Interaction of Anti-lock Braking Systems with Tire Torsional Dynamics

Abstract

ABSTRACT A tire's torsional dynamics couple the responses of wheel/hub inertia to that of the ring/belt inertia. Depending on the effective stiffness, damping, and mass distribution of the tire, the ensuing deflections between the wheel and the ring can cause significant errors in the estimation of the tire's longitudinal slip from wheel speed measurements. However, this remains the established approach for constructing anti-lock braking system (ABS) control algorithms. Under aggressive braking events, the errors introduced by torsional dynamics may significantly affect the ABS algorithm and result in less than optimal braking performance. This article investigates the interaction of tire torsional dynamics and ABS control using a comprehensive system model that incorporates sidewall flexibility, transient and hysteretic tread-ground friction effects, and the dominant dynamics of a hydraulic braking system. It considers a wheel/hub acceleration-based ABS controller that mimics the working steps of a commercial ABS algorithm. Results from multiple sensitivity studies show a strong correlation of stopping distances and ABS control activity with design parameters governing tire/wheel torsional response and the filter cutoff frequency of the wheel acceleration signals used by the controller.