Tractor motion model with deviation from a rectilinear movement under the influence of external off-center forces

A feature of tractor aggregates and road construction machines is a special interaction with the soil. Force action on the base tractor occurs not only through the mover, but also from the side of the working body. Often the external force from the side of the working body is not a central force, that is, the line of its action does not pass through the machine center of gravity. This results in an uncontrolled rotational shift of the base tractor. The machine loses directional stability and deviates from a rectilinear motion under the action of external forces. This uncontrolled curvilinear movement has been little studied to date. It is a combination of rectilinear controlled motion and uncontrolled curvilinear shift. The article developed a mathematical model of uncontrolled tractor movement, consisting of motion equations and a system of force equilibrium. The force interaction of the propulsion device with the soil is based on the mathematical theory of friction. The resulting tangential force and the stabilizing moment in contact are functions of the coordinates of the instant center of motion of the propulsion relative to the ground. Various friction coefficients in the longitudinal and transverse directions made it possible to take into account the anisotropy of the interaction in the contact. The elastic properties of the soil and tires were taken into account due to the variable friction coefficient. The quasistatic mathematical model allows you to build a real motion trajectory taking into account external factors, to determine the lateral tractor deviation from rectilinear motion anywhere in the path. Investigation of the effect of the external force value, its direction and point of application on the movement trajectory on various soil will allow us to further find ways to maintain the machine directional stability when eccentric external forces act on it.