Page - 41 - in Maximum Tire-Road Friction Coefficient Estimation

3 Vehicle model z rr ω rl z fl ω fl z fr ω fr y b x b b ω z z b b ω x b ω y Figure 3.1.: Degrees of freedom (DOF) of vehicle model used for model complexity evaluation. The DOF include the vehicle’s body translational {xb,yb,zb} and rotational {bωx,bωy,bωz} degrees of freedom, as well as the wheels’ vertical displacements {zfl,zfr,zrl,zrr} and the wheel rotational speeds {ωfl,ωfr,ωrl,ωrr}, with the rear right wheel (i= rr) not displayed here. The model is based on Rojas Rojas, [Roj12, p.13-15], the graphic depiction is modified from Hirschberg, [HW12, p.160]. different driving manoeuvres, cf. Figure 3.2. Normalising the mean deviation with the reference curve for each time step enables the comparison of manoeuvres at different longitudinal speeds and friction potentials. With an ∆w of 0 %, the variation of model parameters does not have any effect on the variable investigated. With increasing ∆w, the influence of the model parameter increases for the manoeuvre evaluated. With this definition, ∆w is not limited to 100 %. wref wvar t w Figure 3.2.: Time signal of an exemplary variablew for both reference setup (wref) and varied model setup (wvar). The area between the two curves is the basis for the mean relative deviation ∆w based on Weber, [Web04, p.75] 41