“…where, F x is the wheel longitudinal force(N), F z is the wheel vertical force (N), B x , C x , D x , E x are the parameters representing road characteristic, and are derived from real vehicle experiments, 29 B x = 10.5, C x = 2.51, D x = 1.26, E x = 1, s t represents wheel slip ratio and is calculated by equation (7).…”