Research on interaction law of longitudinal/lateral slip of mountain tractor based on tire-soil model

When the mountain tractor is along the slope contour operation, the driving wheel will cause a longitudinal or lateral slip due to complex driving conditions. In order to investigate the influence law between the longitudinal slip, lateral slip, and deflection slip, the parametrically modified wheel-soil model, dynamics model, and motion trajectory model were established, and the tractor lateral slope simulation model was built based on MATLAB/Simulink and CarSim software. The simulation results show that load traction has the most significant effect on the longitudinal slip rate, lateral slope variation has the most significant impact on the side-slip angle and lateral slip rate, and the lateral slope and load traction together affect the yaw angle and deflection slip rate. When the lateral slope is 15°, the tractor longitudinal speed of 3 and 6 km/h can maintain lateral stability of the longitudinal slip rate of 0.39 and 0.25, respectively. In order to verify the accuracy of the simulation model, the test platform was built. The results show that the average errors of the absolute values of left longitudinal slip rate, right longitudinal slip rate, yaw angle, and side-slip angle are 14.47%, 13.06%, 12.27%, and 11.04%, respectively. To sum up, the extreme driving conditions of the tractor will aggravate the longitudinal slip of the driving wheel, which in turn affects the lateral slip and deflection slip, and should be controlled to avoid tractor instability.