The purpose of this study is to develop a methodology that enables to directly evaluate the wearing effect of sport apparel on athletic performance. The torque due to garment is estimated by using the musculo-skeletal model SIMM, The mechanical properties of garment are obtained from a mechanical test. The relationship between exerted garment torque and movement are induced by using motion equations with the components of the body and a garment on it. With the methodology, the possibility of performance enhancement in sprinting was investigated with a world-wide top athlete by calculating the contribution of exerted garment torque to the sprint speed. The results indicate that the exerted garment torque would help to increase the sprint speed and the contribution of the garment to the performance increased gradually toward the end of contact phase. It is suggested that the garment structure that supports plantar flexion movements in sprinting can provide plantar flexion torque even at take off phase.

Now, an exercise has attention because of an increase in health conscious. But the more exercising population increase, the more number of injured increase. These injured are required for rehabilitation. Then, by departing from an exercise, rehabilitation is prolonged. So applying a competitive exercise to the rehabilitation, it is expected that injured athlete would return to the competitive field in a short term. The purpose of this study is the development of device that can be prevented reducing the muscle, the joint range of motion and the sense in action athletics by using reproduction of the action of running. The rehabilitation device is designed by using a planar 6-link mechanism and to reproduce the movement of the human leg in the action of the running by the movement of the link. Then, it is possible to follow a variety of leg trajectory using adjustable link. The device to follow a motion of foot is improved by adding a linkage for arms to the device.

The purpose of this study is to quantify shoe-sole recovery torque during stance phase in running motion. Five running shoes with different thickness midsole were used as test shoes. The sole bending angle-moment curves of forefoot region in each shoe were obtained from a shoe bending testing machine. One male runner who was heel striker participated and ran on the asphalt surface in the constant speed of 2.78 m/s. Forefoot bending angle during the support phase were calculated based on trajectories of makers attached on the shoe-sole. This study revealed that 1) initial bending stiffness derived from the sole bending angle-moment curve has a correlation with cubed values of the sole thickness, 2) initial bending stiffness in the plantar flexion is higher than that in dorsal flexion, and 3) both maximum plantar and dorsal recovery torques during stance phase correlate with sole bending stiffness.

The purpose of this study is to estimate the ground reaction force in running to use two-dimensional kinetic skeleton model also to examine the validity of their approach with changing running rate. The subjects are healthy 2 people in university. The subjects run 5times; subjectively increasing 5 running rate. The results are as follows. 1) Lowering the cut-off frequency, waveform of the ground reaction force is smooth and the maximum value is decreasing. 2) The vertical waveform of the ground reaction force shows a high cross-correlation coefficient under condition of low sampling rate, but the forward waveform of the ground reaction force shows a high cross-correlation coefficient under condition of high sampling rate. 3) Regardless of the running rate, the vertical waveform of the ground reaction force is smaller. 4) Characteristics of the ground reaction force are different by the subject.

In order to establish the appropriate evaluation method of adhesive properties for shoe sole materials such as rubber and foamed resin, relationship between stress components of the adhesive interface and adhesive strength was precisely investigated. Two types of specimens, T-shaped (TS) and single lap (SL), were tested for considering the difference of stress components. Adhesive strength of SL was much higher than that of TS. It was indicated that adhesive interface has excellent resistance to shear stress direction as contrasted with tensile stress direction. From the results of numerical analyses, by SL specimen, it was found that stress components depended on the deformation of adherend. Contribution of shear stress was proportional to the stiffness of adherend. Judging from the above, it was confirmed that the evaluation of adhesive properties for shoe sole materials should be performed by applying of tensile stress at adhesive interface.

The purpose of this study was to verify the utility of the methodology using the pressure distribution analysis and motion capture system that can measure the pressure distribution, the fluid forces, and the hand kinematics. A male swimmer participated in the study, and imitated the front crawl stroke motion at standing position with changing the stroke patterns and the stroke speeds. During trials, six pressure sensors were attached at swimmer's right hand to measure the pressure distributions around the hand, and to estimate the fluid forces acting on the hand. And five reflecting markers were attached at right hand to analyze the hand kinematics by using the motion capture system (Opus Underwater, Qualisys). As results, the hand velocities significantly correlated with the pressure values and the fluid forces (r = 0.76-0.99, p < 0.05). And the hand acceleration significantly correlated with the pressure valued at dorsal side (r = −0.74-−0.76, p < 0.05). These results suggest that the unsteady flow occurred at dorsal side of hand and increased the fluid forces.

