A Model-Based Approach for Investigating Tire-Pavement Friction Threshold Values

Most ground vehicles related accidents occur when the friction demand to perform a maneuver with a certain vehicle and tires exceeds the coefficient of friction of the pavement surface. As generally known, the forces and moments acting on the vehicle body are mainly generated at the tire-road surface interface. The common characteristics of tire forces on any surface include a linear region where the forces vary linearly with respect to the relative slip values; and a nonlinear region where the forces saturate and may even start decreasing. The experience of most of the daily drivers on the roads is limited within this linear region where the dynamic behavior of the vehicle remains proportional to the driver’s inputs. Therefore, an unexpected change in tire or surface characteristics (due to a change in surface friction, large driver inputs, etc.) may easily cause the driver to panic and/or to lose his/her ability to maintain a stable vehicle. These types of instabilities underline the importance of monitoring the corresponding tire and pavement attributes for improved vehicle performance and controls. For this study a factorial of pavement friction levels, combined with a tire model is used to determine if sufficient forces are produced to safely maneuver without skidding to cause a loss of control and crash. The tire forces and moments are modeled using an extended empirical tire model that can match and emulate the pavement degradation; and integrated into a multi-body chassis model to examine the tire-pavement interaction under a number of maneuvers. The simulation studies are carried out to excite the vehicle system into its instability region; then the quality of interaction is inspected through a number of criteria such as vehicle maneuverability and friction coefficient variations.