## 4 Conclusions  
This work illustrates the potential of a new installation for testing and certifying the stability of agricultural and operating machines. This installation, called a rotating platform or turntable, has the peculiarity of moving the machine positioned on it according to two rotational degrees of freedom (global inclination of the support plane, rotation of the support plane around an axis perpendicular to it). It significantly expands the test scenarios currently proposed by the reference standards (foreseeing, instead, only a lateral overturning test without any measurements of the weights supported by the tyres) with a novel type of test, namely the quasi-static stability tests, allowing to obtain a much wider information content than from a single conventional test. The same installation is predisposed to record the weight supported by each wheel of the agricultural machine positioned on it, both when the platform is stationary and while the above-described movements are being carried out. The mathematical models presented here anticipate and help the future understanding of the trends that will be recorded when the installation is actually active, thus maximizing the information content that will be made available. In the wishes of the authors, such equipment should enable the driver to have a greater awareness of the way in which his vehicle behaves and, thus, to operate in complete safety. In addition, the operative angles of this test equipment that may lead the vehicle to an incipient overturning condition (in terms of angle of inclination \(\alpha\) and rotation \(\beta\) of the support plane) should also be used to guide the development of possible prototypes of the tested machines and/or to set the operating limits of any active safety equipment. In the simplest configuration, one of these devices could be configured as a double inclinometer (or an inertial platform) equipped with a series of acoustic (buzzer) and visual (flashing lights) alarms that signal the driver the approach of the vehicle to its limit angles (by setting, for example, the alarm thresholds to the 90% or 95% of these angles). In a more advanced version, this instrument could also be given the possibility to act on some actuators that, for example, regulate the excursion of the shock absorbers (if any) or the position of the machine body for  
Figure 23: Structure simplification process of the test rig (**a**–**c**); 3D rendering of the test installation currently under development (**d**) and exemplification of its kinematic mechanism to incline the support platform, placed under the ground plane, requiring a pit of adequate size to operate (**e**). those machines that are equipped with a self-leveling system. All these systems can be safely tested using the presented rig. The reported case-study allowed exemplifying the outputs of this test rig after some tests on a conventional tractor. Thanks to this mathematical model, it was possible to anticipate one of the most interesting results that will be made available by the structure when it is built. It is a graph that shows, in correspondence to a set inclination \(\alpha\) of the structure, the trend of the normal load on each support as the rotation angle \(\beta\) of the turntable spans from \(0^{\circ}\) to \(360^{\circ}\) (corresponding to a complete revolution of the turntable). In this graph, the distance of each curve from the abscissae axis represents the safety margin of that machine under the conditions of spatial orientation imposed by the rig (corresponding to a defined angle of roll and pitch). The mathematical model used here has also allowed the quantification of the destabilizing effect of tyres inflated to a pressure of 1.0 bar (i.e., a value usually adopted in field works to avoid over-compacting the ground): the incipient overturning limit is 10% less than if the tyres were neglected. Any rollover prevention system should therefore also include sensors to monitor the tyre pressure in order to adjust the danger threshold.