Bow tuning in the vertical plane

Competition results in sport archery depend to a great extent upon the optimal combination of bow-arrow-archer system parameters. A significant part of bow tuning is vertical adjustment, the aim of which is to give an arrow zero angle of attack. It is conducted in a long and complicated manner and error correction takes a lot of time and effort. The goal of the research was to create an analytical method to determine an optimal combination of bow parameters, which ensures zero angle of attack for an arrow launched from a string. Mechanical and mathematical models of bow and arrow geometry in the vertical plane in braced and drawn situations were investigated. An asymmetrical scheme, rigid beams, concentrated elastic elements and elastic string were the main features of the model. Numerical results of a computer simulation are presented in tabular and graphical form, which makes it easy for sportsmen and coaches to use.     

锡伯族弓箭文化产业化发展研究

本文以新疆锡伯族传统弓箭文化的产业化为主要对象,通过阅读相关的书籍资料,得出锡伯族弓箭文化的发展历史及濒危现状,调查研究理清发展脉络,对存在的问题进行分析,并提出非物质文化遗产项目的顺利运作和政府推动民间组织的"三角模式"互动机制是弓箭文化产业化的重要发展对策。研究结果显示,弓箭文化产业化公司的成立在市场中占据很大的优势地位,建立弓箭文化产业化公司同时也在传承和保护锡伯族濒危的弓箭文化,对于国家级非物质遗产保护项目也有着重要的作用。     

Fine body movements and the cardiac cycle in archery

This study examined the relationships between postural sway, aiming time, the cardiac cycle time and the placement of the first finger movement within the electrocardiac cycle, with the quality of the arrow shot. A small group of elite male and female archers who shot either the recurve or the compound bow, freestyle or bare bow was used in this study. A total of 240 arrows were shot, classified as being of good, average or bad quality and analysed in detail. The analyses were undertaken over two occasions up to 100 days apart. The area of postural sway, as measured by the movement of the centre of pressure coordinates, varied significantly (P less than 0.05-0.001) both within and between trials for all archers and for all quality of arrows shot. There was a tendency for the area of postural sway to increase as the quality of the arrow shot decreased. This increase in postural sway exceeded, for arrows of bad quality, that exhibited as normal postural sway when standing relaxed and addressing the target with the hands at the side. Aiming time was variable within the quality of arrow shot, although it was consistent for each archer. In some cases the aiming time increased as the quality of the arrow decreased, whereas in the case of bare bow archery the aiming time tended to decrease as the quality of the arrow deteriorated. The cardiac cycle time increased significantly (P less than 0.05-0.01) as the archers approached the loose of the good quality arrows but there was no significant increase in cardiac cycle time when arrows of average or bad quality were shot. The most consistent parameter related to the quality of the shot was the placement of the first finger movement within the ST phase or the mid-cycle phase of the electrocardiogram for arrows of good quality (P less than 0.0001).     

On-target trajectories and the final pull in archery

Abstract

At the end of the aiming phase, an archer pulls the arrow back a little bit before he releases the shot. This pulling back of the arrow is called the “final pull”. Simultaneous with the final pull, the archer has to hold the bow calm. The aim of this paper was to examine the motion of the bow and the final pull in highly skilled archers. From a technological point of view, we wished to develop a system to measure the draw-length in the final pull that could be used during archers’ normal training. Seven archers (two males, five females), all of whom were participants at the Junior World Championships and German National Championships, performed 66 shots indoors at a target 30 m away. Each archer shot the same bow as used in competition. On-target trajectories of the aim point movement were measured. Also, the alterations of the draw-length in the final pull were determined. The results suggest that irregularities in the final pull have a negative influence on archers’ scores. Intra-individually, a smaller range of motion of the bow in the last second before the shot appears to have a positive influence on archers’ scores.     

Compound archery bow asymmetry in the vertical plane

The aim of the research was to create a mechanical and mathematical model of a compound bow and analyse its work without any prior hypothesis about the symmetry of limb deflection. The method of the research was based on the methods of theoretical mechanics, applied and computer mathematics. A pair and shift mechanism with cams and levels was used as a basis of the mechanical and mathematical model of a compound bow. The difference between results of modelling and measurement was near 7?%, while the error due to digital image deformation was evaluated to be near 1?% which was considered as acceptable. The calculated results indicated noticeable differences from simulations using the constraint of symmetrical limb deformation. Comparison of symmetrical and asymmetrical simulations with experimental data revealed that the asymmetrical simulation gave a closer match to the measured values for cam angles; the simulated and measured cam angle asymmetry was much greater than any measurement errors. Realisation of a process of solving the problem using computer mathematical system MathCAD makes it possible for specialists of physical education and sports (coaches and sport archers), who do not have a mathematical background, to use the mechanical and mathematical model that was proposed in the research for a study and training process.     

The round-wheel compound bow model revisited: a new extension

An extended offset-eccentric model of an archery twin-round-wheel compound bow is derived. Varying some parameters of the model, the respective effects on the calculated force–draw curve are considered. Two static quality coefficients for the compound bow are introduced. It was found that the twin-round-wheel compound bow can be designed to be more energetic with the help of the model. For a bow with some modifications 18.5% increment of energy was calculated. Also a theoretical limit for the force–draw curve of the compound bow is concluded.     

