Page - 28 - in Maximum Tire-Road Friction Coefficient Estimation

2 Estimation of the friction potential 2000 4000 6000 0 0.2 0.4 0.6 0.8 1 Tire load F z in N 0 40 0 1000 2000 3000 4000 5000 6000 Slip s x in % F z =3000 N F z =4500 N F z =6000 N 1.2 F z =1500 N s x Figure 2.7.: Dependenceofthefrictionpotentialµmaxx (left)andthecoefficientof friction µx (right) on the tire loadFz based on Hirschberg, [HW12, p.23]. 0 100 0 0.2 0.4 0.6 0.8 1 2 4 6 8 0 0.3 0.6 0.9 1.2 Longitudinal Vehicle Speed v x in m/s2 Slip s x in % Asphalt, dry Asphalt, wet 1.2 asphalt, dry 2.5 kph 30 kph 80 kph }} asphalt, wet Figure 2.8.: Dependenceofthefrictionpotentialµmaxx (left)andthecoefficientof friction µx (right) on the vehicle’s longitudinal speed vx for dry and wet asphalt, based on Bachmann, [Bac98, p.95-96]. latter factorsare influencedbythedriver’s inputs. Decreasing inflationpressurehas sim- ilar effects on the friction potential as increasing tire load. Many estimation approaches assumethe tire characteristics tobeknown, e.g. [Web04,p.41, 49, 58], and further inves- tigations have shown that knowledge of the tire characteristics increase the estimation 28