Design concept for an alternative heavy vehicle ABS system

Abstract

This paper investigates the use of slip control on heavy vehicles to reduce stopping distances and compressed air usage in an emergency stop. A hardware-in-the-loop (HiL) rig has been developed to investigate slip control. The hardware includes an air receiver, anti-lock braking system (ABS) or slip-control modulator, brake actuator and brake calliper. The braked wheel and vehicle dynamics are simulated on a micro-processor. A gain-scheduled slip controller using the same pneumatic actuation as used by conventional ABS is developed. The slip control strategy increases the mean fully developed deceleration by 6% and halves the air usage compared to the ABS strategy on the HiL rig. The transient performance of the slip controller is poor due to the sluggish response of the ABS valves, causing a 10% increase in stopping distance. A novel fast-acting brake actuator design is described. Simulations of the new actuator implementing slip control show an improvement of 10% in stopping distance performance and 30% in air usage.