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Proceedings, 2020, ISEA 2020

The 13th Conference of the International Sports Engineering Association

Online | 22–26 June 2020

Volume Editors:
Motomu Nakashima, Tokyo Institute of Technology, Japan
Takeo Maruyama, Tokyo Institute of Technology, Japan
Yusuke Miyazaki, Tokyo Institute of Technology, Japan

Number of Papers: 167
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1 pages, 122 KiB  
Editorial
The 13th Conference of the International Sports Engineering Association (ISEA 2020)
by Motomu Nakashima, Takeo Maruyama and Yusuke Miyazaki
Proceedings 2020, 49(1), 111; https://doi.org/10.3390/proceedings2020049111 - 15 Jun 2020
Viewed by 1607
Abstract
Every second year, the International Sports Engineering Association (ISEA) conducts a conference somewhere around the world. [...] Full article
6 pages, 615 KiB  
Proceeding Paper
Comparison between Indoor Sled Tests on the SkillrunTM Treadmill and Outdoor Field Tests at Increasing Sled Loads
by Alessandro Volpe, Giuseppe Marcolin, Giuseppe Fedele, Silvano Zanuso, Gabriele De Bettio and Nicola Petrone
Proceedings 2020, 49(1), 18; https://doi.org/10.3390/proceedings2020049018 - 15 Jun 2020
Viewed by 3354
Abstract
The aim of the study was to compare the power output during indoor sprints on a SKILLRUNTM treadmill with the power output expressed in outdoor sprints pushing an instrumented sled. The SKILLRUNTM has been chosen because it is able to simulate [...] Read more.
The aim of the study was to compare the power output during indoor sprints on a SKILLRUNTM treadmill with the power output expressed in outdoor sprints pushing an instrumented sled. The SKILLRUNTM has been chosen because it is able to simulate the outdoor sprint pushing a sled setting different loads and providing performance output data like speed and power. Two athletes were involved in this pilot study and were asked to perform indoor and outdoor sprints with the same overloads. Two dynamometric handles were designed and applied both on the treadmill for the indoor sprints and on the sled for the outdoor sprints. Power data were calculated throughout the force measured at the handles and the speed collected during the sprints. Kinematics data of trunk and lower limbs were also calculated by means of a set of inertial sensors (Xsens, Enschede, The Netherlands). The power–speed and the load–speed curves together with the kinematics results derived from the indoor and outdoor tests were compared, showing, in general, a good agreement between the indoor and outdoor conditions. These results highlighted the validity of the SKILLRUNTM treadmill in simulating a sprint with overloads. Full article
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6 pages, 1587 KiB  
Proceeding Paper
Plantar Pressure Distribution under Uniform and Gradient Foam during Running and Jumping
by Olly Duncan, George Naylor, Joel Godfrey M, Tom Allen, Leon Foster, John Hart and Andrew Alderson
Proceedings 2020, 49(1), 116; https://doi.org/10.3390/proceedings2020049116 - 15 Jun 2020
Cited by 1 | Viewed by 3503
Abstract
Auxetic materials have a negative Poisson’s ratio, meaning they contract laterally during axial compression. Auxetics can also absorb more energy during impacts than conventional materials. Auxetic foam was fabricated by volumetrically compressing open cell foam to buckle cell ribs and impart a re-entrant [...] Read more.
Auxetic materials have a negative Poisson’s ratio, meaning they contract laterally during axial compression. Auxetics can also absorb more energy during impacts than conventional materials. Auxetic foam was fabricated by volumetrically compressing open cell foam to buckle cell ribs and impart a re-entrant cell structure, then the imposed structure was fixed by heating and cooling. Passing pins through the foam allowed localised control over compression during fabrication, producing gradient foam with regions with differing Poisson’s ratios and stress vs. strain relationships. Uniform sheets had volumetric compression ratios of three, gradient sheets had volumetric compression ratios of one (unchanged) or three in different regions. One participant jumped barefoot on all foams, cut out to fit pressure sensors; another ran wearing shoes containing uniform converted and unconverted foam insoles. Pressure distribution was measured underneath the foams and foam insoles. Peak pressure was lowest underneath converted foams, warranting further investigation with more participants. Full article
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6 pages, 2890 KiB  
Proceeding Paper
Force Pattern and Acceleration Waveform Repeatability of Amateur Runners
by Ophelie Lariviere, Thomas Provot, Laura Valdes-Tamayo, Maxime Bourgain and Delphine Chadefaux
Proceedings 2020, 49(1), 136; https://doi.org/10.3390/proceedings2020049136 - 15 Jun 2020
Cited by 4 | Viewed by 1730
Abstract
Although accelerometers’ responses during running are not perfectly understood, they are widely used to study performance and the risk of injury. To outline the typical tibial acceleration pattern during running, this study aims to investigate the repeatability of acceleration signals with respect to [...] Read more.
Although accelerometers’ responses during running are not perfectly understood, they are widely used to study performance and the risk of injury. To outline the typical tibial acceleration pattern during running, this study aims to investigate the repeatability of acceleration signals with respect to the ground reaction force waveforms. Ten amateur runners were asked to perform ten trials along a straight line. One participant was asked to perform this protocol over ten sessions. Tibial accelerations and ground reaction forces were measured during the stance phase. The coefficient of multiple correlation R was computed to study the intra- and inter-test and subject repeatability of accelerometric and force waveforms. A good (R>0.8) intra- and inter-test repeatability was observed for all measured signals. Similar results were observed for intra-subject repeatability. A good inter-subject repeatability was observed only for the longitudinal acceleration and vertical and antero-posterior forces. Typical accelerometric signatures were outlined for each case studied. Full article
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7 pages, 541 KiB  
Proceeding Paper
Features Observed Using Multiple Inertial Sensors for Running Track and Hard-Soft Sand Running: A Comparison Study
by Matthew T. O. Worsey, Hugo G. Espinosa, Jonathan B. Shepherd, Julian Lewerenz, Florian S. M. Klodzinski and David V. Thiel
Proceedings 2020, 49(1), 12; https://doi.org/10.3390/proceedings2020049012 - 15 Jun 2020
Cited by 3 | Viewed by 2682
Abstract
Variability in the running surface can cause an athlete to alter their gait. Most literature report running on grass, a treadmill or athletics running tracks using inertial sensors. This study compares the signals obtained by 9 degrees of freedom (DOF) inertial-magnetic sensors incorporating [...] Read more.
Variability in the running surface can cause an athlete to alter their gait. Most literature report running on grass, a treadmill or athletics running tracks using inertial sensors. This study compares the signals obtained by 9 degrees of freedom (DOF) inertial-magnetic sensors incorporating an accelerometer (±16 g), gyroscope (±2000°/s) and magnetometer (±8 gauss). The sensors were placed on the participant’s shank, knee, lower spine and upper spine, and the participants were asked to run on three different surfaces (running track, hard sand and soft sand). The calculated player loads for a 400 m run on each surface type was very similar. The mean and standard deviation values were 577 ± 130, 581 ± 128, 568 ± 124 for soft sand, hard sand and the running track, respectively. This did not correlate with the participant’s self-assessment RPE (Rate of perceived exertion), which demonstrated running on soft sand to be significantly more challenging, yielding a mean and standard deviation of 5.3 ± 2.5 (Hard to Very Hard). Soft sand running had a decreased swing time duration but increased variability (0.44 ± 0.02 s—Swing Time, 6.5 ± 1.1%—CV), hard sand running had the longest swing and intermediate variability duration (0.46 ± 0.02 s—Swing Time, 3.30 ± 2.58 %—CV) and running track running had the medium swing time but lowest variability (0.45 ± 0.02 s, 2.7 ± 0.9%—CV). Gait dominance was not consistent across the surfaces for each participant and remained below a ratio of 0.4. These results provide an insight into how athletes modify their gait mechanics to accommodate different running surfaces. Full article
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7 pages, 394 KiB  
Proceeding Paper
Mechanical Advantages and Disadvantages of a Lower Limb Using Forefoot to Heel Strike Landing
by Takayuki Koike and Norimasa Yamada
Proceedings 2020, 49(1), 15; https://doi.org/10.3390/proceedings2020049015 - 15 Jun 2020
Cited by 1 | Viewed by 2271
Abstract
A previous study reported that habitually barefoot Kenyan distance runners tend to use a mid-foot strike or a forefoot-heel strike (FHS). Current findings indicate FHS helps enhance Kenyans’ running performance. However, no study has investigated how FHS modulates leg stiffness (kleg) [...] Read more.
A previous study reported that habitually barefoot Kenyan distance runners tend to use a mid-foot strike or a forefoot-heel strike (FHS). Current findings indicate FHS helps enhance Kenyans’ running performance. However, no study has investigated how FHS modulates leg stiffness (kleg) and altered running velocity with changes in kleg. Because vertical displacement of the centre of mass and kleg during hopping are applicable to the running process, this study investigated how FHS affects kleg and hopping frequency (fhopping) during hopping. Subjects hopped at 2.2 Hz with normal hopping (NH-2.2Hz) and at a comfortable frequency with FHS (FHS-CF). According to each subject’s comfortable frequency at FHS-CF, they were divided into higher (HG, 2.49 ± 0.11 Hz) and lower (LG, 2.16 ± 0.19 Hz) groups. With FHS-CF, the flight duration in HG was significantly shorter than that in LG. kleg in HG was greater than that in LG. Negative work in the first half of the stance phase and positive work in the second half of the stance phase at all three joints were smaller in HG than in LG. The touchdown angle was larger and angular displacements at the joints were smaller in HG than in LG. The findings indicate that when hoppers used FHS, they increased their preferred fhopping by stiffening their leg joints during the stance phase and jumping with a lower height than in normal hopping; additionally, it is important to increase the touchdown joint angle for a stiffened joint. Full article
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6 pages, 440 KiB  
Proceeding Paper
Measurement of Pelvic Orientation Angles during Sprinting Using a Single Inertial Sensor
by Tomohito Wada, Ryu Nagahara, Sam Gleadhill, Tatsuro Ishizuka, Hayato Ohnuma and Yuji Ohgi
Proceedings 2020, 49(1), 10; https://doi.org/10.3390/proceedings2020049010 - 15 Jun 2020
Cited by 5 | Viewed by 2238
Abstract
The purpose of this study was to elucidate pelvic orientation angles using a single lower back-mounted inertial sensor during sprinting. A single inertial sensor was attached to each sprinter’s lower back, used to measure continuous pelvic movements including pelvic obliquity (roll), anterior-posterior tilt [...] Read more.
The purpose of this study was to elucidate pelvic orientation angles using a single lower back-mounted inertial sensor during sprinting. A single inertial sensor was attached to each sprinter’s lower back, used to measure continuous pelvic movements including pelvic obliquity (roll), anterior-posterior tilt (pitch) and rotation (yaw) during sprinting from a straight to bend section. The pelvic orientation angles were estimated with the three-dimensional sensor orientation using a sensor fusion algorithm. Absolute angles derived from the sensor were compared with angles obtained from an optical motion capture system over a 15 m length. The root mean squared error between the sensor and motion capture data were 4.1° for roll, 2.8° for pitch and 3.6° for yaw. Therefore, the sensor was comparable to the motion capture system for tracking pelvic angle changes. The inertial sensor is now supported as a valid tool to measure movements of the pelvis during sprinting. Full article
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7 pages, 835 KiB  
Proceeding Paper
A Study of Skin-Close Heat and Moisture with Different Types of Backpacks in Cycling
by Mats Ainegren, Frank I. Michel, Robert Klauer, Andrey Koptyug, Mikael Bäckström, David Samuelsson, Magnus Ahnesjö and Stefan Litzenberger
Proceedings 2020, 49(1), 86; https://doi.org/10.3390/proceedings2020049086 - 15 Jun 2020
Viewed by 2478
Abstract
The aim of this project was to evaluate effects of backpacks with different design intended for use during cycling on skin-close temperature and relative humidity, oxygen uptake, heart rate and aerodynamic drag. Seven subjects took part in the study cycling on a mountain [...] Read more.
The aim of this project was to evaluate effects of backpacks with different design intended for use during cycling on skin-close temperature and relative humidity, oxygen uptake, heart rate and aerodynamic drag. Seven subjects took part in the study cycling on a mountain bike mounted on a “smart trainer” placed on a force plate in a wind tunnel. Three series of experiments were carried out: without backpack, with conventional backpack and with a backpack having innovative rear panel design. As hypothesized, the results showed that an innovatively designed backpack with the ducts deflecting part of the airflow towards some areas of the user’s back provided lower temperature and relative humidity for the microclimate compared to a conventional backpack without airflow channels. Further, reference tests without any backpack resulted in the lowest temperature and humidity. However, no differences were found between the three tests for oxygen uptake, heart rate and aerodynamic drag. Full article
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6 pages, 1045 KiB  
Proceeding Paper
Exposure of Children in a Bicycle Trailer to Whole-Body Vibration
by Stefan Schwanitz, Arne Stuff and Stephan Odenwald
Proceedings 2020, 49(1), 114; https://doi.org/10.3390/proceedings2020049114 - 15 Jun 2020
Cited by 1 | Viewed by 2329
Abstract
This study investigated the effects of road surface (tarmac, gravel, cobblestones), load case (single passenger, two passengers), tire pressure (3.0, 4.0, 5.0 bar), and cycling velocity (10.0, 17.5, 25.0 km/h) on the whole-body vibration of children being transported in a bicycle trailer. Two [...] Read more.
