Статті в журналах: "Ball flight"

1

Ward, Matthew, Martin Passmore, Adrian Spencer, Simon Tuplin, and Andy Harland. "Characterisation of football trajectories for assessing flight performance." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 233, no. 1 (May 29, 2018): 16–26. http://dx.doi.org/10.1177/1754337118774414.

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Much discussion surrounds the flight of association footballs (soccer balls), particularly where the flight may be perceived as irregular. This is particularly prevalent in high-profile competitions due to increased camera coverage and public scrutiny. All footballs do not perform in an identical manner in flight. This article develops methods to characterise the important features of flight, enabling direct, quantitative comparisons between ball designs. The system used to generate the flight paths included collection of aerodynamic force coefficient data in a wind tunnel, which were input into a flight model across a wide range of realistic conditions. Parameters were derived from these trajectories to characterise the in-flight deviations across the range of flights from which the aerodynamic performance of different balls were statistically compared. The amount of lateral movement in flight was determined by calculating the final lateral deviation from the initial shot vector. To quantify the overall shape of the flight, increasing orders of polynomial functions were fitted to the flight path until a good fit was obtained with a high-order polynomial indicating a less consistent flight. The number of inflection points in each flight was also recorded to further define the flight path. The orientation dependency of a ball was assessed by comparing the true shot to a second flight path without considering orientation-dependent forces. The difference between these flights isolated the effect of orientation-dependent aerodynamic forces. The article provides the means of quantitatively describing a ball’s aerodynamic behaviour in a defined and robust mathematical process. Conclusions were not drawn regarding which balls are good and bad; these are subjective terms and can only be analysed through comprehensive player perception studies.

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2

Hong, Sungchan, John Eric Goff, and Takeshi Asai. "Effect of a soccer ball’s surface texture on its aerodynamics and trajectory." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 233, no. 1 (October 9, 2018): 67–74. http://dx.doi.org/10.1177/1754337118794561.

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The effect of a soccer ball’s surface texture on its aerodynamics and flight trajectory is not definitively known. For this study, five soccer balls were used, each having 32 panels with different surface textures. Their aerodynamics were examined via wind-tunnel experiments and then several non-spin trajectories were calculated for each ball. The results showed that the aerodynamic forces acting on a soccer ball change significantly depending on the surface texture of the ball, which in turn influences flight trajectories. The study contributes to an understanding of how a soccer ball’s surface influences the aerodynamics, which may impact the future design and development of soccer balls.

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3

Hong, Sungchan, and Takeshi Asai. "Effect of Surface Groove Structure on the Aerodynamics of Soccer Balls." Applied Sciences 10, no. 17 (August 25, 2020): 5877. http://dx.doi.org/10.3390/app10175877.

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Soccer balls have undergone dramatic changes in their surface structure that can affect their aerodynamics. The properties of the soccer ball surface such as the panel shape, panel orientation, seam characteristics, and surface roughness have a significant impact on its aerodynamics and flight trajectory. In this study, we performed wind-tunnel tests to investigate how the introduction of grooves on the surface of a soccer ball affects the flight stability and aerodynamic forces on the ball. Our results show that for soccer balls without grooves, changing the panel orientation of the ball causes a significant change in the drag coefficient. Soccer balls with grooves exhibited a smaller change in air resistance (Cd) in the supercritical region (20 to 30 m/s; 3.0 × 105 ≤ Re ≤ 4.7 × 105), compared to the ungrooved ball where only the panel orientation was changed. Furthermore, at power-shot speeds (25 m/s), the grooved ball exhibited smaller variations in lift force and side force than the ungrooved ball. These results suggest that a long groove structure on the surface of the soccer ball has a significant impact on the air flow around the ball in the supercritical region, and has the effect of keeping the air flow separation line constant.

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4

Passmore, M. A., S. Tuplin, A. Spencer, and R. Jones. "Experimental studies of the aerodynamics of spinning and stationary footballs." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 2 (February 1, 2008): 195–205. http://dx.doi.org/10.1243/09544062jmes655.

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The accurate discrimination of the aerodynamic parameters affecting the flight of sports balls is essential in the product development process. Aerodynamic studies reported to date have been limited, primarily because of the inherent difficulty of making accurate measurements on a moving or spinning ball. Manufacturers therefore generally rely on field trials to determine ball performance, but the approach is time-consuming and subject to considerable variability. The current paper describes the development of a method for mounting stationary and spinning footballs in a wind tunnel to enable accurate force data to be obtained. The technique is applied to a number of footballs with differing constructions and the results reported. Significant differences in performance are noted for both stationary and spinning balls and the importance of the ball orientation to the flow is highlighted. To put the aerodynamic data into context the results are applied in a flight model to predict the potential differences in the behaviour of each ball in the air. The aerodynamic differences are shown to have a considerable effect on the flight path and the effect of orientation is shown to be particularly significant when a ball is rotating slowly. Though the techniques reported here are applied to a football they are equally applicable to other ball types.

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5

Tamaru, Takehiro, Masaki Hiratsuka, and Shinichiro Ito. "Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes." Applied Sciences 11, no. 19 (October 6, 2021): 9269. http://dx.doi.org/10.3390/app11199269.

