# Optimization of Mode-Switching Quality of Hybrid Tractor Equipped with HMCVT
## 3 Optimization of Control Policy for Driver Source Switching
### SimulationX and Matlab/Simulink Interact Analysis
The analysis results show that the switching sequence of clutch C3 had the greatest influence on the impact strength of output shaft, and the switching sequence of clutch C4 had the least. The optimal scheme  
Figure 16: Result analysis of the output shaft velocity drop amplitude. Figure 17: Result analysis of the dynamic load coefficient of the output shaft. was C3A1E1F2B1D3. From the point of view of the range value, clutches C3, C0, C6, and C7 played the main role, and clutches C2 and C4 played a certain role. Therefore, the combination of C3A1E1F2 can meet most of the working conditions, and the upper limit of the impact strength can be reduced from 21.581 m/s3 to 7.21 m/s3, meeting the Chinese impact strength standard \(\left|J\right|\leq\) 17.64 m/s3. The analysis results of mode-switching time by range method are shown in Figure 19, where R represents range value. The results show that the clutch C6 switching sequence had the greatest influence on the switching time, and the clutch C7 switching sequence had the least influence. The optimal scheme was E1D3C3A2B2F2. From the point of view of the range value, clutches C6, C4, C3, C0, and C2 played the main role, and clutch C7 played a small role, so the combination of E1D3C3A2B2 can meet most of the working conditions and can reduce the upper limit of the switching time from 1.301 s to 0.18 s.  
Based on the above analysis results, there are differences in the degree and level of influence of factor A on each evaluation index. Therefore, it is difficult to simply predict at which level factor A has the optimal influence on the comprehensive quality. Other factors can easily predict the switching timing of B1C3D3E1F2 and obtain better mode-switching quality when the output shaft velocity drop amplitude, dynamic load coefficient, impact strength, and switching time of the output shaft are relatively small. To obtain the optimal switching sequence, A1B1C3D3E1F2, A2B1C3D3E1F2, and A3B1C3D3E1F2, were simulated and verified as Scheme 1, Scheme 2, and Scheme 3, respectively. The results are as follows. The rotation speed of the output shafts of Scheme 1, Scheme 2, and Scheme 3 is shown in Figure 20. The corresponding speed reduction amplitude of the three is 1.2%, 1.225%, and 1.63%, respectively. Among the three schemes, Scheme 1 has the best optimization degree for the velocity drop amplitude of the output axis. Figure 19: Switching time result analysis. Figure 18: Impact strength analysis of output shaft. The output shaft torque of Scheme 1, Scheme 2, and Scheme 3 is shown in Figure 13.0 The corresponding dynamic load coefficients of the output axes are 3.01, 2.98, and 2.72, respectively. Among the three schemes, Scheme 3 optimizes the dynamic load coefficient of the output shaft best. The impact strength of the output shafts of Scheme 1, Scheme 2, and Scheme 3 is shown in Figure 13.1 The maximum impact strength of the output shafts corresponding to the three are 7.99 m/s\({}^{3}\), 7.21 m/s\({}^{3}\), and 7.08 m/s\({}^{3}\), respectively. Among the three schemes, Scheme 3 optimizes the impact strength of the output shaft best, but it is far below the Chinese impact strength standard \(|J|\leq 17.64\) m/s\({}^{3}\). Figure 13.2 Comparative analysis of the torque of the three schemes. Figure 13.3 Comparative analysis of the speed of the three schemes. Figure 13.4 Comparative analysis of the impact strength of the three schemes. The switching time of the output axis in Scheme 1, Scheme 2, and Scheme 3 is 0.525 s, 0.42 s, and 0.35 s respectively. Among the three schemes, Scheme 3 has the best optimization degree for the switching time of the output axis. After comprehensive analysis of all simulation results of Scheme 1, Scheme 2, and Scheme 3 above, the output shaft dynamic load coefficient, impact strength, and switching time of Scheme 3 are all the best among the three; therefore, Scheme 3, \(\text{A}_{3}\text{B}_{1}\text{C}_{3}\text{D}_{2}\text{E}_{1}\text{F}_{2}\), is the best scheme.