A comparison of Coulomb and pseudo-Coulomb friction implementations: Application to the table contact phase of gymnastics vaulting

Jackson, Monique; Hiley, Michael J.; Yeadon, Maurice R.

doi:10.1016/j.jbiomech.2011.07.022

Cited by 11 publications

(15 citation statements)

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“…The interaction between the gymnast and the table was simulated using both static and dynamic Coulomb friction. The normal contact force was represented by spring-dampers situated at three points of contact: the fingertip, the knuckle and the base of the palm, while the tangential contact force was modelled using a two-state frictional force representation to allow for both static and dynamic friction (Jackson, Hiley & Yeadon, 2011).…”

Section: Simulation Modelmentioning

confidence: 99%

“…The model parameters (viscoelastic parameters of the shoulder, knuckle, table and contact springs and the static and kinetic coefficients of friction between the hands and the contact surface) were set to those determined in Jackson et al (2011) apart from the damping parameter of the contact spring, which was increased to 10,000 Nm -2 s (Table 1) to prevent the hands from 'bouncing' during the initial part of the table contact phase. The input to the torque-driven model comprised the initial conditions at contact (joint angles and velocities, upper trunk angle and velocity, mass centre position and velocity) together with the activation time histories of the torque generators.…”

Section: Simulation Modelmentioning

confidence: 99%

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Optimal technique for maximal forward rotating vaults in men’s gymnastics

Hiley

Jackson

Yeadon

2015

Human Movement Science

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In vaulting a gymnast must generate sufficient linear and angular momentum during the approach and table contact to complete the rotational requirements in the post-flight phase. This study investigated the optimisation of table touchdown conditions and table contact technique for the maximisation of rotation potential for forwards rotating vaults. A planar seven-segment torque-driven computer simulation model of the contact phase in vaulting was evaluated by varying joint torque activation time histories to match three performances of a handspring double somersault vault by an elite gymnast. The closest matching simulation was used as a starting point to maximise post-flight rotation potential (the product of angular momentum and flight time) for a forwards rotating vault. It was found that the maximised rotation potential was sufficient to produce a handspring double piked somersault vault. The corresponding optimal touchdown configuration exhibited hip flexion in contrast to the hyperextended configuration required for maximal height. Increasing touchdown velocity and angular momentum lead to additional post-flight rotation potential. By increasing the horizontal velocity at table touchdown, within limits obtained from recorded performances, the handspring double somersault tucked with one and a half twists, and the handspring triple somersault tucked became theoretically possible.

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Section: Simulation Modelmentioning

confidence: 99%

Section: Simulation Modelmentioning

confidence: 99%

Optimal technique for maximal forward rotating vaults in men’s gymnastics

Hiley

Jackson

Yeadon

2015

Human Movement Science

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“…An international Brevet judge assessed and ranked the performance of each vault, with the best three vaults selected for subsequent analysis. Details of the methods used to determine the kinematics of the performances are given in Jackson et al (2011).…”

Section: Data Collectionmentioning

confidence: 99%

“…The mass and dimensions of the vaulting table were measured and the inertial parameters calculated as in Jackson et al (2011).…”

Section: Data Collectionmentioning

confidence: 99%

“…The interaction between the gymnast and the table was modelled as detailed in Jackson et al (2011). The normal contact force was represented by spring-dampers situated at three points of contact: the fingertip, the knuckle and the base of the palm, while the tangential contact force was modelled using a two-state frictional force representation to allow for both static and dynamic friction.…”

Section: Simulation Modelmentioning

confidence: 99%

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The influence of touchdown conditions and contact phase technique on post-flight height in the straight handspring somersault vault

Yeadon

Jackson

Hiley

2014

Journal of Biomechanics

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Additional Information:• NOTICE: this is the author's version of a work that was accepted for publication in Journal of Biomechanics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Biomechanics, vol 47 (12), 2014 DOI: 10.1016/j.jbiomech.2014 ABSTRACTIn vaulting the gymnast must generate sufficient linear and angular momentum during the approach and table contact in order to complete the rotational requirements in the postflight phase. This study investigated the effects of touchdown conditions and contact technique on peak post-flight height of a straight handspring somersault vault. A planar seven-segment torque-driven computer simulation model of the contact phase in vaulting was evaluated by varying joint torque activation time histories to match three performances of a straight handspring somersault vault by an elite gymnast. The closest matching simulation was used as a starting point to optimise peak post-flight height of the mass centre for a straight handspring somersault. It was found that optimising either the touchdown conditions or the contact technique increased post-flight height by 0.1 m whereas optimising both together increased post-flight height by 0.4 m above that of a simulation matching the recorded performance. Thus touchdown technique and contact technique make similar contributions to post-flight height in the straight handspring somersault vault. Increasing touchdown velocity and angular momentum lead to additional post-flight height although there was a critical value of vertical touchdown velocity beyond which post-flight height decreased. INTRODUCTIONThe mechanics of the table contact phase of gymnastics vaulting is dependent on the initial contact conditions and the technique used during the contact phase. Although there are numerous coaching publications on vaulting, there is no general consensus about the importance of table contact phase technique. Some authors hold the view that vaulting performance is primarily determined prior to table contact (Still, 1990) while others have suggested that the gymnast has the ability to change the outcome of the vault via table contact technique (Smith, 1982;Boone, 1976). Takei (1988) used correlational analysis to show that a large pre-flight horizontal velocity is an important determinant of success in the tucked handspring somersault vault. Additionally Takei and Kim (1990) found that a large change in mass centre vertical velocity during contact was beneficial. While the horizontal pre-flight velocity is clearly an aspect of touchdown conditions, it is unclear whether the change in vertical velocity is a function of initial conditions or contact technique or both. King et al. (1999) used a passive (no shoulder torque) two-segment simulation model to determine ...

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