Virtual sensors design in tire-road forces and vehicle states estimation

This paper proposes nonlinear observers (virtual sensors) of vehicle states (vehicle sideslip angle and velocity of the center of gravity (v_g)) and tire-road forces. The observers strictly use low cost sensors potentially used or actually mounted in recent vehicles (longitudinal/lateral accelerations, yaw rate, steering angle and angular wheel velocities). The estimation process is based on two blocks in series. The first block estimates tire-road forces based on a sliding-mode observer (SMO), while the second one calculates sideslip angle and velocity of the center of gravity using the single-track model. In SMO, a hyperbolic tangent switching function is used to overcome the chattering problem. Validations with the simulator ve-DYNA and the HILS (hardware in the loop simulation platform) indicate the accuracy and the robustness of the proposed observers.