Identification of tyre characteristics using active force excitation
Paper i proceeding, 2015
Knowledge of the maximum tyre-road friction coefficient can improve active safety
systems by defining actuator boundaries and adaptable intervention thresholds. Estimation of the
coefficient of friction based on tyre response measurements requires large level of force excitation.
Under normal driving conditions, manoeuvres with large tyre utilizations are rare. This study
investigates a method where wheel torques with opposite signs are applied to the front and rear
axle simultaneously. This procedure allows for an intervention with large tyre excitations without
disturbing the motion of the vehicle. The intervention is evaluated in simulations and experiments.
Further, a method is proposed which does not require measurement of the vehicle longitudinal
velocity. The results show that it is possible to estimate the current friction coefficient with the
proposed method, although the assumption made in the proposed method makes the friction estimate
sensitive to measurement noise on the wheel speed signal.
Vehicle motion control