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A floater serve in volleyball is a technique of serving a non-rotating or low-rotating ball, which is difficult to return because the flight path of the ball changes irregularly. On the other hand, the randomness of the trajectory makes it difficult for the ball to fall on the target. Players are required to serve taking into account the variability of the trajectory. In previous studies using wind tunnels, it was shown that aerodynamic characteristics such as drag force and lateral force applied to the ball vary depending on the type of ball and the orientation of the panel. Therefore, in order to control the flight trajectory, it is necessary to understand the aerodynamic characteristics of each ball. Since the velocity of the ball and the fluid force applied to the ball changes during flight, it is important to measure not only the fluid force at a steady state in the wind tunnel but also the actual flight distance of the ball. In this study, to provide valuable information for precise control of floater serves, we measured the drag force applied to the ball in a wind tunnel and the flight distance of the ball using an ejection machine, and clarified the effects of the type of ball and the panel face. In the drag force measurement, the drag force on three types of balls, V200W, MVA200, and FLISTATEC, was measured in the wind speed range of 4 m/s to 30 m/s. In the ejection measurement, the ball flight distances were measured while changing the orientation of the panel using an ejection machine. Basically, the FLISTATEC, MVA200, and V200W, in that order, were more likely to increase the distance and the variability, but it was shown that the drop point could be adjusted slightly by selecting the panel face. This result was also obtained when a human player actually served the ball, indicating the tactical importance of the player consciously controlling the direction of the panel. The tactical importance of the player’s conscious control of the direction of the panel was demonstrated. We also proposed receiver positions that would be effective based on the characteristics of each ball.

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6

Hiratsuka, Masaki, Shinichiro Ito, Keita Miyasaka, and Akihisa Konno. "Stereo three-dimensional particle image velocimetry measurement and aerodynamic force analysis of non-spinning soccer balls." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 234, no. 2 (February 12, 2020): 146–53. http://dx.doi.org/10.1177/1754337119898355.

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A knuckle shot, resulting from non-spinning kicking, is an essential technique in soccer. The irregular flight path of the knuckle shot is caused by the aerodynamic force from the three-dimensional twin vortices generated in the wake behind the ball. However, the detailed behavior of the twin vortices and relation between the jet flow and the acting forces on the balls is still not understood. In addition, a more thorough understanding of the effect of ball panels on the formation of twin vortices and jet flow is important to develop balls with high controllability. To study the effect of the ball panel shape on the flight path, stereo three-dimensional particle image velocimetry wake flow measurements and synchronized force measurements were performed on various soccer balls. It was confirmed that the aerodynamic force on the ball is produced by the jet flow generated by the vortices in the wake flow. The directions of the force followed the changes of the jet flow, and the magnitude of the force was strongly associated with the flow rate of the jet. Moreover, the shape of the ball panels, especially the groove volume, determines the critical Reynolds number and the fluttering of the balls.

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7

Simha, K. R. Y., and Dhruv C. Hoysall. "Spinning ball flight under moderatewind." Resonance 13, no. 4 (April 2008): 378–93. http://dx.doi.org/10.1007/s12045-008-0018-9.

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8

Smith, Lloyd, and Andrea Sciacchitano. "Baseball Drag Measurements in Free Flight." Applied Sciences 12, no. 3 (January 28, 2022): 1416. http://dx.doi.org/10.3390/app12031416.

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While baseball is a popular sport with a storied history, the aerodynamic properties of the seamed sports ball are not fully understood. Reported aerodynamic baseball behaviors are primarily based on force measurements from wind tunnels. The following describes a methodology to measure baseball drag in free flight from changes in its speed. The method relies on a high accuracy ball delivery device and speed measurement system. It avoids the large infrastructure, stinger attachment and blockage effects associated with wind tunnels. In the present work, we examined the baseball drag as a function of orientation and with spin. The drag values retrieved from the proposed method are in good agreement with radar and video measurements. However, they are lower than those reported in other wind tunnel measurements, which was attributed to differences in the balls that were tested or the stinger attachment.

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9

Asai, Takeshi, Kaoru Kimachi, Richong Liu, Masaaki Koido, Masao Nakayama, John Eric Goff, and Sungchan Hong. "Measurements of the Flight Trajectory of a Spinning Soccer Ball and the Magnus Force Acting on It." Proceedings 49, no. 1 (June 15, 2020): 88. http://dx.doi.org/10.3390/proceedings2020049088.

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The trajectory of a soccer ball, kicked with a spin to curve it into the goal, is strongly influenced by aerodynamic factors such as the Magnus force. Several studies using a wind-tunnel and high-speed cameras have investigated the Magnus force acting on a spinning soccer ball. However, the exact effect of the Magnus force on the trajectory of a spinning soccer ball in free flight remains unclear. This study set out to use an optical three-dimensional motion-capture system to record the details of the flight of such a spinning soccer ball. The maximum curvature of the ball’s trajectory occurred in the middle of its flight. The sideways-directed Magnus force acting on the ball decreased as the ball’s speed decreased during the entire flight. Thus, it was concluded that the deflection of the trajectory of the ball decreases as the sideways-acting force decreases throughout the flight.

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10

Javorova, Juliana, and Anastas Ivanov. "Study of soccer ball flight trajectory." MATEC Web of Conferences 145 (2018): 01002. http://dx.doi.org/10.1051/matecconf/201814501002.

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In this paper the trajectories of a soccer ball for the most important kicks in the football game - a corner kick and a direct free kick are studied. The soccer ball is modelled as an ideal rigid hollow spherical body with six degrees of freedom, which performs a general motion in an immovable air environment with constant parameters. The ball 3D orientation is determined by the three Cardan angles. The aerodynamic forces and moments with which the air environment acts to the ball are taken into account. Two of the most dangerous areas of the football goal are defined. Differential equations which describe the motion of the soccer ball are solved numerically by MatLab-Simulink.

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11

Nakashima, Hirotaka, Gen Horiuchi, and Shinji Sakurai. "Standard of the Initial Ball Velocity for a Fly Ball in Baseball Hitting." Proceedings 49, no. 1 (June 15, 2020): 137. http://dx.doi.org/10.3390/proceedings2020049137.

