Ball Spin Research Articles

The effects of vertically oriented resistance training on golf drive performance in collegiate golfers

The purpose of this study was to examine the effects of vertically oriented resistance training on golf driving performance. Ten Division-I collegiate golfers completed two resistance training sessions per week for 10 weeks during the fall tournament season. Pre- and post-training assessments of strength-power and golf performance were compared. To assess strength-power, jump height, peak force, and peak power were measured from static and countermovement vertical jumps; peak force and rate of force development from 0 to 250 ms were measured from an isometric mid-thigh pull. Golf performance was assessed in terms of ball launch speed, spin rate, carry yardage, and total yardage, averaged from five shots using a driver. Following training, all measures of strength-power improved, with countermovement jump peak power improving significantly ( p < 0.00625). The golf performance assessment indicated significant increases ( p < 0.0125) in ball speed, carry yardage, and total yardage. These results suggest that vertically oriented resistance training can improve golf driving performance.

The relationship between segmental kinematics and ball spin in Type-2 cricket spin bowling

ABSTRACTThe techniques of spin bowling in cricket have been largely formulated from the collective intuitions of past players. A standard model of bowling technique has been generally prescribed for both off-spin and leg-spin bowlers, but there has been no biomechanics research to validate this approach. This study measured 20 Type-2 off-spin and 15 Type-2 leg-spin bowlers using a 3D Cortex motion analysis system. Correlation coefficients between segmental kinematic variables and spin rate in the off-spin and leg-spin bowlers revealed that off-spin bowling was associated with an earlier movement time of the thorax, whereas leg-spin bowling was associated with a greater magnitude and earlier movement time of pelvis rotation, as well as a greater magnitude of pelvis-shoulder separation movement. The maximum velocity of rear hip flexion differentiated between both groups of bowlers. The GLM suggested that for off-spinners, rear hip flexion velocity significantly explained the variance in spin rate (subject to sequential timing constraints), while for leg-spinners, the time of maximum rear hip flexion and maximum arm circumduction velocity significantly explained variance in spin rate. This study supports the notion that off-spinners and leg-spinners have significant differences in their joint kinematics, and should not be coached under a one-size-fits-all technical model.

The relationship between foot-ball impact and flight characteristics in punt kicking

In football kicking, a player imparts the initial flight characteristics by impacting the ball with his foot. Imparting the correct combination of flight characteristics is the basis of a successful kick. However, examination of the relationship between foot-ball impact and flight characteristics for a non-spherical ball, the ball shape in Australian football and rugby, has been limited to ball velocity. Consequently, little is known of the relationship with other flight characteristics of ball trajectory and spin. The aim of this study was to determine the relationship between impact and initial ball flight characteristics. A mechanical limb, designed to replicate the impact phase of Australian football, performed punt kicks. Four impact characteristics were systematically examined to determine their influence on flight characteristics: foot velocity, medial–lateral impact location, proximal–distal impact location and ball orientation. This study identified each flight characteristic (ball velocity, elevation angle, azimuth angle and spin rate) were influenced by multiple impact characteristics (foot velocity, ball orientation and/or impact location). For example, elevation angle was increased by foot velocity, relative foot-ball orientation and proximal–distal impact location on the foot. Foot velocity had the largest influence on ball velocity (linear slope = 1.43). Medial–lateral impact location had the largest influence on azimuth angle (linear slope = 2.73). Ball orientation had the largest influence on elevation angle and back-spin rate, both measures were sine dependent (elevation angle curve amplitude = 19.4°; back-spin rate curve amplitude = 2754°/s). Players must control all impact characteristics to successfully kick to their desired destination.

