A variable structure adaptive extended Kalman filter for vehicle slip angle estimation

This paper discussed vehicle slip angle estimation problem when vehicle drops into instability critical area. The accurate measurement of vehicle dynamics states, especially vehicle slip angle, is essential for the vehicle stability control if the vehicle drops into instability critical area. A variable structure adaptive Extended Kalman Filter (EKF) is brought forward to observe the vehicle slip angle under this condition. The modified non-linear vehicle model with multi-degrees and tyre model are constructed; the compensation factors are integrated into the model to correct the load transfer effect, the transient responses of the steering manoeuvre and the road conditions. Reliability Indexed Sensor Fusion (RISF) method is applied to suppress the dynamic errors of sensor system. Meanwhile, the improved direct integration method is used to correct the systematic errors. The real vehicle test validates the accuracy of the proposed method, especially for the vehicle in the instability critical area.