Although several previous studies investigated bathing comfort from the viewpoint of thermal effect or physiology, few studies investigated that from the viewpoint of biomechanics. The objective of this study was to evaluate bathing postures from the biomechanical viewpoint. In the previous study, authors proposed a biomechanical model in bathing postures and shows that joint torque at the ankle and knee were changed due to bathing postures. However, joint torque in the hip joint was not changed significantly, although subjective score relating to relax in the abdomen was changed. In the present study, it was hypothesized that lumbar posture affected to biomechanical change in trunk because lumbar spine was curved characteristically in bathing. To evaluate trunk posture in detail, an improved biomechanical model was developed by focusing on lumbar. Bathing postures and reaction forces from the bathtub to a human were measured for ten healthy male subjects in two bathtub conditions (new bathtub and conventional one). A three-dimensional motion analysis system and 3D force plates were used to measure the experimental data. A biomechanical model in which a human body is represented as a link of body segments was constructed. The result showed that joint angle and joint torque in the lumbar was changed due to bathtub conditions. Change of joint torque in the lumbar corresponded to change of subjective score. These results suggest that the new model was useful for evaluating biomechanical load in trunk.

This paper studies relationship between hull motion and usability for pleasure boats. A ship simulator with a stewart platform to reproduce hull motion is developed. In our experiments with the ship simulator, slalom to avoid obstacles arranged at regular intervals on a straight line is defined as a task. Four type conditions of reproducing hull motion, such as nothing to reproduce, the only rolling, the only pitching and both rolling and pitching are carried out for four subjects. As a result of experiment, it can be seen that the relationship between the degree of reproduction the motion and the usability is a trade-off..

The pitching phenomenon of boat affects the muscle fatigue and rowing difficulty as well as the wave resistance. Initially, in this research, a pitching phenomenon was observed due to change the rowing rates by using a single scull boat. As a result, the amplitude in the specific rate increased. The next, for three different types of boat of the material, structure and weight, vibrations were analyzed. Therefore, the natural frequency affects the pitching, and then the tuning phenomenon of the forced vibration induced due to rate and natural vibration frequency hardly occurs structure of pitching phenomenon has been suggested.

This research extends the three-joint arm's optimal control model with a freezing-like mechanism in its hand joint to a model more analogous to the human three-joint arm's motion control mechanism by changing the model's desired value of its state variable at the final point from joint angle information to visual one (i.e., x and y coordinates of the hand point), and it discusses its effectiveness. Consequently, the following results are obtained: (1) the extended model reproduces human arm's reaching movement characteristics including the freezing characteristic where the hand joint hardly moves during movements; (2) for the extended model's success in reproducing reaching movements, the model requires a larger weight value of the energy term in its criterion function than the previous model so that it can enhance the degree of consumed energy minimization of the extended model; (3) the extended model's reproduction error of the hand-joint angle is magnified with the movement time. These results suggest that the extended model can become a mathematical model more analogous to the human three-joint arm's motion control mechanism, that it requires another constrained condition to further enhance the degree of reproducibility of the hand joint angle, and that there is a stronger possibility that human reaching movements can be generated based on consumed energy minimization.

This research extends the three-joint arm's optimal control model with a freezing-like mechanism in its hand joint to an advanced model that simulates hand-joint constrained reaching movement and is more analogous to the human three-joint arm's motion control mechanism, and it discusses its effectiveness. Actually, the advanced model is achieved by changing the desired value of its state variable at the final point from joint angle information to visual one (i.e., x and y coordinates of the hand point) and predicting its hand posture angles at the final point from ones acquired as visual information. Consequently, the following results are obtained: (1) there exists a linear relationship between hand posture angles acquired as visual information and ones measured experimentally at the final point; (2) the advanced model reproduces human arm's hand-joint constrained reaching movement characteristics; (3) for the advanced model's success in reproducing hand-joint constrained reaching movements, the model requires a larger weight value of the energy term in its criterion function than the previous model so that it can enhance the degree of consumed energy minimization of the advanced model. These results suggest that the advanced model can be effective in simulating hand-joint constrained reaching movements and can become a mathematical model more analogous to the human three-joint arm's motion control mechanism, and that there is a stronger possibility that human reaching movements can be generated based on consumed energy minimization.

In this paper, the relation of plantar loading during the pre-flight phase of a vertical jump and the jump height was studied using a shoe that has MEMS triaxial force sensors on its insole of the right shoe at four points, which were hallux, first metatarsal head, fifth metatarsal head, and heel. It was found that the hallux exerts the largest force among the four anatomical regions of the foot, making it the largest contributor to the downward propulsive force. It was also found that the impulse due to heel increases with increased jump height. Likewise, in higher jumps, the impulse due to metatarsal heads are lower in comparison to that due to hallux and heel, implying that the plantar load shift from heel to hallux during ascent phase occurs more quickly while jumping to a greater height.

