EXPERIMENTAL INVESTIGATION OF TIRE TORSIONAL DYNAMICS ON THE PERFORMANCE OF AN ANTI-LOCK BRAKING SYSTEM

The designs of commercial Anti-Lock Braking Systems often rely on assumptions of torsionally rigid tire-wheel assemblies. However, some recent tire/wheel technologies often involve lower torsional stiffnesses that cannot be captured well using these rigid wheel assumptions. This paper presents both simulation and experimental analysis of the interaction between a typical ABS controller and tire torsional dynamics. The simulation work includes a comprehensive model that incorporated sidewall flexibility, transient and hysteretic tread-ground friction effects, and the dominant dynamics of a hydraulic braking system. The experimental tests were conducted on a quarter-vehicle ABS test fixture built around a chassis dynamometer. Sensitivity studies are completed through changes in the tire/wheel properties such as wheel inertia, torsional stiffness and ABS controller properties such as the controller's filter. cutoff frequency applied to the wheel speed signals. The results showed strong interactions between the tire's torsional natural frequency and the filter cutoff frequency of the controller.