Bicycles have been widely used in Japan. Particularly, the use of city-bicycles (mamachari) is becoming increasingly frequent among people of all generations. However, for younger people especially, bicycles are used in a setting that does not match the body geometry or riding environment. This study examined the effects of riding position on output power measured using a power meter attached to pedals with various cadences and speed conditions to ascertain the most comfortable exercise efficiency. Moreover, the relation between joint moment (hip, knee, ankle) and pedal reaction force, and range of movement for joint were evaluated using a three-dimensional motion analysis system. From the result, outdoor and indoor experiments with the range of this study revealed the optimal saddle height h to minimize the mechanical power output generated in the crank. Moreover, the mechanical power output generated in the crank depends on the tester pedaling skill.

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In order to reduce to load for handicapped person who ride the FES (Functional Electrical Stimulation) cycling, oval gear crank was used for FES cycling instead of circular gear clank. Joint moments were calculated for able-bodied person with voluntary and FES cycling motion by using oval and circular gear crank. Result indicated that joint moment took larger value for voluntary cycling motion than that of FES cycling motion. Moreover, it is clearly that the stimulus timing of the FES signal should be selected properly to realize a stronger rotating torque.

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Riding posture as well as leg motion is very important for cycling. To improve riding skills, it is very useful for riders to show their riding posture during cycling. In this study, we aim for developing a method to estimate a rider's posture only using sensors attached to a bicycle or the rider. For the first step, we propose a method to estimate hand grip position. The method uses Support Vector Machine based on the observed data from a 6-axis force/torque sensor installed at an ahead stem. Through the experiments, our estimation method achieved both high precision and high recall.

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In this study, evaluation method of joint torques during cycling were investigated. Newly designed cleat-sized biaxial load cells and an analytical system using a link model and a free body diagram of the lower limbs were developed. The biaxial load cells, which are made with stainless steel, were attached to the bottom of cycling shoes in place of plastic cleats. Any cyclists were able to use their own bicycle, cycling shoes and bicycle pedals with the load cells which were almost same size to plastic cleats (Shimano Corp). The load cells measure the magnitude and direction of right and left pedal force using a total of 16 strain gauges (8 gauges for vertical load and 8 gauges for horizontal load) in each load cell. This analytical system uses the link model of human limbs to identify the positions and angles of each segment of the lower limbs. The free body diagram of the lower limbs consists of 3 segments: thigh, shank and foot. The positions of each lower limb segment, joint torques and forces can be calculated using this system. Here, the relationship between ankle angle and crank angle were analyzed with this system using image-analysis software (TEMA 3D) with a high-speed camera (Photron FASTCAM SA4). This cycling power analysis and optimization system was applied to beginner and well-trained cyclists to investigate the applicability of our system.

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In previous research, few studies have mentioned the influence of trunk muscles relates to a bicycle pedaling. In this study, we therefore intended to construct a measurement system for estimate the trunk muscle force using inverse dynamics calculations in bicycle pedaling. This system consist 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. As a result, these measured value obtained from the system were equivalent to previous research, and the data from this system can be used in the inverse dynamics problem.

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This research presents a method of kinetic measurement of cycling motion by using a pedal-mounted instrument. In order to measure normal force and angular position of the pedals, a portable instrument was proposed, which consisted of a three-dimensional wireless inertial measurement unit (IMU) and a piezoelectric force sensor mounted on a pedal. The inertial sensor was also placed on the axis of ration of the crankshaft to evaluate crank angle. All data was transmitted to PC via Bluetooth. The pedal and crank angular positions were calculated from acceleration and angular velocities by IMU with Kalman filter. Potential usefulness was examined in our experiment with five healthy subjects in variation of the light, middle, medium, and heavy pedaling load with use of indoor bicycle trainer machine. The pedal angular position and pedaling force was successfully quantified simultaneously. The equipment is capable of attaching outside of normal bicycle pedal. This simple but effortless instrument may be helpful in kinetic analysis of cycling outside of laboratory.

