Experimental evaluation of observers for tire-road forces, sideslip angle and wheel cornering stiffness

This paper proposes a new estimation process to estimate tire-road forces, sideslip angle and wheel cornering stiffness. This method uses measurements from currently-available standard sensors. The estimation process is separated into two blocks: the first block contains an observer whose principal role is to calculate tire-road forces without a descriptive force model, while in the second block an observer estimates sideslip angle and cornering stiffness with an adaptive tire-force model. The different observers are based on an Extended Kalman Filter method. Concerning the vehicle model, for observability reasons, the rear longitudinal forces are neglected relative to the front longitudinal forces. The estimation process was applied and compared to real experimental data, notably wheel force measurements. Experimental results show the accuracy and potential of the estimation process, and a limitation in the estimation of the cornering stiffness.