This study investigated the effects of road surface (tarmac, gravel, cobblestones), load case (single passenger, two passengers), tire pressure (3.0, 4.0, 5.0 bar), and cycling velocity (10.0, 17.5, 25.0 km/h) on the whole-body vibration of children being transported in a bicycle trailer. Two types of passive dummies were utilized to mimic a baby and a toddler passenger in terms of weight and height. Road type and cycling velocity caused statistically significant change on the magnitude of whole-body vibrations. Overall, vibration total values were on the “uncomfortable” level of the vibration discomfort scale or even above. The major limitation of the study is the application of passive dummies, which might not represent the biodynamics of the target population. Full article
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6 pages, 635 KiB  
Proceeding Paper
Understanding the Effect of Gloves on Hand-Arm Vibrations in Road Cycling
by Giuseppe Sanseverino, Stefan Schwanitz, Dominik Krumm, Stephan Odenwald and Antonio Lanzotti
Proceedings 2020, 49(1), 70; https://doi.org/10.3390/proceedings2020049070 - 15 Jun 2020
Cited by 1 | Viewed by 2115
Abstract
The aim of this research was to study the effects of cycling gloves on hand-arm vibrations in realistic load scenarios. A test has been performed in the laboratory, a road bicycle handlebar was mounted to the hydraulic cylinder of a universal testing machine, [...] Read more.
The aim of this research was to study the effects of cycling gloves on hand-arm vibrations in realistic load scenarios. A test has been performed in the laboratory, a road bicycle handlebar was mounted to the hydraulic cylinder of a universal testing machine, and the bicycle was fixed on an indoor trainer. Tests were executed for three different hand sizes (small, medium, large), three different frequency ranges (15–25, 35–45, 85–95 Hz), with two different types of gloves (gel-padded; non-padded) and without gloves. The amplitudes and each frequency bands were obtained from a previous field test. Hand-arm vibrations were quantified by means of root mean square values of the frequency-weighted accelerations measured at the subject’s wrist joint. Analysis of variance (ANOVA) showed no significant effect of gloves in reducing vibration transmissibility. Full article
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6 pages, 1761 KiB  
Proceeding Paper
Bicycle Disc Brake Thermal Performance: Combining Dynamometer Tests, Bicycle Experiments, and Modeling
by Ioan Feier, Joseph Way and Rob Redfield
Proceedings 2020, 49(1), 100; https://doi.org/10.3390/proceedings2020049100 - 15 Jun 2020
Cited by 1 | Viewed by 3267
Abstract
High-power bicycle disc braking can create excessive temperatures and boiling brake fluid, resulting in performance degradation and damage. The goal of this work is to understand brake friction performance and thermal behavior for bicycle disc brakes. A previously described disc braking dynamometer is [...] Read more.
High-power bicycle disc braking can create excessive temperatures and boiling brake fluid, resulting in performance degradation and damage. The goal of this work is to understand brake friction performance and thermal behavior for bicycle disc brakes. A previously described disc braking dynamometer is used to assess brake pad performance of sintered metallic brake pads, organic brake pads, and ‘power’ organic pads in up to 400 W of braking power. The friction coefficient is found to be dependent on both temperature and normal force. Friction curve fits are provided for temperatures between 300 K and 550 K. Organic and ‘power’ organic pads are found to have similar behavior, and have higher friction coefficients compared to metallic pads. Further, brakes on an instrumented bicycle are tested in outdoor field trials during downhill descent. A MATLAB thermal model successfully predicts the downhill field brake disc temperatures when using the friction data curve fits. Full article
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6 pages, 3504 KiB  
Proceeding Paper
On the Effectiveness of Suspension Stems in Reducing the Vibration Transmitted to a Cyclist’s Hands in Road Cycling
by Jean-Marc Drouet, Derek Covill and Antoine Labrie
Proceedings 2020, 49(1), 20; https://doi.org/10.3390/proceedings2020049020 - 15 Jun 2020
Cited by 1 | Viewed by 4318
Abstract
The practice of road cycling is often associated with low levels of comfort for the cyclist and can be a physically painful experience on bad roads. Apart from cushioning in the saddle, applying handlebar tape, or reducing tyre pressure, a road bicycle offers [...] Read more.
The practice of road cycling is often associated with low levels of comfort for the cyclist and can be a physically painful experience on bad roads. Apart from cushioning in the saddle, applying handlebar tape, or reducing tyre pressure, a road bicycle offers in itself few options for comfort improvement, as it is primarily designed for performance, with emphasis on low mass and high stiffness. However, a range of components exist (e.g., suspension stems and seatposts) that can be fitted to a road bicycle, which can potentially improve comfort. In this context, the aim of this study was to assess the effectiveness of suspension stems in reducing the vibration transmitted to a cyclist’s hands in the case of impact loading. The results showed an important reduction in the vibrational energy transmitted to a cyclist’s hands with two commercially available suspension stems compared to a regular stem. Full article
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7 pages, 823 KiB  
Proceeding Paper
Development of a Feedback System to Control Power in Cycling
by Patrick Mayerhofer, Matt Jensen, David C. Clarke, James Wakeling and Max Donelan
Proceedings 2020, 49(1), 22; https://doi.org/10.3390/proceedings2020049022 - 15 Jun 2020
Cited by 1 | Viewed by 1990
Abstract
Here we seek to control mechanical power output in outdoor cycling by adjusting commanded cadence of a cyclist. To understand cyclist’s dynamic behavior, we had one participant match their cadence to a range of commanded cadences. We then developed a mathematical model that [...] Read more.
Here we seek to control mechanical power output in outdoor cycling by adjusting commanded cadence of a cyclist. To understand cyclist’s dynamic behavior, we had one participant match their cadence to a range of commanded cadences. We then developed a mathematical model that predicts the actual mechanical power as a function of commanded cadence. The average absolute error between the predicted power of our model and the actual power was 15.9 ± 11.7%. We used this model to simulate our closed-loop controller and optimize for proportional and integral controller gains. With these gains in outdoor cycling experiments, the average absolute error between the target and the actual power was 3.2 ± 1.2% and the average variability in power was 2.9 ± 1.3%. The average responsiveness, defined as the required time for the actual power to reach 95% of the target power following changes in target power, was 7.4 ± 2.0 s. Full article
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6 pages, 1449 KiB  
Proceeding Paper
The Steel Bicycle Project: Bringing Together Tube Manufacturers, Frame Builders, and Engineers through Sports Engineering
by Derek Covill, Jean-Marc Drouet and Andrés Arregui Velázquez
Proceedings 2020, 49(1), 166; https://doi.org/10.3390/proceedings2020049166 - 15 Jun 2020
Viewed by 2718
Abstract
Steel, being the most commonly used bicycle frame material, has a major role to play in future developments within the bicycle industry, and there is scope to enhance the role of engineering in the development of steel bicycles. This paper introduces The Steel [...] Read more.
Steel, being the most commonly used bicycle frame material, has a major role to play in future developments within the bicycle industry, and there is scope to enhance the role of engineering in the development of steel bicycles. This paper introduces The Steel Bicycle Project (TSBP), an open-ended project which aims to raise awareness of engineering principles that relate to steel bicycle frames and aims to support frame builders in designing and fabricating better and safer products. In this paper, we give details of the main project themes (Design and simulation, Materials and fabrication, Testing and measurements, Knowledge and education) and outcomes. We also present some initial activities from the early stages of the project and will discuss general models to bring together key partners under the umbrella of the sports engineering community. Full article
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5 pages, 946 KiB  
Proceeding Paper
Enhancing the Performance of Elite Speed Skaters Using SkateView: A New Device to Measure Performance in Speed Skating
by Jeroen van der Eb, Sjoerd Gereats and Arno Knobbe
Proceedings 2020, 49(1), 133; https://doi.org/10.3390/proceedings2020049133 - 15 Jun 2020
Cited by 2 | Viewed by 2038
Abstract
In speed skating, environmental circumstances and the near-frictionless movement of the skate in a fore–aft direction over the ice make it difficult to measure technical performance parameters on a regular basis while training in an indoor speed skating rink. SkateView has been developed [...] Read more.
In speed skating, environmental circumstances and the near-frictionless movement of the skate in a fore–aft direction over the ice make it difficult to measure technical performance parameters on a regular basis while training in an indoor speed skating rink. SkateView has been developed to overcome these challenges, comprising of two IMU’s (Inertial Measurement Unit), ultra-light force sensors, a mobile phone and an app providing feedback to coach and skater. The feedback, directly on the ice or shortly after a training session, consists of basic parameters like ice contact time, stroke frequency and lap times, and more parameters can be added. Stroke frequency is an important performance parameter, which is presented on a stroke–by–stroke basis and provides a direct insight into the activity. Full article
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6 pages, 329 KiB  
Proceeding Paper
2D Video Analysis System to Analyze the Performance Model of Figure Roller Skating: A Pilot Study
by Cristian Romagnoli, Vincenzo Bonaiuto, Giorgio Gatta, Naomi Romagnoli, Anas Alashram, Elvira Padua and Giuseppe Annino
Proceedings 2020, 49(1), 155; https://doi.org/10.3390/proceedings2020049155 - 15 Jun 2020
Cited by 1 | Viewed by 2069
Abstract
Figure roller skating is a discipline composed of various movements which involve jumps, artistic figures and spins in a seamless program which has both technical and shapely difficult. A biomechanical analysis of a double salchow was performed using a 2D video analysis of [...] Read more.
Figure roller skating is a discipline composed of various movements which involve jumps, artistic figures and spins in a seamless program which has both technical and shapely difficult. A biomechanical analysis of a double salchow was performed using a 2D video analysis of one European and in two Italian roller skaters. On average, the high level (HL) roller skater showed a horizontal velocity of the center of mass higher than the average, especially in the prop stage, whereas the medium level (ML) and low level (LL) athletes reduced their velocity significantly. The spin angular velocity of the ML and LL skaters was always higher than of the HL. This phenomenon would seem to be a compensatory strategy for a lower jump height, with a reduced trunk-thigh angle and less thigh lever arm (coxo-femur/knee joints) during the take-off and landing phases of the double salchow jump. Full article
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6 pages, 3458 KiB  
Proceeding Paper
Comparing Broom Conditions in Curling: Measurements Using Ice Topography
by Megan Balsdon and Jeffrey Wood
Proceedings 2020, 49(1), 82; https://doi.org/10.3390/proceedings2020049082 - 15 Jun 2020
Cited by 4 | Viewed by 3968
Abstract
The sport of curling is played on an ice surface with raised ice pebbles and uses curling rocks made of granite. The effect of sweeping is thought to straighten the rock’s projected curved path and increase the distance travelled. Recent anecdotes suggest that [...] Read more.
The sport of curling is played on an ice surface with raised ice pebbles and uses curling rocks made of granite. The effect of sweeping is thought to straighten the rock’s projected curved path and increase the distance travelled. Recent anecdotes suggest that sweeping from the center of the running surface with the direction of rotation and curl is thought to increase the amount of curl, whereas sweeping against and opposite the curl is thought to decrease the amount of curl. The purpose of this study is to observe the topography of the ice surface while comparing scratch measurements from different broom materials. Nine conditions were replicated: nipped pebble, rock traversing the ice, and seven broom conditions. Replicas of the ice were created with vinyl polysiloxane and observed with an optical microscope. Roughness profiles of the replicas were measured, and broom materials were compared using data from an optical profiler. Full article
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7 pages, 1922 KiB  
Proceeding Paper
Multi-Technology Correction Based 3D Human Pose Estimation for Jump Analysis in Figure Skating
by Limao Tian, Xina Cheng, Masaaki Honda and Takeshi Ikenaga
Proceedings 2020, 49(1), 95; https://doi.org/10.3390/proceedings2020049095 - 15 Jun 2020
Cited by 3 | Viewed by 2348
Abstract
Jump analysis in figure skating is important. Recovering the 3D pose of a figure skater has become increasingly important. However, issues such as restrictions from an athlete’s clothing, self-occlusion, abnormal pose and so on will result in poor results. This paper proposes a [...] Read more.
Jump analysis in figure skating is important. Recovering the 3D pose of a figure skater has become increasingly important. However, issues such as restrictions from an athlete’s clothing, self-occlusion, abnormal pose and so on will result in poor results. This paper proposes a multi-technology correction framework to obtain a 3D human pose. The framework consists of three key components: temporal information-based mutational point correction, multi-perspective-based reconstructed point selection and trajectory smoothness-based inaccurate point correction. Firstly, temporal information is used to correct the mutational points at the 2D level. Secondly, a multi-perspective is used to select the correct spatial points at the 3D level. Thirdly, trajectory smoothness is used to correct inaccuracies at the 3D level. This work will serve the purpose of displaying the 3D animated pose of a figure skater. The quality grade of the result rate on the test sequences is 87.25%. Full article
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7 pages, 388 KiB  
Proceeding Paper
Kinematic Analysis of Figure Skating Jump by Using Wearable Inertial Measurement Units
by Yuchen Shi, Atsushi Ozaki and Masaaki Honda
Proceedings 2020, 49(1), 124; https://doi.org/10.3390/proceedings2020049124 - 15 Jun 2020
Cited by 4 | Viewed by 2622
Abstract
The purpose of this study was to demonstrate the feasibility of measuring and analyzing characteristics of figure skating jumps using wearable sensors. One elite figure skater, outfitted with five inertial measurement units (IMUs), performed flip jumps with single, double, and triple revolutions. Take-off [...] Read more.
