Look-Up Table-Based Tire-Road Friction Coefficient Estimation of Each Driving Wheel

The tire-road friction coefficient conveys critical information for advanced vehicular active safety systems to significantly enhance driving safety and maneuverability. In this letter, a look-up table based method is proposed to estimate the tire-road friction coefficient of each driving wheel in real time. The table that represents the relations among the normalized longitudinal tire force, tire slip ratio and slip angle, and the tire-road friction coefficient is constructed off-line by collecting data from common onboard sensors under different driving scenarios. By applying the perspective projection procedure, only data from two different road surfaces are required, which facilitates table construction. Then the table is used for estimating the tire-road friction coefficient in real time and the results are post-processed by the Kalman filter to render smooth and reliable estimates. Simulations in the CarSim-Simulink environment are conducted to verify the satisfactory performance of the proposed estimation method for various driving scenarios and sudden changes of road conditions.

I. Introduction

Vehicular active safety systems, such as anti-lock brake systems, electronic stability control, and traction control systems, have been shown to be effective for enhancing driving safety and maneuverability. Tire dynamics plays an important role in designing these active safety systems, especially for those advanced vehicle control methods based on optimal distribution of tire forces [1]–[3]. Tire-road friction coefficient is one of the most critical parameters that has profound effects on tire dynamics, and therefore on-line estimation of the tire-road friction coefficient has been an active research topic for decades.