Ball Spin Research Articles

Research on the difference of stroke characteristics and stroke effect between different stroke duration of table tennis players

This study aimed to explore the differences in joint kinematic characteristics and stroke effect between fast and slow strokes of table tennis players. Thirty-four table tennis players were randomly selected as participants for this experiment. A high-speed infrared motion capture system was used to collect kinematic data of the right-side upper and lower limb joints during strokes. Simultaneously, a high-speed camera was used to measure the stroke effect. According to the duration of a stroke, the stroke data were classified into two types: fast-stroke and slow-stroke using a two-step clustering algorithm. The duration of the three phases of fast-stroke was shorter, with faster ball speed and stronger spin. Compared with slow-stroke, fast-stroke exhibited shorter displacements in the three lower limb joints and faster linear velocities in the three upper limb joints. In addition, the motion angles of the knee and ankle joints were smaller, while the angles of the hip, shoulder, and elbow joints were larger, with higher angular velocities. Increasing the extension speed of the lower limbs, the flexion speed of the elbow joints, and the wrist movement speed can achieve fast strokes, enhancing ball speed and spin. Small and quick hip joint movement can effectively transfer energy to the upper limbs, increasing the movement speed of the elbow and wrist joints, thus improving the ball speed and spin of the stroke.

A Calculation Method of Bearing Balls Rotational Vectors Based on Binocular Vision Three-Dimensional Coordinates Measurement

The rotational speed vectors of the bearing balls affect their service life and running performance. Observing the actual rotational speed of the ball is a prerequisite for revealing its true motion law and conducting sliding behavior simulation analysis. To address the need for accuracy and real-time measurement of spin angular velocity, which is also under high-frequency and high-speed ball motion conditions, a new measurement method of ball rotation vectors based on a binocular vision system is proposed. Firstly, marker points are laid on the balls, and their three-dimensional (3D) coordinates in the camera coordinate system are calculated in real time using the triangulation principle. Secondly, based on the 3D coordinates before and after the movement of the marker point and the trajectory of the ball, the mathematical model of the spin motion of the ball was established. Finally, based on the ball spin motion model, the three-dimensional vision measurement technology was first applied to the measurement of the bearing ball rotation vector through formula derivation, achieving the analysis of bearing ball rolling and sliding characteristics. Experimental results demonstrate that the visual measurement system with the frame rate of 100 FPS (frames per second) yields a measurement error within ±0.2% over a speed range from 5 to 50 RPM (revolutions per minute), and the maximum measurement errors of spin angular velocity and linear velocity are 0.25°/s and 0.028 mm/s, respectively. The experimental results show that this method has good accuracy and stability in measuring the rotation vector of the ball, providing a reference for bearing balls' rotational speed monitoring and the analysis of the sliding behavior of bearing balls.

The difference of dynamic elasticity characteristics and stroke effect between two types of new material seamed plastic table tennis ball

The diameter and weight of different brands of table tennis ball will affect the ball’s elasticity and stroke. The purpose of this study is to analyze the difference of the dynamic elasticity and stroke effect between the two brands of new plastic ball. A self-made experiment was designed to test the dynamic elasticity characteristics of DHS D40 + and Nittaku 40+. Table tennis players (N = 18) were randomly selected from the China Table Tennis College (Mage = 15.16 ± 2.41; Mheight = 1.59 ± 0.32 m; Mweight = 45.72 ± 5.17 kg). Each participant was righthand shake-hands grip. A speedometer was used to record the ball speed and a high-speed camera was used to measure the spin speed. Data normality was verified by using the Kolmogorov-Smirnov test. The independent t-test was conducted to assess the differences of the dynamic elasticity and stroke effect between the two types of plastic ball. Results showed that the rebound speed and decrement rate of DHS D40 + and Nittaku 40 + both increased with the increased falling speed, respectively. When falling at high speed, there was a significant difference of dynamic elasticity between DHS D40 + and Nittaku 40+ (p < 0.01). There was also a significant difference in the ball speed and spin speed between the two types of new material seamed plastic ball during the backhand backspin stroke (p = 0.041, p = 0.022, respectively), and the ball speed and spin speed of DHS D40 + were higher than that of Nittaku 40 + ball. Compared with the DHS D40+, the Nittaku 40 + has a faster rebound speed, higher rebound height, and better dynamic elasticity. Therefore, under same striking conditions, when hitting the Nittaku 40 + ball, players need to increase the swing distance and hit the ball with more strength to improve the ball speed and rotation speed; increase the spin and decrease the ball’s rebound height of the serve.

