Experimental evaluation of a sliding mode observer for tire-road forces and an extended Kalman filter for vehicle sideslip angle

This paper proposes a new process for the estimation of tire-road forces and vehicle sideslip angle. The method strictly uses measurements from sensors potentially integrable or already integrated in recent car (yaw rate, longitudinal/lateral accelerations, steering angle and angular wheel velocities). The estimation process is based on two blocks in series: the first block contains a sliding-mode observer whose principal role is to calculate tire-road forces, while in the second block an extended Kalman filter estimates sideslip angle and cornering stiffness. More specifically, this study proposes an adaptive tire-force model that takes variations in road friction into account. The paper also presents a study of convergence for the sliding-mode observer. The estimation process was applied and compared to real experimental data, in particular wheel force measurements. Experimental results show the accuracy and potential of the estimation process.