Anti-lock Brake Systems (ABS) are one of the most important safety features for road vehicles. They sustain the stability and steerability of a vehicle under heavy braking. The ABS is part of the standard active safety repertoire of commercial vehicles. Current commercial ABS are based on many heuristics and control rules, leading to an increasingly complex system. There is no theory available to assess the stability of the system, nor its performance. Moreover, these algorithms require extensive tuning for different vehicle models. The novel algorithm analysed in this thesis offers a mathematical background and a reduced tuning effort. Previous work involved validating the novel algorithm on a test bench with a fixed vertical load. This limitation is addressed. The goal of this thesis is to determine the influence of load transfer and of tyre-road friction coefficients on the performance of the novel ABS algorithm. An improved adaptive ABS is proposed that utilizes load based sensing. Following the analysis, the results are validated using a four wheel vehicle model in CarSim and Simulink. To evaluate the performance of the improved algorithm against a commercial one, modifications have been made to a test vehicle. The commercial ABS will thus serve as a benchmark for further algorithm developments. Furthermore, research topics have been set so future work may be built upon these foundations. Overall, this thesis contributes to the design, simulation, implementation and validation of a novel ABS algorithm. (Author/publisher)
Abstract