Nonlinear tire lateral force versus slip angle curve identification

Vehicle steering dynamics depends on the tire lateral characteristics. In particular, the relationship between the tire lateral force and the slip angle is a crucial element in the analysis and design of vehicle lateral dynamics and controls. This relationship is generally obtained through laboratory tests, but the laboratory test procedures have two major limitations: (I) the simulated road surface may not represent certain real road conditions; (II) the test environment may not sufficiently mimic the tire characteristics under realistic operating conditions, such as large tire-vehicle interactions under emergency conditions or the changes of suspension and/or steering geometry. It is advantageous to develop an identification approach for tire lateral characteristics using a minimum set of on-board vehicle sensors when the tires are operated in a real configuration and environment. An ideal identification procedure should be insensitive to noise and predict the vehicle lateral behavior accurately. A pointwise updating approach with a Kalman filter using a nonlinear vehicle model is designed to address this problem. The effectiveness of the approach is demonstrated using tires with and without snow chains.