Motion Analysis of a Trailed Harvester with Combing Working Units

The article presents the motion analysis of a trailed harvester equipped with combing working units. The harvesting unit comprises a wheeled tractor, a harvesting machine, and a trailer for collecting the combed heap. The research aims to model the behaviour of the machine under various simulation conditions. To facilitate the analysis of the motion of the three-link harvesting aggregate, constraints of the harvester to the tractor and trailer were replaced with their reactions, and the motion of a single harvester was considered. In the first stage of the studies, a calculation scheme was drawn up indicating the forces and moments of forces influencing the machine and the constraint reactions. Lagrange’s equation of the second kind in generalised coordinates was used to derive a differential equation of the machine’s motion. The rotation angle of the harvester relative to the hitch point with the tractor was taken as a generalised coordinate. After algebraic transformations, a differential equation for the harvester’s motion was obtained. By solving the differential equation, a function was found, which made it possible to analyse the change in the rotation angle of the machine. Further analysis of the motion of the harvester was carried out using experimental methods.

Experimental data is used to verify the model’s accuracy and its correspondence to real processes. If the model accurately predicts the behaviour of the combed heap, it confirms its adequacy. The parameters of the mathematical model can be adjusted based on the results of experiments to improve the accuracy of the prediction. The mathematical model allows predicting the behaviour of the combed heap under various conditions, which can help optimise the process parameters. Experiments can produce results that are difficult to interpret without a theoretical framework. The model helps to explain the mechanisms underlying the observed phenomena. The programme of experimental studies included obtaining the statistical characteristics of the horizontal oscillation amplitude of the harvester within the speed range of 1.2-2.8 m·s⁻¹. The minimum deviation of the mass centre of the harvester from its linear motion was adopted as an estimation criterion for its linear motion. As a result of experimental studies which will be presented in the next article, it was determined that the most acceptable mode of motion that meets this requirement and provides the maximum efficiency of the harvester is the motion speed of 2.0 m·s⁻¹.