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This study aimed to determine the minimum required initial velocity to hit a fly ball toward the same field (left-field for right-handed batters), center field, and opposite field (right field for right-handed batters). Six baseball players hit fastballs launched by a pitching machine. The movements of the balls before and after bat-to-ball impact were recorded using two high-speed video cameras. The flight distance was determined using a measuring tape. Seventy-nine trials were analyzed, and the minimum required initial velocities of batted balls were quantified to hit balls 60, 70, 80, 90, 100, 110, and 120 m in each direction through regression analysis. As a result, to hit a ball 120 m, initial velocities of 43.0, 43.9, and 46.0 m/s were required for the same field, center field, and opposite field, respectively. The result provides a useful index for batters to hit a fly ball in each of the directions.

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12

Simha, K. R. Y. "Tennis ball flight under strong wind." Resonance 7, no. 11 (November 2002): 70–76. http://dx.doi.org/10.1007/bf02868201.

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13

Asai, Takeshi, Yasumi Nakanishi, Nakaba Akiyama, and Sungchan Hong. "Flow Visualization of Spinning and Nonspinning Soccer Balls Using Computational Fluid Dynamics." Applied Sciences 10, no. 13 (June 30, 2020): 4543. http://dx.doi.org/10.3390/app10134543.

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Various studies have been conducted on the aerodynamic characteristics of nonspinning and spinning soccer balls. However, the vortex structures in the wake of the balls are almost unknown. One of the main computational fluid dynamics methods used for the analysis of vortex structures is the lattice Boltzmann method as it facilitates high-precision analysis. Studies to elucidate the dominant vortex structure are important because curled shots and passes involving spinning balls are frequently used in actual soccer games. In this study, we identify the large-scale dominant vortex structure of a soccer ball and investigate the stability of the structure using the lattice Boltzmann method, wind tunnel tests, and free-flight experiments. One of the dominant vortex structures in the wake of both nonspinning and spinning balls is a large-scale counter-rotating vortex pair. The side force acting on a spinning ball stabilizes when the fluctuation of the separation points of the ball is suppressed by the rotation of the ball. Thus, although a spinning soccer ball is deflected by the Magnus effect, its trajectory is regular and stable, suggesting that a spinning ball can be aimed accurately at the outset of its course.

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14

Starkes, Janet L. "Attention Demands of Spatially Locating Position of a Ball in Flight." Perceptual and Motor Skills 64, no. 1 (February 1987): 127–35. http://dx.doi.org/10.2466/pms.1987.64.1.127.

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This study assessed the relative attention demands of an “open skill”, that of spatially locating position of a ball in flight, using the dual task technique. 7 right-handed male university students stood behind a large Plexiglas screen and spatially matched a ball projected over a distance of 20 feet. After 1-sec. flight time the ball contacted the Plexiglas. A secondary cask required response to an auditory stimulus, designed to probe ball flight at 700, 800, or 900 msec. Both vocal and manual responses to the secondary probe were recorded. No significant correlations were noted between radial error and probe RT for either manual or vocal responses. Subjects did not trade off between tasks. Radial error across all probe positions, including catch trials, showed no significant differences. Three factor analyses of variance for manual and vocal probe types showed that more attention was devoted to monitoring the ball as it neared the screen.

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15

Seo, Kazuya, Osamu Kobayashi, and Masahide Murakami. "1605 Multi-optimization of rugby ball flight." Proceedings of the Fluids engineering conference 2005 (2005): 237. http://dx.doi.org/10.1299/jsmefed.2005.237.

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16

SEO, Kazuya, Osamu KOBAYASHI, Shingo SAKAMOTO, and Masahide MURAKAMI. "Behavior of a rugby ball during flight." Proceedings of the JSME annual meeting 2004.7 (2004): 45–46. http://dx.doi.org/10.1299/jsmemecjo.2004.7.0_45.

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17

Regan, David. "Visual Judgements and Misjudgements in Cricket, and the Art of Flight." Perception 21, no. 1 (February 1992): 91–115. http://dx.doi.org/10.1068/p210091.

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To hit the ball with the centre of percussion of a bat so that the ball goes where he intends it to go, a batsman must estimate visually where the ball will be at a specific future time (when), and coordinate his swing accordingly. A number of visual cues are available to the batsman. Retinal image information provides an accurate indication of time to contact (ie when), even when the trajectory of the ball is inclined to the line of sight, and there is evidence that the human visual system is specifically sensitive to time-to-contact information. But only part of the necessary information about position (ie where) is available to the batsman. If the batsman's head is directly in the line of flight, the velocity ratio of the retinal images in the left and right eyes provides a precise cue to the trajectory of the ball in the horizontal plane. However, humans have only poor visual sensitivities to the absolute distance and to the line-of-sight velocity of a ball. Therefore, a batsman has inadequate retinal image information about the absolute vertical velocity of a ball. It is suggested in this paper that batsmen supplement inadequate retinal image information about where the ball will hit the ground with prior knowledge built up over the preceding few deliveries. Some slow bowlers can induce the batsman to misjudge where the ball will hit the ground. I suggest that these bowlers manipulate the flight of the ball so as to induce the batsman to supplement his inadequate retinal image information with inappropriate prior knowledge, and thus to misinterpret the vertical angular speed of the retinal image of the ball.

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18

Zhang, Xue, He Ming Cheng, Jian Yun Li, Si Qing Zhou, and Tie Xin Yang. "Numerical Simulation of Pressure Difference about Curve Ball in Flight." Applied Mechanics and Materials 444-445 (October 2013): 505–8. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.505.

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Life lies in movement, Football is now the most popular sport in the world. Fluent12.1 software is employed in this thesis to model the numerical simulation of the pressure which the ball with different angular velocity and different velocity bears. Simulation results show that the pressure difference on the surface of the ball with a certain speed will increase if the angular velocity increases. The pressure difference on the surface of the ball with a certain angular velocity will increase if the velocity increases. The radian of ball will become more bigger.

