Page - 106 - in Maximum Tire-Road Friction Coefficient Estimation

5 Tire/road friction estimator describes the linear momentum of the vehicle in longitudinal direction, and substituting bax= v˙x−bωz ·vy, the overall tire forces for accelerating and braking are given by∑ i bFx,i=mb ·bax−FA. (5.12) The total of longitudinal forces ∑ i bFx,i has to be apportioned to the four wheels based on the driving and braking torque distribution. Since the tested vehicle was front-wheel driven, 50 % was assigned to each front wheel during driving. During deceleration, a braking distribution of 60 % on the front axle and 40 % on the rear axle is considered. On each axle, the left and the right wheel are assigned 50 % of the axle’s theoretical braking force each. These assigned forces could have been used directly in the particle filter to be compared to the longitudinal tire forces for the different particles of µmax. However, it is assumed that a good wheel torque estimate will improve the algorithm and may be available in an industrial implementation. 106