Measurement of tensile force at the fundamental tillage using tractor’s build-in sensor and external sensor connected between machines and their comparison
 M. Kroulík*, J. Chyba and V. Brant
 Czech University of Life Sciences Prague, Kamýcká 129, Prague 6 – Suchdol, 165 21, Czech Republic;  *Correspondence: kroulik@tf.czu.cz
Abstract:
 The  value  of  tensile  force  during  soil  tillage  is  crucial  for  estimating  the  energy performance of trailed machines. For tensile force measurements, a mouldboard plough with working width of 4 m was used. The ploughing speed was approximately 7 km h-1. Measurements were carried out on two plots with different soil texture. Loam-sandy soil dominated on the first plot, whereas clay soil dominated on the second one. The slopes of the plots are 1.1° and 2.4° respectively. Both plots have been left without stubble modification after harvest. The dynamometer LUKAS type S-38 was used for  measuring  tensile  force.  The  dynamometer  was  placed  on  a  hinge,  which  was  positioned between two tractors. As a second method of tensile force measurement, electro-hydraulic hitch sensors were used, from which the values were recorded. The obtained values of tensile force were approximately 30 kN on the first plot and 54.3 kN on the  second  plot.  The  interdependence  values  of  tensile  forces  between  internal  and  external sensors showed a high coefficient of determination R2 = 0.91 in regression data analysis.  The  comparison  of  tensile  force  measurements  using  a  special  dynamometer  and  electro-hydraulic tractor sensor proved that the outputs of serial sensors can be used for the continuous monitoring  of  tensile  forces  during  operating  the  machine.  The  automated  storage  of  data collected from tractor sensors during tillage can greatly simplify this work, while no additional expenses are incurred to obtain data. Thus, the findings can be used to determine the variability of the land.
Key words:
force sensing, soil mapping., soil tillage, soil variability, tensile force