Tire-road forces estimation based on sliding mode observer

The development of advanced vehicle control systems such as ABS, TCS and ESP, depend upon the information about tire-road force, which can not be measured directly in modern cars. A model-based estimation methodology of the tire-road force using a sliding model observer is proposed in this paper. Hyperbolic tangent function is chosen to cover chattering effects of observer. A simulation platform which provides real-time circumstance to validate the estimation results and test the realtime performance of the observer is established based on xPC Target, Real Time Workshop in Matlab. An eight degrees-of-freedom vehicle model which provides real vehicle data is downloaded to the Target PC, and the sliding mode observer run in the dSPACE 1104. The vehicle model and observer exchange data by acquisition data cards. The observer is evaluated on the platform under a sudden steering maneuver on flat road, without any drive or brake torque acting on the vehicle. The results demonstrate the effectiveness of the proposed observer in providing tire-road force estimations.