The higher spike jump amount is created from run-approach and take-off sequence motion. However, some detailed mechanisms are not understood clearly. Therefore, in the present study, I discussed about the generation mechanism of floor reaction force to jump higher. At the first, it is assumed that floor reaction force are created from the kinetic energy of an approach run, floor reaction force is changed to elastic energy, and then elastic energy is changed to initial vertical velocity. At the next, passive control jump simulation was carried out, and it was made clear that elastic energy is changed to "jump motion". Furthermore, it was also showed that "regimental practice for volleyball" is dangerous by using discussion about mass balance.

A great deal of attention has been paid for effectiveness of instantaneous motion utilizing free-fall motion of body center of mass in sports. Previous research demonstrated that this motion is quicker and could push forward stronger compared with general motion. There was a lot of research into the effectiveness of instantaneous motion utilizing free-fall motion of body center of mass. However, a little research into how people build this motion was established. This research had focused on learning process of this motion and how to support for building instantaneous motion utilizing free-fall motion of body center of mass. The three approaches, focused on a sense of moving body center of mass, the moment of extending a hind leg and a gap between barycentric orbit and brachistorechrone curve, were employed to resolve the difficulties of building the motion and were applied to design support system for building the motion. This system could easily be carried and adjust physique differences. In addition, it has an enough strength structure for withstanding the impact during used. Then the process of building instantaneous motion utilizing free-fall motion of body center of mass using the machine was suggested.

The purpose of this study is to make thoracoabdominal tolerance during the crowd accident. A healthy female subjects (n=3) underwent loading to chest 20 kg and loading to abdominal 20 kg. Subjects also measured vital capacity and tidal volume. Breathing parameter compared loading condition with unloading condition. In addition, breathing parameter was assessed changed over time. As a result, parameter (vital capacity, tidal volume) for breathing during crowd accident was able to show that chest pressure was main factor quantitatively.

We have developed a finger external fixator which considered motion trajectory of joint. The external fixator has design conditions of four as follows: (i) Material that is easy to penetrate X-ray. (ii) Conceived the link mechanism of the same movement as the finger joint. (iii)Small size that can be mounted on the dorsal surface of finger. The following results were obtained from the research:(i)The Material used CFRP is easy to penetrate X-ray. (ii)Movement of the rotation center when the finger bends is obtained, and a link mechanism similar to the function has been devised. (iii)Because it is small in comparison to the typical fixator, it's considered that the difficulty in daily life is reduced.

At the present time, a safety criterion for human support robot has not been established in spite of the fact that it will be doubtless widespread due to decreasing birthrate and aging of the population in Japan, Under this situation, an attempt is made to estimate the strength and fracture in the human metatarsals by conducting the simulation of human-robot interactions and modeling the human foot on the basis of CT images.

Hallux valgus is a degenerative joint disease that was much seen in middle and aged female. Sometime it accompanies by foot pain and affect to the activities of daily living. Therefore, hallux valgus is thought to be one of the reasons of locomotive syndrome and frail. However, the influence of hallux valgus on physical function of the elderly is not clear. Therefore, we conducted field test for the elderly and measured three dimensional foot shapes, locomotive syndrome risk test, toe-gap force, and self reported Hallux valgus. As the result, first and fifth digit angles of hallux valgus group was significantly larger that of non-hallux valgus group. On the other hand, no significant differences were not seen in locomotive syndrome risk test and toe-gap force. The result of comparison analysis showed no significant correlation between digit angle and physical function indices. The result suggests progression of hallux valgus may not influence physical function directly among healthy elderly.

In this study, Effect of the string diameter on dynamics characteristic of the string bed of tennis rackets were evaluated by rebound tests. Rebound tests between string-bed and tennis ball were conducted for 6-types of string-bed which diameter of string and distance of strings were different. Strings of 1.10 mm and of 1.60 mm in diameter were made for only this test. Because displacement sensor enabled to measure the contact state of the ball and the string-bed, contact time between string-bed and tennis ball and maximum amount of deformation of string-bed was measured. As a result, the distance of strings was longer, the contact time between string-bed and tennis ball was longer. In addition, while coefficient of restitution between string-bed and tennis ball was not related to the diameter of strings and the distance of strings, it was dependent on approaching velocity. Therefore, if string-bed had enough distance of strings, the big diameter string is available.

