^{\prime}\)) \\ \hline Characteristic angles of vehicle (roll, pitch, yaw) & (\(\varphi\), \(0\), \(0\)) = (\(\alpha\), \(0\), \(0\)) & (\(0\), \(8\), \(0\)) = (\(0\), \(\alpha\), \(0\)) & (\(\varphi\), \(\delta\), \(\psi\)) \\ \hline Test able to generate the described scenario & Traditional test; turntable test (in partic.: global completely static tests with \(\beta^{\prime}=\pm 90^{\circ}\)) & Traditional test; turntable test (in partic.: global completely static tests, global quasi-static test) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: possible scenarios that can be experimented by a vehicle placed on an inclinable platform (angles \(\alpha\) and \(\beta^{\prime}\)). Figure 3: (a) lateral inclination of an agricultural machine, the imposed angle \(\alpha\) corresponds to the roll angle \(\varphi\); (b) frontal inclination of an agricultural machine, the imposed angle \(\alpha\) is the pitch angle \(\delta\); (c) general inclination of an agricultural machine, the two set angles \(\alpha\) and \(\beta^{\prime}\) impose angles of roll \(\varphi\), pitch \(\delta\) and yaw \(\psi\) to the vehicle under test. * completely static mode (i.e., no revolution of the turntable around its axis of rotation) to have a global static stability test; (phase 1) the vehicle is placed on the platform when the support structure is horizontal (\(\alpha=0^{\circ}\)) and the sides of the quadrant are aligned with the inclination hinge (\(\beta=0^{\circ}\) or \(\beta=\pm 90^{\circ}\) or \(\beta=\pm 180^{\circ}\)), thanks to the measurement of the weights supported by each quadrant, it is possible to place the center of gravity in relation to the center of the platform; (phase 2) subsequently, without moving the vehicle (its wheels are fixed to the quadrants), the support structure is tilted at a fixed angle (however far from the vehicle rollover); by doing so it is therefore possible to identify the height of the \(CoG\) of the machines under test; (phase 3) the support structure is tilted until the (lateral, frontal) overturning angle is reached;
* quasi-static mode (i.e., very slow rotation of the turntable and of the vehicle on it) to have a global quasi-static stability test; (phase 1) when the support structure is horizontal, the vehicle is positioned on the platform and the vehicle wheels are fixed to the quadrants; (phase 2) the support structure is tilted at different angles with respect to the horizontal plane and, at each fixed inclinations, the rotating subsystem is then activated thus making the vehicle revolute around the turntable rotation axis (the rotation speed should be around 0.026 rad\(\cdot\)s\({}^{-1}\) as declared in [41], i.e., a full rotation is completed in about 4 min); in the meantime, the weights supported by each quadrant (hence, supported by each wheel of the vehicle) are measured, thus characterizing the balance of the vehicle at different angles of roll, pitch and yaw (see next paragraphs); (phase 3) the procedure described in the previous phase is repeated till reaching an overturning condition. It is worth noting that the slowness of movement should make it possible to avoid (or, at least, mitigate) the vibrations that unfortunately occur in structures in which there are rotating organs [44], that can be a serious disturbance when measurements are made. However, another possibility to consider after first real-scale tests is eventually transforming the continuous movement into an intermittent one.