Measurement of mechanical properties of snow for simulation of skiing

Mössner, Martin; Innerhofer, Gerhard; Schindelwig, Kurt; Kaps, Peter; Schretter, Herwig; Nachbauer, Werner

doi:10.3189/2013jog13j031

Cited by 23 publications

(29 citation statements)

References 30 publications

(42 reference statements)

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“…We adopted the ski–snow contact model proposed by Mossner et al . [MIS*13, MHS*14, HMKN10], including a ski model and a snow force model, to describe the ski–snow interaction and assist the controller to track the desired trajectories.…”

Section: Ski–snow Contact Modelmentioning

confidence: 99%

“…The reaction force, as shown in Figure , at each contact point i can be decomposed into (1) a penetration force

f_{normalp, i}

acting in the direction

e_{normalp, i}

, perpendicular to the snow surface of the slope, (2) a shear force

f_{normals, i}

with direction

e_{normals, i}

, parallel to the snow surface and traverse to the ski edge and (3) a friction force

f_{normalf, i}

in the opposite direction of the contact point velocity

v_{normalc, i}

{bolde}_{normalf} = \frac{v_{normalc, i}}{false∥ {boldv}_{c, i} false∥}

[MIS*13, MHS*14, HMKN10].…”

Section: Ski–snow Contact Modelmentioning

confidence: 99%

“…We also use a to determine whether a ski is flat or inclined as follows:

({, \begin{matrix} \tan false| θ false| \geq \frac{a}{w} & an inclined ski, \\ \tan false| θ false| < \frac{a}{w} & a flat ski . \end{matrix})

The shear force magnitude, derived from the orthogonal metal cutting theory [MHS*14], for the i th contact point is given by

f_{s, i} false(ε_{normals, i} false) = S_{normalf} ε_{s, i} ℓ,

where S f is the failure shear stress (

0.057 \pm 0.008 N / {mm}^{2}

) [MHS*14], and

ε_{normals, i}

is the width of snow pile plowed by a ski, as shown in Figure (b). The shear force magnitude in the existing model [MIS*13, MHS*14, HMKN10] is proportional to ε p . However, we found that the penetration depth is usually too small to provide sufficient penetration forces to compensate the skier's weight, especially when the inclined angle is small.…”

Section: Ski–snow Contact Modelmentioning

confidence: 99%

“…However, we found that the penetration depth is usually too small to provide sufficient penetration forces to compensate the skier's weight, especially when the inclined angle is small. The shear force model of the ski–snow contact was constructed based on the static measurement without considering the dynamic effects during the ski movement [MIS*13]. Therefore, we introduce ε s as another degree of freedom for shear force to model the dynamic effects of ski movement and snow plow.…”

Section: Ski–snow Contact Modelmentioning

confidence: 99%

“…Specifically, skiers have to weight their skis by extending legs when skiing through the bottoms and unweight their skis by retracting legs when moving over the tops of the bumps. As our framework simulates these techniques by using a momentum‐based motion controller with the ski–snow contact model [MIS*13, MHS*14, HMKN10] to track the reference trajectories of ski, CoM and pose produced by the motion planner, our approach can generate skiing motions that are more realistic than existing skiing animation approaches.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Skiing Simulation Based on Skill‐Guided Motion Planning

Lee

Liou

et al. 2019

Computer Graphics Forum

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Skiing is a popular recreational sport, and competitive skiing has been events at the Winter Olympic Games. Due to its wide moving range in the outdoor environment, motion capture of skiing is hard and usually not a good solution for generating skiing animations. Physical simulation offers a more viable alternative. However, skiing simulation is challenging as skiing involves many complicated motor skills and physics, such as balance keeping, movement coordination, articulated body dynamics and ski‐snow reaction. In particular, as no reference motions — usually from MOCAP data — are readily available for guiding the high‐level motor control, we need to synthesize plausible reference motions additionally. To solve this problem, sports techniques are exploited for reference motion planning. We propose a physics‐based framework that employs kinetic analyses of skiing techniques and the ski–snow contact model to generate realistic skiing motions. By simulating the inclination, angulation and weighting/unweighting techniques, stable and plausible carving turns and bump skiing animations can be generated. We evaluate our framework by demonstrating various skiing motions with different speeds, curvature radii and bump sizes. Our results show that employing the sports techniques used by athletes can provide considerable potential to generate agile sport motions without reference motions.