The purpose of this study was to demonstrate the feasibility of measuring and analyzing characteristics of figure skating jumps using wearable sensors. One elite figure skater, outfitted with five inertial measurement units (IMUs), performed flip jumps with single, double, and triple revolutions. Take-off event and flight phase of each trial were under analysis. Kinematic differences among jumps with variant revolutions as well as key factors for performing successfully landed triple jumps were determined by IMU signals. Compared with a video-based method, this study revealed the following characteristics that coincide with previous studies: at take-off event, the skater performed pre-rotation and took off with preferred postural positions as revolutions increased (p < 0.01); during flight, the skater struggled more to maintain the smallest inertial of moment as revolutions increased (p < 0.01); in order to perform successfully landed jumps, it was crucial that the skater improved the control of preparation for flight at take-off (p < 0.05). Full article
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6 pages, 753 KiB  
Proceeding Paper
Optimal Shooting Cadence in the Laser-Run Trial of Modern Pentathlon
by Tom Maddalena, Vincent Bacot, Caroline Cohen and Christophe Clanet
Proceedings 2020, 49(1), 46; https://doi.org/10.3390/proceedings2020049046 - 15 Jun 2020
Cited by 4 | Viewed by 1787
Abstract
In the laser-run trial in modern pentathlon, athletes must perform series of five successful shots with a laser pistol. A miss does not lead to a penalty but costs the time needed to lower the arm, charge the weapon and raise the arm. [...] Read more.
In the laser-run trial in modern pentathlon, athletes must perform series of five successful shots with a laser pistol. A miss does not lead to a penalty but costs the time needed to lower the arm, charge the weapon and raise the arm. Pentathletes face the following dilemma: is it better to shoot fast or accurately? We investigate experimentally the effect of the shooting cadence on the accuracy. We then predict the consequence of this unavoidable speed-accuracy tradeoff in terms of total time needed to succeed the specific trial of laser-run. We find an optimal shooting cadence for each athlete, which minimizes this time. Full article
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6 pages, 1051 KiB  
Proceeding Paper
Use of Acceleration Sensors in Archery
by Markus Eckelt, Franziska Mally and Angelika Brunner
Proceedings 2020, 49(1), 98; https://doi.org/10.3390/proceedings2020049098 - 15 Jun 2020
Cited by 1 | Viewed by 2777
Abstract
Archery is a quasi-static sport. Nevertheless, it requires maximum concentration, as well as precision from the archer. Previous research used combinations of several sensors, video analysis and electromyography to analyse the motion sequence and to identify parameters leading to a worse score. Therefore, [...] Read more.
Archery is a quasi-static sport. Nevertheless, it requires maximum concentration, as well as precision from the archer. Previous research used combinations of several sensors, video analysis and electromyography to analyse the motion sequence and to identify parameters leading to a worse score. Therefore, the aim of this study is to verify if solely an acceleration sensor on the archer’s hand, without complex data processing, could be used to set up a feedback system. For testing, six participants with a three dimensional acceleration sensor on each hand shot indoors at a vertical triple target. The parameters analysed were the duration of the movement, the range of motion and the coefficient of variation. The results indicate that the analysis of the coefficient of variation shows no correlation with the score reached, whereas the analysis of the duration and the range of motion does. Full article
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6 pages, 708 KiB  
Proceeding Paper
Experimental and Computational Study of Archery Arrows Fletched with Straight Vanes
by Julio Ortiz, Atsushi Serino, Toshinari Hasegawa, Takahito Onoguchi, Hiroki Maemukai, Takeshi Miyazaki and Hiroki Sugiura
Proceedings 2020, 49(1), 56; https://doi.org/10.3390/proceedings2020049056 - 15 Jun 2020
Viewed by 2112
Abstract
The aerodynamic characteristics of archery arrows fletched with two types of straight vanes, for which the area is different, were studied. The arrows’ pitching moment (CM), lift (CL) and drag (CD) coefficients were measured [...] Read more.
The aerodynamic characteristics of archery arrows fletched with two types of straight vanes, for which the area is different, were studied. The arrows’ pitching moment (CM), lift (CL) and drag (CD) coefficients were measured in the 60 × 60 cm Magnetic Suspension and Balance System (MSBS) from JAXA. At a Reynolds number of Re = 1.2 × 104, the values of CD were 1.56 and 2.05 for the short and large vanes, respectively. In a second experimental procedure, the arrows’ deceleration in free flight was measured by inserting an acceleration sensor inside their shafts. For shots with an initial velocity of around 56.4 ms−1, a velocity decay of around 8% was measured. A turbulent–laminar boundary layer transition during free flight was found for shots with an average Re = 1.8 × 104. Lastly, through numerical computations, the area difference of the two vanes was analyzed to verify the importance of CM and CL during the arrows’ flights. Full article
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7 pages, 865 KiB  
Proceeding Paper
Development of an Archery Robot for the Selection of Arrows
by Masashi Ohara, Naoki Kawasaki, Jun Nakahama, Yogo Takada and Hitoshi Watanabe
Proceedings 2020, 49(1), 115; https://doi.org/10.3390/proceedings2020049115 - 15 Jun 2020
Viewed by 2070
Abstract
The appropriate selection of arrows in the sport of archery is important to the achievement of high-quality results. In this regard, a shooting machine that is compatible with the wide variety of available bows and arrows is necessary. However, bow strength and arrow [...] Read more.
The appropriate selection of arrows in the sport of archery is important to the achievement of high-quality results. In this regard, a shooting machine that is compatible with the wide variety of available bows and arrows is necessary. However, bow strength and arrow length vary among different athletes. It is also important to develop a shooting machine that reproduces the movement of the right fingers that releases an arrow, and the forward jump of a bow after shooting an arrow. In this study, a shooting machine was developed that considered these factors. Its efficacy was examined in terms of its ability to determine the characteristics of each arrow, and to distinguish between normal and flawed arrows. Based on the experimental results, we identified the factors that affected the shooting accuracy of arrows. In addition, the developed shooting machine was able to distinguish between normal and flawed arrows. Full article
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6 pages, 1972 KiB  
Proceeding Paper
Motion and Muscle Activity of Synchronized Rolling-Type Double-Leg Circles on a Pommel Horse
by Motoyuki Nawa, Ayaka Yamada, Kazuie Nishiwaki, Kyoji Yamawaki, Yosuke Ikegami, Yoshihiko Nakamura and Taiga Yamasaki
Proceedings 2020, 49(1), 31; https://doi.org/10.3390/proceedings2020049031 - 15 Jun 2020
Viewed by 1513
Abstract
Experimental analyses of motions of a double-leg circle were conducted for a smooth and dynamic movement. A motion capture system provided the data for two different gymnasts; one is well trained and the other has an average skill level. Lissajous analysis was done [...] Read more.
Experimental analyses of motions of a double-leg circle were conducted for a smooth and dynamic movement. A motion capture system provided the data for two different gymnasts; one is well trained and the other has an average skill level. Lissajous analysis was done for a tip-toe circling motion and a rolling motion around a longitudinal axis of a body. The results show that synchronization between the tip-toe circling and the body-rolling around the body’s longitudinal axis is crucial. Muscle activity was also analyzed from electromyogram data when the gymnasts performed double-leg circles, and the muscle activity characteristics of synchronized rolling-type circles were uncovered. Full article
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6 pages, 1244 KiB  
Proceeding Paper
Investigation of the Athlete’s Motion Using the Gymnastics Apparatus’s Motion
by Naoki Arakawa, Kenya Ohtsuka and Aoki Yoshio
Proceedings 2020, 49(1), 120; https://doi.org/10.3390/proceedings2020049120 - 15 Jun 2020
Cited by 1 | Viewed by 1289
Abstract
In gymnastics, the skeleton of the athletes can be estimated from many points with three-dimensional coordinate data by measurement control using Laser Imaging Detection and Ranging (LIDAR), and the motion can be derived. However, the system cannot know what kind of load is [...] Read more.
In gymnastics, the skeleton of the athletes can be estimated from many points with three-dimensional coordinate data by measurement control using Laser Imaging Detection and Ranging (LIDAR), and the motion can be derived. However, the system cannot know what kind of load is being put on the athletes’ bodies. Additionally, it is not possible to know in detail how top-level athletes handle apparatus. Therefore, it is important to understand the dynamic response of the apparatus to the athlete’s motion. This study shows that the apparatus’s motion can be identified by performing a static load test using a multi-sensing system that can sense how the bar deforms during a game and determine the apparatus’s motions as an inverse analysis. Full article
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7 pages, 896 KiB  
Proceeding Paper
Fully Coupled Modeling of Athlete Force Application and Power Transfer in Rowing Ergometry
by Stephen Tullis and Cameron Galipeau
Proceedings 2020, 49(1), 108; https://doi.org/10.3390/proceedings2020049108 - 15 Jun 2020
Viewed by 1386
Abstract
A fully coupled model of an athlete’s muscular force output combined with a load resistance is developed and investigated in context of ergometer rowing. The athlete force is based on a simple Hill equation hyperbolic-in-speed, and parabolic-in-length model. Coupling this force function with [...] Read more.
A fully coupled model of an athlete’s muscular force output combined with a load resistance is developed and investigated in context of ergometer rowing. The athlete force is based on a simple Hill equation hyperbolic-in-speed, and parabolic-in-length model. Coupling this force function with the dynamics of the ergometer load and inertia and athlete’s own body mass inertia produces a trajectory of the resultant motion in force-speed-length space. The coupled equations were solved using a first order time-marching procedure, and iteratively calculated starting conditions based on ergometer spin-down during the recovery period between strokes. The results agree well with experimental measurements available from Kleshnev particularly given the relatively simple, and untuned, athlete force model used. Changing the load resistance changed the trajectory of the stroke, with qualitative agreement with the expected outcomes. Full article
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6 pages, 976 KiB  
Proceeding Paper
Association between Changes in Swimming Velocity, Vertical Center of Mass Position, and Projected Frontal Area during Maximal 200-m Front Crawl
by Sohei Washino, Akihiko Murai, Hirotoshi Mankyu and Yasuhide Yoshitake
Proceedings 2020, 49(1), 60; https://doi.org/10.3390/proceedings2020049060 - 15 Jun 2020
Cited by 1 | Viewed by 1470
Abstract
We examined the association between changes in swimming velocity, vertical center of mass (CoM) position, and projected frontal area (PFA) during maximal 200-m front crawl. Three well-trained male swimmers performed a single maximal 200-m front crawl in an indoor 25-m pool. Three-dimensional (3D) [...] Read more.
We examined the association between changes in swimming velocity, vertical center of mass (CoM) position, and projected frontal area (PFA) during maximal 200-m front crawl. Three well-trained male swimmers performed a single maximal 200-m front crawl in an indoor 25-m pool. Three-dimensional (3D) shape data of the whole body were fitted to 3D motion data during swimming by using inverse kinematics computation to estimate PFA accurately. Swimming velocity decreased, the vertical CoM position was lowered, and PFA increased with swimming distance. There were significant correlations between swimming velocity and vertical CoM position (|r| = 0.797–0.982) and between swimming velocity and PFA (|r| = 0.716–0.884) for each swimmer. These results suggest that descent of the swimmer’s body and increasing PFA with swimming distance are associated with decreasing swimming velocity, although the causal factor remains unclear. Full article
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5 pages, 598 KiB  
Proceeding Paper
Simulation Model of Flip Turn in Swimming
by Daichi Mori and Motomu Nakashima
Proceedings 2020, 49(1), 165; https://doi.org/10.3390/proceedings2020049165 - 15 Jun 2020
Viewed by 1906
Abstract
The swimming turn is one of the important factors in producing results in a race. Knowing the mechanical quantities in turns is useful to quantify the turning technique. However, experimental measurements often require considerable time and costs. The aim of this study was [...] Read more.
The swimming turn is one of the important factors in producing results in a race. Knowing the mechanical quantities in turns is useful to quantify the turning technique. However, experimental measurements often require considerable time and costs. The aim of this study was to construct a simulation model of a flip turn in the crawl stroke by extending the swimming human simulation model SWUM. The joint motion was created based on the standard crawl motion and a turn commentary video on the Internet. Furthermore, the contact with the wall was represented as forces by virtual springs and dampers and the frictional forces. As a result of simulation, a successful turning motion was confirmed. It was also found that the simulated contact time, the maximum force, and the impulse were within the ranges of the previous research. Full article
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6 pages, 492 KiB  
Proceeding Paper
The Difference of Propulsive Force between Water Surface and Underwater Conditions in Flutter Kick Swimming
by Hiroshi Ichikawa, Hirofumi Shimojo, Yasuhiro Baba, Takao Mise, Rio Nara and Yoshimitsu Shimoyama
Proceedings 2020, 49(1), 167; https://doi.org/10.3390/proceedings2020049167 - 15 Jun 2020
Viewed by 2630
Abstract
This study investigates differences in propulsive force between the water surface and underwater conditions in the flutter kick swimming technique. The subjects were well-trained university male swimmers. A towing device was set up in a 25 m swimming pool to measure the towing [...] Read more.
