Determining Tyre Adhesion Characteristics Based on the Road Tests of Automobiles

The motion of automobiles significantly depends on the conditions of interaction between a tyre and a road surface. One of the most frequently used ways of presenting the conditions of cooperation between a tyre and a road surface is a characteristic showing a longitudinal adhesion coefficient as a function of a longitudinal slip of a tyre. One of the methods for determining tyre-to-road adhesion characteristics is to use a special trailer combined with a towing vehicle. This type of method is commonly used to determine adhesion characteristics for a braked wheel. This article presents a method for determining adhesion characteristics for a driven wheel based on the road tests of automobiles. For this purpose, vehicle wheel velocity signals from a vehicle CAN network and a vehicle velocity signal from a GPS receiver were used. The signals from the CAN network were recorded using a special measurement card and an application developed in LabVIEW environment. The application developed in LabVIEW also allowed for simultaneous recording of automobile velocity from the GPS receiver. In this paper, the courses of a wheel velocity, longitudinal acceleration of automobile, longitudinal slip of the front wheels in time domain, as well as the coefficient of tyre-to-road longitudinal adhesion as a function of the longitudinal slip of the wheel are presented.