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1.
Svein Ohm Linge 《Sports Engineering》2011,14(1):39-47
The purpose of this work was to develop a new 2D gymnast-high bar model with horizontal bar endpoint dynamics included. To
this end, a three-spring high bar model was extended with a five segment gymnast model followed by evaluation and sensitivity
analysis. Evaluation over more than a complete giant swing (420°) was favourable (bar position rms errors <0.017 m, center
of mass angular position rms error <11°). Single parameter perturbations (10%) caused little deterioration in model performance
(lower 180°of the giant swing-bar position rms errors <0.006 m, arms’ angle rms error <0.9°). Combinations of parameter perturbations
gave bar position rms errors <0.008 m and arms’ angle rms error <1.8°. Model performance was most sensitive to errors in high
bar stiffness values. 相似文献
2.
3.
Tyler J. Stidwill Rene Albert Turcotte Phil Dixon David J. Pearsall 《Sports Engineering》2009,12(2):63-68
The purpose of this study was to develop a portable force measurement system for ice hockey skating. The system consisted
of three strain gauge pairs affixed to an ice hockey skate’s blade holder with wire leads connected to a microprocessor controlled
data acquisition device carried in a backpack worn by the skater. The configuration of the strain gauges simultaneously determined
the vertical and medial–lateral force components experienced by the blade holder with a resolution accuracy of 1.9 N and a
coefficient of variation of 9.2%. On-ice testing of this system with subjects performing forward start, acceleration, and
constant velocity skating permitted unencumbered, natural movement and demonstrated clear, unambiguous signal responses, high
trial-to-trial repeatability, and easy data retrieval. The practicality and accuracy of this testing approach have many applications,
such as a quantitative tool for skating force assessment to aid athletes and coaches, as well as providing the means to examine
other skill-specific dynamics. 相似文献
4.
All those who compete in the sport of rowing have used the land rowing machine, Ergometer (commonly called the ‘erg’), manufactured
by Concept II (Morrisville, Vermont, USA). Ergon is the Greek word for work, hence the Ergometer measures work. Rowers are
commonly ranked according to their ‘erg score.’ The fault in this ranking is that the land Ergometer cannot account for many
of the important technical aspects associated with rowing on the water. The goals of this project were to (1) develop a system
for on-the-water measurement of work during rowing and then (2) demonstrate the potential of such a system to quantify performance
and improve rowing technique. To achieve these goals, force was measured using strain gauges glued to the shaft of the rowing
oar and angular displacement was measured using a potentiometer. The force and displacement measurements were sent to a microcontroller,
which calculated the total work done in a particular stroke, as well as other parameters, and displayed the values to the
rower. The parameters were used to evaluate the performance of three collegiate rowers on the water. The data were also used
to plot force profiles, which were reviewed with each rower and the coach to illustrate the rowers’ habits and facilitate
improving technique. One rower was ‘tutored’ with the device through five on-the-water practices, after which his force profiles
and parameter values demonstrated significant improvement. The device not only provided a standard to which all rowers were
compared on the water, but also supplied the rowers with important information on technical aspects of their strokes and pacing
themselves. 相似文献
5.
Knowledge of external forces acting on an athlete is often required to study performance and injury mechanisms, but direct
measurements are difficult to obtain. While transducers in the rings cables typically measure external forces experienced
by gymnasts performing static balances and swinging movements on rings, this solution is not always acceptable and an accurate
technique that does not hinder the gymnasts’ performances is desirable. This study evaluates a video-based technique for estimating
cable tension on the rings apparatus. Static loading of a rings frame coupled with a planar video analysis of the mandatory
damped elastic devices (DEDs) provided a tension-deflection calibration curve. Three-dimensional video and cable tension data
were obtained for two male gymnasts performing static balances and dynamic swinging movements. Cable tension was measured
using a force link while a planar video analysis determined time histories of the DED deflections. Combined cable tension
time histories were estimated fromrelative DED deflections coupled with the tension-deflection calibration curve and the orientation of the rings cables, and were compared
to measured values to evaluate the proposed technique. For static balances the RMS difference between measured and estimated
combined cable tension was 83 N. For dynamic swinging movements the maximum RMS difference was 189 N, equivalent to a 4% difference
when expressed as a percentage of the peak value. The indirect video-based technique developed in this study accurately estimates
combined cable tension throughout movements on rings and may be considered for studies where a remote measurement is required.