Shock attenuation property of sports surfaces is especially important not only for the athlete's performance but also for injury prevention. To evaluate the properties of the sports surfaces, some sports governing bodies often adopt friction tests and shock attenuation tests to determine the horizontal and vertical characteristics, respectively. Although the diagonal impacts are often observed in athletic sports, shock attenuation test only treats the vertical impact test. Therefore we developed a two-dimensional impact test device for examining the two-dimensional cushioning characteristics of sports surfaces in previous studies. To produce a simultaneous two-dimensional force against a test specimen, we incorporated a parallelogram linkage in the measuring system. In previous study, it was examined for hysteresis for three types of hardness samples. In this study, we improved the two dimensional impact test device and experiments were performed to three kinds of different samples. To evaluate the hysteresis properties of sports surfaces, the energy loss of each impact was calculated. As the results, Hysteresis property in the vertical direction was found to depend on the hardness of the sports surfaces. However, it was found that the hysteresis property in the horizontal direction is more complex than the vertical direction.

It is difficult to shoot a ball of high speeds with horizontal and gyroscopic spins for a currently commercial table tennis robot (table tennis machine). In this study, the table tennis machine which can shoot the ball of various shot types (loop, smash, drive, knuckle, chiquita, etc.) was developed. The machine has two launch and two gyro rollers, and the rotation direction and the revolutions of the four rollers are controlled independently. From the results of the shot experiments, the machine has high performance to shoot the balls of assorted spin types (top, back, side and gyro spins) with the maximum spin rate (over 10,000 rpm) and the maximum speeds 43.1 m/s (155 km/h). Moreover, the bound behavior in the service was simulated using finite element models of the ball and table for a table tennis. From the results of the bound simulations, it was found that the change amount in the reflection angle of the gyro spin ball was larger and the rebound speed of the top spin ball was increased.

Badminton racket is composed of string bed, frame, shaft and grip handle. A shuttlecock contacts directly with the strings where their deformation would affect the initial condition of the hitted shuttlecock. The final goal of this research will be to predict the performance of badminton racket by quantifying the influence of mechanical properties of the racket parts on the launch condition of the hitted shuttle. As the first step of the research, the purpose of this study was to propose a simulation method that quantifies the static deformation of the strings against a forced displacement inputs. The string is modelled as a elastic cord intersecting with each other. Displacements of the cross points of the cord with forced displacement input was caluculated by using an equation which simulates the deformation of the cord.

The purpose of this study was to extract optimal bat orientation angle and ball-impact position for maximizing flight distance in opposite-field hitting. Three-dimensional finite element analysis method was used to construct an impact model between a baseball and a wooden baseball bat, and a series of simulations with various impact conditions were conducted. Horizontal bat angle was set in a range from -31 to 20° and vertical bat angle was set from 0 to 51° with an interval of 3°. The line of impact was set to incline in a range from 5 to 40° with an interval of 5°. The linear and angular velocities of the batted ball, the angle from horizontal and from center line of the batted ball immediately after impact were determined for each simulated condition. Additionally, flight distance and ball drop point were calculated. The results showed that near maximum flight distance (> 90m) toward the opposite field for the given velocities of ball and bat was obtained by an impact with a large range of horizontal bat angle (-22~-7°) and the line of impact inclined at 20° when the vertical bat angle was zero (the bat head is in the same height as the grip-end). When the vertical bat angle was as large as 45° (the bat head is located lower than the grip-end), slightly reduced maximum flight distance (80-88m) was obtained with a narrow range of horizontal bat angle (2~14°) and the line of impact inclined at 20~25°.

The important characteristics include the baseball bat's center of gravity, moment of inertia, length and mass when analyzing a baseball bat swing. The purpose of the present study was to investigate the effect of the center of gravity on bat's acceleration. An experimental bat was designed, which provided five conditions for the center of gravity. The knob of the experimental bat was equipped with accelerometers to measure the three liner and three angular components of acceleration applied to the bat. The subjects were trained four baseball players. These six components of acceleration were measured using the experimental bat for give conditions of the center of gravity. The bat center of gravity were found to affect linear and angular acceleration during bat swing. But, effects of the center of gravity is different of each player, and each player has permissible range for conditions of the center of gravity. Thus, it is necessary to consider the bat characteristic that suit each player and to analyze each batter's motion during bat swing.

