# Control of Automotive Semi-Active MR Suspensions for In-Wheel Electric Vehicles
## 3 Results and Discussion
### QoV
#### 3.1.1 Open Loop
Where the road holding is improved when working with a hard suspension (\(2.5A\)) and decreased by employing a soft one (\(0A\)). From this, we can say state that, for guaranteeing a road holding improvement for the M\(QoV\) in open loop considering as reference a \(1.25A\) baseline suspension, the \(2.5A\) (hard suspension) current level might be employed. In the case of the useful lifetime, a similar situation occurs, for the step, sprung mass and unsprung mass tests (Figure 14a-c), where the \(2.5A\) enhances the useful lifetime by 25%, 22%, and 10%, respectively. By the side of the frequency domain, occurs almost the same, where a hard suspension (\(2.5A\)) decreases the gains in the pseudo-bode plot for the suspension deflection and increases the IPSD. For the time domain tests, the useful lifetime increases with \(2.5A\) of current and decreases when working with \(0A\). In a similar way, in the four bandwidths of the frequency domain, the \(2.5A\) guarantees an improvement of the useful lifetime according to the IPSD (Figure 14f) and tothe pseudo-bode gains from Figure 14h. According to the results described above, the \(2.5A\) of current (hard suspension) guarantees the useful lifetime improvement for the MQ\({}_{0}V\) in open loop considering as reference a \(1.25A\) baseline suspension. Figure 13: Results from open loop simulations for the comparison in a nonlinear QoV model considering a \(1.25A\) baseline suspension. In the M_Qo_VFV, the highest comfort improvement (25%) during the step and sprung mass tests (Figure 15a,b) is given by the 2.5\(A\) current level. In both cases, the performance decreases as well as the current does. Besides, in the frequency domain, comfort enhancement is given in a 10% by the 2.5\(A\) in accordance with the IPSD (Figure 15e) as well as with the lower gains from the pseudo-bode plot (Figure 15g). That's why it can be said that the 2.5\(A\) gives the best improvement for the M_Qo_VFV in open loop is given by the 2.5\(A\), which probably means that the presence of the unbalanced vertical force, demands a harder suspension for improving comfort. The road holding is improved by 42% and 35% in the step and sprung mass tests (Figure 15a,c), respectively. Where the road holding decreases, the current also does. In the frequency domain it occurs in almost the same way; a higher current guarantees the road holding. The highest road holding improvement is of 10% in accordance with the IPSD (Figure 15e) and is given by the 2.5\(A\) as well as the lowest gains for the tire deflection in the pseudo-bode plot (Figure 15i). The 0\(A\) current level gives a negative improvement. According to the performance discussed above, it can be said that a harder suspension (2.5_A_) guarantees the road  
Figure 14: Results from open loop simulations for the comparison in a nonlinear modified QoV model considering a 1.25\(A\) baseline suspension. holding in the MQ\({}_{0}\)VFV in open loop. By the side of the useful lifetime the \(2.5A\) improves it for the step, sprung mass and unsprung mass tests (Figure 15a) by 10%, 20% and 15%, respectively. Whereas in the other \(Q\)\(V\) models, the useful lifetime increases as the current level does. In the frequency domain it occurs almost the same way; the suspension deflection is enhanced by the \(2.5A\) in a 5% according to the IPSD (Figure 15f) as well as to the lower gains shown in the pseudo-bode plot (Figure 15h). As can be seen, higher current values guarantee a higher useful lifetime. The best useful lifetime improvement is given by the \(2.5A\) of current for the MQ\({}_{0}\)VFV in open loop considering as reference a \(1.25A\) baseline suspension. For the comfort in the N\(Q\)\(V\), the M1S controller enhances it during the step test (Figure 16a) by 10%. Which means that the M1S is working better during the compression of the damper. In this case the SH and FEB controllers decreases the comfort. While in the sprung mass test (Figure 16b), the FEB improves comfort by 15%, followed by the M1S.