There is potential for the technique to be extended to other sporting situations, where indirect accurate estimates of external
forces acting on an athlete are needed. 相似文献
6.
Toshiyuki Fujihara Takafumi Fuchimoto Pierre Gervais 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):22-38
The aim of this study was to analyse the principal mechanics of circles. Seventeen university male gymnasts performed circles on an instrumented pommel horse model that enabled the pommel reaction forces to be recorded at 1000 Hz with two force plates. The circles were also videotaped using two digital video cameras operating at 60 frames per second. During circles, the vertical component of the reaction forces peaked in the double-hand support phases. Changes in the velocity of the centre of mass corresponded to the change in the tangential components of horizontal reaction forces. The velocity of the centre of mass had its peaks in the single-hand support phases and its local minimums in the double-hand support phases. The velocity of the ankles and that of the centre of mass of the head and trunk were minimal in the single-hand support phases and were maximal in the double-hand support phases. These results suggest that the circles were composed of vertical movements and two kinds of rotations: rotation of the centre of mass and rotation of the body itself about the centre of mass. These two kinds of rotations, which influence the legs' rotational velocity, are phase dependent. To further our understanding of circles, research on circles in different orientations on the pommel horse will be beneficial. 相似文献
7.
A system was developed for measuring and analyzing the forces placed on a bicycle pedal during operation of a stationary ergometer.
Forces are measured in the plane parallel to the ergometer in directions normal and tangential to the surface of the pedals,
encompassing the plane of propulsive forces. The pedals are designed to be structurally and functionally equivalent to standard
clipless pedals. The stock pedal spindle and bearing assembly was replaced with a new spindle that was instrumented with two
Wheatstone bridges of foil strain gauges. The bearings were relocated to the crank-arm/pedal-spindle interface. The original
pedal body was then pinned to the new spindle. Additionally, the pedals were instrumented with optical encoders to measure
the pedal angle relative to the crank arm. An optical encoder was also mounted near the bottom bracket to measure crank-arm
angle. Signals were transmitted via a cable tethered to the cyclist’s leg from the pedals to an instrumented chassis, where
the strain gauge signals were conditioned and the digital optical encoder signals converted to analogue signals. From the
instrumented chassis, seven signals are ready for standard analogue data collection. Data collected from this new system has
proved to be both comparable with previously published literature and accurate when compared with expected power output values. 相似文献
8.
通过运用计算机仿真技术对体操运动进行技术分析和动作优化设计。作者建立了一个单杠上人体回环运动的５环多刚体系统模型,动用凯恩方法推导出运动方程,并采用Ｃ语言开发出相应的计算机仿真程序,该仿真程序能够帮助运动员改进运动技术并最终获得最优化的运动技术,研究结果表明：（１）所建立的单杠上人体回环运动的模型是可行的;（２）动用凯恩方法推导动力学方程简单而方便,运动方程以隐式呈现并易于编写计算机仿真程序;（３ 相似文献
9.
Measuring the performance of a sports surface is typically derived from a series of field and laboratory tests that assess
the playing properties under simulated game conditions. However, from a player’s perspective their own comfort and confidence
in the surface and its playing characteristics are equally if not more important. To date no comparative study to measure
playing preference tests has been made. The aim of this research was to develop a suitable method for eliciting player perceptions
of field hockey pitches and determine the key themes that players consider when assessing field hockey pitches. To elicit
meaningful unbiased human perceptions of a playing surface, an individual subjective analysis was carried out, using interviews
and inductive analysis of the recorded player statements. A qualitative analysis of elite hockey players (n = 22) was performed to obtain their perceptions immediately after a competitive match. The significant surface characteristics
that emerged as part of an inductive analysis of their responses were grouped together and formed five general themes or dimensions:
player performance, playing environment, pitch properties, ball interaction and player interaction. Each dimension was formed
from a hierarchy of sub-themes. During the analysis, relationships between the dimensions were identified and a structured
relationship model was produced to highlight each relationship. Players’ responses suggested that they perceived differences
between pitches and that the majority of players considered a ‘hard’ pitch with a ‘low’ ball bounce facilitating a ‘fast’
game speed was desirable. However, further research is required to understand the relative importance of each theme and to
develop appropriate measurement strategies to quantify the relevant engineering properties of pitch materials. 相似文献
10.