It's conceivable that Baseball batting is affected by position of center of gravity (C.G) of bat. And there is a possibility that it is related to the impact position of bat. In present study, batting experiments were carried out by the bat to differ the position of C.G, and the impact position was measured by the three-dimensional direct liner transformation (DLT) method. And it was discussed about effects of position of C.G on impact position in baseball batting. As a result, it was indicated the relationship that the impact position is also near bat head when the bat that the position of C.G is near bat head is used in several subjects. Therefore, the impact position was proved to have possibilities to be affected by the position of C.G. Also, the difference of the position of C.G wasn't the thing which greatly influenced the distance from the impact position in the impact to the major axis of bat. But it was confirmed in several subjects that the swing angle in the impact changed by the kind of bat, and it was recognized that the position of C.G of bat might influence it in the timing of the ball impact.

The purpose of this study was to examine kinematic factors (swing speed, angular speed of the bat, impact position, center of rotation of the bat, etc.) influencing batted ball speed in baseball. Applying the law of the conservation of angular momentum, we derived a computational formula to determine batted ball speed for given kinematic parameters. A series of computational simulation were conducted to clarify the influence of each of these parameters to the batted ball speed. The simulation outcome demonstrated two characteristic phenomena: One phenomenon is that, batted ball speed decreases without altering the bat head speed when the angular speed of the bat at impact is reduced (in this case, the center of rotation of the bat was shifted away from the center of mass); and the other phenomenon is that, the impact position of the bat that maximizes batted ball speed deviates slightly from “the sweep spot“ toward the bat head when the angular speed of the bat at impact is increased without altering the bat head speed (the center of rotation of the bat was shifted toward the center of mass of the bat, in this case). These phenomena can be explained only when the coefficient of restitution of a bat is not uniform across different positions over the bat surface as well as across various swing characteristics, such as angular speed of the bat and the center of rotation of the bat.

In order to stabilize the standing or walking, disabled people have to work their muscles well. There are many rehabilitation systems to stabilize them. However, it is too difficult for severe disabled people that cannot stand or walk by themselves to use rehabilitation systems. On the basis of this situation, rehabilitation systems that severe disabled people can use safely are required. We focus on reach movement when sitting because this is one of the basic movement that reacquisition is desired. The purpose of this study is to clarify the effects of our prototype rehabilitation device on sitting posture. An healthy adult and a disabled adult participated in this study. Each participant was performed 10 repeated forward reaching tasks in different posture conditions. These tasks were recorded by a motion analysis system synchronized 2 force plates and a wireless electromyography. For healthy adult, an Tibialis anterior muscle in flexible sitting posture was less active than that in extended sitting posture. On the other hand, by using our prototype rehabilitation device, this muscle became more active. In disabled adult, this muscle became more active by using our prototype. A force that applied to the buttocks was larger than the force applied to the foot in reach movement. And our prototype suppress the highly weight shift. These findings suggest that our prototype rehabilitation device might improve sitting posture in disable people.

In this study, we propose an EMG control system including switching system of action mode using EMG (electromyogram) signal by the elevation of scapula for upper-limb prosthesis. This EMG control system operates elbow, wrist and hand of upper-limb prosthesis, using surface EMG signal of the biceps brachii and the triceps brachii. The switched these three action modes are controlled by surface EMG signals of the elevation of scapula. The main muscle working in the elevation of scapula is the trapezius. Some practical myoelectric prostheses use EMG of human arm's contraction as switching plural actions. However, this study proposed by the elevation of scapula instead of arm's contraction. As a reason for that the proposed upper-limb prosthesis uses EMG signal of arm's contraction-relaxation action as input signal, for realization of flexibly elbow's action in the prosthesis. The proposed EMG control system including a simple upper-limb prosthesis was manufactured using Arduino microcomputer. As results of the test operation, it confirmed that the working of three actions are switched in sequence by the elevation of scapula.

In order to evaluate the joint moment of cycling motion using FES cycling (Functional Electrical Stimulation cycling for people with disabilities), The authors developed three kind of FES cycling. In this study, using two types of FES cycling, among them, the effect of riding position on the joint moments of lower limb were evaluated for able-bodied person with and without FES by using 6axis force sensor and 3D motion analysis setup. Moreover, using EMG measurement system, evaluate the effect of riding position on the muscle operation timing and EMG values.

Recently, “core training” is getting popular to enhance stability in the various sports scene and improve posture in the dairy life. It has been said that “core training” is important to strengthen the outer/ inner muscles of a body trunk. In order to improve the good stability and right posture through the “core training”, the inner muscle strengthening becomes essential and a front bridge workout is especially effective to strengthen the inner muscles of body trunk. However, it is assumed that influence of posture with different contact positions of arms and feet on inner muscle activity in front bridge workout. The purpose of this study is to quantify the relationship between activities of inner muscles (i.e. internal and external abdominal oblique muscle) and support positions in front bridge workout effectiveness based on kinetic and kinematic experimental results. Furthermore, front bridge workout is also discussed under barefoot and shod condition in terms of effectiveness of the inner muscle strengthening.

