## 5 Conclusions  
Aimed towards optimizing the configuration of a hybrid tractor loaded with HMCVT, this paper focuses on the research and analysis of hydraulic mode and mechanical hydraulic transmission mode. Based on bench test data, the interpolation modeling method was applied to establish a theoretical model of an engine. The system simulation model was developed using the SimulationX software. The following were chosen as evaluation metrics for mode switching quality: output shaft velocity drop amplitude, dynamic load coefficient, impact strength, and switching time. We optimized the quality of the switching process between the hydraulic mode and the mechanical hydraulic mode. The mode switching involves four interacting clutches. The orthogonal test was carried out using the L\({}_{16}\)(2\({}^{15}\)) orthogonal table. The simulation results indicate that the A\({}_{1}\)D\({}_{1}\)C\({}_{1}\)B\({}_{2}\) configuration provides the optimal comprehensive horizontal scheme. This entails switching clutches C1, C2, and C4 0.5 s ahead of schedule, while clutch C5 is engaged on time. This strategy achieves a reduction in the output shaft's velocity drop amplitude from 17.647% to 6.591%, representing a 62.7% improvement. The dynamic load coefficient is also minimized, decreasing from 2.743 to 1.857, resulting in a 32.3% optimization range. The impact of the output shaft has been reduced from 14.125 to 5.67 m/s\({}^{3}\), with an optimization range of 59.9%. Switch time has been reduced from 2.13 to 1.71 s. with an optimization range of 19.7%. We established a model-in-the-loop test platform and designed an MIL test scheme. The enclosed test cabinet and the upper unit formed the physical part of the model-in-the-loop test. The whole-machine model constructed using SimulationX iwass transformed into dll files, which were then integrated into NI VeriStand for utilization. The test results were analyzed using the variance method. The experimental outcomes were juxtaposed with the simulation findings. The results show that there are some errors in the main factors affecting the velocity drop amplitude, dynamic load coefficient, and impact strength of the output shaft. This is caused by the error in the MIL test results. The effect of this on the switching time is small. This is because the switching time in the MIL test was mostly \begin{table}
\begin{tabular}{c c c c c c} \hline
**CA** & **EI** & **Speed Drop** & **Dynamic Load Factor** & **Impact Strength** & **Switching Time** \\ \hline \multirow{4}{*}{MT} & BS & A\({}_{1}\)D\({}_{1}\)B\({}_{1}\)C\({}_{2}\) & A\({}_{2}\)D\({}_{2}\)B\({}_{1}\)C\({}_{1}\) & C\({}_{1}\)D\({}_{2}\)A\({}_{2}\)B\({}_{2}\) & A\({}_{1}\)D\({}_{1}\)C\({}_{1}\)B\({}_{1}\) \\ \cline{2-6}  & \multirow{2}{*}{FP} & A major & AD major & C major & A major \\ \cline{3-6}  & & D mid & D mid & D mid & \\ \cline{3-6}  & & BC minor & BC minor & AB minor & DCB minor \\ \hline \end{tabular}  
* In the table: CA stands for comparative analysis; El stands for evaluation index; SA stands for simulation analysis; BS stands for best solution; FP stands for factor priority; MT stands for MIL test.  
\end{table} 
Table 12: _Cont._concentrated at about 1.5 s. There was little difference between the test results, so the significance of each factor was low. The optimization method proposed in this study significantly improves the quality of clutch mode switching and effectively reduces the fluctuation in the transmission system. This achievement provides a key piece of technology for achieving smoother, more efficient, and reliable mode switching in hybrid mechanical hydraulic composite transmission systems. The effectiveness of this method was verified through MIL testing, demonstrating its feasibility for practical application and laying a solid foundation for subsequent research and development. In the study of mode switching in this article, the friction coefficient of the clutch and the damping and dynamics of the transmission system between planetary gear mechanisms were not considered in the simulation modeling.