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19

Ismail, Mohamed A. A., Edward Balaban, and Jens Windelberg. "Spall Fault Quantification Method for Flight Control Electromechanical Actuator." Actuators 11, no. 2 (January 20, 2022): 29. http://dx.doi.org/10.3390/act11020029.

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Flight control electro-mechanical actuators (EMAs) are among the primary onboard systems that significantly influence the reliability and safety of unmanned aerial vehicles. Recent reliability studies have shown that the ball-screw element of a flight control EMA is subject to oscillating operating conditions that may initiate rapid degradation, such as fatigue spall defects. Accordingly, detecting and quantifying such faults are crucial for developing efficient fault prognostic and remaining useful life estimation capabilities. In this study, a vibration-based fault quantification method is developed to quantify the fatigue faults of a ball-screw mechanism of an EMA. The method is based on identifying the ball passing instants through a localized surface defect on the vibrational jerk rather than the vibrational acceleration measurement. The jerk is numerically determined from conventional accelerometers using a Savitzky–Golay differentiator. This method was successfully tested for ball bearings and it is adjusted in this paper for ball-screw faults. The experimental validation is investigated on a set of fault-seeded samples on NASA’s Ames Research Center Flyable Electro-Mechanical Actuator test stand.

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20

MIYAGAWA, Naoya, Shinichiro ITO, and Masaki HIRATSUKA. "Flow around the ball during peculiar flight behavior of soft tennis ball." Proceedings of Mechanical Engineering Congress, Japan 2019 (2019): J23302P. http://dx.doi.org/10.1299/jsmemecj.2019.j23302p.

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21

Babbs, Charles F. "Biomechanics of Heading a Soccer Ball: Implications for Player Safety." Scientific World JOURNAL 1 (2001): 281–322. http://dx.doi.org/10.1100/tsw.2001.56.

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To better understand the risk and safety of heading a soccer ball, the author created a set of simple mathematical models based upon Newton�s second law of motion to describe the physics of heading. These models describe the player, the ball, the flight of the ball before impact, the motion of the head and ball during impact, and the effects of all of these upon the intensity and the duration of acceleration of the head. The calculated head accelerations were compared to those during presumably safe daily activities of jumping, dancing, and head nodding and also were related to established criteria for serious head injury from the motor vehicle crash literature. The results suggest heading is usually safe but occasionally dangerous, depending on key characteristics of both the player and the ball. Safety is greatly improved when players head the ball with greater effective body mass, which is determined by a player�s size, strength, and technique. Smaller youth players, because of their lesser body mass, are more at risk of potentially dangerous headers than are adults, even when using current youth size balls. Lower ball inflation pressure reduces risk of dangerous head accelerations. Lower pressure balls also have greater “touch” and “playability”, measured in terms of contact time and contact area between foot and ball during a kick. Focus on teaching proper technique, the re-design of age-appropriate balls for young players with reduced weight and inflation pressure, and avoidance of head contact with fast, rising balls kicked at close range can substantially reduce risk of subtle brain injury in players who head soccer balls.

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22

Chen, Lei, and Yones Kafilaleh. "Simulation of Tennis Spinning Ball Flight Path Based on Fuzzy Reasoning Algorithm." Discrete Dynamics in Nature and Society 2022 (August 11, 2022): 1–13. http://dx.doi.org/10.1155/2022/8292571.

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Topspin is one of the most widely used hitting techniques in a tennis match and it is an effective tool to win over the opponent. Hence, flight path simulation of a spinning ball can be a tremendous analysis tool to help tennis players perfect their game. This article proposes a fuzzy logic model based on the principles of kinematics and mechanics. This study analyzes the physical characteristics of a spinning ball during the flight process, which are divided into two categories: the characteristics of the ball on impact (including the floating and rotating it causes) and the landing rebound characteristics. These two characteristics are considered as the constraints of the flight path simulation and the inputs of the fuzzy logic model. Fuzzy logic is used to fuzzify the impact and landing rebound information of the ball based on the knowledge base, solve the problem, and finally defuzzify the results into crisp outputs, that is, accurate flight trajectory. The simulation results show that the estimation error of the proposed model is lower than 3.7 cm/s and 0.9°, and the success rate of accurate topspin execution is 100%, indicating that the proposed model is effective to train tennis players.

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23

Sakamoto, Yuki, Masaki Hiratsuka, and Shinichiro Ito. "Effect of Soccer Ball Panels on Aerodynamic Characteristics and Flow in Drag Crisis." Applied Sciences 11, no. 1 (December 30, 2020): 296. http://dx.doi.org/10.3390/app11010296.

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The panel patterns of soccer balls that change with each World Cup have a significant impact on the balls’ aerodynamic and flight characteristics. In this study, the aerodynamic forces of eleven types of soccer ball with different panel patterns were measured in a wind tunnel experiment. We characterized the panel shapes of soccer balls by the length, cross-sectional area, and the panel grooves’ volume. The results confirmed that the drag and drag crisis characteristics are dependent on the groove length and volumes. Flow separation points were visualized by an oil film experiment and particle image velocimetry (PIV) measurement to understand the drag crisis of the soccer balls. The results showed that the panel shape of the ball significantly changes the position of the separation point near the critical region, where the drags crisis occurs. In the critical region, laminar and turbulent flows coexist on the ball. On the other hand, the effect of panel shape on the separation point position is small in subcritical and supercritical states.

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24

Tamaru, Takehiro, Shinichiro Ito, and Masaki Hiratsuka. "Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes." Proceedings 49, no. 1 (June 15, 2020): 146. http://dx.doi.org/10.3390/proceedings2020049146.

