## 4 Results and Discussion
### Random Road Excitation  
To further evaluate the advantages of the reliable robust controller, the performances of electric vehicles are investigated at a speed of 25 km/h on a B-class road. Figure 17 and Table 1 show the stochastic responses of three suspensions (K\({}_{\text{C}}\), K\({}_{\text{P}}\), and the passive suspension). Responses of the sprung mass acceleration and the rotor eccentricity are plotted in Figure 17. A detailed numerical comparison using the root mean square values (RMS) is shown in Table 1. One can observe that both of active control methods K\({}_{\text{C}}\) and K\({}_{\text{P}}\) can obviously enhance the ride comfort and slightly intensify the rotor eccentricity compared with passive suspension. It can be found that compared with K\({}_{\text{C}}\), the RMS of the sprung mass acceleration controlled by K\({}_{\text{P}}\) decreased by 4.5%, from 0.7 to 0.67, and the rotor eccentricity only rose by 0.8%, from 174.5 to 176. The comprehensive performance of K\({}_{\text{P}}\) is obvious better than that of K\({}_{\text{C}}\). Figure 16: The in-wheel motor dynamic responses: (**a**) the rotor eccentricity under 0% actuator loss; (**b**) the rotor eccentricity under 0% actuator loss; (**c**) UEF under 0% actuator loss; (**d**) UEF under 40% actuator loss. Figure 17: The responses under stochastic excitation: (**a**) body acceleration; (**b**) the rotor eccentricity. Figure 15: Body acceleration of the vehicle: (**a**) under 0% actuator loss; (**b**) under 40% actuator loss. Figure 18 and Table 2 show the stochastic responses of three suspensions (K\({}_{\text{P}}\), K\({}_{\text{PF}}\) and the passive suspension). It can be seen from Table 2 and Figure 18 that the reliable robust controller achieves a lower peak value and lower RMS value of sprung mass acceleration, compared with passive system and the parameter-dependent controller system without actuator fault-tolerant, which clearly illustrates that K\({}_{\text{PF}}\) can effectively improve the ride comfort. Furthermore, from Table 2, it can be observed that when the extent of failure is minor, the RMS of the body acceleration is greatly reduced and the RMS of the UEF increased slightly compared to passive suspension and the parameter-dependent control system. The results imply that the reliable robust controller with slight actuator failure can significantly enhance the ride comfort and avoid large increases of the coupling effect in IWM. When the extent of failure is major, both the body acceleration and the UEF decreased to a certain extent, indicating that the ride comfort and the IWM performance are improved. According to the analysis, it can be inferred that in the presence of actuator failure and model parameter uncertainties, the active suspension system with the reliable robust controller improves the ride comfort and PMBDC motor operation performance. In general, the active suspension system considering the eccentricity of the rotor can greatly enhance the ride comfort and weaken the influence of UEF on the performance of the hub-driven EV. When the model parameters are perturbed, the parameter-dependent controller shows better comprehensive performance than conventional robust controller. In addition, the reliable robust controller can achieve better vehicle and motor performance in the presence of different actuator thrust losses and parameter variation, compared with the conventional robust controller and parameter-dependent controller.