Relationships between clubshaft motions and clubface orientation during the golf swing

Since clubface orientation at impact affects ball direction and ball spin, the ability to control clubface orientation is one of the most important skills for golfers. This study presents a new method to describe clubface orientation as a function of the clubshaft motions (i.e., swing plane orientation, clubshaft angle in the swing plane, and clubshaft rolling angle) during a golf swing and investigates the relationships between the clubshaft motions and clubface orientation at impact. The club motion data of driver shots were collected from eight skilled golfers using a three-dimensional motion capture system. The degrees of influence of the clubshaft motions on the clubface orientation were investigated using sensitivity analysis. The sensitivity analysis revealed that the swing plane horizontal angle affected the clubface horizontal angle to an extent of 100%, that the clubshaft angle in the swing plane affected both the clubface vertical and horizontal angles to extents of 74 and 68%, respectively, and that the clubshaft rolling angle affected both the clubface vertical and horizontal angles to extents of -67 and 75%, respectively. Since the method presented here relates clubface orientation to clubshaft motions, it is useful for understanding the clubface control of a golfer.

Measurements of drag and lift on smooth balls in flight

Measurements are presented on the drag and lift coefficients for three relatively smooth balls launched in air and tracked with two cameras separated horizontally by 6.4 m. The ball spin was varied in order to investigate whether the Magnus force would increase or decrease when the ball spin was increased. For one ball, the Magnus force increased. For another ball, the Magnus force decreased almost to zero after reaching a maximum. For the third ball, the Magnus force was negative at low ball spins and positive at high ball spins. For one of the balls, the ball spin increased with time as it travelled through the air.

Training Level Does Not Affect Auditory Perception of The Magnitude of Ball Spin in Table Tennis.

Identifying the trajectory and spin of the ball with speed and accuracy is critical for good performance in table tennis. The aim of this study was to analyze the ability of table tennis players presenting different levels of training/experience to identify the magnitude of the ball spin from the sound produced when the racket hit the ball. Four types of “forehand” contact sounds were collected in the laboratory, defined as: Fast Spin (spinning ball forward at 140 r/s); Medium Spin (105 r/s); Slow Spin (84 r/s); and Flat Hit (less than 60 r/s). Thirty-four table tennis players of both sexes (24 men and 10 women) aged 18-40 years listened to the sounds and tried to identify the magnitude of the ball spin. The results revealed that in 50.9% of the cases the table tennis players were able to identify the ball spin and the observed number of correct answers (10.2) was significantly higher (χ2 = 270.4, p <0.05) than the number of correct answers that could occur by chance. On the other hand, the results did not show any relationship between the level of training/experience and auditory perception of the ball spin. This indicates that auditory information contributes to identification of the magnitude of the ball spin, however, it also reveals that, in table tennis, the level of training does not interfere with the auditory perception of the ball spin.

Dynamical analysis of manipulating ball spin by fingers

Dynamical analysis of manipulating ball spin by fingers

The physics of juggling a spinning ping-pong ball

Juggling a spinning ball with a ping-pong paddle represents a challenge both in terms of hand-eye coordination and physics concepts. Here, we analyze the ping-pong ball's motion, and explore how the correct paddle angle relates to the ball's spin and speed, as it moves vertically up and down. For students, this requires engaging with concepts like momentum, angular momentum, free-body diagrams, and friction. The activities described in this article include high-speed video motion tracking of the ping-pong ball and the investigation of the frictional characteristics of the paddle. They can be done in a physics lab or at home, requiring only inexpensive or commonly used equipment, and can be undertaken by high school or college students.

Influence of football size on kicking performance in youth Australian rules footballers

ABSTRACTIn Australian rules football structured increases in ball size during development end with the transition to the Size 5 (adult) ball at the Under-15 age group. This study assessed changes in kick technique and performance in experienced junior performers when using Size 4 and 5 Australian rules footballs. Participants (n = 22, 13.77 ± 0.61 years) performed drop punt kicks in 2 representative tasks; a Decision-Making Test (DMT) (n = 14) and Set-Shot Test (SST) (n = 14 + 8). Results indicate participants sustained their level of kick performance (accuracy and quality of ball spin) in both tests when using a Size 5 football. Sustained kick performance in the DMT primarily resulted from adaptations to time-point technical measures at ball release. No significant differences were detected for technical measures between ball sizes in the SST. A dynamic kicking task (DMT) in combination with ball size manipulation may have placed greater demand on skill execution in comparison to a self-paced kicking task (SST). Results provide initial support for the utility of challenging representative dynamic and self-paced tasks, such as the DMT and SST used here for Australian football, for skill testing and practice in sport