基于目标向量函数模型的射箭训练监控案例研究

研究目的:定量研究特定运动员某阶段射箭训练中各影响因素对中靶情况的作用,为改进训练提供依据。方法:用自行设计的射箭运动训练多参数实时同步检测系统对训练中的瞬时心率曲线、弓片应变、撒放时间、动作视频、靶视频、箭初速等参数进行实时同步检测,在非线性时变目标向量函数模型的一阶简化基础上,估算各影响因素的扰动量。结论:对两名运动员实测分析表明,撒放时间、心率等因素对不同运动员中靶的影响不同,为运动员个性化训练提供了参考方向。     

Postural stability,clicker reaction time and bow draw force predict performance in elite recurve archery

Recurve archery is an Olympic sport that requires extreme precision, upper body strength and endurance. The purpose of this research was to quantify how postural stability variables both pre- and post-arrow release, draw force, flight time, arrow length and clicker reaction time, collectively, impacted on the performance or scoring outcomes in elite recurve archery athletes. Thirty-nine elite-level recurve archers (23 male and 16 female; mean age?=?24.7?±?7.3 years) from four different countries volunteered to participate in this study prior to competing at a World Cup event. An AMTI force platform (1000Hz) was used to obtain centre of pressure (COP) measurements 1s prior to arrow release and 0.5s post-arrow release. High-speed footage (200Hz) allowed for calculation of arrow flight time and score. Results identified clicker reaction time, draw force and maximum sway speed as the variables that best predicted shot performance. Specifically, reduced clicker reaction time, greater bow draw force and reduced postural sway speed post-arrow release were predictors of higher scoring shots. It is suggested that future research should focus on investigating shoulder muscle tremors at full draw in relation to clicker reaction time, and the effect of upper body strength interventions (specifically targeting the musculature around the shoulder girdle) on performance in recurve archers.     

Novel field equipment for assessing the stability of natural and hybrid turfs

Natural turf pitches are used for many outdoor sports. Turf is a complex network of interacting organic material, soil textures and water content. Turf is susceptible to damage under large surface forces, caused by intensive player movements in rugby union and football. To assess and monitor surface stability, there needs to be a reliable test method for ground staff and other stakeholders. At present, no turf stability mechanical test method exists that represents player–surface interaction, especially to represent a linear movement across the surface such as in a rugby scrummage. This paper describes the development of a novel device for assessing turf stability. Verification was undertaken in the laboratory on a variety of controlled soil samples, and during a field study. The device measurements were shown to be sensitive to the shear strength of a high clay content soil at varying water content and to the density and type of sandy soils. A programme of field data on high quality pitches suggested a large effect of the turf root reinforcement. A conceptual model of soil failure induced by the device was developed to identify the key soil variables and support experimental data interpretation.     

Development of a test device for testing soccer boots under gamerelevant highrisk loading conditions

Soccer boots are the most important piece of equipment used by a soccer player. They have been improved from heavy bold leather shoes to lightweight aerodynamic designer objects. As traction is one of the key factors of performance, industry experiments with new stud designs, hoping to improve traction behaviour in the different directions. However, excessive traction may contribute to the occurrence of non-contact injuries of the anterior cruciate ligament (ACL). Therefore, many researchers have investigated the shoe-surface interaction of studded boots with mechanical test devices. As yet, a final conclusion regarding correlation between stud design and ACL injuries has not been obtained. Most of the current test devices do not test the soccer boots under game-relevant loading conditions. A new approach has been taken in order to overcome this limitation. In the first step, real ACL injury situations were analysed in detail. The results of this analysis were then used as input data for a multi-body computer model of the human body, to calculate internal forces at the injured leg. Based on this data, a new test device, the TrakTester, was developed including an artificial lower leg with a replica human ankle joint. This paper presents details of the development of the new traction test device and gives an overview of the research options the TrakTester may provide for the future.     

原地双手头上抛掷实心球错误动作解析——基于鞭打动作原理

双手头上抛掷实心球技术动作实质上是投掷标枪技术动作的最后一部分,即从＂满弓＂到器械出手,属于鞭打用力过程。双手头上抛掷实心球错误动作的产生与鞭打动作正确与否有很大关系。运用鞭打动作原理解析抛掷实心球的错误动作,便于学生理解。     

艺术体操圈项目器械联合动作研究

运用文献资料法、问卷调查法、图像分析法、专家访谈法和观察法等综合研究方法,对艺术体操圈项目器械联合动作进行研究。结果显示:圈器械联合动作根据其联合动作的数量分为,两个器械动作的联合与两个以上器械动作的联合,二者均可由同类或不同类器械动作联合构成。其中,同类器械动作联合主要有连抛和滚动两种类型;不同类动作联合类型比较多样。器械联合动作的广泛运用是器械技术进一步发展的必然结果,使成套器械动作的连接更加紧密、流畅,观赏性、刺激性大大增强。     

