Kinematic analysis of rotary harrows

This article presents the kinematic analysis of the tine motion of a rotary harrow. In particular, it analyses the trajectories that the tines describe when they are pulled by the motion of the tractor and rotated by the rotors. This analysis, has led to the identification of the parameters that influence the motion of the tines and how these parameters intervene in the secondary tillage. The interaction between the tines and the soil is evaluated considering a plastic soil, i.e. without any cleavage and its propagation. With this hypothesis, the dimensions of the soil clods created by the passage of the tines in the soil have been analysed. The trajectories described by the tines of the machine, and therefore the dimensions of the portions of worked or unworked soil, are influenced by the operating parameters of the soil tillage process, such as the tractor speed and the angular speed of the tines themselves. Furthermore, a contribution is also given by the geometric parameters of the machine, such as the rotor radius and the geometric configuration of the rotary harrow in terms of rotor arrangement. This study is based on the creation of a mathematical model of the trajectories of the tines of a rotary harrow during soil tillage. The model is parametric and makes it possible to simulate and optimise the tillage process. The approach adopted also makes it possible to visualise the trajectories in graphic form for an easy visual interpretation of the results.