Experimental determination of the tire-road friction coefficient for a vehicle with anti-lock braking system

In the present study, technical analysis of an experimental research has been carried out to verify tire-road friction coefficient of a vehicle with an anti-lock braking system (ABS) in the process of maximum braking force and in different types of surfaces. The study was conducted using three independent methods, including effective braking distance reading, deceleration measurement with an accelerometer, and a numerical experiment to study vehicle deceleration. The obtained polynomial determined the dependence of the coefficient of friction as a function of the velocity of the center of mass. Verification of experimental results from the first and second experiment was carried out by numerical analysis on the vehicle's deceleration implementing mechanical-mathematical model with ABS module. The results obtained from both the conducted experiment and numerical analysis on tire-road friction coefficient were processed by the methods and means for statistical analysis and expert assessments to determine the extent of results validity and credibility of the performed experiments. Considering the conducted dynamic study on the vehicle braking performance with an anti-lock braking system and the displayed graphic dependences, it has been proved that the maximum braking delay is achieved at constant pressure on the brake pedal. The coefficient of friction decreases with the increase of initial speed for different types of surfaces. High coefficient of friction is explained by the fact that the wheels of the car roll on the highest available slip and the coefficient of friction is similar to that at rest.