Estimation of Tire–Road Friction Based on Onboard 6-DoF Acceleration Measurement

This paper presents a tire–road friction coefficient estimation method based on the six-degrees-of-freedom (6-DoF) vehicle body acceleration. The key principle of the proposed method is to estimate the tire–road friction coefficient from the accelerations at the tire. A vehicle model is applied to the 6-DoF vehicle body acceleration to derive longitudinal, lateral, and normal accelerations at each tire. Then, the recursive least squares (RLS) method is applied to the accelerations thus derived to estimate the tire–road friction coefficient. The main advantage of the proposed method is that it can be implemented with a 6-DoF accelerometer, which may be available in today's passenger vehicles equipped with accelerometers and gyroscopes. The method was validated with experiments in a passenger sedan, which demonstrates that the method is able to estimate tire–road friction coefficients accurately in real time during longitudinal emergency braking.