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Volleyball is a sport that starts with a serve, so effective service is essential to win the game. The trajectory of the ball is complicatedly affected by the fluid force, which depends on the speed, spin speed, and panel shape. To understand the aerodynamic characteristics of the ball and to propose an ideal serve method, we measured the fluid force and flight trajectory. The fluid force applied to the ball was measured at a wind speed of 4–30 m/s in the wind tunnel. The fluid force on the ball was strongly dependent on the ball type and orientation of the panel. In the flight trajectory measurement, the trajectory of the ball was measured using a high-speed camera under controlled speed and spin speed using a shotting machine. The effect of the panel orientation shown by the fluid force measurement was consistent with the results of the trajectory analysis, clarifying the importance of the panel orientation in serving.

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25

Starkes, Janet L. "Catching and Spatially Locating a Ball in Flight: Variables Underlying Their Development." Perceptual and Motor Skills 63, no. 3 (December 1986): 1275–86. http://dx.doi.org/10.2466/pms.1986.63.3.1275.

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Two experiments assessed relative contributions of stereo-acuity, simple reaction time, chronological age, and experience in ball sports to the development of catching as measured by actually catching a ball and a spatial matching task. The spatial matching task was designed to tap underlying perceptual requirements in catching by reducing motor requirements of the task. In Exp. 1 the contribution of each factor was assessed in boys aged 8 to 13 yr. as well as adults. Exp. II replicated certain age groups from Exp. I and also addressed the question of sex differences in catching a ball and spatial matching of location. Both experiments indicated that age and to a lesser extent ball-sport experience, did influence catching a ball, as well as spatial matching performance. Stereoacuity and reaction time showed little influence on catching for either boys or girls. Sex-related differences were routinely found at all ages for both catching a ball and spatial matching.

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26

ASAI, Takeshi. "Vortex Visualisation of an Actual Flight Soccer Ball." Journal of the Visualization Society of Japan 29-1, no. 1 (2009): 351. http://dx.doi.org/10.3154/jvs.29.351.

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27

Mizota, Taketo, Kazuyuki Yamamoto, Satoki Ogura, Yuji Ohya, Atsushi Okajima, Manabu YAMAMOTO, Koji KONDO, et al. "Erratic Behavior of Less Spinning Soccer Ball Flight." Wind Engineers, JAWE 2007, no. 111 (2007): 193–202. http://dx.doi.org/10.5359/jawe.2007.193.

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28

Alcock, Alison, Wendy Gilleard, Nick A. T. Brown, John Baker, and Adam Hunter. "Initial Ball Flight Characteristics of Curve and Instep Kicks in Elite Women’s Football." Journal of Applied Biomechanics 28, no. 1 (February 2012): 70–77. http://dx.doi.org/10.1123/jab.28.1.70.

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Initial ball flight characteristics of curve and instep kicks were investigated. Fifteen international female footballers performed curve and instep kicks from a distance of 20 m from goal and at a 1 m2 target. Seventeen Vicon cameras tracked three-dimensional coordinates of four reflective markers adhered to the ball. Ball flight characteristics were quantified, and the coordinates of the ball relative to the target center were recorded. The lateral launch angle and the angle of the spin axis relative to the horizontal best predicted the horizontal placement of the ball relative to the target. The vertical launch angle, antero-posterior velocity and amount of backspin best predicted the vertical coordinate. Regression models demonstrated how carefully controlled the flight characteristics must be with launch angles constrained within 3° to hit the target. Curve kicks were characterized by significantly greater lateral and vertical launch angles, increased sidespin and spin about the antero-posterior axis, and a more vertical spin axis. This information is beneficial for coaches in training players to achieve the characteristics required to score a goal and avoid a defensive wall. For example, if players consistently kick above or below the target, these findings identify the variables that will help rectify that error.

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29

Carneiro, Diogo, Filipe Silva, and Petia Georgieva. "Robot Anticipation Learning System for Ball Catching." Robotics 10, no. 4 (October 15, 2021): 113. http://dx.doi.org/10.3390/robotics10040113.

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Catching flying objects is a challenging task in human–robot interaction. Traditional techniques predict the intersection position and time using the information obtained during the free-flying ball motion. A common pain point in these systems is the short ball flight time and uncertainties in the ball’s trajectory estimation. In this paper, we present the Robot Anticipation Learning System (RALS) that accounts for the information obtained from observation of the thrower’s hand motion before the ball is released. RALS takes extra time for the robot to start moving in the direction of the target before the opponent finishes throwing. To the best of our knowledge, this is the first robot control system for ball-catching with anticipation skills. Our results show that the information fused from both throwing and flying motions improves the ball-catching rate by up to 20% compared to the baseline approach, with the predictions relying only on the information acquired during the flight phase.

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Fidgen, Jeffrey G., Ronald E. Fournier, Mark C. Whitmore, Chris J. K. MacQuarrie, and Jean J. Turgeon. "Factors affecting Velcro-covered balls when used as a sampling device for wool of Adelges tsugae (Hemiptera: Adelgidae)." Canadian Entomologist 151, no. 1 (November 1, 2018): 101–14. http://dx.doi.org/10.4039/tce.2018.50.

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AbstractAdelges tsugae Annand (Hemiptera: Adelgidae) has caused extensive mortality of hemlocks (Tsuga (Endlicher) Carrière; Pinaceae) in the eastern United States of America and was discovered recently in Nova Scotia, Canada. We evaluated the use of a Velcro-covered racquetball as a sampling device for A. tsugae wool. Specifically, we report on improvements to an earlier design and evaluate several factors seen in routine sampling that influence the ability of the ball to trap and retain adelgid wool. Velcro was found to be critical for trapping and retaining adelgid wool on the ball during flight and landing. Wooden beads, inserted in the ball, reduced deflection during flight and bounce during landing. Higher probability of trapping wool on the ball was associated with an ascent through the crown, with increasing diameter and density of ovisacs on branch tips, and with increasing abundance of woolly twigs on the forest floor. Higher probability of retaining wool on the ball was associated with Velcro surface area and with amount and location of wool loaded on the ball. These modifications improved detection surveys for A. tsugae in general.