Ballroom dancing has characteristics of natural movement of human walking with a fixed constant musical tempo. The natural walking movement appears especially in the rise and fall in the swing dances of modern standard dances. The rise and fall in these dances is analyzed in the mechanical point of view. The rising and lowering processes in the swing action are discussed in detail in terms of mechanical energy. The case of natural turn in waltz is taken as an example and compared with other cases. A sinusoidal function of simple vibration is employed featuring the natural movement of rising and lowering process of the body. The height of center of gravity of dancer and its vertical acceleration are quantitatively exhibited in graphs for each basic movement of the figures of waltz, representing the standard modern ballroom dancing. It is shown that highest position in the movement depends on each figure in each dance and that it is limited by the lowering process in the figure.

In order to evaluate a double-leg circle, we focused on the relation between the body rotation and the hip rotation and proposed the evaluation diagram to see the synchronization of these two rotations by analyzing the data acquired with a motion capture system in a previous paper. In this paper, we applied this method to evaluate the performances of the skills of Moore and loop. As a result, it is revealed that this diagram also is useful for evaluating these skills. It is shown that the double-leg circle is important as a fundamental skill in applying a similar criterion to the evaluations of different skills of circling performances on a pommel horse.

Today, the ratio of the lifestyle-related diseases has increased to approximately 30%, and Nation as well as people is getting more and more health-conscious. In particular attention has been made to core or trunk because it is key for injury prevention, sports progress, and beauty. And various training methodologies have been proposed to increase the muscle mass of the trunk. However, in the physical expression fields such as dance sport, the strength of the trunk is mainly influenced by smooth use of the trunk rather than its muscle mass. In order to evaluate the use of the trunk twist movement, we proposed two trunk torsion standard movements and a new trunk twist model. We also developed an evaluation application “Axis Visualizer” that score goes up when you twist the shoulders or hips smoothly with axis fixed and high frequencies. The aim of the application is to support trainers and coaches to visualize the use of customers' trunk and to increase the training effect. In this paper, we evaluate the trunk twist model.

The “turbo-jav” is used for the javelic throw in the Junior Olympic Games and in the National Sports Festival for People with Disabilities. To improve the record in these flowing events, it is important to elucidate the flight characteristics of the turbo-jav. We have measured the aerodynamic characteristics of the turbo-jav in the wind tunnel tests at the wind speed U up to 25 m/s for various angles of attack α. In the present study, we report the drag coefficient, the lift coefficient and the pitching moment coefficient for the turbo-jav thus obtained for 0 ≤ α ≤ 25 o, as well as our recent measurements in support interface free by the Magnetic Suspension and Balance System (MSBS) at Tohoku University for 10 ≤ U ≤ 40 m/s at small α (-5 o ≤ α ≤ 5 o). We also present the wind tunnel tests for the rolling turbo-jav model at the frequency of 0 to 20 rps. It was found that the obtained aerodynamic coefficients oscillate in time but their averaged values are almost independent of the rolling frequency.

Recently we enjoy the sport “Ultimate” using flying disc in the world. The flying discs used in this competition have not made in Japan. So, it is expected to develop an alternative supply, the inexpensive and highly efficient flying disc of Ultimate. In this research, the aerodynamic properties of flying disc by fluid forces measurement and Stereo-PIV measurement, CFD analysis were performed. Also, the appropriateness of CFD analysis by comparing fluid coefficients of experiment with that of CFD analysis was verified. A highly efficient flying disk was suggested in this research.

An experimental study and a computational study are conducted to understand the aerodynamics of the shuttlecock especially about the effect of the chamber of the blade. The lift, drag, pitching moment coefficient is measured in the experiment. It was found that the chamber of the blade can change the aerodynamic properties. The increase in camber causes increase in lift and a decrease in drag. PIV measurements revealed that this decrease in the drag is related to the decrease in the width of wake which is caused by the flow of outside of the shuttle flows along the chamber. A pressure coefficient calculated by CFD reveal that the each blade work as single blade at low angle of attack. On the other hand, at high angle of attack, not so high lift was observed. It is because the front of the outside of the upper blade is inside of the separation region from the cork.