An Explicit Finite-Element Model to Investigate the Effects of Elastomeric Bushing on Bearing Dynamics

This work presents a numerical simulation which studies the effect of elastomeric bushing on the dynamics of a deep-groove ball bearing. To achieve the objective, a three-dimensional (3D) explicit finite element method (EFEM) was developed to model a cylindrical elastomeric bushing, which was then coupled with an existing dynamic bearing model (DBM). Constitutive relationship for the elastomer is based on the Arruda–Boyce model combined with a generalized Maxwell-element model to capture both hyperelastic and viscoelastic behaviors of the material. Comparisons between the bushing model developed for this investigation and the existing experimental elastomeric bushing study showed that the results are in good agreement. Parametric studies were conducted to show the effects of various elastomeric material properties on bushing behavior. It was also shown that a desired bushing support performance can be achieved by varying bushing geometry. Simulations using the combined EFEM bushing and DBM model demonstrated that the elastomeric bushing provides better compliance to bearing misalignment as compared to a commonly used rigid support model. As a result, less ball slip and spin are generated. Modeling with a bearing surface dent showed that vibrations due to surface abnormalities can be significantly reduced using elastomeric bushing support. It has also been shown that choosing a proper bushing is an efficient way to tuning bushing vibration frequencies.

Relation Between Lift Force and Ball Spin for Different Baseball Pitches.

Although the lift force (F(L)) on a spinning baseball has been analyzed in previous studies, no study has analyzed such forces over a wide variety of spins. The purpose of this study was to describe the relationship between F(L) and spin for different types of pitches thrown by collegiate pitchers. Four high-speed video cameras were used to record flight trajectory and spin for 7 types of pitches. A total of 75 pitches were analyzed. The linear kinematics of the ball was determined at 0.008-s intervals during the flight, and the resultant fluid force acting on the ball was calculated with an inverse dynamics approach. The initial angular velocity of the ball was determined using a custom-made apparatus. Equations were derived to estimate the F(L) using the effective spin parameter (ESp), which is a spin parameter calculated using a component of angular velocity of the ball with the exception of the gyro-component. The results indicate that F(L) could be accurately explained from ESp and also that seam orientation (4-seam or 2-seam) did not produce a uniform effect on estimating F(L) from ESp.

The effect of dimple error on the horizontal launch angle and side spin of the golf ball during putting

ABSTRACTThis study aimed to examine the effect of the impact point on the golf ball on the horizontal launch angle and side spin during putting with a mechanical putting arm and human participants. Putts of 3.2 m were completed with a mechanical putting arm (four putter-ball combinations, total of 160 trials) and human participants (two putter-ball combinations, total of 337 trials). The centre of the dimple pattern (centroid) was located and the following variables were measured: distance and angle of the impact point from the centroid and surface area of the impact zone. Multiple regression analysis was conducted to identify whether impact variables had significant associations with ball roll variables, horizontal launch angle and side spin. Significant associations were identified between impact variables and horizontal launch angle with the mechanical putting arm but this was not replicated with human participants. The variability caused by “dimple error” was minimal with the mechanical putting arm and not evident with human participants. Differences between the mechanical putting arm and human participants may be due to the way impulse is imparted on the ball. Therefore it is concluded that variability of impact point on the golf ball has a minimal effect on putting performance.