This study investigates differences in propulsive force between the water surface and underwater conditions in the flutter kick swimming technique. The subjects were well-trained university male swimmers. A towing device was set up in a 25 m swimming pool to measure the towing force and velocity of the swimmer under two conditions: the swimmer was near the water surface and at a depth of 0.60 m. The swimmers performed the gliding trials and the kicking trials with maximum effort with five towing velocities from 1.2 to 2.4 m/s. The passive drag and the resultant force of the propulsive and drag forces in kick swimming were formulated, respectively. The propulsive force was calculated from the difference between the two formulas. A difference of the propulsive force under conditions in high swimming velocity was observed. This suggests that the water surface condition has advantages of raising the foot above water. Full article
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7 pages, 1869 KiB  
Proceeding Paper
Comparing the Aerodynamic Behaviour of Real Footballs to a Smooth Sphere Using Tomographic PIV
by Matthew Ward, Martin Passmore, Adrian Spencer, Andy Harland, Henry Hanson and Tim Lucas
Proceedings 2020, 49(1), 150; https://doi.org/10.3390/proceedings2020049150 - 15 Jun 2020
Cited by 1 | Viewed by 1410
Abstract
Many studies have investigated the forces acting on a football in flight and how these change with the introduction or modification of surface features; however, these rarely give insight into the underlying fluid mechanics causing these changes. In this paper, force balance and [...] Read more.
Many studies have investigated the forces acting on a football in flight and how these change with the introduction or modification of surface features; however, these rarely give insight into the underlying fluid mechanics causing these changes. In this paper, force balance and tomographic particle image velocimetry (PIV) measurements were taken on a smooth sphere and a real Telstar18 football at a range of airspeeds. This was done under both static and spinning conditions utilizing a lower support through the vertical axis of the ball. It was found that the presence of the seams and texturing on the real ball were enough to cause a change from a reverse Magnus effect on the smooth ball to a conventional Magnus on the real ball in some conditions. The tomographic PIV data showed the traditional horseshoe-shaped wake structure behind the sphere and how this changed with the type of Magnus effect. It was found that the positioning of these vortices compared well with the measured side forces. Full article
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7 pages, 8658 KiB  
Proceeding Paper
Numerical Investigation of the Flow around a Feather Shuttlecock with Rotation
by John Hart and Jonathan Potts
Proceedings 2020, 49(1), 28; https://doi.org/10.3390/proceedings2020049028 - 15 Jun 2020
Viewed by 2706
Abstract
This paper presents the first scale resolving computational fluid dynamic (CFD) investigation of a geometrically realistic feather shuttlecock with rotation at a high Reynolds number. Rotation was found to reduce the drag coefficient of the shuttlecock. However, the drag coefficient is shown to [...] Read more.
This paper presents the first scale resolving computational fluid dynamic (CFD) investigation of a geometrically realistic feather shuttlecock with rotation at a high Reynolds number. Rotation was found to reduce the drag coefficient of the shuttlecock. However, the drag coefficient is shown to be independent of the Reynolds number for both rotating and statically fixed shuttlecocks. Particular attention is given to the influence of rotation on the development of flow structures. Rotation is shown to have a clear influence on the formation of flow structures particularly from the feather vanes, and aft of the shuttlecock base. This further raises concerns regarding wind tunnel studies that use traditional experimental sting mounts; typically inserted into this aft region, they have potential to compromise both flow structure and resultant drag forces. As CFD does not necessitate use of a sting with proper application, it has great potential for a detailed study and analysis of shuttlecocks. Full article
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7 pages, 647 KiB  
Proceeding Paper
Investigation of the Aerodynamic Drag of Baseballs with Gyro Spin
by Bin Lyu, Jeff Kensrud and Lloyd Smith
Proceedings 2020, 49(1), 162; https://doi.org/10.3390/proceedings2020049162 - 15 Jun 2020
Viewed by 2333
Abstract
The following considers drag measurements of baseballs with backspin (spin axis horizontal and normal to trajectory) and gyro spin (spin axis parallel to trajectory) orientations. Balls were propelled through still air in a laboratory setting at 36 m/s and spin ranging from 1250 [...] Read more.
The following considers drag measurements of baseballs with backspin (spin axis horizontal and normal to trajectory) and gyro spin (spin axis parallel to trajectory) orientations. Balls were propelled through still air in a laboratory setting at 36 m/s and spin ranging from 1250 rpm to 1750 rpm. Balls were projected with backspin and gyro spin in the two- and four-seam orientations. Speed and position sensors measured the speed and location of the balls at three locations from which the coefficient of drag and lift were found. Drag was observed to depend on spin rate, spin axis and seam orientation. The largest and smallest coefficient of drag was found with the gyro four-seam and two-seam spin orientation, respectively. Drag was observed to correlate with seam height with back spin, but not with gyro spin. Lift was observed for baseballs with back spin, but not with gyro spin. Full article
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6 pages, 331 KiB  
Proceeding Paper
Influence of Surface Properties on Soccer Ball Trajectories
by John Eric Goff, Sungchan Hong and Takeshi Asai
Proceedings 2020, 49(1), 143; https://doi.org/10.3390/proceedings2020049143 - 15 Jun 2020
Cited by 3 | Viewed by 2271
Abstract
In this paper, we summarize our recent research work on soccer balls. Employing wind tunnels and analyses of simulated trajectories, we have gained an understanding of how various surface features influence soccer ball aerodynamics. Wind tunnels provide aerodynamic coefficients for non-spinning soccer balls. [...] Read more.
In this paper, we summarize our recent research work on soccer balls. Employing wind tunnels and analyses of simulated trajectories, we have gained an understanding of how various surface features influence soccer ball aerodynamics. Wind tunnels provide aerodynamic coefficients for non-spinning soccer balls. The coefficients then help determine the trajectories of various simulated kicked balls. Surface features include panel texturing, seam width, and seam depth. We have determined that small changes in surface texturing can lead to hard-kicked soccer balls experiencing lateral deflections as large as 10%–20% of their horizontal ranges. We have also found that the critical Reynolds number for soccer balls is more strongly correlated with seam width than with seam depth. Full article
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6 pages, 1195 KiB  
Proceeding Paper
Comparison of Aerodynamic Properties of Badminton Feather and Synthetic Shuttlecocks
by Kenichi Nakagawa, Hiroaki Hasegawa and Masahide Murakami
Proceedings 2020, 49(1), 104; https://doi.org/10.3390/proceedings2020049104 - 15 Jun 2020
Viewed by 2396
Abstract
The purpose of this study is to investigate the difference in aerodynamic properties between the feather shuttlecock and the synthetic shuttlecock. In particular, we focus on the aerodynamic stability of the two types of shuttlecock during impulsive change of an angle of attack [...] Read more.
The purpose of this study is to investigate the difference in aerodynamic properties between the feather shuttlecock and the synthetic shuttlecock. In particular, we focus on the aerodynamic stability of the two types of shuttlecock during impulsive change of an angle of attack (flip movement). Wind tunnel experiments are performed by using two types of the badminton shuttlecock (feather and synthetic shuttlecocks) to measure the fluid forces, and to visualize the flow fields around the shuttlecock. It is confirmed that the pitching moment coefficient at a near-zero angle-of-attack for feather shuttlecock is larger than that for synthetic shuttlecock. The results indicate that the feather shuttlecock demonstrates high stability in response to the flip phenomenon. Full article
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6 pages, 2280 KiB  
Proceeding Paper
Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes
by Takehiro Tamaru, Shinichiro Ito and Masaki Hiratsuka
Proceedings 2020, 49(1), 146; https://doi.org/10.3390/proceedings2020049146 - 15 Jun 2020
Cited by 1 | Viewed by 3786
Abstract
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 [...] Read more.
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. Full article
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7 pages, 4201 KiB  
Proceeding Paper
Difference of Reynolds Crisis Aspects on Soccer Balls and Their Panels
by Yuki Sakamoto, Shinichiro Ito and Masaki Hiratsuka
Proceedings 2020, 49(1), 117; https://doi.org/10.3390/proceedings2020049117 - 15 Jun 2020
Cited by 1 | Viewed by 1476
Abstract
The soccer ball panel pattern, which changes every World Cup, greatly affects the ball’s aerodynamics and flight characteristics. In this study, the fluid force of 11 soccer balls with different panel patterns was measured by wind tunnel tests. The drag crises with different [...] Read more.
The soccer ball panel pattern, which changes every World Cup, greatly affects the ball’s aerodynamics and flight characteristics. In this study, the fluid force of 11 soccer balls with different panel patterns was measured by wind tunnel tests. The drag crises with different Reynolds numbers were confirmed depending on the panel shape. To understand this, the shapes of panel grooves were measured and the relationship between them was investigated. The flow separation point was also visualized by the oil film method and the particle image velocimetry (PIV) analysis. The separation points were confirmed to be different depending on the panel groove by the oil film method in a supercritical Reynolds region. The flow separation points were found to be almost the same position in the subcritical and supercritical state and to be partly different around the Reynolds number of drag crisis. Full article
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8 pages, 1147 KiB  
Proceeding Paper
Measurement of the Aerodynamic Forces Acting on a Non-Spinning Javelin Using an MSBS
by Takuto Kobayashi, Kazuya Seo, Shoya Kaneda, Kasumi Sasaki, Kento Shinji, Shogo Oyama, Hiroyuki Okuizumi, Yasufumi Konishi, Hiroaki Hasegawa and Shigeru Obayashi
Proceedings 2020, 49(1), 144; https://doi.org/10.3390/proceedings2020049144 - 15 Jun 2020
Cited by 1 | Viewed by 1908
Abstract
Using the world’s largest magnetic suspension and balance system (MSBS) and a low-turbulence wind tunnel, we successfully measured the aerodynamic forces acting on a non-spinning women’s javelin. It was found that the drag and the lift increased as the angle of attack was [...] Read more.
Using the world’s largest magnetic suspension and balance system (MSBS) and a low-turbulence wind tunnel, we successfully measured the aerodynamic forces acting on a non-spinning women’s javelin. It was found that the drag and the lift increased as the angle of attack was increased up to 18°. The pitching moment increased for angles of attack up to about 9°, and then decreased, becoming negative above 12°, indicating nose-down rotation. We used a pseudo supporting rod to simulate a javelin attached to a support, as used in a conventional setup, and confirmed that this interferes with the javelin by creating differences between the aerodynamics forces acting on the javelin with and without the pseudo supporting rod. Full article
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7 pages, 800 KiB  
Proceeding Paper
Measurements of the Flight Trajectory of a Spinning Soccer Ball and the Magnus Force Acting on It
by Takeshi Asai, Kaoru Kimachi, Richong Liu, Masaaki Koido, Masao Nakayama, John Eric Goff and Sungchan Hong
Proceedings 2020, 49(1), 88; https://doi.org/10.3390/proceedings2020049088 - 15 Jun 2020
Cited by 1 | Viewed by 3146
Abstract
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 [...] Read more.
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. Full article
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6 pages, 786 KiB  
Proceeding Paper
Effect of Horizontal Ground Reaction Forces during the Golf Swing: Implications for the Development of Technical Solutions of Golf Swing Analysis
by Maxime Bourgain, Christophe Sauret, Grégoire Prum, Laura Valdes-Tamayo, Olivier Rouillon, Patricia Thoreux and Philippe Rouch
Proceedings 2020, 49(1), 45; https://doi.org/10.3390/proceedings2020049045 - 15 Jun 2020
Viewed by 2627
Abstract
The swing is a key movement for golf. Its in-field performance could be estimated by embedded technologies, but often only vertical ground reaction forces (VGRF) are estimated. However, as the swing plane is inclined, horizontal ground reaction forces (HGRF) are expected to contribute [...] Read more.
The swing is a key movement for golf. Its in-field performance could be estimated by embedded technologies, but often only vertical ground reaction forces (VGRF) are estimated. However, as the swing plane is inclined, horizontal ground reaction forces (HGRF) are expected to contribute to the increase of the club angular velocity. Thus, this study aimed at investigating the role of the HGRF during the golf swing. Twenty-eight golf players were recruited and performed 10 swings with their own driver club, in a motion analysis laboratory, equipped with a full body marker set. Ground reaction forces (GRF) were measured with force-plates. A multibody kinematic optimization was performed with a full body model to estimate the instantaneous location of the golfer’s center of mass (CoM). Moments created by the GRF at the CoM were investigated. Results showed that horizontal forces should not be neglected regarding to VGRF because of their lever arm. Analyzing golf swing with only VGRF appeared not enough and further technological developments are still needed to ecologically measure other components. Full article
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6 pages, 254 KiB  
Proceeding Paper
Just Noticeable Differences in the Length of Golf Irons
by Josh P. Sumner, Jonathan R. Roberts and Aimée C. Mears
Proceedings 2020, 49(1), 147; https://doi.org/10.3390/proceedings2020049147 - 15 Jun 2020
Viewed by 2633
Abstract
Current custom fitting guidelines for golf clubs suggest the smallest change in club length from a standard length iron should be 6 mm (1/4”). However, no previous research suggests why this length change is used. This study aims to identify the minimum noticeable [...] Read more.
