# Study on the Control of Torque Distribution of 4 WD Corn Harvester Operation Drive
## 3 Simulation and Result Analysis
### Front Left Wheel Slip Simulation  
The initial state of the simulation was the left front wheel slipping, after the inter-axle torque control. The adjustment control process was to brake the slipping wheel to a certain extent based on the inter-axle differential clutch combination, so that part of the driving torque was transferred to the well-attached driving wheels, and if it slipped again, further torque control was carried out, and if necessary, engine output torque control was carried out in conjunction with engine throttle control. Finally, the traction force of the whole \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Condition** & **Parameter** & **Value** & **Parameter** & **Value** \\ \hline \multirow{4}{*}{Transmission system} & Engine power (kw) & 110 & Rated speed (r/min) & 2200 \\  & Front axle gearbox ratio: \(i_{\mathit{if}}\) & 6.2 & Rear-axle gearbox ratio: \(i_{\mathit{cr}}\) & 6.2 \\  & Engine lag time constant: \(T_{\mathit{cl}}\) (s) & 0.01 & Engine time constant: \(T_{\mathit{cl}}\) (s) & 0.5 \\  & Friction coefficient of main clutch & 0.25 & Friction coefficient of control clutch & 0.25 \\  & friction plate: \(\mu_{\mathit{x}}\) & & friction plate: \(\mu_{\mathit{c}}\) & \\  & Effective working radius of the main & & Control clutch effective working & \\  & clutch: \(\mu_{\mathit{x}}\) (mm) & & radius: \(\mu_{\mathit{c}}\) (mm) & \\  & Reduction ratio of belt drive: \(i_{\mathit{b}}\) & 2 & Front and rear axle transmission & \\  & & & efficiency: \(\mu_{\mathit{of}}\) & \\ \hline \multirow{2}{*}{Brakes} & Brake peak pressure: \(P_{\mathrm{max}}\) (MP\({}_{\mathrm{a}}\)) & 13 & Braking system time factor: \(K_{\mathit{l}}\) & 3.5 \\  & Front brake wheel cylinder diameter: & 45 & Rear brake wheel cylinder diameter: & 35 \\  & \(D_{\mathit{f}}\) (mm) & & \(D_{\mathit{l}}\) (mm) & \\ \hline \multirow{2}{*}{Wheels} & Drive wheel rolling radius (m) & 0.6 & Tire section width (mm) & 315 \\ \hline \multirow{3}{*}{Whole machine} & Harvester quality (kg) & 4600 & Front and rear wheelbase (mm) & 3000 \\  & Moment of inertia of the whole & & Distance of the mass center from the & 1220 \\  & machine around \(z\)-axis: \(j_{\mathit{z}}\) (kg:m\({}^{2}\)) & & front axis: \(a\) (mm) & \\  & Front axle wheelbase (mm) & 1600 & Rear-axle wheelbase (mm) & 1600 \\ \hline \multirow{2}{*}{Road state} & \multirow{2}{*}{Field adhesion coefficient: \(\mu_{\mathit{t}}\)} & \multirow{2}{*}{0.6} & Coefficient of rolling resistance in & \\  & & & field: \(f_{\mathit{R}}\) & 0.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main parameters used in the simulation. Figure 7: Initial state of harvester simulation. machine was improved. The simulation results are shown in Figure 8a,b. The dashed lines were the variation law of the harvester speed and the speed of the slipping wheel with time when no control was applied, and the solid lines were the corresponding speed variation law after the control was applied. The simulation results showed, when no control was applied to the harvester, within 1.7 s, the speed of the slipping wheel first rose sharply to the maximum value due to slippage and then fell sharply to below 3 km/h due to the increase in attachment, during which the speed of the harvester showed a decreasing trend due to the slip of the wheel. After 1.7 s, the speed of the harvester increased with the speed of the slipping wheel and finally reached the uniform speed at the same time. The harvester speed and the slip wheel speed fluctuated greatly during the whole process, and the speed of the slip wheel was overshoot, the maximum overshoot was 17.86%; after the torque control was applied, as shown in the solid line in Figure 8, the speed of the harvester and the speed of the slipping wheel rose steadily during the whole adjustment process, and the adjustment time to reach the uniform speed was 43.3% shorter than that without control.