Abstract
Tractors rollover, with its nearly 140 fatal accidents each year in Italy, represents one the major safety issues in farm activities. The risk increases when tractors operate in critical conditions such as a mountain environment, where slopes and the presence of ground obstacles reduce the rollover stability margin. Therefore, the development of stability models and simulators to study the behaviour of existing vehicles operating in hazardous conditions results very important, especially if they are originally designed to work on flat surfaces. However, the validation of these models is still a challenge as they must be compared and calibrated with experiments on real machines (i.e. too much complexity in working with bulky and heavy machines even from a safety point of view). The aim of this study is the experimental validation of a mathematical model to predict the behaviour, in terms of static stability, of a tractor travelling a slope characterised by the presence of obstacles. For this purpose, a four-wheel-drive narrow-track tractor (New Holland TN75V) has been considered as a test case. A mathematical model of static rollover stability has been derived to predict all the instabilities of the machine with any terrain conformation. The results have been then compared with an experimental test campaign performed on a real tractor and taking advantage of an innovative vehicle stability test rig available at the Agroforestry Innovations Lab (AFILAB) of the Free University of Bozen-Bolzano.