In Ski Jumping and Nordic Skiing, good gliding properties are required for success. Among many parameters, the tribological system is affected by the material properties of the ski running surface and various wax combinations that are applied on the top of the ski sole to minimize kinetic friction. The major research of this study has focused on the material changes due to the waxing process, in addition to the evaluation of the content of fluorine in waxes. Moreover, special attention has been paid to the additives like BN and SiC particles in nanometer size, mixed with high fluorine content waxes as powder. Characterization on the ski base materials, both with and without waxes, were evaluated by X-ray-fluorescence (XRF) analysis, Vickers hardness test, surface roughness analysis, contact angle measurement of water droplets, and tribometry to measure the coefficient of friction (C.O.F). It was found that the fluorine content in waxes on the top surface was not directly affected by the hardness, the surface roughness and the contact angle. The COF on ice was slightly lowered with the increase of fluorine content in waxes. The hardness was significantly improved by the addition of BN and SiC nanoparticles in high fluorine content waxes, especially twice as high as that for the case of BN nanoparticle, without any degradation in the surface roughness and the contact angle.

Some sports wears are used at a top speed of about 25 m/s in a specific sport. This means that some sports wears are used in harsh environments. Therefore, reduction of air resistance is in great demand. A high-performance sportswear contributes to improvement of a record. This study is investigated the aerodynamic behavior of functional fabric on a cylinder model. A cylinder model imitates a trunk of a human body and arms by connecting a cylinder different in the diameter. Seams are imitated in this cylinder model. This fabric was tasted in a wind tunnel from 3 to 30 m/s. The wake of this fabric was visualized by the PIV measurement. The single cylinder showed drag crisis in Re =0.6～0.8×105. However, the Cylinder model didn't exhibit drag crisis. These results are correlated with Visualization of the wake. The arms of human body are important for studying aerodynamic characteristics of sportswear.

Ski jumping is a sport which competes for the flight distance and flight form. Thereby jumpers attempt to fly as far as possible. In the regulations for ski jumping competition, the outstretched fabric must show the air permeability of a minimum of 40 L/m²/sec with the differential pressure of the pressure head 10 mm. However, the effect of the air permeability of ski jumping suits on aerodynamic characteristics has not been completely clarified yet. The purpose of this study is to investigate the effect of air permeability of jumpsuit fabrics on aerodynamic characteristics, and four types of fabric with different air permeability are examined from aerodynamic point of view. The wind tunnel experiments were carried out using the fabric clothed elliptical cylinder. The flight distance for each test cylinder was calculated with the aerodynamic force data assuming that the elliptic cylinder flies. The drag coefficient decreases with increasing the air permeability. The maximum lift coefficient indicates the highest value for no air permeability case among the all cases. However, the stall delay occurs for high air permeability cases, and the lift to drag ratio at the high angle of attack can be improved. It was presumed that the flight distance can be extended by adjusting the air permeability of ski jumping suits.

While driving a vehicle, a driver must occasionally react quickly to avoid collision with pedestrians who suddenly jump out in front of the vehicle. This research analyzed the steering response of drivers, using a car simulator and driving simulation software. The experiment, simulated in a city situation, evaluated the driving responses of eight university students, each driving in three different weather conditions; fine weather, light rain, and heavy rain. Result show a 136ms delay in driver steering response time between a fine weather situation and a rainy weather situation.

This paper proposes a compensation method for degree of freedom of shoulder joint in reproduction of human motion with small humanoid robot. The proposed method uses a mapping to transform the human position into the robot position at each moment in a series of the target motion. The deep breath motion of radio exercises number 1 is selected as the target motion in our verification experiment. For motion reproduction by the forward kinematics based on the musculoskeletal analysis data, it is confirmed that the proposed method can compensate for the difference in the degree of freedom of the shoulder.

Curling is one of the winter sports called chess on ice. Athletes are required high level skill and smart strategy. This paper deals with curling phenomenon of rotation stone on the ice.To Understand this phenomenon, polypropylene and Teflon sheet makes low friction environment, and curling stone experiment was carried out. Then curling stone phenomenon was reproduced on force plate instead of ice.

Movement of a curling stone was studied with high-precision digital image analysis in order to obtain the relationship between curl ratio and angular velocity at each moment of its slide, using sequential images taken with a camera located on the ceiling. Calibrations to remove lens aberration were done prior to the experiment. Defining the reference line as the direction of movement of the curling stone at a moment, a curl distance was measured at a translation distance 1000 mm, and converted to curl ratio. The 217 deliveries were performed in total, and 212 deliveries were successfully analysed in the range of translational velocity 0.5 - 3.0 m/s and angular velocity 0.3 - 3.0 rad/s. In the analysis, curl ratio at each moment of the slide of stone for the deliveries was derived by the image processing. It was shown that the curl ratio has tendency to become smaller as the angular velocity increases for the same range of the translational velocity.

