A driver model of a two-man bobsleigh

Braghin, Francesco; Donzelli, Mauro; Melzi, Stefano; Sabbioni, Edoardo

doi:10.1007/s12283-011-0066-3

Cited by 9 publications

(7 citation statements)

References 9 publications

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“…However, the coefficient of friction between blades and ice has not actually been measured on equipment used in the sport of bobsleigh. Past publications [1][2][3][4] estimate that this value may range from (7 to 50) 9 10 -3 . It is therefore the goal of this work to achieve a better understanding of the science of ice friction by determining the coefficient of friction between a two-men training bobsleigh and different competitive ice surfaces, and through these studies improve the understanding of the science of friction as applied to the sport of bobsleigh.…”

Section: Introductionmentioning

confidence: 99%

“…In their simulations, they have used a coefficient of friction between bobsleigh runners and ice of 14 9 10 -3 . A newer model developing a virtual driver estimates a coefficient of friction of (50 ± 10) 9 10 -3 [4] referring to experiments performed at the Cesana Pariol track in Italy without providing details of those experiments. In this paper, the researchers mention that the coefficient of friction should normally vary with the normal force.…”

Section: Introductionmentioning

confidence: 99%

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Experimental analysis of ice friction in the sport of bobsleigh

et al. 2011

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We report the first derivation of the coefficient of friction between bobsleigh runners and ice from experimental measurements performed in a controlled environment. In a series of experiments on both horizontal ice and a track sloped at 6.80°, a radar gun was used to sample the speed of a moving sled in the range of (1-10) m/s at a sample rate of 31.25 Hz. The acceleration of the sled, and thus the coefficient of friction, was extracted from these data, with a value of (4.2 ± 0.9) 9 10 -3 for the coefficient of friction associated with a set of two-man bobsleigh runners. There was no detectable variation in the coefficient of friction with velocity at this range of speeds and experimental accuracy. This result improves our knowledge of this coefficient over currently accepted values determined from indirect measurements, and indicates that the coefficient is lower than the currently accepted range.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental analysis of ice friction in the sport of bobsleigh

et al. 2011

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“…According to Scherge [18], the lateral friction for a bobsled is ten times higher than longitudinal friction, which would account for µ y = 0.05 − 0.09. Braghin et al [19] developed a bob driver model for bobsled optimization and provided an equation for the lateral friction force F y based on the normal force F z and the side slip angle of the runner α…”

Section: Lateral Frictionmentioning

confidence: 99%

Modeling Ice Friction for Vehicle Dynamics of a Bobsled with Application in Driver Evaluation and Driving Simulation

von Schleinitz,

Wörle,

Graf

et al. 2021

Preprint

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We provide an ice friction model for vehicle dynamics of a two-man bobsled which can be used for driver evaluation and in a driver-in-the-loop simulator. Longitudinal friction is modeled by combining experimental results with finite element simulations to yield a correlation between contact pressure and friction. To model lateral friction, we collect data from 44 bobsleigh runs using special sensors. Non-linear regression is used to fit a bob-specific one-track vehicle dynamics model to the data. It is applied in driving simulation and enables a novel method for bob driver evaluation. Bob drivers with various levels of experience are investigated. It shows that a similar performance of the top drivers results from different driving styles.

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“…Development of a driver model and track model may prove to be useful in order to find more accurate links between sled parameters and performance in competition. These models are to be developed based off of code made by Braghin et al [7] and Mössner et al [8]. As a part of the driver model in [7], the interaction between the ice and the runners on the sled will need to be defined.…”

Section: Project Deliverablesmentioning

confidence: 99%

“…These models are to be developed based off of code made by Braghin et al [7] and Mössner et al [8]. As a part of the driver model in [7], the interaction between the ice and the runners on the sled will need to be defined. Going into further depth on ice-steel friction properties will be the primary focus of this project.…”

Section: Project Deliverablesmentioning

confidence: 99%

Thermal-Fluid Dynamic Model of Luge Steels

Stell¹

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Thermal-Fluid Dynamic Model of Luge Steels Brandon Stell Luge is an Olympic sport in which athletes ride feet-first on sleds down an ice-covered track. Competitors spring from the starting position and accelerate their sled by paddling with spiked gloves against the ice surface. Once the Luger leaves the starting section, their downhill motion is solely propelled by the effects of gravity. Athletes compete, one after the other, for the fastest time. Runs can differ by as little as a thousandth of a second, meaning that every minor sled adjustment, change of line choice, and shift of body position is critical. In the past, the sport of Luge has progressed through a series of steps involving trial and error, where changes to the sled and strategy rely more on intuition and race results, rather than in-depth, mathematical analysis. In an effort to try and improve track times for the US Olympic Luge team, a track and driver model is in development in order to simulate a sled going down the track. By doing this, the hope is to be able to pinpoint areas of possible improvement to the sled and see how adjustments can affect the optimum line down the track. A part of this model, which is the focus of the following paper, is the inclusion of an analysis to identify the frictional relationship between the ice surface and the steels of the sled. The model created of the ice-steel interaction was put in the form of a function file, which includes inputs of down force, ice temperature, sled velocity, and steel geometry. Creation of this model and completion of a set of parametric studies allowed for further understanding the interaction between the sled steels and ice surface, specifically applying to the sport of Luge. The model predicts for lower temperatures that at slower sled velocities the coefficient of friction is greater compared to faster sled velocities. This relationship inverts as the ice temperature moves closer to the melting temperature. A sharper steel edge radius was found to be beneficial in lowering the coefficient of friction at lower sled velocities. The sharp edge radius friction benefit decreases as the sled speed increases and is predicted to actually increase friction slightly compared to duller v blades at greater velocities. A flat as possible rocker radius lowers friction at all sled velocities, as well as in banked turns where two contact patches are possible. On curves, the pressure on the steel is increased due to the effects of centripetal accelerations. A 1 g versus 5 g normal loading, experienced on the last turns of the track, increases the coefficient of friction on the blade, but also increases the allowable lateral force on the sled before side slip occurs. Understanding the relationships of these parameters, along with the information that may be gained from the driver model, may prove to be useful in choosing optimum sled characteristics and line choice.

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A driver model of a two-man bobsleigh

Cited by 9 publications

References 9 publications

Experimental analysis of ice friction in the sport of bobsleigh

Experimental analysis of ice friction in the sport of bobsleigh

Modeling Ice Friction for Vehicle Dynamics of a Bobsled with Application in Driver Evaluation and Driving Simulation

Thermal-Fluid Dynamic Model of Luge Steels

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