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Road - scaled Magic Formula for braking performance of cars

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Author: Hogt, R.M.M. · Oosten, J.J.M. van
Publisher: VDI-Verlag
Place: Düsseldorf
Institution: TNO Wegtransportmiddelen
Source:3. Darmstädter Reiferkolloquium 19. Oktober 2000, 125-135
Fortschritt-Berichte VDI Reihe 12: Verkehrstechnik/Fahrzeugtechnik
Identifier: 362268
Keywords: Braking performances · Tyre-road interaction · Magic Formula · automobiles · brakes · sliding friction · wheels · tires · road transport · mathematical models · augmentation


Ths skid resistance of the road surface is one of the parameters that influence the active vehicle safety and consequently the traffic safety. Up till now, in the Netherlands skid resistance has been evaluated by means of of a statistical relation between the skid resistance value and accident risk. In order to be able to fulfil the demands of a more detailed evaluation an approach is suggested with the focus on the physical description of mechanisms in traffic safety. This approach is innovative and quite different from standard solutions in traffic safety research. One of the major challenges in this approach is to integrate a wide range of disciplines, i.e. road technology, tyre-road interaction, vehicle dynamics and human factors for the prediction of the braking performance of vehicle from specified road characteristics. In this way, the braking performance model supports a better mutual understanding between the governments, road constructors and vehicle manufacturers. One of the crucial elements in the model is the accurate description of the tyre-road interaction. The Magic Formula tyre model is a general accepted model to describe interaction forces within the automotive industry. This paper focuses on the extension of the Magic Formula tyre model with speed dependent friction for especially the wet conditions and also the scaling of the Magic Formula parameters based on standard road-skid resistance and road macro texture measurements. This extended model is valid for dry and wet surfaces. It enables the scientist to enlarge the accuracy and validity range of the tyre-road interaction model towards a wide range of surfaces and thus increasing the accuracy of the prediction of the vehicle braking performance