Current custom fitting guidelines for golf clubs suggest the smallest change in club length from a standard length iron should be 6 mm (1/4”). However, no previous research suggests why this length change is used. This study aims to identify the minimum noticeable difference in the length of 7-iron clubs using just noticeable difference analysis techniques. Fifty golfers of varying ability were asked to compare a standard length 7-iron to test 7-irons of varying lengths, regarding changes in the perception of club length and body position at address. Irrespective of golfing ability, golfers could perceive a just noticeable difference of 13 mm (1/2”) from the standard length club. However, when asked if changes in body position were present, category 1 golfers noticed differences with a 6 mm change in club length and category 2 golfers noticed differences with a 13 mm change. No changes in body position were perceived by highly handicapped golfers. Full article
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6 pages, 322 KiB  
Proceeding Paper
Investigating the Influence of Shaft Balance Point on Clubhead Speed: A Simulation Study
by William McNally and John McPhee
Proceedings 2020, 49(1), 156; https://doi.org/10.3390/proceedings2020049156 - 15 Jun 2020
Cited by 1 | Viewed by 1531
Abstract
In this study, a dynamic golfer model was used to investigate the influence of the golf shaft’s balance point (i.e., center of mass) on the generation of clubhead speed. Three hypothetical shaft designs having different mass distributions, but the same total mass and [...] Read more.
In this study, a dynamic golfer model was used to investigate the influence of the golf shaft’s balance point (i.e., center of mass) on the generation of clubhead speed. Three hypothetical shaft designs having different mass distributions, but the same total mass and stiffness, were proposed. The golfer model was then stochastically optimized 100 times using each shaft. A statistically significant difference was found between the mean clubhead speeds at impact (p < 0.001), where the clubhead speed increased as the balance point moved closer to the grip. When comparing the two shafts with the largest difference in balance point, a 1.6% increase in mean clubhead speed was observed for a change in balance point of 18.8 cm. The simulation results have implications for shaft design and demonstrate the usefulness of biomechanical models for capturing the complex physical interaction between the golfer and golf club. Full article
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7 pages, 431 KiB  
Proceeding Paper
Influence of Grip Mass on Driving Performance
by Sasho MacKenzie, Luc Champoux and Erik Henrikson
Proceedings 2020, 49(1), 81; https://doi.org/10.3390/proceedings2020049081 - 15 Jun 2020
Cited by 2 | Viewed by 1519
Abstract
The purpose of the study was to determine the influence of grip mass on driver clubhead kinematics at impact as well as the resulting kinematics of the golf ball. Three club mass conditions (275, 325, and 375 g) were tested by 40 experienced [...] Read more.
The purpose of the study was to determine the influence of grip mass on driver clubhead kinematics at impact as well as the resulting kinematics of the golf ball. Three club mass conditions (275, 325, and 375 g) were tested by 40 experienced golfers (handicap = 7.5 ± 5.3) representing a range of clubhead speeds (36 to 54 m/s). Each participant executed 12 drives per condition using matched grips and shafts and a single clubhead. Club mass was modified by inserting 50 g and 100 g into the grips of the two heavier conditions. The heaviest condition was associated with the slowest clubhead speed (p = 0.018) and highest vertical launch (p = 0.002), which resulted in no net influence on driving distance (p = 0.91). Lateral dispersion was greatest with the 325 g condition (p = 0.017), as was horizontal impact spot variability on the driver face (p = 0.031). Findings at the individual golfer level were not reliable enough to suggest that grip mass could be effectively used in a fitting environment to either shift ball flight tendencies or improve consistency. Full article
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6 pages, 880 KiB  
Proceeding Paper
Clustering Golfers through Force Plate Analysis
by Jonathan Shepherd, Erik Henrikson, Scott Lynn and Paul Wood
Proceedings 2020, 49(1), 63; https://doi.org/10.3390/proceedings2020049063 - 15 Jun 2020
Cited by 2 | Viewed by 2097
Abstract
Golf is a sport which requires players to use ground interaction to generate clubhead speed in order to propel the ball towards the target. Force platforms are a technology which can be used to measure these ground reaction forces. Golfers generate force through [...] Read more.
Golf is a sport which requires players to use ground interaction to generate clubhead speed in order to propel the ball towards the target. Force platforms are a technology which can be used to measure these ground reaction forces. Golfers generate force through a combination of jumping, sliding or twisting actions during the swing. Understanding how golfers generate these forces and if there are any groups which golfers could be clustered into could be used to enhance golf instruction as well as clubhead design or fitting practices for golf equipment. A total of 105 right-handed experienced golfers (handicap mean = 8.32 ± 8.31) consented to participate in the study of different swing speeds (31 below 95 mph, 41 over 105 mph and 33 between 95 and 105 mph). A calibrated single force plate was used for the test which sampled at 1000 Hz and recorded force and moment data in three axes. After a self-guided warm up, the players were instructed to hit five 7-iron shots and five drives to the best of their ability in an indoor hitting bay which used a launch monitor to record the club delivery and ball flight information. It was found that handicap or swing speed did not dictate the primary force production mechanism (sliding, jumping or twisting/spinning). This knowledge could aid engineers to design equipment better suited to the individual and help coaches build individualized programs to create power and clubhead speed in all players. Full article
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7 pages, 1260 KiB  
Proceeding Paper
Proposal of Golf Swing Analysis Method Using Singular Value Decomposition
by Kenta Matsumoto, Nobutaka Tsujiuchi, Akihito Ito, Hiroshi Kobayashi, Masahiko Ueda and Kosuke Okazaki
Proceedings 2020, 49(1), 91; https://doi.org/10.3390/proceedings2020049091 - 15 Jun 2020
Cited by 3 | Viewed by 1821
Abstract
We analyzed the relationship between the cooperative actions of golf swings and the differences in swing trajectory. To extract cooperative actions from different swings, we acquired swing data in an experiment on an experienced golfer who swung with two different trajectories. We measured [...] Read more.
We analyzed the relationship between the cooperative actions of golf swings and the differences in swing trajectory. To extract cooperative actions from different swings, we acquired swing data in an experiment on an experienced golfer who swung with two different trajectories. We measured the swings with motion capture system (VICON). We built an observance matrix from the collected positional data and conducted singular value decomposition (SVD) on it. The SVD yielded the cooperative actions as independent modes. Next, we compared the cooperative actions of different swing trajectories in the main mode. The results indicate that the analysis of the golf swing could be divided into a dominant behavior and an accompanying behavior. Full article
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6 pages, 669 KiB  
Proceeding Paper
The Effect of Golf Club Moment of Inertia on Clubhead Delivery and Golfer Kinematics
by Josh Turner, Stephanie E. Forrester, Aimée C. Mears and Jonathan R. Roberts
Proceedings 2020, 49(1), 96; https://doi.org/10.3390/proceedings2020049096 - 15 Jun 2020
Cited by 1 | Viewed by 2113
Abstract
The purpose of this study was to determine the effect of modifying whole club moment of inertia (MOI) on clubhead delivery, thorax and wrist kinematics. Seven skilled golfers hit ~10 shots with two driver conditions (MOI difference ~400 kg∙cm2). A GOM [...] Read more.
The purpose of this study was to determine the effect of modifying whole club moment of inertia (MOI) on clubhead delivery, thorax and wrist kinematics. Seven skilled golfers hit ~10 shots with two driver conditions (MOI difference ~400 kg∙cm2). A GOM system tracked the clubhead at impact and a 12-camera Vicon system was used to determine golfer biomechanics. Paired sample t-tests were conducted to quantify the effect of MOI on clubhead delivery, whilst biomechanical differences during the downswing were determined using statistical parametric mapping. Increasing MOI significantly reduced clubhead velocity (p = 0.001) but had a small and non-significant effect (p ≥ 0.294) on clubhead direction and orientation. The increase in MOI significantly decreased lead wrist flexion, thorax lateral bend and thorax axial rotation velocities during the downswing. The timing and magnitude of the decreases in both thorax velocities, suggests that these were contributing factors of the observed decrease in clubhead velocity. Full article
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6 pages, 456 KiB  
Proceeding Paper
Introducing a New Activity-Based Balance Index Using Accelerometer Data and Evaluating It as a Predictor of Skill Level among Elite Junior Soccer Players
by Shahram Lenjannejadian, Jalil Reisi and Mehdi Salimi
Proceedings 2020, 49(1), 78; https://doi.org/10.3390/proceedings2020049078 - 15 Jun 2020
Viewed by 1462
Abstract
The aim of this study was to introduce a new activity-based balance index by using accelerometer data. Twenty-seven junior soccer players from the Iranian premier league were selected. Four functional tests, consisting of one leg stance, dynamic Y balance, running and dribbling tests, [...] Read more.
The aim of this study was to introduce a new activity-based balance index by using accelerometer data. Twenty-seven junior soccer players from the Iranian premier league were selected. Four functional tests, consisting of one leg stance, dynamic Y balance, running and dribbling tests, were conducted to assess the players’ balance, activity and skill. During these four tests, besides their relative scores, the acceleration of their body center was also recorded. Activity-based balance index (ABI) was calculated using these acceleration data. The results showed positive correlations between ABI and both static and dynamic balance scores. Additionally, negative correlations were found between ABI and dribbling scores, which demonstrate the agility required for this skill. It seems that this new index achieves the evaluation of both the balance and the skill level of soccer players. Perhaps this is a new way of talent identification and also a re-development of balance tests from traditional to modern. Full article
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6 pages, 494 KiB  
Proceeding Paper
Development and Verification of a Highly Accurate and Precise Passing Machine for American Football
by Bernhard Hollaus, Christian Raschner and Andreas Mehrle
Proceedings 2020, 49(1), 94; https://doi.org/10.3390/proceedings2020049094 - 15 Jun 2020
Cited by 1 | Viewed by 2604
Abstract
Passing a ball is a central aspect in the game of American Football. However, current passing machines do not fulfill the high quality standards for adequate catch training. The goal was to realize a passing machine that could do precise and accurate passes [...] Read more.
Passing a ball is a central aspect in the game of American Football. However, current passing machines do not fulfill the high quality standards for adequate catch training. The goal was to realize a passing machine that could do precise and accurate passes in a fully automated way in order to create high quality automated catch training. Automation was carried out to a degree that the release angle in terms of azimuth and elevation, release velocity and the release spin of the ball could be controlled via a wireless device within a reasonable range. Additionally, a pass prediction model was developed to determine where the pass went to and which height to catch it by least squares fit of 225 sample points with a second order function (R2>0.99). Normalized precision and accuracy of the machine were verified in an experiment with precision being less than 1% and accuracy less than 3% for more than 90% of all relevant passes. Full article
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6 pages, 909 KiB  
Proceeding Paper
Peak Compression Force Physics in Rugby Union Scrum
by Benjamin Lallemand, Christophe Clanet, Sylvain Blanchard, Patricio Noriega, Julien Piscione, Olivier Chaplain, Didier Retière and Caroline Cohen
Proceedings 2020, 49(1), 151; https://doi.org/10.3390/proceedings2020049151 - 15 Jun 2020
Cited by 1 | Viewed by 3562
Abstract
Scrums play a major role in Rugby Union games, and are historically known as a showdown between the two packs of opposing teams, composed of their eight forwards players organized in a 3-4-1 configuration, respectively. We investigate scrum mechanics by working with professional [...] Read more.
Scrums play a major role in Rugby Union games, and are historically known as a showdown between the two packs of opposing teams, composed of their eight forwards players organized in a 3-4-1 configuration, respectively. We investigate scrum mechanics by working with professional male forward players from Racing 92, a high-level French Rugby club, and measuring the forces they apply on the French Rugby Federation instrumented scrum machine. Signal analysis reveals two major phases in the force production during a scrummaging effort: an impulsive engagement force, and then a force sustained for a few seconds. We experimentally compare individual performances of the engagement phase. We discuss the influence of the mass and the engagement speed of the players, and we introduce the model we are investigating to describe the individual impact on a scrum machine. We expect this model to be the elementary component of a collective model of a pack. Full article
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6 pages, 1647 KiB  
Proceeding Paper
Non-Parametric Shape Optimization of a Football Boot Bottom Plate
by Jeong-Ro Lee, Andy Harland and Jonathan Roberts
Proceedings 2020, 49(1), 152; https://doi.org/10.3390/proceedings2020049152 - 15 Jun 2020
Cited by 1 | Viewed by 1905
Abstract
This paper describes the non-parametric shape optimization process for a football boot bottom plate. The non-parametric shape optimization process changes the nodes’ location of a model and outputs an optimum shape, which satisfies an optimization objective. The methodology presented in this study was [...] Read more.
This paper describes the non-parametric shape optimization process for a football boot bottom plate. The non-parametric shape optimization process changes the nodes’ location of a model and outputs an optimum shape, which satisfies an optimization objective. The methodology presented in this study was able to change the shape of the football boot bottom plate, especially the dimensions of key features, to achieve four different target bending stiffnesses. Tosca Structure sensitivity-based shape optimization was used to perform the optimization process and output optimum bottom plates. Future research is needed to investigate the accuracy of the process in comparison with that of the previously developed parametric optimization process. Full article
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7 pages, 877 KiB  
Proceeding Paper
Simulation-Driven Design of a Portable Basketball Hoop System
by Drew Burkhalter
Proceedings 2020, 49(1), 131; https://doi.org/10.3390/proceedings2020049131 - 15 Jun 2020
Viewed by 1654
Abstract
A simulation-driven design process is proven to generate improved, more robust, and cost-effective designs within a shorter design cycle. Incorporating simulation and optimization early in the design cycle helps shape the concept designs so fewer iterations and rework are necessary as the design [...] Read more.