Radiated Sound and Transmitted Vibration Following the Ball/Racket Impact of a Tennis Serve

Shock-induced vibrations transmitted from the racket to the tennis player’s upper limb have interested researchers, whether for investigating their effect on injury risk, or for designing new equipment. Measuring these vibrations is, however, very challenging in an ecological playing situation: sensors must be of very high quality in order to precisely measure high-energy and broad-frequency signals, as well as non-invasive in order to allow the players to perform their usual movements. The working hypothesis of this paper is that contactless sound recordings of the ball/racket impact carry the same information as direct vibratory measurements. The present study focuses on the tennis serve, as being tennis’ most energy-demanding stroke, therefore possibly being the most traumatic stroke for the upper limb. This article aims (a) to evaluate the propagation of vibration from the racket to the upper limb; and (b) to identify correlations with acoustic signals collected simultaneously. Eight expert tennis players performed serves with three rackets and two ball spin effects. Accelerometers measured the vibration on the racket and at five locations on the upper limb, and a microphone measured the impact sound. Resulting signals were analyzed in terms of energy and spectral descriptors. Results showed that flat serves produced louder sounds, higher vibration levels, lower acoustic spectral centroids, and higher vibratory spectral centroids than kick serves. The racket only had a marginal influence. Similarities between acoustic and vibratory measurements were found (levels were correlated), but so were differences (spectral centroids tended to be negatively correlated), encouraging further studies on the link between sound and vibration for the in situ measurement of shock-induced vibration.

Enhancing Tennis Practice: Sensor Fusion and Pose Estimation with a Smart Tennis Ball.

This article demonstrates the integration of sensor fusion for pose estimation and data collection in tennis balls, aiming to create a smaller, less intrusive form factor for use in progressive learning during tennis practice. The study outlines the design and implementation of the Bosch BNO055 smart sensor, which features built-in managed sensor fusion capabilities. The article also discusses deriving additional data using various mathematical and simulation methods to present relevant orientation information from the sensor in Unity. Embedded within a Vermont practice foam tennis ball, the final prototype product communicates with Unity on a laptop via Bluetooth. The Unity interface effectively visualizes the ball's rotation, the resultant acceleration direction, rotations per minute (RPM), and the orientation relative to gravity. The system successfully demonstrates accurate RPM measurement, provides real-time visualization of ball spin and offers a pathway for innovative applications in tennis training technology.

Transition from bouncing to rolling on a horizontal surface

If a ball is incident obliquely on a horizontal surface and is allowed to bounce more than once, then it is likely to bounce many times before it starts rolling along the surface. The number of bounces before rolling commences depends on the initial vertical speed and the normal coefficient of restitution. The transition from bouncing to rolling is examined using a simple theoretical model and is compared with experimental data obtained by filming the process with a video camera. We find that the final rolling speed is proportional to the initial horizontal speed of the ball and depends on the initial ball spin, but is independent of the tangential coefficient of restitution. Representative videos for different balls are included as supplementary material, including a superball thrown with a backspin that creates a back and forth motion. Instructors could use the experiment and/or analysis for an advanced undergraduate lab or use a simplified observational exercise for non-majors.

