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2022, Vol. 20, No. 2

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/7700

Sirvi

Sirvi 2022, Vol. 20, No. 2 Autor "Estonian University of Life Sciences. Institute of Technology" järgi

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  • Pisipilt
    Kirje
    Assessment of power characteristics of unmanned tractor for operations on peat fields
    (Estonian University of Life Sciences, 2022) Kägo, Riho; Vellak, Priit; Ehrpais, Hendrik; Noorma, Mart; Olt, Jüri; Estonian University of Life Sciences. Institute of Technology
    In this article, power characteristics of a state-of-the-art unmanned ground vehicle (UGV) are characterised. It is demonstrated that in terms of power characteristics requirements, purposebuilt computer aided autonomous UGV systems are capable of replacing systems that utilise conventional tractors in peat field operations, with milled peat extraction operations as a case study. The authors demonstrate the viability of the UGV in achieving optimal mobility capabilities in operating on peatland surface. The UGV of interest was assessed for two operations of milled peat extraction: milling and harrowing. For both operations, the power consumption of the UGV and the drawbar pull of the implements (passive miller and harrower) were measured and analysed. The required drawbar pull values of the investigated implements remained in the range of 4–8 kN, which corresponded to the drawbar power of 14–36 kW. It was found that the UGV of interest is capable of carrying out milled peat operations in terms of traction capacity. However, it was found that the power supply capacity to be insufficient, thus requiring an improved solution.
  • Pisipilt
    Kirje
    A mathematical model of the rear-trailed top harvester and an evaluation of its motion stability
    (Estonian University of Life Sciences, 2022) Olt, Jüri; Bulgakov, V.; Beloev, H.; Nadykto, V.; Ihnatiev, Ye.; Dubrovina, O.; Arak, Margus; Bondar, M.; Kutsenko, A.; Estonian University of Life Sciences. Institute of Technology
    Improving the quality of sugar beet harvesting to a great extent depends on the first operation in the process, which involves cutting and harvesting sugar beet tops. This technological process is performed with the use of either the haulm harvesting modules of beet harvesters or top harvesting machines as separate agricultural implements, which are aggregated with a tractor. At the same time, front-mounted harvesters are as widely used as trailed asymmetric implements, in which case the aggregating tractor moves on the already harvested area of the field. The purpose of this work is to determine the optimal design and kinematic parameters that would improve the stability in the performance of the technological process of harvesting sugar beet tops by means of developing the basic theory of the plane-parallel motion performed by the rear-trailed asymmetric top harvester. As a result of the analytical study, an equivalent scheme has been composed, on the basis of which a new computational mathematical model has been developed for the plane-parallel motion of the asymmetric top harvester in the horizontal plane on the assumption that the connection between the wheeled tractor and the rear-trailed top harvester is made in the form of a cylindrical hinge joint. Using the results of mathematical modelling, the system of linear second-order differential equations that determines the transverse movement of the centre of mass of the aggregating wheeled tractor and the rotation of its longitudinal symmetry axis by a certain angle about the said centre of mass as well as the angle of deviation of the rear-trailed asymmetric top harvester from the longitudinal symmetry axis of the tractor at an arbitrary instant of time has been obtained. The solving of the obtained system of differential equations provides for determining the stability and controllability of the motion performed by the asymmetric machine-tractor unit, when it performs the technological process of harvesting sugar beet tops.