Author(s)

Marco Bietresato & Fabrizio Mazzetto

Abstract

The stability of a vehicle (especially if operating off-road, such as a farm tractor, possibly with an im- plement attached) can be statically investigated by means of a test installation such as the one described here. It consists of a platform (dimensions: 6.42 × 4.46 m) having two degrees of freedom (inclination, rotation) and on which the vehicle is positioned motionless. By acting on these degrees of freedom, it is possible to precisely and simultaneously control all the characteristic angles of a vehicle (roll, pitch, yaw), thus discovering, in complete safety, its operational limits (i.e. its incipient rollover conditions). Furthermore, the ability to misalign up to two of the four quadrants composing the platform allows the testing of further critical situations for the vehicle, in which the front-axle pivot joint and the tyres elasticity are involved, potentially up to a scenario in which the vehicle rests on only three of its four supports and its support polygon degenerates into a triangle. The basic test scenarios that can be investigated with this installation allow the study of many aspects of a vehicle, pertaining both to the general chassis performance of the vehicle (therefore related to its balance) and to the load state of some spe- cific components (internal or interfacing the vehicle with the outside, e.g. the wheels). The obtained data, referred to reference test scenarios, allow the experimenters to: (1) interpret sensors readings in real operating situations, thus including also the contribution of the tyres vertical flattening and lateral deflection, (2) complete the safety documentation at the users’ disposal with some specific graphs, the vehicle ‘equilibrium maps’ (or ‘stability charts’), possibly referred also to the vehicle with some accessories/implements connected to it. By demonstrating the undeniable usefulness of such an installation, the authors hope to propose new testing paradigms with the ultimate aim of increasing the overall safety of vehicles and, particularly, of agricultural and work machinery.

Keywords

Euler angles, rotating platform, stability on sloping grounds, stability test, tilting platform, turntable, vehicle overturning, vehicle rollover, vehicle stability.