Page - 61 - in Maximum Tire-Road Friction Coefficient Estimation

3 Vehicle model cT,y, [Hir09b], the longitudinal tire dynamics are omitted within this work. This is also consistentwiththe investigationsmadeconcerningthemodelcomplexity, seeSection3.1. In vehicle dynamics, transient tire dynamics are commonly described by first order filters. For example, the transient tire contact forces FDy according to Rill depend on the steady-state value of the lateral forceFy by τ · F˙Dy +FDy =Fy, (3.29) [Ril06], including the time function τ, which reads τ= 1 cT,y · ( Fy sα 1 re · |ωr| ) (3.30) with sα = tanα and the transport velocity re · |ωr|, with which the particles in the tire tread are moving through the contact patch, [Ril06]. See Appendix B.2 for a more detailed description. 3.4. Environment model Otherthanaerodynamicdrag,additionalwindforcesandaerodynamicdownforcesacting on the chassis are not considered. Vertical excitation of the wheels induced by the road geometry is omitted as roll and pitch are also not considered in the simplified vehicle model, cf. Section 3.1. Thus, only the friction potential and road slope and banking are necessary to describe the environment. These inputs are forwarded to the vehicle model. 61