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Langdon, Genevieve S., Ruixuan Qi, Trevor J. Cloete, and Steeve Chung Kim Yuen. "Influence of Ball Bearing Size on the Flight and Damage Characteristics of Blast-Driven Ball Bearings." Applied Sciences 12, no. 3 (January 21, 2022): 1133. http://dx.doi.org/10.3390/app12031133.

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This paper presents insights into the influence of ball size on the flight characteristics and damage of a ball bearing embedded in a rear detonated cylindrical charge. It includes results from a post-test damage analysis of ball bearings from previously reported experiments. Computational simulations using Ansys Autodyn were used to provide extra information about the velocity variation during flight and the damage sustained by the ball bearings during the blast event. The influence of bearing size (diameter and mass) was investigated using the validated simulation models to extend the dataset beyond the initial experimental work. The peak bearing velocity is influenced by the charge mass to ball bearing mass ratio and the aspect ratio of the charge. Larger ball bearings require extra momentum to accelerate them to higher velocities, but their higher surface area means a greater portion of the explosive charge is involved in transferring kinetic energy to the projectile. Tensile spalling was to be the major damage mechanism within the ball bearings. The charge aspect ratio also influenced the hydrostatic pressure propagation within the ball bearing itself, affecting the location and degree of internal cracking within the bearings. These findings will prove valuable to blast protection engineers considering the effects of embedded projectiles in improvised explosive devices.

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Hong, Sungchan, and Takeshi Asai. "Aerodynamic Differences between New and Used Soccer Balls." Applied Sciences 11, no. 16 (August 4, 2021): 7204. http://dx.doi.org/10.3390/app11167204.

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The surface structure of soccer balls, such as the number and shapes of the ball panels, has recently changed, and research on the aerodynamics and flight trajectories of new soccer balls is actively proceeding. However, these studies are focused on new soccer balls, whereas the used soccer balls were never studied. In this study, the aerodynamic characteristics of soccer balls kicked 1000 times by a robot were investigated through wind tunnel tests. The results were compared with those obtained using new soccer balls. Regarding the aerodynamic characteristics of the soccer balls, it was found that the critical Reynold number, Recrit, changes with usage. This is related to the transition from laminar to turbulent flow of airflow around the ball. The comparison of the drag coefficients of the balls at Recrit showed that the drag coefficients of the new and used Telstar18 balls were 0.15 (Re = 2.5 × 105) and 0.14 (Re = 2.2 × 105), respectively; those of the new and used Merlin were 0.13 (Re = 2.8 × 105) and 0.13 (Re = 2.2 × 105), respectively; and finally, those of the new and used Derbystar were 0.14 (Re = 2.1 × 105) and 0.14 (Re = 2.1 × 105), respectively. The surface conditions of a soccer ball, such as the surface roughness and surface damages, are essential factors to determine the aerodynamics of the soccer balls.

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Nakashima, Hirotaka, Gen Horiuchi, and Shinji Sakurai. "Three-dimensional batted ball in baseball: effect of ball spin on the flight distance." Sports Engineering 21, no. 4 (November 20, 2018): 493–99. http://dx.doi.org/10.1007/s12283-018-0290-1.

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Pearce, B. "Gluteus medius kinesio-taping: the effect on torso-pelvic separation, ball flight distance and accuracy during the golf swing." South African Journal of Sports Medicine 27, no. 4 (May 25, 2016): 97. http://dx.doi.org/10.17159/2413-3108/2015/v27i4a1262.

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Background. The kinesio-taping method, which is becoming increasingly popular, may provide support and stability to joints and muscles without inhibiting range of motion. Objective. The aim of the study was to determine the effect of kinesio-taping of the gluteus medius muscle on x-factor (torsopelvic separation), ball flight distance and accuracy (smash factor ratio). A specific aim was to determine whether a correlation exists between hip abduction strength and x-factor, ball distance and accuracy. Methods. This study is a one group pretest-posttest quasiexperimental design which took place at a golf facility. Twentynine amateur golfers with handicap of scratch ±2, who were between the ages of 18- and 25-years, participated in this study. Biomechanical outcomes were recorded with and without kinesio-tape applied on the gluteus medius muscle of the trail leg. Biomechanical golf swing analysis with the iClub™ Body Motion System determined the x-factor at the top of the backswing. Ball flight distance and accuracy were measured with FlightScope® and dominant hip abduction strength was measured with the MicroFET Hand-held Dynamometer. Results. Kinesio-tape is effective in improving the relative hip abduction strength (p<0.001), although the effect size was small (Cohen’s d=0.24). With regard to the biomechanical outcome measures, namely x-factor (p=0.28), ball flight distance (p=0.53) and accuracy (p=0.1), there was no significant improvement. Conclusion: Even though the relative hip abduction strength was improved, there was no effect on golf swing biomechanics. This can be explained due to the fact that x-factor, ball flight distance and accuracy are dependent on a combination of body movements to produce the golf swing. Keywords. Golf, X-factor, pelvic stability, taping

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Féry, Yves-André, and Alain Vom Hofe. "Imagery Processes in Evaluating Duration of a Ball Flight." Perceptual and Motor Skills 87, no. 3_suppl (December 1998): 1129–30. http://dx.doi.org/10.2466/pms.1998.87.3f.1129.