Paper 21: Anatomic Medial Ulnar Collateral Ligament Reconstruction with Internal Brace Augmentation in Throwing Athletes

Objectives: Injury to the Medial Ulnar Collateral Ligament (MUCL) is a common setback experienced by many throwing athletes often requiring reconstruction with 12-18 months of rehabilitation. Current reconstructive techniques fail to anatomically restore the MUCL which may contribute to the prolonged course of rehabilitation. In recent years, we described an anatomic MUCL reconstruction with internal brace augmentation which demonstrated improved biomechanical strength when compared to the docking technique in cadaveric specimens. The purpose of this study was to evaluate the postoperative course of both amateur and professional throwing athletes that underwent anatomic MUCL reconstruction with internal brace augmentation. We hypothesized that throwers would return to the same level of play and that return to play (RTP) would be a shorter duration compared to current reported outcomes. Methods: In this surgical technique, the native MUCL is formally repaired. The graft and a suture tape are folded over a suspensory loop and secured in a socket of the medial epicondyle of the humerus to maximize tendon to bone contact. On the ulnar side, the graft and internal brace are secured proximally by two suture anchors on either side of the sublime tubercle and further secured across the sublime tubercle ridge distally to re-create the anatomic triangular insertion of the native ligament. All surgeries were performed by a single surgeon. Patient reported outcomes in addition to date of RTP, level of play, and functional outcomes were retrospectively gathered. All patients initially followed an Accelerated Rehabilitation Protocol and were converted to a Standard Paced protocol if setbacks were encountered. Results: A total of 26 baseball players underwent primary (n=23) or revision (n=3) MUCL reconstruction with the Anatomic Technique. Of these, 15 were professional and 11 were amateur athletes. 92% of throwers returned to play at a mean of 9.9 months following reconstruction. 89% were able to advance through the accelerated postoperative protocol without issues and 85% returned to the same role and level of play. Post injury KJOC scores improved from 41 to 86.9 and SANE scores improved from 32.5 to 95.5. No significant difference was identified in pre-injury versus post-reconstruction throwing velocity, ball spin rate, or horizontal/vertical ball movement. Conclusions: Anatomic reconstruction of the MUCL with internal bracing is a viable option for MUCL injuries. Advantages include increased tendon-bone contact of the reconstruction, multiple fixation points, and anatomic restoration of the MUCL. This technique allowed an expedited return to sport for these baseball athletes.

Effect of balls’ quantities, preload and raceway diameters on rotation accuracy and vibration of rigid rotor-bearing system based on nonlinear dynamic model

The rotation accuracy and vibration of the bearing-rotor system are important evaluation indicators for the working accuracy of machine tools. In this work, an innovative nonlinear dynamic model of the ball bearing-rotor system is first developed by considering the slip, spin and gyroscopic effects of ball and the whirl motion of cage. Secondly, this developed model is validated through experimental methods. On this basis, the coordination of balls' quantities and preload is studied to obtain the desired rotation accuracy and vibration of rotor. The effect of raceway diameters on the rotation accuracy and vibration of rotor is investigated. The influence mechanism of the odd and even number of balls in the left and right bearings on the rotation accuracy and vibration is revealed. The analyzed results illustrate that the reasonable contact load of the ball by adjusting the preload of the bearing-rotor system or the balls’ quantity can prompt good rotation accuracy and low vibration of rotor, here, the maximum contact loads of 65 N should be adopted in the left and right bearings to select the preload. Additionally, odd or even balls assembled in the left and right bearings synchronously are conducive to obtaining a favorable trajectory and rotating accuracy of rotor.

Systematic training of table tennis players' physical performance based on artificial intelligence technology and data fusion of sensing devices

This research emphasises the value of physical training for table tennis players, particularly as ball speed and spin rate decline and emphasises how important intensity quality is to the game. Chinese table tennis players' dual identities place greater demands on the general growth of their learning and training as a crucial component of talent development preparation. Athletes' general quality, competitive level, and ability to avoid sports injuries are all improved by scientific and focused physical training. In order to achieve the functions of intelligent camera, multi-angle broadcasting, and 3D scene reproduction, this study combines the physical training model of artificial intelligence. This gives the audience a more engaging and in-depth viewing experience. More feature extraction of the match footage is made possible by deep learning and convolutional neural networks when combined with large-scale video data, greatly enhancing the match information for viewers. The experimental findings demonstrate that the accuracy of table tennis human technical movement recognition reaches 98.88 % based on the enhanced AM-Softmax classification algorithm.