A comparison of service efficiency between players of male and female doubles at professional tennis tournaments

Male and female players have a different quality of service. For example, men can reach a higher service speed, or use more ball spin. Tennis service has also a different efficiency on different surfaces. Every surface has specific characteristics and has different effects on ball impact and ball bounce. The aim of our study was to compare the amount of service points won between male and female players in men’s and women’s doubles at ATP (Association of Tennis Professionals) and WTA (Women Tennis Association) tournaments on three different surfaces. We observed a total of 303 matches. Matches were played on clay, hard and grass courts. With the help of match records, we found that men won around 10% service points more than women. Results indicate that women’s doubles matches show greater differences in performance between opponents. Men also need to win more service points than women, to win a match. Fast surfaces provide a greater advantage for serving teams, both for men and women. The lowest serve efficiency was reached on clay (slow surface) both in the men’s and women’s doubles.

Ball Positioning in Robotic Billiards: A Nonprehensile Manipulation-Based Solution

The last two decades have seen a number of developments in creating robots to play billiards. The designed robotic systems have successfully incorporated the kinematics required and have had appropriate machine vision elements for a decent gameplay. Independently, computer scientists have also developed the artificial intelligence programs needed for the strategy to play billiards. Despite these developments, the accurate ball manipulation aspect of the game, needed for good performance, has not been addressed enough; two important parameters are the potting accuracy and advantageous cue ball positioning for next shot. In this regard, robotic ball manipulation by predicting the ball trajectories under the action of various dynamic phenomena, such as ball spin, impacts and friction, is the key consideration of this research. By establishing a connection to the methods used in nonprehensile robotic manipulation, a forward model is developed for the rolling, sliding, and two distinct types of frictional impacts of billiards balls are developed. High-speed camera-based tracking is performed to determine the physical parameters required for the developed dynamic models. To solve the inverse manipulation problem, i.e., the decision on shot parameters, for accurate ball positioning, an optimization based solution is proposed. A simplistic ball manipulator is designed and used to test the theoretical developments. Experimental results show that a 90% potting accuracy and a 100–200 mm post-shot cue ball positioning accuracy has been achieved by the autonomous system within a table area of $6 \times 5$ ft2.

The Effect of Ball Spin Rate on Distance Achieved in a Long Soccer Throw-in

In this study a skilled soccer player performed throws for maximum distance while manipulating the backspin on the ball. A video analysis was used to obtain measures of the ball projection variables. We found that putting greater backspin on the ball did not reduce the player's ability to produce a high projection velocity. Throw distance increased at a rate of about 0.6 m per 1 rev/s increase in backspin, and the experimental data was consistent with the predictions of a mathematical model. We recommend players apply the highest possible backspin when performing a long throw-in.

502 スピン制御型アーム式ピッチングマシンの開発(OS5-1 機械力学(1)機械の動的解析と設計問題)

502 スピン制御型アーム式ピッチングマシンの開発(OS5-1 機械力学(1)機械の動的解析と設計問題)

Combined Explicit Finite and Discrete Element Methods for Rotor Bearing Dynamic Modeling

This article presents a new approach in which the explicit finite element method (EFEM) and the discrete element method (DEM) are coupled to investigate dynamics of flexible rotor systems supported by deep-groove ball bearings. In this investigation, DEM is used to develop the bearing (dynamic motion) model in which all of the components of the bearing (i.e., inner and outer race, balls, and cage) have 6 degrees of freedom. The flexible shaft is modeled with a full 3D elastic formulation using the EFEM rather than the reduced form, which implements component mode synthesis. The EFEM and DEM were combined to investigate the dynamics of flexible shaft rotor systems supported by ball bearings. Rotor and inner races of the bearings are fully coupled such that both translation and rotation of the flexible rotor are transmitted to the bearings. At each time step, the translational motion and rotation/tilt angle of the rotor cross section at the location of an inner race are applied to the inner race of the bearing. The resulting reaction forces and moments calculated in the dynamic bearing model are in turn applied to the nodes of the shaft. The combined model is used to investigate the motions of the inner races and the resulting reaction forces and moments from the supporting bearings due to an applied load on the shaft. In the current coupled modeling approach, the deformation of the shaft affects the internal components of the bearing by altering the orientation of the inner race, which results in ball spin and slip.

