Characterization of the loss of grip condition in the Strain-Based Intelligent Tire at severe maneuvers

The early detection of the instantaneous tire–road condition enables the control systems to react against the risk of the vehicle’s loss of control. This situation usually occurs when the phenomena of stick–slip is not present in the tire–road interaction yielding the full slip of the tire (the whole contact patch is gliding). The relation between the friction force and the vertical load of the tire can be used as an indicator of this loss of grip when it is higher than the maximum capacity of friction used for the surfaces in contact. Nonetheless, this limit of friction is currently unknown. This study proposes the development of the tire as an active sensor able to provide all this information. Previous studies have shown that the Strain-based Intelligent Tire enables the monitoring of the forces in the tire–road interaction, the wheel load, the effective radius, the contact length, and the wheel velocity in the contact patch. These parameters affect the tire–road friction characterization. Therefore, it is proposed the integration of the LuGre model with the achievements of the Strain-Based Intelligent Tire in order to estimate the adherence limit. To show the effectiveness of the methodology proposed it is used the CarSim™ simulation software. The validation process is carried out monitoring the limit of adherence with a set of vehicle’s severe maneuvers, where the dynamic behavior of the vehicle highlights its influence in the operational condition of the tire in order to expose the wheels to full slip.