Vehicle Lateral Velocity and Tire-Road Friction Coefficient Estimation

Real-time knowledge of the tire-road friction coefficient (TRFC) and vehicle states are of critical importance for vehicle dynamic control systems. A vehicle lateral velocity and TRFC estimation method is proposed in this paper. When tires work in the linear tire force region, the dynamic model-based lateral speed estimator is adapted to give the lateral speed estimation. When the tires work in the nonlinear tire force regions, the dynamic model-based estimator is switched to the kinematics based one such that the vehicle lateral speed can be estimated without using the TRFC information. As the tire force model is not used to estimate the lateral speed in the kinematics-based estimator, the TRFC can be indentified simultaneously with a tire force model. The proposed estimation method has the potential of estimating the TRFC and vehicle lateral speed with low-cost sensors. Experimental results with a four wheel independently-actuated (FWIA) electric vehicle show the effectiveness of the proposed estimation method.