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Section: Ski–snow Contact Modelmentioning

confidence: 99%

“…The reaction force, as shown in Figure , at each contact point i can be decomposed into (1) a penetration force

f_{normalp, i}

acting in the direction

e_{normalp, i}

, perpendicular to the snow surface of the slope, (2) a shear force

f_{normals, i}

with direction

e_{normals, i}

, parallel to the snow surface and traverse to the ski edge and (3) a friction force

f_{normalf, i}

in the opposite direction of the contact point velocity

v_{normalc, i}

{bolde}_{normalf} = \frac{v_{normalc, i}}{false∥ {boldv}_{c, i} false∥}

[MIS*13, MHS*14, HMKN10].…”

Section: Ski–snow Contact Modelmentioning

confidence: 99%

“…We also use a to determine whether a ski is flat or inclined as follows:

({, \begin{matrix} \tan false| θ false| \geq \frac{a}{w} & an inclined ski, \\ \tan false| θ false| < \frac{a}{w} & a flat ski . \end{matrix})

The shear force magnitude, derived from the orthogonal metal cutting theory [MHS*14], for the i th contact point is given by

f_{s, i} false(ε_{normals, i} false) = S_{normalf} ε_{s, i} ℓ,

where S f is the failure shear stress (

0.057 \pm 0.008 N / {mm}^{2}

) [MHS*14], and

ε_{normals, i}

Section: Ski–snow Contact Modelmentioning

confidence: 99%

Section: Ski–snow Contact Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Skiing Simulation Based on Skill‐Guided Motion Planning

Lee

Liou

et al. 2019

Computer Graphics Forum

View full text Add to dashboard Cite

show abstract

On Ski–Snow Contact Mechanics During the Double Poling Cycle in Cross-Country Skiing

Hindér,

Kalliorinne,

Sandberg

et al. 2024

Tribol Lett

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Of the medals awarded during the Winter Olympics Games, most are awarded for sports involving cross-country (XC) skiing. The Double Poling (DP) technique, which is one of the sub-techniques used most frequently in XC skiing, has not yet been studied using simulations of the ski–snow contact mechanics. This work introduces a novel method for analysing how changes in the distribution of pressure on the sole of the foot (Plantar Pressure Distribution or PPD) during the DP motion affect the contact between the ski and the snow. The PPD recorded as the athlete performed DP, along with an Artificial Neural Network trained to predict the geometry of the ski (ski-camber profile), were used as input data for a solver based on the boundary element method, which models the interaction between the ski and the snow. This solver provides insights into how the area of contact and the distribution of pressure on the ski-snow interface change over time. The results reveal that variations in PPD, the type of ski, and the stiffness of the snow all have a significant impact on the contact between the ski and the snow. This information can be used to improve the Double Poling technique and make better choices of skis for specific snow conditions, ultimately leading to improved performance. Graphical Abstract

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Effect of flexural stiffness distribution of a ski on the ski–snow contact pressure in a carved turn

et al. 2021

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The design of the flexural stiffness distribution of a ski is one of the important factors in its development. On the other hand, the ski-snow contact pressure during a turn is thought to be an important factor in a skier's feeling. However, the relationship between the flexural stiffness distribution and ski-snow contact pressure has not been made clear. The purpose of this study was to understand how flexural stiffness distribution affects the contacting pressure, applying load, and ski-snow contacting condition through measurement on these items. The measurement system consisted of a ski deflection sensor beam with bending sensors, pressure sensors installed near the ski edge, and four points of load cells connected between the binding plate and the ski. Measurements were performed on the different flexural stiffness distributions of Skis A and B on hard snow and soft snow surfaces. The peak of the flexural stiffness of Ski A was on the boot center, and Ski B was stiffer with a peak under the heel of the boot. An increase in the flexural stiffness under the heel of the boot for Ski B caused less deflection in the rear part of the ski, and the applied force from the binding plate shifted forward. By fitting the ski deflection on the snow groove, so the rear section of the ski after the pressure peak fitted on the sliding surface of the snow groove, the compression zone increased and the sliding zone was reduced in Ski B. The pressure peak in Ski A was under the boot center, whereas, for Ski B it was behind the boot center. These results show that changes in flexural stiffness distribution alter ski deflection and ski-snow contact pressure.

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Measurement of mechanical properties of snow for simulation of skiing

Cited by 23 publications

References 30 publications

Skiing Simulation Based on Skill‐Guided Motion Planning

Skiing Simulation Based on Skill‐Guided Motion Planning

On Ski–Snow Contact Mechanics During the Double Poling Cycle in Cross-Country Skiing

Effect of flexural stiffness distribution of a ski on the ski–snow contact pressure in a carved turn

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