A simulation-driven design process is proven to generate improved, more robust, and cost-effective designs within a shorter design cycle. Incorporating simulation and optimization early in the design cycle helps shape the concept designs so fewer iterations and rework are necessary as the design matures. For this case study, a portable basketball hoop system is chosen for several reasons. This is a product that is common in everyday life, easily understood, and has several design challenges. To achieve the various design goals for this product, several optimization tools and simulation disciplines are coupled: multibody simulation to determine the kinematics and dynamics; finite element analysis to find displacements and stresses caused by external loads; topology optimization to define the essential structure to efficiently support the loads the product endures throughout its life cycle; and finally, multimodel optimization to consider all the loads when the structure is in several configurations during the optimization process. Full article
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7 pages, 387 KiB  
Proceeding Paper
Analysis of Arm Joint Torques at Ball-Release for Set and Jump Shots in Basketball
by Hiroki Okubo and Mont Hubbard
Proceedings 2020, 49(1), 4; https://doi.org/10.3390/proceedings2020049004 - 15 Jun 2020
Viewed by 2811
Abstract
A kinetic model of the shooting arms has estimated arm joint torques for one-hand set- and jump-shots in basketball. The dynamic model has three rigid planar links with rotational joints imitating an upper arm, forearm and hand with shoulder, elbow and wrist joints. [...] Read more.
A kinetic model of the shooting arms has estimated arm joint torques for one-hand set- and jump-shots in basketball. The dynamic model has three rigid planar links with rotational joints imitating an upper arm, forearm and hand with shoulder, elbow and wrist joints. In general shots controlled by hand, forearm and upper arm motions, there are many torque combinations of shoulder, elbow and wrist joints to produce shooters’ desired ball-release speed, angle and backspin angular velocity. The minimum of the sum of squares of the torque combinations exists at ball-release, when the release angular velocities of the hand and forearm are equal, and the release angular accelerations of the hand and forearm are also equal. Each torque of the shooting arm joints for the set-shot with upward shoulder speed is smaller than that for the jump-shot. Shoulder, elbow and wrist torques increase in proportion to horizontal shot distances. As release backspin angular speed increases, each of the shoulder, elbow and wrist torques also increases. The torques of the shoulder, elbow and hand affect the horizontal shot distance and the ball-release backspin. Full article
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6 pages, 319 KiB  
Proceeding Paper
Differences in Simulated EMG Activities between a Non-Rotational Shot and an Ordinary Instep Kick Identified by Principal Component Analysis
by Tasuku Miyoshi, Yasuhisa Kamada and Yoshiyuki Kobayashi
Proceedings 2020, 49(1), 154; https://doi.org/10.3390/proceedings2020049154 - 15 Jun 2020
Viewed by 1401
Abstract
The aim of this study was to clarify the major differences in the electromyographic (EMG) activities in the hip joint required to achieve a non-rotational (NR) shot as compared with an instep kick from the spatiotemporal data. For this purpose, simulated EMG activities [...] Read more.
The aim of this study was to clarify the major differences in the electromyographic (EMG) activities in the hip joint required to achieve a non-rotational (NR) shot as compared with an instep kick from the spatiotemporal data. For this purpose, simulated EMG activities obtained from NR shots and instep kicks were analyzed using principal component analysis (PCA). The PCA was conducted using an input matrix constructed from the time-normalized average and the standard deviation of the EMG activities (101 data x (15 muscles; iliacus, gluteus maximus, rectus femoris, biceos femoris, vastus lateralis, vastus medialis, vastus intermedius, semimembranosus, semitendinosus, sartorius, tensor fasciae latae muscle, adductor magnus muscle, adductor longus muscle, gasctrocnemius, and tibialis anterior)). The PCA revealed that the 3rd, 4th and 8th principal component vectors (PCVs) of the 10 generated PCVs were related to achieving the NR shot (p < 0.05). Full article
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6 pages, 509 KiB  
Proceeding Paper
The Coefficient of Friction of Soccer Balls
by Adin Ming Tan, Yehuda Weizman, Firoz Alam and Franz Konstantin Fuss
Proceedings 2020, 49(1), 92; https://doi.org/10.3390/proceedings2020049092 - 15 Jun 2020
Viewed by 3054
Abstract
Nine soccer balls were tested for their friction against a leather sheet, using a force plate. An average normal force of 63.6 N was applied and the movement of the ball had an average velocity of 15 mm/s. Each test was repeated 15 [...] Read more.
Nine soccer balls were tested for their friction against a leather sheet, using a force plate. An average normal force of 63.6 N was applied and the movement of the ball had an average velocity of 15 mm/s. Each test was repeated 15 times and the average Coefficient of Friction (COF) was reported. The following results were obtained: Jabulani (COF: 0.62 ± 0.05); Fracas (COF: 0.41 ± 0.01); Ordem 3 (COF: 0.63 ± 0.02); Teamgeist (COF: 0.38 ± 0.01); Brazuca (COF: 0.45 ± 0.01); Kopanya (COF: 0.39 ± 0.01); React (COF: 0.37 ± 0.01); Finale 15 (COF: 0.39 ± 0.06); Vintage T-panel leather ball (COF: 0.41 ± 0.02). Overall, the COF of all balls tested ranged between 0.37 and 0.62. The Finale 15 ball showed a decreasing COF trend with repeated trials and the React ball produced pronounced slip-stick phenomenon. Full article
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7 pages, 284 KiB  
Proceeding Paper
Comparison of Biomechanical Factors among Straight, Curve and Knuckle Kicking Motions in Soccer
by Kaoru Kimachi, Richong Liu, Masaaki Koido, Sungchan Hong, Shuji Shimonagata, Masao Nakayama and Takeshi Asai
Proceedings 2020, 49(1), 119; https://doi.org/10.3390/proceedings2020049119 - 15 Jun 2020
Viewed by 1578
Abstract
The rotation of a soccer ball is affected by several factors, such as impact point and foot posture, which are generated by joint torque in the lower limb. This study aimed to investigate joint torque in the lower limb that generates foot posture [...] Read more.
The rotation of a soccer ball is affected by several factors, such as impact point and foot posture, which are generated by joint torque in the lower limb. This study aimed to investigate joint torque in the lower limb that generates foot posture and swing trajectory, and compare three types of kicks before and after a practice period for participants to learn to control the ball rotation. An optical three-dimensional motion capture system was used to record the kicking motion of the participants. The results indicate that the adduction torque of the hip joint at the moment of impact decreased for curve kicks (from 0.56 to 0.25 Nm/kg) and increased for knuckle kicks (from −0.09 to 0.37 Nm/kg). We considered that the curve and knuckle kicks swing towards the inside (because of their positive values in the post experiment) with hip joint adduction before impact to control ball rotation. Full article
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6 pages, 772 KiB  
Proceeding Paper
Development of Silicone Elastomer for Use in the Assessment of Padded Clothing in Rugby Union
by Angus Hughes, Heather Driscoll and Matt Carré
Proceedings 2020, 49(1), 77; https://doi.org/10.3390/proceedings2020049077 - 15 Jun 2020
Cited by 5 | Viewed by 1848
Abstract
Rugby Union is a collision sport, with both player to player and player to pitch impacts being frequent. Current test standards for padded clothing in rugby use impact surrogates, which may not accurately replicate the human response. Modern technologies use silicone elastomers to [...] Read more.
Rugby Union is a collision sport, with both player to player and player to pitch impacts being frequent. Current test standards for padded clothing in rugby use impact surrogates, which may not accurately replicate the human response. Modern technologies use silicone elastomers to represent human soft tissue when testing padding, however many commercially available silicones do not match the load response seen by human tissue. This paper describes the fabrication and validation of a bespoke formulation of commercially available silicone elastomer and deadener concentrations that portray a similar load response to relaxed organic muscle tissue. The mechanical responses, both at quasi-static and dynamic strain rates, have been compared, with improved, more representative behaviour being presented. The validation of this silicone elastomer formulation is important in developing a more biofidelic impact surrogate for the assessment of padded clothing in rugby. Full article
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6 pages, 614 KiB  
Proceeding Paper
Perception of Running Shoe Cushioning: Objective and Subjective Measurements in Short-Distance Running
by Bahador Keshvari, Nick Schubert, Veit Senner and Jürgen Mitternacht
Proceedings 2020, 49(1), 121; https://doi.org/10.3390/proceedings2020049121 - 15 Jun 2020
Cited by 1 | Viewed by 2290
Abstract
The aim of this study is to investigate the link between the cushioning feature of running shoes in objective and subjective measurements (OM and SM). In OM, four insoles materials were chosen after impact tests (S1 = 12.6 g, S2 = 7.2 g, [...] Read more.
The aim of this study is to investigate the link between the cushioning feature of running shoes in objective and subjective measurements (OM and SM). In OM, four insoles materials were chosen after impact tests (S1 = 12.6 g, S2 = 7.2 g, G = 11.54 g, and E = 32.41 g). In SM (n = 19), perceived cushioning comfort of insoles was measured using pairwise comparison tests and a Visual analogue scale (VAS) during running. Lower impact peak (IP) leads to greater perceived comfort of cushioning only between S1, S2 and G. But insole E with the highest IP was rated as the most comfortable in cushioning. Its relationship can be explained by associating acceleration magnitudes from the beginning contact to the IP in two possible ways: i) participants did not reach the critical impact peak in SM or ii) participants perceived the critical impact peak, but other factors such as energy rebound and perceived stability influenced their rating in the pairwise comparison tests. Full article
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6 pages, 481 KiB  
Proceeding Paper
Influence of Running Shoes and Running Velocity on “Ride” during Running
by Franziska Mally, Otto Hofstätter and Markus Eckelt
Proceedings 2020, 49(1), 54; https://doi.org/10.3390/proceedings2020049054 - 15 Jun 2020
Cited by 1 | Viewed by 2032
Abstract
“Ride” has been established to subjectively describe the heel-to-toe transition during walking and running. Recently, a study was published aiming to quantify “ride” by linking it to the maximum velocity of the anterior-posterior (AP) progression of the center of pressure (COP) during the [...] Read more.
“Ride” has been established to subjectively describe the heel-to-toe transition during walking and running. Recently, a study was published aiming to quantify “ride” by linking it to the maximum velocity of the anterior-posterior (AP) progression of the center of pressure (COP) during the first 30% of the stance phase. While that study investigated the parameter when running at a constant velocity of approximately 3.5 m/s (i.e., 12.6 km/h), this study was carried out to evaluate the influence of running velocity on “ride” when running. Five healthy participants performed runs on a treadmill at 8, 10 and 12 km/h with three different running shoes, and their plantar pressure was measured at 300 Hz using pressure-sensing insoles. “Ride” was calculated as suggested by the previously mentioned study. In two of the three shoes, “ride” decreased with increasing running speed. Between the shoes, however, there is no clear image of how the shoes influence this parameter. Full article
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5 pages, 533 KiB  
Proceeding Paper
In-Shoe Plantar Pressure Measurement—Influence of Insole Placement on Selected Parameters during Running
by Franziska Mally, Otto Hofstätter and Markus Eckelt
Proceedings 2020, 49(1), 50; https://doi.org/10.3390/proceedings2020049050 - 15 Jun 2020
Cited by 1 | Viewed by 2345
Abstract
While it is assumed that pressure-sensing insoles are usually placed directly below the foot and on top of the shoes’ standard insoles, nearly no previously published study actually describes the procedure, which leaves a slight uncertainty. Therefore, the aim of this study was [...] Read more.
While it is assumed that pressure-sensing insoles are usually placed directly below the foot and on top of the shoes’ standard insoles, nearly no previously published study actually describes the procedure, which leaves a slight uncertainty. Therefore, the aim of this study was to evaluate whether the placement has an influence on selected parameters or not. Five healthy participants took part in the measurements and ran on a treadmill at a running velocity of 10 km/h with three different running shoes. Plantar pressure was measured using pressure-sensing insoles, which were once placed on top and once below the shoes’ standard insoles. Selected parameters were the maximum and mean pressure and the range of the center of pressure (COP) in anterior–posterior and medial–lateral directions. The results indicate that maximum and mean pressure decrease when the pressure-sensing insole lies below the shoe’s insole and the medial–lateral COP is the least effected parameter. Full article
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7 pages, 215 KiB  
Proceeding Paper
Running Shoes—Possible Correlations of Biomechanical and Material Tests
by Markus Eckelt and Franziska Mally
Proceedings 2020, 49(1), 25; https://doi.org/10.3390/proceedings2020049025 - 15 Jun 2020
Viewed by 2263
Abstract
Today’s development of running shoes is often supported by the assessment of biomechanical tests (BIOs) as well as material tests (MATs). In order to possibly reduce the number of relevant tests, the aim of this study was to find out whether there are [...] Read more.