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MIZOTA, Taketo. "Aerodynamic Instability of Bluff body on Sports Ball Flight." Wind Engineers, JAWE 2008, no. 116 (2008): 222–31. http://dx.doi.org/10.5359/jawe.2008.222.

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Chalkley, Daniel, Clare MacMahon, and Kevin Ball. "Predicting Ball Flight in Cricket from an Umpire's Perspective." International Journal of Sports Science & Coaching 8, no. 3 (September 2013): 445–54. http://dx.doi.org/10.1260/1747-9541.8.3.445.

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Spathopoulos, Vassilios M. "A spreadsheet model for soccer ball flight mechanics simulation." Computer Applications in Engineering Education 19, no. 3 (March 27, 2009): 508–13. http://dx.doi.org/10.1002/cae.20331.

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Kanwar, Kiran D., and Mark D. Mann. "Effects of a golf swing intervention on senior golfers’ ball striking and motivation to play golf." International Journal of Sports Science & Coaching 13, no. 4 (April 16, 2018): 607–15. http://dx.doi.org/10.1177/1747954118764179.

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Several golf swing movements have been correlated with the production of club speed in skilled golfers. However, less skilled golfers, such as senior golfers, may not be capable of many of those movements. One golf swing—Minimalist Golf Swing—reduces the downswing range of motion through which a golfer’s body must move to reach the impact positions seen in skilled golfers. The purpose of this study was to assess whether the MGS could improve senior golfers’ ball flight and consistency, and increase their motivation to play golf. Twenty-two seniors (16 males, 6 females), aged 54–81, participated in an 11-session study comprising pretest, intervention, and posttest sessions. During the test sessions, participants hit 20 shots with each of their own 6-iron and driver clubs. Ball movement immediately after impact was measured using a camera-based ball launch monitor. Participants’ motivation to play golf before and after the intervention was assessed using the Sports Motivation Scale II. A mixed effects model was used for the statistical analysis of this repeated measures study, in which participants served as their own controls. Statistically significant per-session results were an increase in the ball’s speed (6-iron and driver) and trajectory (6-iron), and a change in direction (both clubs) from left to slightly right (for right handed golfers). Consistency of ball flight, total motivation and intrinsic motivation increased slightly post-intervention, while amotivation decreased, none significantly. Therefore, some senior golfers can improve ball flight, consistency, and motivation to play golf after six MGS training sessions.

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Qian, Li Lin, Jian Wu Tao, Fei Yu, and Hai Fa Dai. "Ball-Nose Vehicle's Atmospheric Parameters Estimation Based on Airflow Velocity." Applied Mechanics and Materials 696 (November 2014): 3–7. http://dx.doi.org/10.4028/www.scientific.net/amm.696.3.

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The airflow velocity over blunt sphere is used to calculate ball-nose vehicle's atmospheric parameters about angle of attack, angle of sideslip and flight speed. A final model satisfying compressible flow is developed, and the expressions for atmospheric parameters is derived from three strategically selected sensors' velocity. The expressions of atmospheric parameters are verified through Fluent stimulation. The result of stimulation demonstrates a good accuracy of angles and flight speed, and the system has a good real-time performance.

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Tuplin, Simon, Martin Passmore, David Rogers, Andy R. Harland, Tim Lucas, and Chris Holmes. "The application of simulation to the understanding of football flight." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 226, no. 2 (April 25, 2012): 134–42. http://dx.doi.org/10.1177/1754337112444402.

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This paper demonstrates the value of using a flight model in the analysis of the flight of a football, and explores the complexity of the model required to produce useful results. Two specific aspects of the simulation are addressed: the need to include a model of spin decay and the requirement to include a full aerodynamic drag profile as a function of Reynolds number rather than a single indicative value. Both are aspects of the ball performance that are experimentally intensive to obtain. The simulated flights show that the inclusion of spin degradation is important if flight validation is the objective, but that it may be unnecessary in a comparative study. The simple analytical model of spin degradation is shown to over-estimate the reduction in lateral deviation when compared to experimentally acquired data. Therefore, the experimental method is preferred. The analysis of the shape of the drag profile (drag coefficient against Reynolds number) is explored, and it is shown from the simulated flights that post-critical coefficients of drag have the greatest effect on trajectories, and an average drag value is sufficient for most modelled scenarios.

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Senot, Patrice, Myrka Zago, Francesco Lacquaniti, and Joseph McIntyre. "Anticipating the Effects of Gravity When Intercepting Moving Objects: Differentiating Up and Down Based on Nonvisual Cues." Journal of Neurophysiology 94, no. 6 (December 2005): 4471–80. http://dx.doi.org/10.1152/jn.00527.2005.

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Intercepting an object requires a precise estimate of its time of arrival at the interception point (time to contact or “TTC”). It has been proposed that knowledge about gravitational acceleration can be combined with first-order, visual-field information to provide a better estimate of TTC when catching falling objects. In this experiment, we investigated the relative role of visual and nonvisual information on motor-response timing in an interceptive task. Subjects were immersed in a stereoscopic virtual environment and asked to intercept with a virtual racket a ball falling from above or rising from below. The ball moved with different initial velocities and could accelerate, decelerate, or move at a constant speed. Depending on the direction of motion, the acceleration or deceleration of the ball could therefore be congruent or not with the acceleration that would be expected due to the force of gravity acting on the ball. Although the best success rate was observed for balls moving at a constant velocity, we systematically found a cross-effect of ball direction and acceleration on success rate and response timing. Racket motion was triggered on average 25 ms earlier when the ball fell from above than when it rose from below, whatever the ball's true acceleration. As visual-flow information was the same in both cases, this shift indicates an influence of the ball's direction relative to gravity on response timing, consistent with the anticipation of the effects of gravity on the flight of the ball.