Spin measurement system for table tennis balls based on asynchronous non-high-speed cameras

Abstract The spin of the ball plays a crucial role in table tennis tactics. However, it has rarely been measured and reported for the broadcast audience to better understand table tennis matches. This paper introduces a system designed to measure the spin of a table tennis ball without using electrically synchronized shutters or high-speed cameras. The system employs multiple unsynchronized cameras to detect the logos printed on the ball and estimates its three-dimensional translational motion to determine the spin rate (rotational velocity expressed in the revolutions per unit time) and spin axis (imaginary line around which the ball rotates). An experimental analysis indicated median errors of 0.78 rps and 12.5° in spin rate and axis, respectively. Additionally, the system exhibited sufficient resolution to analyze the spin rate and axis of a service ball in table tennis, distinguishing between spin axes that differ by 30° with 95.8% confidence. The developed system was used in the Japanese T-League to report the spin of several services after the live streaming of matches. The developed system successfully measured the spins of 92.1% of the served balls, confirming that the system has sufficient capability to feedback spin data immediately after a match.

The Effect of Biomechanics Information on Driver Swing Learning of Intermediate Golfers

PURPOSE This study investigates the effectiveness of biomechanics information on intermediate golfers driver swing learning. It analyzes changes in center of pressure (COP) patterns, GRF Direction Inclination, driver performance, and learners psychological responses to determine the learning effects.METHODS Subjects were 32 right-handed male golfers (handicap 15-23) who had no difficulty in performing the golf driver swing (Full swing). Four groups were selected, BF (Biomechanics Feedback group), BVC (Biomechanics Verbal Cue group), CB (Combination group), and CT (Control group), and assigned randomly. Driver swing learning showed results after 6 weeks,and a transfer test was conducted 1 week after the completion of the learning.RESULTS Analysis of COP patterns and GRF Direction Inclination indicated changes in the BF, BVC, and CB groups. Furthermore, analysis of driver distance (m), club head speed (km/h), and ball spin rate (rpm) revealed that during the 6-week acquisition phase, all three groups (excluding the control group) showed improvements in driver distance, club head speed, and ball spin rate. However, there were no statistically significant differences among the groups. In contrast, the transfer test showed statistically significant differences among the groups, with the CB group exhibiting the highest driver distance. Learners' psychological responses during the learning process were trust, understanding, and satisfaction. The understanding factor was relatively higher in the CB and BVC groups compared to the BF group.CONCLUSIONS In summary, biomechanics information (BI) was effective in improving driver performance, and changesappeared in the COP pattern and GRF Direction Inclination, indicating a change in movement. Therefore, BI can be fully utilized for athletes or high-level advanced players and for motor learning for intermediate-level students.However, BI can only improve learning effects by strengthening learners' “understanding” when visual feedback forms and verbal cues are provided together.

Impact of a cue with a billiard ball

Experimental results are presented to show how the speed and spin of a billiard ball vary as the impact point of the cue is varied above and below the center of the ball. The results are compared with a simple impact model to estimate how the normal and tangential impact forces vary with impact location.

Comparison of Grip Strength, Forearm Muscle Activity, and Shock Transmission between the Forehand Stroke Technique of Experienced and Recreational Tennis Players Using a Novel Wearable Device.

Upper limb tennis injuries are primarily chronic, resulting from repetitive overuse. We developed a wearable device which simultaneously measures risk factors (grip strength, forearm muscle activity, and vibrational data) associated with elbow tendinopathy development resulting from tennis players' technique. We tested the device on experienced (n = 18) and recreational (n = 22) tennis players hitting forehand cross-court at both flat and topspin spin levels under realistic playing conditions. Using statistical parametric mapping analysis, our results showed that all players showed a similar level of grip strength at impact, regardless of spin level, and the grip strength at impact did not influence the percentage of impact shock transfer to the wrist and elbow. Experienced players hitting with topspin exhibited the highest ball spin rotation, low-to-high swing path brushing action, and shock transfer to the wrist and elbow compared to the results obtained while hitting the ball flat, or when compared to the results obtained from recreational players. Recreational players exhibited significantly higher extensor activity during most of the follow through phase compared to the experienced players for both spin levels, potentially putting them at greater risk for developing lateral elbow tendinopathy. We successfully demonstrated that wearable technologies can be used to measure risk factors associated with elbow injury development in tennis players under realistic playing conditions.