Today’s development of running shoes is often supported by the assessment of biomechanical tests (BIOs) as well as material tests (MATs). In order to possibly reduce the number of relevant tests, the aim of this study was to find out whether there are correlations between the selected BIO and MATs. Therefore, four different running shoes were tested. For the BIO, the ground reaction force and tibial acceleration of 19 experienced runners were measured. The evaluated parameters were first peak, time to first peak, impulse during the first 75 ms of stance, maximum vertical ground reaction force, loading rate, mean peak acceleration and median power frequency. The MATs included compression tests and an impact test with and without insoles at the forefoot as well as the heel area. The results show that carrying out MATs (especially impact tests) without insoles give the most insight into the parameters analysed with the BIO. Full article
7 pages, 839 KiB  
Proceeding Paper
Effect of Rest Periods on Mechanical Ageing of Running Shoes
by Tom Allen, Matthew Pagan, Ryan Martin and Olly Duncan
Proceedings 2020, 49(1), 138; https://doi.org/10.3390/proceedings2020049138 - 15 Jun 2020
Viewed by 4030
Abstract
Running is a popular form of exercise, although runners are prone to injury from repeated impact. Running shoes can limit impact forces, but they deteriorate with use. Mechanical ageing typically involves repeatedly compressing the midsole while measuring the energy absorbed within compression cycles [...] Read more.
Running is a popular form of exercise, although runners are prone to injury from repeated impact. Running shoes can limit impact forces, but they deteriorate with use. Mechanical ageing typically involves repeatedly compressing the midsole while measuring the energy absorbed within compression cycles to assess degradation. Literature suggests mechanical aging often causes a higher rate of degradation than natural ageing. This work investigated the effect of introducing rest periods into mechanical ageing. Five shoes were mechanically aged using a sine plus dwell waveform (1.25 Hz, max. load 1.5 kN) for seven hours, equating to a simulated distance of 60 km. Three of the shoes were rested for 22 hours every 20 km. The shoes aged with rest periods absorbed more energy than their unrested counterparts for the first 10 km when testing recommenced. This finding has implications for the mechanical ageing, design and recommended lifespan of running shoes. Full article
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7 pages, 485 KiB  
Proceeding Paper
Classification of the Runner’s Preferences in Running Shoes Based on Equilibrium-Point-Based Muscle Synergies
by Daisuke Kogawa, Hiroaki Hirai and Hideya Okamoto
Proceedings 2020, 49(1), 85; https://doi.org/10.3390/proceedings2020049085 - 15 Jun 2020
Cited by 2 | Viewed by 1368
Abstract
For many runners, mechanical characteristics of running shoes, such as cushioning ability, are important in finding their suitable shoes. In addition to that, subjective comfort has come to be regarded as a non-negligible factor these days. According to previous studies, it has been [...] Read more.
For many runners, mechanical characteristics of running shoes, such as cushioning ability, are important in finding their suitable shoes. In addition to that, subjective comfort has come to be regarded as a non-negligible factor these days. According to previous studies, it has been found that more comfortable shoe conditions are associated with less oxygen consumption and fewer injury frequencies as compared to the less comfortable shoe conditions. However, there is also the fact that the shoes that they feel comfortable with are different from runner to runner, and it still remains unclear why the runners consider their shoes comfortable. Therefore, in this study, we tried to find the differences between several groups with different shoe preferences, applying an equilibrium-point (EP)-based muscle synergy analysis to know the reason why runners consider the shoes comfortable. As a result of the study, it was found that ankle EP velocity could distinguish between the groups classified by shoe preference. This fact indicates that some force-related parameters calculated from posture and stiffness affect the feeling of comfort. Full article
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6 pages, 356 KiB  
Proceeding Paper
Impact of Alternative Synthetic Turf Infills on Athlete Performance and Safety
by Kyley Dickson, John Sorochan and William Strunk
Proceedings 2020, 49(1), 35; https://doi.org/10.3390/proceedings2020049035 - 15 Jun 2020
Cited by 1 | Viewed by 1727
Abstract
The objective of this study is to determine the impact of three alternative infills of various particle size on athlete performance and safety in a third generation (3G) synthetic fields. A complete randomized design composed of three different infill materials (thermoplastic elastomer, coconut [...] Read more.
The objective of this study is to determine the impact of three alternative infills of various particle size on athlete performance and safety in a third generation (3G) synthetic fields. A complete randomized design composed of three different infill materials (thermoplastic elastomer, coconut and cork mixture, and recycled Nike shoes (Nano)) with all infills having the same infill depth, fiber length, fiber density, and shock pad. The study took place at the Center for Athletic Field Safety (CAFS) during the summer of 2017 in Knoxville, TN. Each plot received 120 traffic events with the CAFS traffic simulator. This study found that alternative infills do impact the safety and performance of the field, while showing a variation of performance properties among the alternative infills. The results of this study indicate that particle size and distribution of the infill plays a key role in the superior field performance in 3G turf. Full article
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6 pages, 510 KiB  
Proceeding Paper
Impact of Brushing and Infill Maintenance on Field Safety of Third Generation Synthetic Turf
by Kyley Dickson, John Sorochan, William Strunk and Taylor Williams
Proceedings 2020, 49(1), 34; https://doi.org/10.3390/proceedings2020049034 - 15 Jun 2020
Viewed by 1671
Abstract
The objective of this study was to investigate the impact of brushing and infill maintenance of third generation (3G) synthetic turf on field safety. A split-plot randomized complete block design was used with six different fiber pile heights, infill depths, and shock pad [...] Read more.
The objective of this study was to investigate the impact of brushing and infill maintenance of third generation (3G) synthetic turf on field safety. A split-plot randomized complete block design was used with six different fiber pile heights, infill depths, and shock pad combinations subjected to 120 games in the summer of 2017 at the Center for Athletic Field Safety (CAFS) in Knoxville, TN, USA. Traffic was applied with a CAFS traffic simulator. Half of the plots received maintenance every 20 games with a rotating power broom and infill applied to those below manufacturer’s recommendations. All 3G synthetic turf systems required maintenance to the same degree, and maintenance was necessary to keep surface hardness of 3G synthetic turf systems consistent and acceptable. Overall, field safety and consistency increased in this study due to maintenance, thus suggesting brushing and infill maintenance plays a vital role in maintaining high performance on 3G synthetic fields. Full article
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6 pages, 378 KiB  
Proceeding Paper
A Penetrometer for Quantifying the Surface Stiffness of Sport Sand Surfaces
by David V. Thiel, Matthew T. O. Worsey, Florian Klodzinski, Nicholas Emerson and Hugo G. Espinosa
Proceedings 2020, 49(1), 64; https://doi.org/10.3390/proceedings2020049064 - 15 Jun 2020
Cited by 2 | Viewed by 2170
Abstract
Sand sports include running, volleyball, soccer, beach flags, ironman, and fitness training. An increased amount of soft tissue injuries have been widely reported. A novel technique of determining the surface stiffness of beach sand in-situ used a simple drop-test penetrometer. The relationship between [...] Read more.
Sand sports include running, volleyball, soccer, beach flags, ironman, and fitness training. An increased amount of soft tissue injuries have been widely reported. A novel technique of determining the surface stiffness of beach sand in-situ used a simple drop-test penetrometer. The relationship between drop height and the depth of penetration squared was linear (Pearson’s correlation coefficient r2 > 0.92). The stiffness ratio between the soft dry sand and ocean-saturated wet sand compacted by eight hours of coastal water exposure was approximately seven, which was similar to previously reported stiffness measurements in a sand box. However, the absolute stiffness values were much smaller. While this technique was manually operated, an automatic system is postulated for future studies. Full article
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7 pages, 1006 KiB  
Proceeding Paper
Influence of Ambient Temperature on TVOC Released from Polyurethane Athletics Track
by Gan Liu, Weitao Zheng and Hong Wang
Proceedings 2020, 49(1), 1; https://doi.org/10.3390/proceedings2020049001 - 15 Jun 2020
Viewed by 1422
Abstract
The athletics track consists of multiple organic hydrocarbons and their derivatives, which are easy to release TVOC under specific conditions such as high temperature. Taking polyurethane athletics track as the research object, the TVOC release of an athletics track is carried out in [...] Read more.
The athletics track consists of multiple organic hydrocarbons and their derivatives, which are easy to release TVOC under specific conditions such as high temperature. Taking polyurethane athletics track as the research object, the TVOC release of an athletics track is carried out in a 0.1 m3 environmental chamber, and TVOC mass concentration detection is performed using a TVOC gas detector. The results show that the increase in ambient temperature will promote the release of VOCs from a PU athletics track, and the increase rate and decline rate of TVOC mass concentration will increase with the increase in ambient temperature. The increase in ambient temperature will result in a significant shortening of the rapid release of VOCs released from a PU athletics track and a prolonged slow-release period. The ambient temperature rises, the maximum and 24 h value of TVOC mass concentration of the PU athletics track are steadily increasing, and this trend is more significant in the high-temperature section. The research conclusions can provide a basis for the improvement of athletics tracks. Full article
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6 pages, 1686 KiB  
Proceeding Paper
Shoe–Surface Tribology in Hardcourt Tennis
by John Hale, Roger Lewis and Matt J. Carré
Proceedings 2020, 49(1), 90; https://doi.org/10.3390/proceedings2020049090 - 15 Jun 2020
Cited by 1 | Viewed by 1975
Abstract
Sports shoes used for hardcourt tennis vary greatly in outsole tread design. In this study, a series of experiments were conducted on individual shoe tread elements, replicating the tribological conditions they will experience during hardcourt step and slide movements. It was found that [...] Read more.
Sports shoes used for hardcourt tennis vary greatly in outsole tread design. In this study, a series of experiments were conducted on individual shoe tread elements, replicating the tribological conditions they will experience during hardcourt step and slide movements. It was found that tread element orientation does not influence the friction during step movements, but has a moderate effect on the friction during hardcourt slides. This is considered to be due to differing amounts of wear and frictional heat experienced. Full article
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7 pages, 1833 KiB  
Proceeding Paper
Spatial Measurements for Artificial Turf Systems Using Hall Effect Sensors
by David Cole, Paul Fleming, Steph Forrester and Kelly Morrison
Proceedings 2020, 49(1), 160; https://doi.org/10.3390/proceedings2020049160 - 15 Jun 2020
Viewed by 1583
Abstract
The purpose of this study was to evaluate a bespoke spatial measurement methodology using Hall Effect Sensors (HES), i.e., utilizing inductance between a permanent magnet and sensor to indirectly measure the magnet position. The aim is to embed the magnet in a boot’s [...] Read more.
The purpose of this study was to evaluate a bespoke spatial measurement methodology using Hall Effect Sensors (HES), i.e., utilizing inductance between a permanent magnet and sensor to indirectly measure the magnet position. The aim is to embed the magnet in a boot’s stud and use an array of sensors in the artificial turf. To evaluate the accuracy and applicability of a HES system in sports turf, two studies were carried out. To measure the spatial position vertically, a standard mechanical dynamic impact testing with the magnet embedded, and the sensors below the turf carpet, was compared to the gold standard optical reference measurement system (GOM UK Ltd.: Coventry, UK) . A second study evaluated the horizontal spatial accuracy for sensors in a variable array with a controlled incremental step movement of the magnet on a precise engineering workshop table. Full article
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7 pages, 695 KiB  
Proceeding Paper
Hardness Safety Testing of Artificial Turf
by Paul Fleming, Charlie Watts, Jon Gunn and Steph Forrester
Proceedings 2020, 49(1), 130; https://doi.org/10.3390/proceedings2020049130 - 15 Jun 2020
Cited by 3 | Viewed by 1790
Abstract
This paper compares four sport surface hardness impact test devices, for use on artificial turf (AT) surfaces to control safety. Sports governing bodies require sport surfaces to be assessed with the “Advanced Artificial Athlete” (AAA) mechanical test. The AAA data presented here demonstrate [...] Read more.
This paper compares four sport surface hardness impact test devices, for use on artificial turf (AT) surfaces to control safety. Sports governing bodies require sport surfaces to be assessed with the “Advanced Artificial Athlete” (AAA) mechanical test. The AAA data presented here demonstrate that this high energy test causes compaction of the particulate rubber infill during testing, such that the derived “field test value” is less relevant to the initial state of the surface and arguably also to player comfort. This paper reports on alternative impact test methods and their correlation to the AAA, including a novel comparison to the more portable Fieldtester. The potential use of a lightweight 0.5 kg Clegg Hammer for assessing the change in state of the infill and monitoring the effectiveness of field maintenance is also reported. These results expand our understanding of factors influencing surface hardness and safety, with useful implications for practitioners. Full article
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7 pages, 666 KiB  
Proceeding Paper
High Load Stress-Strain Property of Natural Turf for Professional Use, Various Types of Natural, Hybrid and Artificial Turfs in Football
by Hiroyuki Nunome, Koichiro Inoue, Kevin Ball, Shinya Sano and Yasuo Ikegami
Proceedings 2020, 49(1), 142; https://doi.org/10.3390/proceedings2020049142 - 15 Jun 2020
Cited by 2 | Viewed by 1654
Abstract
High load quasi stress-strain (qSS) properties of professionally maintained natural turf (N-pro) was compared with eight natural, hybrid or artificial turfs: one professionally maintained natural turf in a sub field and one grown in a test field without maintenance, two hybrid turfs (one [...] Read more.