By using MEMS 3-axis force sensors, we demonstrated that we can measure the three axial force distribution when a curling stone rotates and translates on the ice. We cut a curling stone horizontally in order to separate the stone into two parts. Then we fixed the MEMS 3-axis force sensors between the upper and lower parts. We conducted the measurement experiments at the curling rink, and confirmed that our proposed measurement method is effective to evaluate the force acting on the bottom surface of the curling stone.

Friction and abrasion are inevitable when the ice surface is swept with any smooth brush head. Heat produced by friction reduces the ice friction coefficient and makes the stone slide farther. Abrasion produces a local slope and fine ice particulates through mechanical deformation and destruction of pebbles. The gravity force due to the local slope formed in front of the stone must be taken into consideration in the stone motion. Our calculation showed that with powerful sweeping it is possible in principle to manipulate the trajectory of a stone, that is, to accelerate or change the direction and extent of curl. Sweeping using a brush head with hard rough surface is not discussed in the present paper, which may produce serious mechanical damage on ice surfaces, e.g., scratches and ditches, and may not be used in usual curling games.

There are few studies have mentioned the influence of trunk muscles relates to a bicycle pedaling. In our previous research, we therefore intended to construct a measurement system for estimate the trunk muscle force using inverse dynamics calculations in bicycle pedaling. The system consists of measurement devices, (1) reacting force of the bicycle (pedal force, saddle force, handle force), (2) Pedaling action (pedaling posture, crank angle) and (3) Electromyogram (EMG) of right leg. In this study, these measured value obtained from the system were try to use in the inverse dynamics problem of bicycle pedaling. As a result, current model of inverse dynamics calculation is not well matched to the actual muscle force, and the improvement of the analysis model is required.

Bicycles have been widely used in Japan. However, especially for younger people, bicycles are used in a setting that does not match their body geometry or riding environment. In this study, first, the authors examined the effects of riding position on output power using a power meter attached to pedals with various cadences conditions. Next, the effect of saddle height on the joint moments of lower limb were evaluated by using three dimensional motion analysis system and six axis type pedal sensor. Moreover, evaluate the muscle operation timing and EMG values for various saddle height settings.

In this paper, we investigated energy distribution of a sports bicycle for evaluating the acceleration performance quantitatively. As the input force for measurement of the performance, constant weight was put on one side pedal of the bicycle positioned on a running roller, and the rotational speed of the wheel was measured under various conditions. The acceleration performance was then calculated by dividing the increased rotating rolling energy by the input energy. The result shows that almost 60% of the input energy was used for the acceleration of the bicycle. In addition, we also investigated influence of the wheel weight (moment of inertia) and air pressure of the tire on the performance. As the results, the performance was increased about 5% by the 30% reduction of the inertia. On the other hand, the performance was observed to decrease about 4% by the 30% reduction of the tire pressure. From these results, we could obtain the influence of the wheel and the tire characteristics on the acceleration performance of the sports bicycle quantitatively.

During standing pedaling in a bicycle race, a human body and a bicycle are swinging in right and left. In order to investigate such movement, sagittal plane models and experiments using an ergometer in the previous studies were insufficient. In the present study, a three dimensional simulation model to analyze such problem was constructed using a multibody dynamics software. In this model, pedaling motion was achieved by PID control of joints of the human body. The simulation of sitting pedaling at the rate of 120 rpm for a power output of 200W as well as standing pedaling at the rate of 73 rpm for a grade of 8% were conducted, respectively. By comparing the results with those in previous studies, the validity of the simulation model was confirmed. In the simulation of standing pedaling, the knee joint torque and crank torque increased at a power phase and the crank torque decreased at a recovery phase when the bicycle swung. It was suggested that the rider makes the bicycle swinging to obtain the larger crank torque at the power phase.

In the field of cycling competition, maximizing the performance of a cyclist is necessary to satisfy the following conditions: 1) Improving the pedaling skills that convert his/her physical strength to the impulsive force of a bicycle and 2) Setting the mechanical components of a bicycle to meet his/her physical properties. The relation between pedaling skill and mechanical components of a bicycle has not been discussed thoroughly for a long time. This study aims to propose a method to extract the pedaling motion with a three-axis accelerometer among different levels of cyclists and to assess stability from the mechanical information of the bicycle and extracted features by Kernel principal component analysis. In this paper, we concluded that a skilled cyclist switches their pedaling motion at a certain crank rotation angle; however, this is not the case with beginner and intermediate cyclists. These results suggested that cooperative motions of lower extremities contribute to a stable pedaling motion and optimize the efficiency of cyclists' pedaling motion.