Page - 119 - in Maximum Tire-Road Friction Coefficient Estimation

6 Results and conclusion Time in s 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 -2 -1.5 -1 -0.5 0 0.5 13 Figure 6.11.: Longitudinal acceleration bax during gentle braking manoeuvre on varying µmax with a maximum deceleration bax ≈ -2 m/s2. The manoeuvre was started at vx≈ 40 km/h and ended at 15 km/h. 8 9 10 11 12 13 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 Time in s Figure 6.12.: Standard deviation of variable particles versus time during a braking ma- noeuvrewithamaximumdecelerationof≈−2m/s2 foraµ step manoeuvre with µmax≈ 1 before and µmax≈ 0.3 after second 9. The corresponding estimate µˆmax is shown as a light gray line in Figure 6.10. 6.4. Braking manoeuvre onµ split conditions The last case which is examined are different road conditions for the left and the right sides of the vehicle, a so-calledµ split condition. In the investigated case, the left side of the vehicle (i.e. wheel indicesfl and rl) was located on a low-friction surface (µmax≈ 0.3), whereas the right side (i.e. wheel indices fr and rr) was located on a surface with µmax≈1. Thedriverwas supposedtokeepthevehicle straight (yawangleψ≈0)during the manoeuvre using steering inputs. 119