Gertjan Ettema Jo Hooiveld Steinar Braaten Maarten Bobbert 《Journal of sports sciences》2016,34(11):1081-1087
We examined the effect of boundary conditions in imitation ski jumping on movement dynamics and coordination. We compared imitation ski jumps with – and without – the possibility to generate shear propulsion forces. Six elite ski jumpers performed imitation jumps by jumping from a fixed surface and from a rolling platform. The ground reaction force vector, kinematics of body segments, and EMG of eight lower limb muscles were recorded. Net joint dynamics were calculated using inverse dynamics. The two imitation jumps differed considerably from each other with regard to the dynamics (moments, forces), whereas the kinematics were very similar. Knee power was higher and hip power was lower on the rolling platform than on the fixed surface. Mean EMG levels were very similar for both conditions, but differences in the development of muscle activity were indicated for seven of eight muscles. These differences are reflected in a subtle difference of the alignment of ground reaction force with centre of mass: the ground reaction force runs continuously close to but behind the centre of mass on the rolling platform and fluctuates around it on the fixed surface. This likely reflects a different strategy for controlling angular momentum. 相似文献
11.
Gareth Irwin David G. Kerwin 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):361-374
Kinetic analyses of the chalked bar longswing on high bar and its associated progressions were used to explain musculoskeletal contributions during the performance of these skills. Data on four international male gymnasts performing three series of chalked bar longswings and eight progressions were recorded. Customized body segment inertia parameters, two-dimensional kinematics (50 Hz), and bar forces (1000 Hz) were used as input to inverse dynamic modelling. The analysis focused on the relative contributions of the knees, hips, and shoulders with root mean squared differences between the chalked bar longswing and the progressions being used to rank the progressions. Seventy per cent of the total work occurred between 200° and 240° of angular rotation in the longswing, 67% of which was contributed by the shoulders. The shoulders were also dominant in all progressions, with the largest such contribution occurring in the looped bar longswing with “no action”. The least similar progression was the looped bar pendulum swing, while the most similar was the chalked bar bent knee longswing. This study provides a useful means for ranking progressions based on their kinetic similarity to the chalked bar longswing and builds on earlier research in identifying that progressions can be classified into those similar in physical demand (kinetics) and those similar in geometry (kinematics). 相似文献
12.
This paper describes current progress made towards the realization of a match-racing simulator. The aim of the project is
to be able to simulate and to modify typical situations while introducing quantifiable data for strategic and tactical analysis.
The fundamental model consists of six fully coupled equations of the dynamics of two boats. The largest possible number of
variables is taken into account, even though some are initially approximations. The influences of the three attitude angles
on the hydrodynamic forces are taken into account using the ‘experiment planning method’ applied to towing-tank tests. For
the aerodynamics, empirical models (for example IMS) are adopted. The interaction between the two boats is obtained by representing
the sail perturbation by means of a single horseshoe vortex and a self-preserved viscous plane wake. The simulator has a modular
structure, which allows the progressive improvement of each part as studies and knowledge advance. Comparisons with calculations
of three-dimensional flows and with wind tunnel measurements validate the interaction model. The results presented show a
satisfactory agreement with the polar velocity diagram available for the studied boat, even if more reliable trials at sea
are needed, with measurements of boat behaviour, wind and sea state. Simulations allow us to quantify the relative influence
of model coefficients on boat behaviour. Thus it is possible to identify which factors must be improved first. Tacking simulations
are used to illustrate this possibility. To conclude, an example of the practical use of the simulator is presented by comparing
two tactical scenarios for the final part of the upwind leg. 相似文献
13.
