TYRE LONGITUDINAL VELOCITY AND SLIP MEASUREMENTS FROM THE INSIDE OF A TYRE

In tyre testing the longitudinal tyre velocity and slip are important measurements in the development and parameterization of tyre models. The longitudinal slip of a tyre is often determined using three independent measurements namely the rotational velocity, tyre rolling radius and vehicle speed. However, during terremachanics tests the tyre rolling radius is almost impossible to measure from the outside. Methods have been created to determine the rolling radius on the inside of a tyre using lasers, however these methods generally only provide a single measurement point every few degrees. In this study a stereoscopic rig is used on the inside of the tyre to determine the longitudinal velocity of a large portion of the tyre in contact with the terrain. This measurement inherently includes the rotational velocity and rolling radius of the tyre. The measurement of the internal longitudinal velocity is used to determine the longitudinal velocity at the tyre-terrain contact interface. The longitudinal slip is determined from the measured longitudinal velocity and the velocity of the rim center. The method is evaluated on a Terramechanics rig using prepared sandy loam as the deformed soil material