Lateral Vehicle Dynamics on Rutted Roads

A vehicle may experience lowly damped oscillations and stability issues when driving through a rut. The tire response to camber variations plays a decisive role in this phenomenon, which is known as wandering. Realistic ranges for the cornering, camber and other stiffnesses have been determined using a database with Magic Formula parameters for a large number of passenger car tires. A linear model is developed for a single wheel in a rut to analyze the parameters governing its stability. As a next step the stability of the single track vehicle model in a rut is evaluated. With this model the lowly damped wandering motion can be captured well. It is shown that the normalized camber stiffness of both the front an rear tire are decisive for vehicle stability. An analytical expression has been obtained to describe one of the stability boundaries.