Sprint push-off technique is fundamental to sprint performance and joint stiffness has been identified as a performance-related variable during dynamic movements. However, joint stiffness for the push-off and its relationship with performance (times and velocities) has not been reported. The aim of this study was to quantify and explain lower limb net joint moments and mechanical powers, and ankle stiffness during the first stance phase of the push-off. One elite sprinter performed 10 maximal sprint starts. An automatic motion analysis system (CODA, 200 Hz) with synchronized force plates (Kistler, 1000 Hz) collected kinematic profiles at the hip, knee, and ankle and ground reaction forces, providing input for inverse dynamics analyses. The lower-limb joints predominately extended and revealed a proximal-to-distal sequential pattern of maximal extensor angular velocity and positive power production. Pearson correlations revealed relationships (P < 0.05) between ankle stiffness (5.93 ± 0.75 N x m x deg(-1)) and selected performance variables. Relationships between negative power phase ankle stiffness and horizontal (r = -0.79) and vertical (r = 0.74) centre of mass velocities were opposite in direction to the positive power phase ankle stiffness (horizontal: r = 0.85; vertical: r = -0.54). Thus ankle stiffness may affect the goals of the sprint push-off in different ways, depending on the phase of stance considered. 相似文献
14.
Abstract This is the second study of the series, and its aim was to investigate the influence of using the suspended aid on circle kinetics. In addition to the kinematic data recorded for part one (Fujihara & Gervais, 2012), the pommel reaction forces and the force applied from the suspended aid (aid reaction force) were analysed in relation to the motion of a whole-body mass centre. The hip joint moment was also computed by combining all segments in the lower extremities into a single rigid segment. Generally, the use of the aid changed the magnitude of the mass-centre trajectory or horizontal pommel reaction forces but not their patterns. The results also showed that the net hip joint moment was altered during circles with the aid. In summary, a suspended aid can be used as a progression for a variety of goals because it allows gymnasts to practise circles which would not be possible without the aid. When a suspended aid is used, however, practitioners should be aware of the possible kinetic alteration caused by the external force from the aid. 相似文献
15.
Tendon stress may be one of the important risk factors for running-related tendon injury. Several methods have been used to estimate Achilles tendon (AT) loading during a human performance such as inverse dynamics (ID) and inverse dynamics-based static optimisation (IDSO). Our purpose was to examine differences between ID and IDSO estimates of AT loading during running. Kinematic data were captured simultaneously with kinetic data. Imaging of the AT cross-sectional area was performed with ultrasound for 17 healthy runners (height: 170.2 ± 6.2 cm, mass: 63.9 ± 11.0 kg, age: 21.8 ± 1.4 years). AT stress, strain, and force were estimated from both ID and IDSO approaches. The two methods resulted in minimal differences (3.6–4.7%) in estimated peak AT stress, strain, and force (P = 0.051–0.054); however, IDSO estimates were greater (32.7–36.8%) during early-stance phase of running (P = 0.000–0.008). This difference in AT load during early-stance may be due to the inability of the ID to account muscle coactivation. The similarity between the peak AT loading for ID and IDSO methods revealed that the advantage of IDSO used to estimate muscle forces had little effect on the ankle plantar flexor peak forces during running. Therefore, the use of IDSO with a higher computational cost compared with ID may not be necessary for estimating AT stress during running. 相似文献
16.
Irwin G Kerwin DG 《Sports biomechanics / International Society of Biomechanics in Sports》2007,6(3):361-374
Kinetic analyses of the chalked bar longswing on high bar and its associated progressions were used to explain musculoskeletal contributions during the performance of these skills. Data on four international male gymnasts performing three series of chalked bar longswings and eight progressions were recorded. Customized body segment inertia parameters, two-dimensional kinematics (50 Hz), and bar forces (1000 Hz) were used as input to inverse dynamic modelling. The analysis focused on the relative contributions of the knees, hips, and shoulders with root mean squared differences between the chalked bar longswing and the progressions being used to rank the progressions. Seventy per cent of the total work occurred between 200 degrees and 240 degrees of angular rotation in the longswing, 67% of which was contributed by the shoulders. The shoulders were also dominant in all progressions, with the largest such contribution occurring in the looped bar longswing with "no action". The least similar progression was the looped bar pendulum swing, while the most similar was the chalked bar bent knee longswing. This study provides a useful means for ranking progressions based on their kinetic similarity to the chalked bar longswing and builds on earlier research in identifying that progressions can be classified into those similar in physical demand (kinetics) and those similar in geometry (kinematics). 相似文献
17.
