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Digital image correlation techniques for measuring tyre–road interface parameters: Part 2 – Longitudinal tyre slip ratio measurement

Theunis R. Botha, P. Schalk Els  
Journal of Terramechanics, Volume 61, October 2015, Pages 101-112, ISSN 0022-4898,
Measurement of tyre longitudinal slip-ratio is often estimated from three independent measurements devices namely wheel rotation speed, vehicle speed and tyre rolling radius. This produces an expensive measurement system to indirectly determine the slip-ratio. This paper presents a method by which the slip-ratio is determined from a video camera using digital image correlation techniques. The camera, mounted in such a way that the contact patch region is captured, enables the system to measure the tyre tread speed and ground speed at the contact patch. The slip-ratio is then determined from these two measurements.
Keywords: Longitudinal slip; Digital image correlation; Camera; Longitudinal tyre force; Contact patch velocity