Page - 115 - in Maximum Tire-Road Friction Coefficient Estimation

6 Results and conclusion Time in s 2.5 3 3.5 4 4.5 -4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 5 Figure 6.7.: Longitudinal acceleration bax during a braking manoeuvre on varying µmax with a maximum deceleration bax≈ -4.5 m/s2. The manoeuvre was started at vx≈ 50 km/h and ended at 30 km/h. 2.5 3 3.5 4 4.5 50.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 Time in s Reference µmax(fixed particles), no resampling µmax(sampled particles), SD limited µmax(sampled particles), ∆µmax limitedˆ ˆ ˆ ˆ Figure 6.8.: Estimates ofµmax using fixed particles (black dotted), variable particles re- initialised based on SD (light gray) or variable particles re-initialised based on ∆µˆmax (dark gray) versus time during a braking manoeuvre with decel- eration of≈−4.5 m/s2 for a µ step manoeuvre with µmax≈ 1 before and µmax≈0.3after second2.75. MAEandmaximumabsoluteerrorsare shown in Table 6.2. an MAE below 0.06 and the fast detection of the change inµmax. The overall accuracy of the estimate using ∆µˆmax, described by its MAE of 0.1035, performs slightly worse than the two other approaches, due to the low value ofµmax not being accurately met. 115