An overview of cricket ball swing 总被引：1，自引：0，他引：1
Rabindra D. Mehta 《Sports Engineering》2005,8(4):181-192
The aerodynamic properties of a cricket ball have intrigued cricket players and spectators for years, arguably since the advent
of the game itself. The main interest is in the fact that the ball can follow a curved flight path that may not always be
under the control of the bowler. The basic aerodynamic principles responsible for the nonlinear flight or ‘swing’ of a cricket
ball were identified decades ago and many papers have been published on the subject. Over the last 25 years or so, several
empirical investigations have also been conducted on cricket ball swing, which revealed the amount of attainable swing and
identified the parameters that affect it. Those findings are reviewed here with emphasis on phenomena such as late swing and
the effects of humidity on swing. The relatively new concept of ‘reverse swing’, how it can be achieved in practice, and the
role in it of ‘ball tampering’, are also discussed in detail. In particular, the ability of some bowlers to effectively swing
an old ball in the conventional, reverse and the newly termed ‘contrast’ swing mode is addressed. A discussion of the ‘white”
cricket ball used in the 1999 and 2003 World Cup tournaments, which supposedly possesses different swing properties compared
to a conventional red ball, is also included. This is a current overview of cricket ball swing rather than a detailed review
of all research work performed on the topic. The emphasis is on presenting scientific explanations for the various aerodynamic
phenomena that affect cricket ball swing on a cricket ground. 相似文献
18.
This is the second study of the series, and its aim was to investigate the influence of using the suspended aid on circle kinetics. In addition to the kinematic data recorded for part one (Fujihara & Gervais, 2012), the pommel reaction forces and the force applied from the suspended aid (aid reaction force) were analysed in relation to the motion of a whole-body mass centre. The hip joint moment was also computed by combining all segments in the lower extremities into a single rigid segment. Generally, the use of the aid changed the magnitude of the mass-centre trajectory or horizontal pommel reaction forces but not their patterns. The results also showed that the net hip joint moment was altered during circles with the aid. In summary, a suspended aid can be used as a progression for a variety of goals because it allows gymnasts to practise circles which would not be possible without the aid. When a suspended aid is used, however, practitioners should be aware of the possible kinetic alteration caused by the external force from the aid. 相似文献
19.
Natsuki Sado Shinsuke Yoshioka Senshi Fukashiro 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(2):258-271
The purpose of this study was to investigate the effect of lumbosacral kinetics on sprinting. Twelve male sprinters performed 50 m sprints at maximal effort. Kinematic and ground reaction force data were recorded at approximately 40 m from sprint commencement. A whole-body inverse dynamics approach was applied to calculate joint forces and torques at the hip and lumbosacral joints. The contribution of the hips and lumbosacral joint torques to pelvic rotation was subsequently calculated, with joint force powers indicating the rate of mechanical energy transfer between segments across joint centres calculated for both hip joints. The kinetic analysis indicated that the lumbosacral torsional torque contributed significantly to pelvic rotation. Additionally, the pelvic rotation exerted anterior–posterior joint forces on the hips, contributing to the large positive joint force power at the hip of the stance leg. These hip joint force powers assisted in motion recovery during sprinting. In conclusion, the lumbosacral torsional torque might contribute to the recovery motion in sprinting through application of the anterior–posterior joint forces at the hip joints via pelvic rotation. 相似文献
20.
This paper presents an approximate analytical model of the dynamics of a tapered fly line during a standard overhead cast.
During casting, the line forms a nonlinear propagating wave that is frequently referred to as a ‘loop’ by fly casters. The
geometry of the loop is described by three distinct parts: a straight bottom segment (attached to a stationary fly rod), a
semi-circular segment that is propagating (i.e. the loop), and a straight top segment that is also propagating, (i.e. the
traveling line). A fly (particle) is attached at the end of the traveling line. A work-energy balance yields the velocity
of the fly as a function of the length of the traveling line. For a uniform fly line (level line), a closed-form solution
is found, while for a tapered fly line, the solution is obtained by quadrature. A critical loop diameter arises in the analysis,
and it determines whether the final velocity of the fly is greater or lesser than the initial velocity of the traveling line.
The analytical solutions are critically compared against numerical solutions of a general model for fly line dynamics that
relaxes many of the assumptions employed in the analytical model. The agreement between the two solutions remains close during
the loop propagation phase, provided a significant amount of fly line remains in the traveling line. However, as the traveling
line vanishes and the loop ‘turns over’, the two solutions diverge abruptly due to the many simplifying assumptions employed
in the analytical model. 相似文献