Page - 72 - in Maximum Tire-Road Friction Coefficient Estimation

4 Sensitivity Analysis 5 10 15 20 25 30 0 1 1.5x 10 -5 b a x = 0.45 in m/s2 f s =0.1 f s =0.3 f s =0.5 f s =0.7 f s =0.9 b a x = 2.45 in m/s2 b a x = 0.45 in m/s2 b a x = 2.45 in m/s2 v x,0 in m/s 5 10 15 20 25 30 −2.5 −2 −1.5 −1 −0.5 0 x 10 -3 5 10 15 20 25 30 0 1 2 3 4 5 6x 10 -4 5 10 15 20 25 30 −0.07 −0.06 −0.05 −0.04 −0.03 −0.02 −0.01 0 v x,0 in m/s f s =0.5 f s =0.7 f s =0.9 v x,0 in m/s vx,0 in m/s Figure 4.4.: Dependenceof selectedsensitivities∂vx/∂µ(left)and∂ωfl/∂µ(right)ver- sus the initial longitudinal velocity vx,0 for µ max = 1 for pure longitudinal acceleration of 0.45 m/s2 (above) and 2.45 m/s2 (below) and different scaling factors fswithin the simulation. gorithm. Thus, it is not necessary to compensate for the influence of the longitudinal speed. However, it has to be mentioned that within each driving state region as defined in Figure 4.10, the initial longitudinal velocity vx,0 for the manoeuvres is the same. Comparison of sensitivities for longitudinal and lateral manoeuvres To ensure comparable results, simulations that start with longitudinal excitation and then add lateral excitation (LQ) are compared to simulations that start the other way around (QL) at the sameµmax and acceleration profiles. Both simulations are compared at specific acceleration points. 72