Page - 44 - in Maximum Tire-Road Friction Coefficient Estimation

3 Vehicle model 3.1.3. Model parameters Table 3.1 shows the model parameters that were varied for certain manoeuvres, which are described below. Within the reference simulation, the highest model complexity and standard parameters were used. During variation simulations, only one model or parameter is varied. The specific values used for the vehicle parameters are described in Appendix D. •Anti-roll bars (ARB) Anti-roll bars (ARB) with linear behaviour were simulated at the front and rear axles in the reference setup, and the stiffness of the ARB for front and rear axle was modelled as zero in the variation setup. •Wheel kinematics and compliance In the reference setup, the three-dimensional wheel movement during bound, re- bound and steering is considered (e.g. camber, toe and caster angle), as well as elastic deformations in the steering system. For the variation setup, the wheels’ motions were limited to vertical translation relative to the body and, for the front wheels, a steering motion around the vertical axes. Fixed values of 0 degrees have been used for camber angles, toe and caster angles. In this setup, no compliance was considered, neither for suspension components nor for the steering system. • Spring and damper The reference setup considers spring and damper characteristics that are based on measured and identified curves, [Roj12, p.205]. The variation setup only considers linear characteristics for both spring and damper. • Steering model As reference, a steering ratio measured between steering wheel angle and wheel steering angle based on a characteristic measured by Kollreider is used, [Kol09, p.69]. It is compared to a constant steering ratio. •Roll and pitch centre In the reference setup, the roll and pitch axes used were identified using an op- timization routine that includes a kinematic model and measurements. For the variation setup, constant points hIC,φ for roll and hIC,θ for pitch centre with re- spect to the ground are modelled. • Transient tire dynamics The reference model includes tire dynamics for both longitudinal and lateral tire 44