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Fuss, Franz Konstantin. "The Effect of Instrumentation on Sports Balls During Flight, Exemplified by A Smart AFL Ball: Model and Experiment." Proceedings 49, no. 1 (June 15, 2020): 102. http://dx.doi.org/10.3390/proceedings2020049102.

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Sensors incorporated in a sports ball for data collection can affect the properties of a ball, specifically the spin rate of a ball if the mass distribution (moments of inertia, MOI) is altered. This paper provides a method for assessing the MOIs of a smart ball by means of spin rate data, collected from a gyroscopic sensor. The critical elevation angle of the angular velocity vector defines the separatrix condition, which decides whether the angular velocity vector precesses about the axis with the greatest MOI or with the smallest MOI. The critical elevation angle can be directly determined from the experimental of the angular velocity data, and, together with the ratio of precession speed to angular velocity, applied to calculating the three MOIs. In the smart AFL ball used for the experiments, the critical angle was 13.5°, and the ratio of the two small MOIs was 1.014.

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Tamada, Chandan Varma, and Sai Ganesh Sabbavarapu. "Flow Visualization of Footballs to Analyze the Factors Affecting their Aerodynamic Performance Using CFD." Volume 5 - 2020, Issue 9 - September 5, no. 9 (September 23, 2020): 460–75. http://dx.doi.org/10.38124/ijisrt20sep296.

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The motion of a football in air is influenced by the combination of various aerodynamic effects caused by the parameters such as velocity, surface roughness, panel orientation and shape. This paper analyzes the individual and combined effects of these parameters on the flight characteristics of various footballs using CFD Analysis. Four balls, a smooth sphere, a 32-panel conventional football, 14-panel Teamgeist and 6-panel Brazuca ball are subjected to different velocities of air flow over them, both in the laminar and turbulent regime, different surface roughness values and the influence of these parameters on the aerodynamics of the balls is evaluated by the drag force, drag coefficient and hydrodynamic boundary layer separation angle. The effect of the seam length, number of panels and panel orientation are also compared. The results of these effects are discussed later in the paper and are used to explain the knuckling effects and unpredictable trajectory of the Jabulani ball.

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Ismail, M. A. A., and J. Windelberg. "Fault detection of ball screw-based electromechanical actuators using electrical, ultrasound and accelerometer sensors." International Journal of Condition Monitoring 8, no. 2 (April 1, 2018): 52–57. http://dx.doi.org/10.1784/204764218823029048.

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Electromechanical actuators (EMAs) are considered a promising energy-efficient technology for actuating the flight controls of future aircraft. When it comes to aerospace systems, the degradation of EMAs should be checked during regular maintenance events or through condition-based maintenance. Ball bearings have a significant failure rate for flight control EMAs and are usually monitored by vibration noise. A challenge for detecting bearing faults, using state-of-the-art industrial methods, is the presence of a ball-screw mechanism that produces nominal vibration noise similar to that of faulty bearings. No prior research has investigated this problem. This paper explores vibration noise generated from a set of healthy and faulty bearings included in a typical ball-screw EMA. In addition, a method is introduced for evaluating fault diagnosis performance for different time and frequency vibration features. The technique has been validated on an EMA actuator at the German Aerospace Center (DLR).

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Lefebvre, Carole, and Greg Reid. "Prediction in Ball Catching by Children with and without a Developmental Coordination Disorder." Adapted Physical Activity Quarterly 15, no. 4 (October 1998): 299–315. http://dx.doi.org/10.1123/apaq.15.4.299.

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This study aimed to determine how predicting ability in ball catching changes with age and to explore this among children with developmental coordination disorder (DCD) as judged by performance on the Movement Assessment Battery for Children (Henderson & Sugden, 1992) and by clinical evaluation. In Experiment 1, participants were 157 non-DCD children, age 5-12. In Experiment 2, 46 participants (age 5-7) from Experiment 1 were controls for 40 same-age children with a DCD. In Experiment 1, younger children (age 5-6) did not predict ball flight as well as older groups at short viewing times, and girls did not predict as well as boys. In Experiment 2, DCD children predicted more poorly at most viewing times compared to non-DCD peers. It was concluded that age and gender are crucial factors in predicting ball flight and that predicting ability is a fundamental problem in catching for younger, female, and DCD children.

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Nagami, Tomoyuki, Takatoshi Higuchi, Hiroki Nakata, Toshimasa Yanai, and Kazuyuki Kanosue. "Relation Between Lift Force and Ball Spin for Different Baseball Pitches." Journal of Applied Biomechanics 32, no. 2 (April 2016): 196–204. http://dx.doi.org/10.1123/jab.2015-0068.

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Although the lift force (FL) 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 FL 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 FL 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 FL could be accurately explained from ESp and also that seam orientation (4-seam or 2-seam) did not produce a uniform effect on estimating FL from ESp.

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OGURA, Satoki, and Taketo MIZOTA. "3D flight analysis of knuckle ball with high-speed camera." Journal of the Visualization Society of Japan 25, Supplement1 (2005): 359–60. http://dx.doi.org/10.3154/jvs.25.supplement1_359.

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Zerrik, Meryem, Houda Echchachoui, Zakaria Iloughmane, Choukri El’mhadi, Salaheddine Elkhader, Laila Benaissa, and Mohamed Chemsi. "Cannon Ball Diagnosis and Management in a Flight Attendant Candidate." Aerospace Medicine and Human Performance 88, no. 10 (October 1, 2017): 958–61. http://dx.doi.org/10.3357/amhp.4756.2017.

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Miller, Glenn A., Thomas S. Cross, and Thomas C. Barnhart. "Golf Instruction: Learning from the Flight of the Golf Ball." Journal of Physical Education, Recreation & Dance 63, no. 4 (April 1992): 17–20. http://dx.doi.org/10.1080/07303084.1992.10604151.

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