Influência da utilização do ABS na segurança veicular baseada na eficiência de frenagem e na probabilidade de travamento de roda / Influence if the ABS use on vehicular safety based on braking efficiency and on the probability of wheel lockup

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The ABS (Antilock Braking System) is a supplementary system to the regular service brake system, which prevents the wheel lock in any braking situation, mainly in emergency braking maneuvers, and it will guarantee stability and steerability of the vehicle and reduces, in most of the situations, the stopping distance in relation to the regular brake system. By the way, the wheel lock when braking has a strong relationship with traffic accidents. This thesis presents an assessment of the effciency of the ABS in the reduction of traffic accidents in daily conditions of use of the vehicle, based on a dynamic feature of the vehicle: the braking efficiency. Usually, this evaluation of the effectiveness of the ABS in the prevention of accidents is done through database statistics of accidents and records of vehicles. The wheel lock occurs when the friction demand of the vehicle, which is directly related to the desired deceleration, is larger than the friction provided by the interaction between the tire and the road surface. So through probability curves of availability of friction, probability curves of friction demand and statistics on the use of the vehicle, it is possible to estimate the probability of occurrence of wheel lock-ups. This study presents estimations of brake applications to cause a lock-up, estimations of distance travelled to cause a lock-up and estimations of time so that a wheel locks. The estimations are made for dry and wet concrete roads. To clarify the operation of the system, it was simulated the ABS system in Matlab/Simulink. In order to do this, it was developed a finite state controller, which was implemented in a full vehicle model. The simulation carried out was a straight line brake until the complete stop of the vehicle in a homogeneous high friction road. This study found out that the ABS has a great potential to reduce traffic accidents, both on wet road and on dry road. The ABS presents a gain in vehicles safety even in relation to a perfectly balanced brake system. It should be noted that this result can be affected by the driver factor, this change is caused by ignorance of the operation and use of the system or even misuse.

ASSUNTO(S)

simulation vehicular safety abs traffic accidents segurança veicular simulação acidente de trânsito abs

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