Analytical model of duckfoots draught force prediction based on soil parameters and technical tools, and its validation in laboratory conditions

The scientific objective of this work was to develop an analytical model for predicting the draught force required to overcome soil resistance by row weeders’ duckfoots. The model considered variable duckfoot geometry, dynamic soil effects (i.e., changes in density, moisture, cohesion, and friction under tool loading), and nonlinear soil-implement interactions. The model was validated for three duckfoots with widths of 105 mm, 133 mm, and 202 mm. The tools were mounted on two types of flexible tines: a conventional S tine (stiffness 5.3 kN·m −1 ) and a Vibro Crop tine (VCO, stiffness 8.3 kN·m −1 ). The experiments were carried out in a soil bin filled with clay sand with a moisture content of 10 % and 14 % and a compactness of 486 kPa, using an instrumented measurement setup based on strain-gauge, laser, and optical sensors to acquire draught force, working depth and travel speed at duckfoots depths of 30, 50, and 70 mm and working velocities of 0.84, 1.67, and 2.31 m·s −1 . The draught forces were predicted considering optimised values of the soil internal friction, soil–tool friction, and tool setting angles identified from the measurement data. The model showed good agreement with the experimental draught force values. For 10 % and 14 % soil moisture, the global errors were 18.0 % and 24.7 %, respectively, and the mean relative error was 0.8 % in both cases. The model was validated and confirmed the hypothesis, but it requires further refinement and probabilistic analysis.