Seite - 14 - in Maximum Tire-Road Friction Coefficient Estimation

1 Introduction the velocity prediction for a suggested pre-fire time of 80 ms is± 0.94 m/s2, according to Eichberger, [Eic11, p.115-120]. As the pre-collision scenario is the same for airbag pre-firing and AEB, the requirements for the accuracy ∆µ and time delay τM for an estimate of the friction potential are the same as in Figure 1.8. 1.3.3. Requirements for an estimate of the friction potential for VDC The requirements for an estimate of the friction potential to be applied in the systems ABS,ESCandactive frontsteering(AFS)werethoroughly investigatedandpresented in the work of Weber, [Web04]. Straight braking, lane change and curve braking manoeu- vres were evaluated on even road surface. It was assumed that the mounted tires and the corresponding tire model parameters were known (not including the current road condition). Table 1.1 shows the requirements determined by Weber, [Web05]. This in- Table 1.1.: Requirements on friction potential estimate for different manoeuvres con- cerning tolerable deviation ∆µ and maximum time delay τM, according to Weber, [Web05]. Manoeuvre Tolerable Deviation ∆µ Tolerable Time Delay τM Full braking straight -0.03 - 0.08 26 ms Lane change -0.08 - 0.03 - Full braking in a curve -0.02 - 0.02 10 ms vestigationalso showedthat thehighestbenefitofanadaptation to the frictionpotential was achieved at high longitudinal speeds and low friction potentials. 1.4. Thesis contribution and outline The functionality of today’s vehicles is limited because the current friction potential be- tweenroadandtiresduringdriving isnotknown. With increasingautomationofdriving tasks, informationonthecurrent frictionpotential getsmore important. Theaimof this thesis is to present an algorithm to estimate the friction potential between tire and road. Within this work, only vehicle-based solutions are considered (e.g. no C2x systems), and, among these, only those methods that consider measurements of the vehicle’s dy- namic reaction (e.g. no optical sensors). Although application for other vehicle types is not excluded, the focus is the applicability for passenger cars. An automated emer- gencybrakingsystem(AEB)ischosenasanapplicationcase forthedevelopedalgorithm. 14