High load quasi stress-strain (qSS) properties of professionally maintained natural turf (N-pro) was compared with eight natural, hybrid or artificial turfs: one professionally maintained natural turf in a sub field and one grown in a test field without maintenance, two hybrid turfs (one in the sub field and one grown in the test field without maintenance), three new artificial turfs (sand, rubber and sand/rubber infill) and one aged artificial turf (eight years old with sand/rubber infill). N-pro was characterized with a distinctive magnitude of plastic deformation and hysteresis profile, indicating its more energy absorbable properties compared to the artificial turfs. Apparent differences exist between N-pro and other natural turfs, suggesting factors such as daily maintenance work and sod compositions are very influential. Clear differences were also observed when the hybrid turf was professionally maintained. The aged artificial turf becomes substantially stiffer indicating usage over years affects the stiffness. Full article
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5 pages, 569 KiB  
Proceeding Paper
Sprint and Change of Direction Performances on Three Different Futsal Playing Surfaces
by Shariman Ismadi Ismail, Hiroyuki Nunome, Yuji Tamura, Takahito Iga and Shusei Sugi
Proceedings 2020, 49(1), 17; https://doi.org/10.3390/proceedings2020049017 - 15 Jun 2020
Cited by 1 | Viewed by 1553
Abstract
This study was conducted to clarify the differences in sprint and change of direction performances on different futsal flooring systems (area-elastic (AE) vs. combined-elastic (CE)). Eight recreational athletes were recruited to perform the 505-agility test on three different EN 14904-certified futsal playing surfaces [...] Read more.
This study was conducted to clarify the differences in sprint and change of direction performances on different futsal flooring systems (area-elastic (AE) vs. combined-elastic (CE)). Eight recreational athletes were recruited to perform the 505-agility test on three different EN 14904-certified futsal playing surfaces (AE, CE1 and CE2). All participants wore an identical footwear during the test. Timing-gate systems were utilized to record the time of 5-m sprint run-up and the change of direction components from the agility test. Participants were also requested to evaluate the perceived shoe-surface overall traction performance after each trial. The differences of performance across all surfaces were analyzed by one-way ANOVA repeated measures (p < 0.05). Results revealed that there was significant difference in change of direction performance between CE1 and CE2 surfaces (p = 0.04). It was also found that the mean score of the perceived traction performance evaluated by the participants were significantly different across all surfaces (p < 0.05). Full article
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8 pages, 1179 KiB  
Proceeding Paper
The Role of Friction and Tangential Compliance on the Resultant Launch Angle of a Golf Ball
by Erik Henrikson, Paul Wood, Chris Broadie and Tom Nuttall
Proceedings 2020, 49(1), 27; https://doi.org/10.3390/proceedings2020049027 - 15 Jun 2020
Cited by 2 | Viewed by 2401
Abstract
A thorough understanding of how the delivered face angle and club path of a golf club influences the initial launch direction of a golf ball can play a significant role in the design of various club types as well as help players and [...] Read more.
A thorough understanding of how the delivered face angle and club path of a golf club influences the initial launch direction of a golf ball can play a significant role in the design of various club types as well as help players and coaches better understand performance in the field. A theoretical model based on a Hertzian impact formulation with the inclusion of tangential compliance via Coulomb friction is compared to empirical results. This comparison demonstrates that the initial launch direction of a golf ball for a given club path and face angle can be sufficiently predicted by the theoretical model, providing insights into the mechanisms leading to different launch direction percentages relative to face angle for various club types. Additionally, the relationship between launch direction and the coefficient of friction is explored for various angles of incidence. Full article
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7 pages, 666 KiB  
Proceeding Paper
Adjusting a Momentum-Based Golf Clubhead-Ball Impact Model to Improve Accuracy
by Behzad Danaei, William McNally, Erik Henrikson and John McPhee
Proceedings 2020, 49(1), 47; https://doi.org/10.3390/proceedings2020049047 - 15 Jun 2020
Cited by 3 | Viewed by 2040
Abstract
In this paper, two simple and physically meaningful adjustments were made to a momentum-based clubhead-ball impact model to predict golf ball launch conditions with better accuracy. These adjustments were motivated by two shortcomings of the momentum-based impact model, namely the absence of shaft [...] Read more.
In this paper, two simple and physically meaningful adjustments were made to a momentum-based clubhead-ball impact model to predict golf ball launch conditions with better accuracy. These adjustments were motivated by two shortcomings of the momentum-based impact model, namely the absence of shaft effects and golf ball deformation. Kinematic data from a golf impact motion capture experiment was used to empirically determine the parameter adjustments that minimized the ball speed and spin errors. It was found that the original model’s ball speed deficiency could be corrected by adding less than 3 g to the clubhead mass, and the amount of added mass correlated with the mass of the shaft. Additionally, the original model’s backspin and sidespin errors were significantly reduced by making a slight adjustment to the golf ball’s center of mass position relative to the impact location. Specifically, moving the golf ball center of mass approximately 0.5 mm downward and 0.07 mm towards the heel reduced the mean backspin and sidespin errors by approximately 85% each. Full article
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7 pages, 907 KiB  
Proceeding Paper
Exploration of Center of Gravity, Moment of Inertia, and Launch Direction for Putters with Ball Speed Normalizing Face Properties
by Jacob Lambeth, Dustin Brekke and Jeff Brunski
Proceedings 2020, 49(1), 2; https://doi.org/10.3390/proceedings2020049002 - 15 Jun 2020
Cited by 1 | Viewed by 2467
Abstract
The forgiveness of golf putters is traditionally achieved through weight distribution. Putters are often designed with large footprints, which help to increase the moment of inertia (MOI), but consequently move the center of gravity (CG) farther behind the face. The use of higher [...] Read more.
The forgiveness of golf putters is traditionally achieved through weight distribution. Putters are often designed with large footprints, which help to increase the moment of inertia (MOI), but consequently move the center of gravity (CG) farther behind the face. The use of higher MOI putters will result in less ball speed loss on impacts away from the sweet spot (i.e., more forgiveness). It has been shown that certain face properties, such as milling patterns, grooves, or soft inserts, can be leveraged to have a similar effect. This paper explores the relationships between impact location, MOI, CG depth, discretionary mass placement, and launch direction for these putters. A novel design strategy is proposed. Minimizing CG depth for putters with ball speed normalizing face properties, even at the expense of MOI, can result in more consistent launch direction and distance control for the average player. Full article
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7 pages, 2782 KiB  
Proceeding Paper
A Review of Equestrian Polo and a Methodology for Testing the Mechanical Properties of the Mallet
by Paul Ewart, Ken Louie and Hong Zhou
Proceedings 2020, 49(1), 99; https://doi.org/10.3390/proceedings2020049099 - 15 Jun 2020
Viewed by 1360
Abstract
: Equestrian polo is struggling to grow and attract young players due to the perception it is a game played by royals and the rich only, and is not a real sport. This study highlights the high level of skill and athletic challenge [...] Read more.
: Equestrian polo is struggling to grow and attract young players due to the perception it is a game played by royals and the rich only, and is not a real sport. This study highlights the high level of skill and athletic challenge faced by the players. Literature is scarce for polo despite its global appeal and the high value of the game in terms of historical reach and investment by the polo community. The game is also unique in sports due to the multiplicity of interactions such as player–pony, pony–ground, player–mallet, and mallet–ball. This work introduces the basics of the game with a graphical interpretation of the motion of the mallet during play. The mallet is constructed of natural materials, the shaft from a rattan cane whilst the handle and head are crafted from hardwood. Using a materials analysis approach, a testing methodology is proposed that will enable quantifiable data to be produced based on the properties and performance of the mallet. The purpose of this is to enable benchmarking of the mallet based on the material properties and their assembled response to the testing. Quasi-static load tests using a universal testing instrument are followed by dynamic testing using inertial sensors. All testing is done in planes chosen to replicate the common lines of action of match play. The quasi-static tests enabled a value for stiffness (k), and the dynamic testing enabled a damping coefficient (c) to be calculated. These quantities will enable a quantitative measure for the properties and performance of any mallet and thereby remove the subjective nature of assessment. Subsequent study will then determine how these data correlate with the performance in play, as well as impact, trajectory, and fatigue responses. Full article
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7 pages, 766 KiB  
Proceeding Paper
Effects of Pimple Height of a Table Tennis Rubber on Ball Rebound Behavior
by Yoshiya Miyazawa, Akihiro Hadano and Katsumasa Tanaka
Proceedings 2020, 49(1), 55; https://doi.org/10.3390/proceedings2020049055 - 15 Jun 2020
Cited by 2 | Viewed by 2222
Abstract
The objective of this study was to construct a finite element (FE) model of table tennis rubber (Sandwich rubber) with pimples structure, which can accurately estimate the rebound behavior of the ball at impact, and to investigate effects of its structure on ball [...] Read more.
The objective of this study was to construct a finite element (FE) model of table tennis rubber (Sandwich rubber) with pimples structure, which can accurately estimate the rebound behavior of the ball at impact, and to investigate effects of its structure on ball rebound behavior. The sandwich rubber is composed of a combination of a rubber and foam layers. The FE model of the sandwich rubber was constructed with non-linearity, strain rate dependency, and energy absorption which were expressed based on the results of material tests. Impact analyses were conducted using the developed model of sandwich rubber and ball with different pimple heights. The simulation results of rebound behavior do not tend to be proportional to the pimple height. The trend of the rebound behavior was mainly affected by the amount of impulse during impact calculated using the horizontal component of the contact force which was varied with changes in pimple height. Full article
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8 pages, 1672 KiB  
Proceeding Paper
A Study on the Mechanical Characteristics of String Planes of Badminton Racquets by Nonlinear Finite Element Analysis
by Masatomo Takizawa, Akihiro Matsuda and Tomohiro Hashiguchi
Proceedings 2020, 49(1), 42; https://doi.org/10.3390/proceedings2020049042 - 15 Jun 2020
Cited by 1 | Viewed by 2107
Abstract
In this study, the finite element analysis of the string planes of badminton racquets was investigated to evaluate the effect of the mechanical characteristics of polymer strings. The nonlinear mechanical characteristics of commercially available polymer strings were obtained by the uniaxial loading tests [...] Read more.
In this study, the finite element analysis of the string planes of badminton racquets was investigated to evaluate the effect of the mechanical characteristics of polymer strings. The nonlinear mechanical characteristics of commercially available polymer strings were obtained by the uniaxial loading tests experimentally. The effects of the strain rate on the mechanical characteristics of the polymer strings were also investigated to consider the dynamic effect on the numerical simulation. The numerical simulation code used to analyze the string planes of the badminton racquets was developed originally. A nonlinear elastic model (Yeoh model) was applied to the mechanical characteristics of the polymer string. Simulated results were compared with the experimental results. The effect of the mechanical characteristics of the polymer strings and the geometrical shape of the badminton racquets on the out-of-plane stiffnesses were investigated. Full article
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5 pages, 2075 KiB  
Proceeding Paper
Impact Characteristics of a Badminton Racket with Realistic Finite Element Modeling
by Shih-Rong Yin, Hung-Chih Chang and Kuangyou B. Cheng
Proceedings 2020, 49(1), 106; https://doi.org/10.3390/proceedings2020049106 - 15 Jun 2020
Cited by 1 | Viewed by 2130
Abstract
The tension of strings on a badminton racket can be adjusted by players according to their personal experiences. The best way to execute such an adjustment remains unclear. A finite element model was employed in this study to investigate the effect of having [...] Read more.
The tension of strings on a badminton racket can be adjusted by players according to their personal experiences. The best way to execute such an adjustment remains unclear. A finite element model was employed in this study to investigate the effect of having nonuniform string tension on string-bed deformation, and the direction of force applied to shuttlecock head upon impact. The racket model was based on a commercially available racket with a simplified string-bed of 16 strings established using SolidWorks. A displacement was applied to the ball to simulate impacting on the string-bed. The simulations revealed that slightly lowering the tension of off-centered strings had a minimal effect on the von Mises stress distribution of the ball and string-bed. The off-centered impact caused comparable contact force magnitude but altered force direction. Further investigation is needed for understanding the effect of varying string tension on badminton racket performance. Full article
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7 pages, 820 KiB  
Proceeding Paper
Influence of Ball Impact Location on Racquet Kinematics, Forearm Muscle Activation and Shot Accuracy during the Forehand Groundstrokes in Tennis
by Masahiro Ikenaga, Nobue Okuma, Hiroki Nishiyama, Shinichiro Chiba, Katsutoshi Nishino, Go Omori and Hiroyuki Nunome
Proceedings 2020, 49(1), 89; https://doi.org/10.3390/proceedings2020049089 - 15 Jun 2020
Cited by 4 | Viewed by 1991
Abstract
We aimed to clarify the effect of ball–racquet impact locations on the dynamic behavior of tennis racquet, the accuracy of shots and muscle activation of the forearm. Eight male intermediate tennis players performed ten forehand groundstrokes. A motion capture system was used to [...] Read more.
We aimed to clarify the effect of ball–racquet impact locations on the dynamic behavior of tennis racquet, the accuracy of shots and muscle activation of the forearm. Eight male intermediate tennis players performed ten forehand groundstrokes. A motion capture system was used to measure the motions of racquet, ball and human body at 2000 Hz, and electromyography (EMG) activities of wrist extensor and flexor muscles were measured simultaneously. The flight parameters of the ball were measured by ballistic measurement equipment. All shots were divided into tertiles based on ball impact location along the lateral axis of tennis racquet. We found that the off-center, upper-side impact induces a larger muscular activity in extensor carpi radialis. Passive radial deviation of the wrist occurring immediately after ball impact may account for this. Furthermore, the off-center, upper-side impact could be associated with a missed shot having a lower, outward ball launch angle. Full article
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