Estimating Braking Torque Uncertainties at the Individual Wheel Level of an Automobile

This paper presents two estimation approaches of braking torque uncertainties at the individual wheel dynamics, which are due to unmodeled dynamics or parametric uncertainties. First, a Luenberger state observer is designed by means of considering the uncertainties as a torque disturbance to the modeled wheel dynamics and augmenting the state space to include the disturbance torque for observation. Second, an adaptive scheme is adopted to estimate the uncertainties, which are lumped together on the braking pads friction coefficient of each wheel, as one varying parameter. The proposed estimation schemes are implemented in the MATLAB/Simulink® environment and validated via co-simulation on CarSim®. The obtained results validate the effectiveness and accuracy of both schemes, with the adaptive estimator exhibiting faster transient response.