A simple method for assessment of muscle force,velocity, and power producing capacities from functional movement tasks

A range of force (F) and velocity (V) data obtained from functional movement tasks (e.g., running, jumping, throwing, lifting, cycling) performed under variety of external loads have typically revealed strong and approximately linear F–V relationships. The regression model parameters reveal the maximum F (F-intercept), V (V-intercept), and power (P) producing capacities of the tested muscles. The aim of the present study was to evaluate the level of agreement between the routinely used “multiple-load model” and a simple “two-load model” based on direct assessment of the F–V relationship from only 2 external loads applied. Twelve participants were tested on the maximum performance vertical jumps, cycling, bench press throws, and bench pull performed against a variety of different loads. All 4 tested tasks revealed both exceptionally strong relationships between the parameters of the 2 models (median R = 0.98) and a lack of meaningful differences between their magnitudes (fixed bias below 3.4%). Therefore, addition of another load to the standard tests of various functional tasks typically conducted under a single set of mechanical conditions could allow for the assessment of the muscle mechanical properties such as the muscle F, V, and P producing capacities.     

A mathematical model of the oar blade - water interaction in rowing

Our aim was to present a mathematical model of rowing and sculling that allowed for a comparison of oar blade designs. The relative movement between the oar blades and water during the drive phase of the stroke was modelled, and the lift and drag forces generated by this complex interaction were determined. The model was driven by the oar shaft angular velocity about the oarlock in the horizontal plane, and was shown to be valid against measured on-water mean steady-state shell velocity for both a heavyweight men's eight and a lightweight men's single scull. Measured lift and drag force coefficients previously presented by the authors were used as inputs to the model, whichs allowed for the influence of oar blade design on rowing performance to be determined. The commonly used Big Blade, which is curved, and it's flat equivalent were compared, and blade curvature was shown to generate a 1.14% improvement in mean boat velocity, or a 17.1-m lead over 1500 m. With races being won and lost by much smaller margins than this, blade curvature would appear to play a significant role in propulsion.     

Postural consistency in skilled archers

The consistency of an archer's postural set at the moment of loose (arrow release) is commonly perceived to be an important determinant of success. The coach seeks, among other things, to provide the archer with information about postural consistency, details of which he acquires by eye or occasionally by video-recordings. The gains that might be achieved from more precise information are examined here. Nine skilled archers, classified into either skilled or elite groups according to their officially computed handicap, were continuously monitored and measured with a three-dimensional co-ordinate analyser (Charnwood Dynamics Coda-3 Scanner) while shooting two ends (series) of three arrows each. Considerable variability was observed in the precision with which the positions of head, elbow and bow at the moment of loose were replicated by archers of similar levels of skill. These results are interpreted to suggest that precise postural consistency may not be the primary feature distinguishing between the performance of archers at the higher skill levels.     

试析弓箭文化的特征

弓箭作为我国传统的体育项目,是各民族弓箭文化的交汇融合的产物,充分反映了我国各民族的文化特征。从春秋战国开始,历经两晋、南北朝、宋、元等几个重要的发展变化时期,形成独具东方特色的一种文化现象。弓箭文化发展的特征主要是弓箭文化的战争化、礼法化、教育化、机械化、标准化、理论化。对弓箭文化的深入研究不但有助于我们了解我国弓箭文化的发展,而且也有助于我国体育事业的更进一步的提高。     

A mathematical model of the oar blade – water interaction in rowing

Abstract

Our aim was to present a mathematical model of rowing and sculling that allowed for a comparison of oar blade designs. The relative movement between the oar blades and water during the drive phase of the stroke was modelled, and the lift and drag forces generated by this complex interaction were determined. The model was driven by the oar shaft angular velocity about the oarlock in the horizontal plane, and was shown to be valid against measured on-water mean steady-state shell velocity for both a heavyweight men's eight and a lightweight men's single scull. Measured lift and drag force coefficients previously presented by the authors were used as inputs to the model, whichs allowed for the influence of oar blade design on rowing performance to be determined. The commonly used Big Blade, which is curved, and it's flat equivalent were compared, and blade curvature was shown to generate a 1.14% improvement in mean boat velocity, or a 17.1-m lead over 1500 m. With races being won and lost by much smaller margins than this, blade curvature would appear to play a significant role in propulsion.     

Lightweight design optimization of a Bow Riser in Olympic Archery applying evolutionary computing

Recurve bows that are used in competitions like the Olympic Games are high-technology products. Good risers are lightweight but retain a high stiffness. The aim of this study was to design a riser with a stiffness comparable to that of the lightest riser currently used by the archers of the German National Archery Team, but with a considerably reduced weight. We computed the loads that are applied to a riser of a drawn recurve bow (the RADIAN model used by the German team) and created a 3-D solid CAD model of a riser with 24 variable parameters. We used evolutionary computing to optimize the 24 parameters of the model according to these criteria. We selected the most optimal riser out of the 1650 CAD models generated, manufactured it, and had it tested by three archers of the German National Archery Team. The mass of our manufactured riser is 871g, which is 243g or 22% less mass than the RADIAN riser.