Relating Baseball Seam Height to Carry Distance

Past work has shown large variation in the drag of baseballs. Little is known concerning the causes of variation in ball drag. Ball diameter, weight, seam height, surface roughness, and shape influence lift and drag, and therefore carry distance. The aim of this work was to quantify the effect of seam height and roundness on ball lift and drag, which, to our understanding, has never been done outside of a wind tunnel. A bespoke, non-contact, ball surface profiler, was used to measure ball radius, including seam height. The profiles were analyzed to describe ball roundness and seam height separately. Balls with three different seam heights were projected in an enclosed stadium 102-122 m (describing a typical fly ball). Redundant radar devices were used to measure launch angle, speed, and flight paths. High speed video was used to confirm launch angle and ball spin rate. Hit distance was verified with a physical tape measure. The ball's roundness influenced the effective height of a seam. Measurements of the non-seam area of a ball were necessary to characterize the seams of a ball. A strong correlation was observed between seam height and a ball's drag coefficient. Lift, however, was not sensitive to seam height or ball shape.

Evaluation of the blunt thoracic trauma caused by solid sports ball impacts

Evaluation of the thoracic injury due to blunt impacts during the contact and collision sports activity is very crucial for the development and validation of the chest protectors for the athletes and safety balls of the sports such as cricket, baseball, lacrosse and the golf. In order to evaluate the thoracic injury due to solid sports ball impacts, a series of nonlinear transient dynamic, finite element simulations were carried out by impacting the FE model surrogate of the thorax 'MTHOTA' (Mechanical THOrax for Trauma Assessment) with a baseball (both soft-core and synthetic) and a cricket ball at impact speed of 10–45 m/s, with an increment of 5 m/s. Only for the impact speed for which measured VCmax was 1 m/s, further simulations were carried out by introducing the ball spin (1000 – 8000 rpm, with an increment of 1000 rpm). Soft-core baseball, synthetic baseball and cricket ball impacts have caused VCmax = 1.0 m/s (25% probability for AIS3+ injuries) at impact speeds of 30.7 m/s, 27.9 m/s and 23.2 m/s respectively. For the normal impacts, spin (about impact direction and two directions perpendicular to the impact direction) of the ball has got no impact on the blunt thoracic trauma. At usual pitching speeds, soft-core baseball didn't offer any safety and performance point of view, it was found to be as bad as synthetic baseball.

Humans use predictive kinematic models to calibrate visual cues to three-dimensional surface slant.

When the sensory consequences of an action are systematically altered our brain can recalibrate the mappings between sensory cues and properties of our environment. This recalibration can be driven by both cue conflicts and altered sensory statistics, but neither mechanism offers a way for cues to be calibrated so they provide accurate information about the world, as sensory cues carry no information as to their own accuracy. Here, we explored whether sensory predictions based on internal physical models could be used to accurately calibrate visual cues to 3D surface slant. Human observers played a 3D kinematic game in which they adjusted the slant of a surface so that a moving ball would bounce off the surface and through a target hoop. In one group, the ball's bounce was manipulated so that the surface behaved as if it had a different slant to that signaled by visual cues. With experience of this altered bounce, observers recalibrated their perception of slant so that it was more consistent with the assumed laws of kinematics and physical behavior of the surface. In another group, making the ball spin in a way that could physically explain its altered bounce eliminated this pattern of recalibration. Importantly, both groups adjusted their behavior in the kinematic game in the same way, experienced the same set of slants, and were not presented with low-level cue conflicts that could drive the recalibration. We conclude that observers use predictive kinematic models to accurately calibrate visual cues to 3D properties of world.