“…However, the explanatory power of any such ideas is limited by the maximum lateral displacement they may account for: even in the extreme case of assigning all the friction to the trailing half, the resulting lateral displacement has been estimated to be approx. half of that empirically observed 5 . Figure 2 Previously proposed alternative mechanisms to explain the curled trajectory of a curling stone: ( a ) Front-rear friction asymmetry and ( b ) the scratch-guiding mechanism.…”
The curling motion of the curling stone on ice is well-known: if a small clockwise rotational velocity is imposed to the stone when it is released, in addition to the linear propagation velocity, the stone will curl to the right. A similar curl to the left is obtained by counter-clockwise rotation. This effect is widely used in the game to reach spots behind the already thrown stones, and the rotation also causes the stone to propagate in a more predictable fashion. Here, we report on novel experimental results which support one of the proposed theories to account for the curling motion of the stone, known as the “scratch-guiding theory”. By directly scanning the ice surface with a white light interferometer before and after each slide, we observed cross-scratches caused by the leading and trailing parts of the circular contact band of the linearly moving and rotating stone. By analyzing these scratches and a typical curling stone trajectory, we show that during most of the slide, the transverse force responsible for the sideways displacement of the stone is linearly proportional to the angle between these cross-scratches.
“…However, the explanatory power of any such ideas is limited by the maximum lateral displacement they may account for: even in the extreme case of assigning all the friction to the trailing half, the resulting lateral displacement has been estimated to be approx. half of that empirically observed 5 . Figure 2 Previously proposed alternative mechanisms to explain the curled trajectory of a curling stone: ( a ) Front-rear friction asymmetry and ( b ) the scratch-guiding mechanism.…”
The curling motion of the curling stone on ice is well-known: if a small clockwise rotational velocity is imposed to the stone when it is released, in addition to the linear propagation velocity, the stone will curl to the right. A similar curl to the left is obtained by counter-clockwise rotation. This effect is widely used in the game to reach spots behind the already thrown stones, and the rotation also causes the stone to propagate in a more predictable fashion. Here, we report on novel experimental results which support one of the proposed theories to account for the curling motion of the stone, known as the “scratch-guiding theory”. By directly scanning the ice surface with a white light interferometer before and after each slide, we observed cross-scratches caused by the leading and trailing parts of the circular contact band of the linearly moving and rotating stone. By analyzing these scratches and a typical curling stone trajectory, we show that during most of the slide, the transverse force responsible for the sideways displacement of the stone is linearly proportional to the angle between these cross-scratches.
“…Several scientific papers in the field of curling try to explain the mechanism that induces a curl (lateral motion) in the stone [2,3,[5][6][7][8][9][10][11][12][13]19,23,24]; moreover, the papers attempt to analyze the effect of sweeping on the stone motion [25][26][27]. However, to the authors' best knowledge, no attempt has been made to develop a method to assess curling ice quality objectively.…”
Section: Discussionmentioning
confidence: 99%
“…The physics behind curling stone movement is still not fully described, and new models are being proposed. Recently proposed models include front-back asymmetry models (assuming an asymmetry of friction forces at the front and the back of a running curling stone) [3][4][5][6][7][8][9][10][11] and pivot-slide models (taking that the curling stone pivots around specific points in the ice during its movement) [12,13]. Currently, no model is widely accepted, and scientists' discussions about various models are still ongoing [14][15][16][17][18][19].…”
Despite the significant influence of ice conditions on results in the sport of curling, players and ice technicians lack a measurement device that would objectively measure ice quality during a curling competition. This paper presents such a new measurement method by using a device consisting an inertial measurement unit (IMU) attached to the handle of the curling stone and data processing software. IMU is used to measure the vibration of curling stone during its movement on the surface of the ice. The acceleration signal is recorded, and then the software calculates the value of so-called R parameter in frequency domain. The value of R allows one to determine if an ice sheet had been pebbled and if the shape of pebbles is suitable for the game of curling. The presented system was tested in various ice conditions—on both freshly prepared and used ice. Ice technicians and players may use the proposed system to decide whether the ice surface is suitable for play or if it should be remade.
“…The curling behaviour of a stone sliding on ice has been explained by three models: a left-right asymmetry model (LR model, with different frictional forces on the left and right sides of a stone) 4-7 , a front-back asymmetry model (FB model, with different frictional forces on the front and back sides of a stone) [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] and a pivot-slide model (PS model, where brief pivots of a stone around a point between a stone and pebbles cause the curling behaviour) [25][26][27] .…”
mentioning
confidence: 99%
“…Because the LR models failed to explain why a curling stone curls 8 , the FB and the PS models have been developed. The FB models are divided into six models, in which different mechanisms have been proposed for different front and back frictional forces: a pressure difference model (a larger pressure works on the front running band than on the back running band) [9][10][11] , a water layer model (a water layer is assumed to be produced by frictional heating, and the layer reduces the frictional forces at the front running band) [12][13][14] , a snowplow model (small ice debris are formed by a stone and accumulate at the front running band) 15 , an evaporation-abrasion model (with an asymmetrical effect on evaporation and abrasions on the tops of pebbles and the effects of ice debris) [16][17][18] , a scratch-guiding model (guiding of small scratches left on the tops of pebbles by a stone) [19][20][21][22] and an edge model (with different rake angles of a stone at the front and back of the stone) 23,24 . Recent papers discuss a possibility of the PS model [25][26][27] , which was originally suggested by Penner 8 .…”
Curling is a sport in which players deliver a cylindrical granite stone on an ice sheet in a curling hall toward a circular target located 28.35 m away. The stone gradually moves laterally, or curls, as it slides on ice. Although several papers have been published to propose a mechanism of the curling phenomenon for the last 100 years, no established theory exists on the subject, because detailed measurements on a pebbled ice surface and a curling stone sliding on ice and detailed theoretical model calculations have yet to be available. Here we show using our precise experimental data that the curl distance is primarily determined by the surface roughness and the surface area of the running band on the bottom of a stone and that the ice surface condition has smaller effects on the curl distance. We also propose a possible mechanism affecting the curling phenomena of a curing stone based on our results. We expect that our findings will form the basis of future curling theories and model calculations regarding the curling phenomenon of curling stones. Using the relation between the curl distance and the surface roughness of the running band in this study, the curl distance of a stone sliding on ice in every curling hall can be adjusted to an appropriate value by changing the surface roughness of the running band on the bottom of a stone.
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