## 4 Simulation and Experiment
### Experimental Verification  
In order to verify the real-time algorithm performance, we used the driving simulator platform illustrated in Figure 6; five screens were positioned around the simulator vehicle, with three screens displaying the front traffic scenes and two displaying the back view. The CarSim software was embedded in the driving simulator to reflect the real vehicle movement features. In order to simulate real driving situations, the vehicle was supported by numerous hydraulic cylinders to achieve pitch, roll and yaw motions. For comparison with the simulation results, the vehicle model in CarSim was selected to be the same as in the simulation and the experimental testing conditions were designed almost the same as those in the simulation, as indicated in Table 9.  
Experimental testing condition E1: The condition for a straight uniform speed is selected and the desired speed is set to 72 km/h, with single left front motor failure at the 0 th second, as in the simulation. In this manner, we can conclude that, through the cooperative control of the drive system in Figure 7a and steering system in Figure 7b, the vehicles can maintain the expected speed, as indicated \begin{table}
\begin{tabular}{c c c} \hline \hline
**Item** & **Without Control** & **With Control** \\ \hline Maximum yaw rate deviation (rad/s) & 0.3582 & 0.0444 \\ Maximum speed deviation (km/h) & 11.6823 & 1.811 \\ Maximum lateral deviation /(m) & 27.9077 & 0.58 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Statistical control effect under F3 condition. Figure 6: Driving simulator platform. in Figure 6(c), as well as the lateral ability, as illustrated in Figure 6(d),e. Table 10 displays the vehicle speed, yaw rate and later position deviation with control or without control after failure of the drive system. It is demonstrated that the experimental verification results are similar to the simulation results. Moreover, in the driving simulator verification experiment, the system control period is less than 50 ms, so the verification of the control algorithm exhibits satisfactory real-time performance. Experimental testing condition E2: The condition of straight uniform speed is selected; the desired speed is set to 72 km/h and drive motor failure at the opposite side is selected so that the left front motor and right front motor become completely ineffective at the 0 th seconds. In this manner, we can \begin{table}
\begin{tabular}{c c c} \hline \hline
**Item** & **Without Control** & **With Control** \\ \hline Maximum yaw rate deviation (rad/s) & 0.224 & 0.003 \\ Maximum speed deviation (km/h) & 2.75 & 1.1422 \\ Maximum lateral deviation /(m) & 15.5312 & 0.0548 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Statistical control effect under E1 condition. Figure 7: Experimental comparison with/without control under E1 condition. conclude that, through the cooperative control of the drive system in Figure 8a and steering system in Figure 8b, the vehicle can maintain the expected speed, as indicated in Figure 8c, as well as the lateral ability, as illustrated in Figure 8d. Table 11 displaces the vehicle speed, yaw rate and later position deviation with control or without control after failure of the drive system. It is demonstrated that the experimental verification results are similar to the simulation results. Furthermore, in the driving simulator verification experiment, the system control period is less than 50 ms, so the verification of the control algorithm exhibits satisfactory real-time performance. Experimental testing condition E3: The condition of a uniform turning speed is selected, the desired speed is set to 72 km/h and the single left front motor is selected to fail at the 0 th second. When motor failure occurs at the 0 th second, the remaining motor torque instantly increases and through the cooperative control of the drive system in Figure 9a and steering system in Figure 9b, the vehicles can maintain the expected speed, as indicated in Figure 9c, as well as the lateral ability, as illustrated in Figure 9d,e.