Skid and roll on sloped artificial putting surfaces

Engineering of Sport 15 - Proceedings from the 15th International Conference on the Engineering of Sport (ISEA 2024)

To improve performance in putting, training aids have been developed for indoor and outdoor applications that help players read greens correctly and hit putts at the intended line and speed. Physical models predict the trajectory of the ball on a given green by using a threedimensional model of the putting surface. The deviation of the read and the putt played to the modelled line (ideal line) is useful feedback to players. An accurate ideal line prediction requires the knowledge of friction parameters that describe the surface-ball interaction, which can be separated into a skid and a roll phase. During the skid phase, the ball experiences an interplay between airborne and sliding. Previous research suggests that with an appropriate skid friction coefficient this interplay can be approximated as one skid phase. The airborne is a result of the vertical launch of the ball, while the sliding is due to the initial angular velocity (𝜔) not matching the initial linear velocity, 𝑣 ≠ 𝜔 ∙ 𝑅. While the ball (with radius 𝑅) skids, linear velocity decreases and angular velocity decreases, until 𝑣 = 𝜔 ∙ 𝑅, from which point pure rolling commences. Parameters describing the skid-roll transition such as skid time, roll ratio, skid and roll friction coefficients can be derived from a velocity-time trace, 𝑣(𝑡), but have not yet been reported for up- or downhill slopes. With the emergence of moving greens, it was possible to investigate the effect of slopes on the skid/roll behaviour more systematically in this study.