Abstract: The identification of road friction plays an important role in the vehicle state observation and stability control system. When the vehicle comes across a critical situation, the estimation of road friction should be reliable and timely for the electronic stability control system(ESC), which is a harsh requirement for the practicality and reliability of the algorithm. So two indexes based on the bias of the yaw rates and that of the lateral accelerations are proposed. These two indexes can reflect the nonlinearity of the vehicle totally. According to the relationship between the nonlinearity and the use of the friction in the lateral direction, the friction-compensation algorithm is put forward. When estimating the road friction, treat the lateral acceleration as the base value compensated with the estimation error to get the original friction, which then is passed through a generalized filter to reduce the oscillation for a better control result. Experimental vehicle tests validate the effectiveness of the estimation of road friction and torque control of ESC based on the estimation algorithm gives a good result.

Key words: electronic stability control system;road friction coefficient;degree of nonlinearity;identification algorithm