Development of Velocity Dependent Front Wheel Angle Relation Based on Tire Workload Distribution

During a cornering manoeuvre, in a vehicle equipped with Ackerman steering geometry, the inner tire operates at a higher slip angle relative to the outer tire. As lateral load transfer occurs, the potential of the inner tires to produce the lateral force reduces and with systems like active steering, the saturation of lateral force occurs even earlier. In order to have an ideal steering geometry, at low speeds the system should follow Ackerman geometry closely and at higher speeds it should follow anti-Ackerman geometry. The tire workload (TW) distribution is a critical variable to be analyzed to prevent tire force saturation. The present paper aims to formulate the wheel angle relation for front wheel steering based on tire workload distribution. The tire workload difference (TWD) between the steered wheels is chosen as the active variable to arrive at the wheel angle relation. To study the transient behavior of the vehicle with tire workload redistribution (TWR), the Mimuro plot is used. The developed wheel angle relation utilizes the tire forces effectively and the results show improved cornering performance of the vehicle. This type of study which accounts for balancing tire workload for both lower and higher cornering speeds based on wheel angle relation has not been reported earlier in literature.