The effect of aerodynamics on table tennis

In the table tennis sport category, the different spin formula of table tennis ball will show different motion state, in which the important physical knowledge that is permeated aerodynamics. Besides the effect of aerodynamics, the balls can obtain different trajectories because of Magnus effect and Bernoulli principle. By using these three mainly professional knowledge, this paper analyzed the forces that the top-spin ball and back-spin ball acquired. What is more, the movement of side spin balls also be introduced through these professional knowledge. In addition to these analysis, 40mm and 38mm table tennis balls are compared in the paper. By using the principle of physical mechanics to reveal the secret and mechanism of the spin of table tennis ball, it provides a theoretical basis for improving the spin skill of table tennis ball.

Mechanism for control of ball spin rate by the upper limb in baseball pitching based on singular value decomposition

This study aims to examine the mechanism by which the ball spin rate during fastball pitching is controlled by synergistic joint torque. The participants were seven baseball players. The kinematics and kinetics of the fingers, wrist, elbow, and shoulder were calculated using the inverse dynamics method. The synergistic relationship between the joint torques was calculated using singular value decomposition. The similarity of the spatial pattern of the joint torque in each participant was evaluated using cosine similarity. The results indicated that there were three types of synergistic torque control: (1) two pitchers had a synergistic torque control that was primarily based on shoulder internal rotation torque, (2) two pitchers had a synergistic torque control that was primarily based on elbow extension torque, and (3) three pitchers had a synergistic torque control that was primarily based on shoulder horizontal adduction torque. In particular, pitchers with a high spin rate relative to the ball velocity (SPV) had a torque control of the shoulder internal rotation type. In contrast, pitchers with a low SPV had a torque control of the shoulder horizontal adduction type. It is considered that pitchers with a high SPV execute shoulder internal rotation torque, which has the same direction as that of ball spin, based on hierarchical control to increase the ball spin rate. These results suggest that pitchers with high and low SPVs exhibit different motor patterns. Pitchers and coach need to focus on the shoulder joint as well as the fingers when they throw fastball.

A Systematic Review of Spatial Differences of the Ball Impact within the Serve Type at Professional and Junior Tennis Players

Since the flat serve (FS) minimizes the ball spin and kick serve (KS) combined topspin and sidespin, this systematic review aimed to explore the ball impact location (BI) within the FS and KS at the professional men, junior men, and women tennis players. The PRISMA guideline was used, and the original articles were searched in Scopus, Web of Science, and PubMed. The means and standard deviations computed from the distance of BI from the origin within the FS and KS on the x, y, and z axes (global coordinate system) were normalized by the participants’ height and weighted by the number of participants in one-way ANOVA. Ten articles with a pooled sample of 133 males and 51 females aged 11–25 were included. The professional men had more stable BI on the x-axis within the FS by 56% (p &lt; 0.001), within the KS by 58% (p &lt; 0.001), and on the y-axis within the KS by 90% (p &lt; 0.001) than junior men. The professional and junior men had the BI more leftwards from the origin on the x-axis within the KS by 188% (p &lt; 0.001) and 88% (p &lt; 0.001), respectively than within the FS.

Technical skills in complex tennis situations: Dutch talented players U15 compared to players U17.

Technical skills in complex situations appear crucial for progress towards elite tennis performance. However, it is unknown how these skills develop in different age categories in a group of talented youth players. The aim of this study is to evaluate possible differences in technical skills among Dutch talented youth tennis players U15 compared to U17. A total of 19 players (12 males, 7 females; age 14.6 ± 1.4 years) were tested on ball speed, accuracy, percentage errors and spin rate using the on-court Dutch Technical-Tactical Tennis Test. With a ball machine, four games were simulated which were either fixed (game 1 and game 2) or variable (game 3 and game 4), depending on the complexity of the task. Each game consisted of two offensive, two neutral and two defensive rallies, representing different tactical situations. A two-way ANOVA revealed a statistically significant interaction between the effects of age category and sex for ball speed (F(1,15) = 5.472, p = 0.034, η 2 = 0.267), indicating that males U17 produced higher ball speed compared to males U15, whereas no differences were found between females U15 and U17. A one-way ANCOVA showed that, regardless of sex, players U17 scored significantly higher on accuracy than players U15 (F(1,16) = 5.021, p = 0.040, η 2 = 0.239). No differences were found between players U15 and U17 for spin rate and percentage errors (p > .05), although there was a medium to large effect size for males U17 to produce higher spin rates compared to males U15. A closer examination of accuracy revealed that players U17 scored significantly higher compared to players U15 in game 4 (F(1,17) = 6.358, p = .022, η 2 = .272) and in defensive situations (F(1,17) = 9.602, p = .007, η 2 = .361). In conclusion, the results of the current study suggest that technical skills, especially ball speed for males and accuracy in complex situations for both males and females, continue to develop in adolescence in talented tennis players. There is an increased understanding about underlying technical skills that contribute to progress towards elite tennis performance. To effectively develop technical skills, coaches are encouraged to design specific practices where these skills are performed in complex situations under high cognitive and temporal pressure.

Observer based Control for Paddle Juggling with Considering Ball Spin Effect

This paper deals with the 2-dimensional paddle juggling where a racket hit a ball vertically and iteratively. The racket rebound model is considered where both the translational and rotational velocities of the ball change at the rebound due to the effect of the racket rubber. The LQ servo controller is derived based on the complete ball transition with the racket rebound model. In addition, a whole observer system to estimate all the ball states is proposed which consists of a continuous one for the free flying ball and a discrete one for the ball rebound. Note that it is essential that the rotational velocity can be only estimated by the discrete observer at the rebound. A numerical simulation is performed in order to verify the effectiveness of the total discrete output feedback controller.

A topspin rate exceeding 110 rps reduces the ball time of arrival to the opponent: a table tennis rally study

ABSTRACT This study experimentally investigated the factors affecting the time a table tennis ball with topspin takes to reach the opponent. Six skilled young players and one coach performed topspin forehand strokes under the observation of three high-speed cameras. As the distribution of the participants’ measurements was uneven, additional data were collected using a launching machine that could control the ball speed and spin. To verify the effect of the spin rate on speed decay by drag, the translational speed was measured at 0.15 s after passing the baseline (23 m/s); the balls with topspin ≥110 rps, close to participants’ average (117 ± 29 rps) were 1.4 m/s faster than those with topspin ≤80 rps. The horizontal ball speed changed in the range of −3.1 to 2.6 m/s owing to table bounce. At topspins ≥110 rps the ball reached a point 1 m past the end line (estimated receiving position) 27 ± 5 ms faster than at topspins ≤80 rps, for the same initial speed. The relationship between spin rate and travel time was non-linear with boundaries at 80 and 110 rps. Therefore, maintaining a spin rate of ≥ 110 rps along with a high initial speed is an effective strategy for reducing the opponent’s preparation time.

Effect of grip-enhancing agents on sliding friction between a fingertip and a baseball

Friction between a pitcher’s fingers and the leather surface of a baseball is a key factor that influences ball delivery, causing Major League Baseball in the United States to recently enhance enforcement of rules banning the unauthorized use of friction-enhancing agents or sticky substances. Here, we examine how the application of rosin powder and sticky substances alters the friction coefficient between a fingertip and the leather of a baseball. We find that sticky substances increase friction which can positively affect ball spin rate, while rosin has the advantage of keeping friction consistent within and between individuals. Additionally, we find that baseballs used by the Nippon Professional Baseball Organization in Japan are less slippery compared with the ones used in Major League Baseball, suggesting that grip-enhancers may have a larger impact on friction for baseballs used in the United States compared to Japan. Furthermore, our results indicate that changing the characteristics of the leather the baseball is made from may increase friction, reducing the unauthorized use of sticky substances.