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Amount of daily physical activity is strongly associated with the prevalence of lifestyle-associated diseases, and thus maintaining a certain level of physical activity is recommended. Amount of physical activity, namely energy expenditure, is commonly estimated from linear regression analysis of oxygen uptake during steady-state exercise of different intensities. Short-duration exercise, mainly walking lasting less than 3 minutes, has been reported to account for over 90% of the daily energy expenditure of healthy adults. In a rodent study that measured the oxygen consumption of rodents running for different durations, the energy cost of exercise was shown to decrease as exercise duration increased, so that the oxygen consumption level asymptotically converged at a steady-state level. Wearable accelerometer-based activity counters have widely been used for physical activity assessment. The estimation of energy expenditure by these devices, however, is based on steady-state exercise of more than 5 minutes, and energy consumption of shorter duration exercise is not commonly considered. Oxygen consumption remains elevated for some period of time after exercise. Then, the estimation of energy expenditure for short duration exercise must include excess post-exercise oxygen consumption (EPOC). The amount of EPOC change in duration exercise. Therefore, we attempted to elucidate the energy expenditure for VO_2 kinetics. Healthy men (age 20-40) walked for 1, 3 and 5 minutes on a treadmill at constant speed. Oxygen consumption during and post-exercise was measured using a portable gas analyzer in breath-by-breath mode. A best-fit exponential equation to estimate oxygen consumption from exercise duration and walking speed was generated. The measured data of 3 subjects not used in generating the formula were assessed for systematic error. Cross-validation of estimated oxygen consumption revealed 3.86(ml/kg/min) RMS, and the results of the Bland-Altman analysis revealed neither fixed nor proportional bias. An equation for the estimation of energy expenditure at shorter durations of exercise was successfully generated. Accumulation of additional data may further improve the equation.

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The Semmes-Weinstein monofilaments (SWMs) are used by medical staff for testing and measuring of the threshold of tactile sensory perception. The purpose of this study is to measure operator hand motion during the SWMs test. The ten subjects (6 men and 4 women), ranging in age from 20 to 60 years (mean age 42 years) were recruited. The SWM of the 5.07/10 g filament was selected in this study. In this experiment, we measured their hand motion by a motion capture system and the buckling force of the SWMs by a force sensor. These results showed that the maximum velocity of the subject hand was 0.33 mm/s, and the minimum velocity was 0.15 mm/s. Furthermore, the maximum buckling force was 8.5 g, and the minimum bucking force was 6.8 g. Thus, the hand motion during the SWMs test has varied through each medical staff. In conclusions, the SWMs test is useful way of the tactile threshold measuring in a clinic, but it depends on hand motion of the medical staff.

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I measure the metabolism efficiency of the volitional and electrical stimulation cycling by FES and report it. A purpose of this study is that metabolism efficiency of the cycling by FES considers a low factor. It was 2 patterns of 20Hz and 50Hz, and the stimulation condition of FES calculated metabolism efficiency from the work that joint went at the time of a cycling for normal men and an oxygen uptake and a carbon dioxide output. The result was the efficiency that the cycling by FES was lower than the metabolism efficiency of the voluntary movement. It will be necessary to do a timing to stimulate a line to improve efficiency appropriately and strength of the stimulation is changed to make up for the mechanical work that decreased by muscle having got tired in future.

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The acetabular dysplasia is pathological condition that acetabulum is incomplete growth compared to healthy people. In other words it is not possible to sufficiently cover the femoral head. In everyday life movement of the hip joint is indispensable and life while always felt the pain and discomfort is significant failure. Further, by that operation to protect the hip by pain, which can cause a secondary disability. So a variety of treatments exist for acetabular dysplasia. The acetabular shelf arthroplasty is also one of them. It is a surgery to increase the load area transplanted with autologous bone. It has feature that is excellent in improving postoperative pain. In this study, subjected to acetabular shelf arthroplasty in a patient with acetabular dysplasia, create a 3D model from CT images of postoperative preoperative, then investigated the effect by using the finite element method. As a result, the variance of the stress has been confirmed. It can be said that the acetabular shelf arthroplasty is an effective means for acetabular dysplasia.

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Heading impact influences on brain during a soccer game such as concussion have been repeatedly reported in the statistical or neuropsychological basis. Even though, overall evaluations or conclusions have yet to be determined because few report have discussed the heading impact in the point of mechanics inside the brain. In this paper, a numerical impact analysis between a computed-tomography oriented voxel model on human head and a soccer ball expressed by shell elements has been performed. The calculated results showed that higher Mises stress is observed at the central position of the brain while the HIC values are higher in the brain tissues near the skull.

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In most judo accident, recently, it is reported that the victims suffers severe head injury and in particular, the acute subdural hematoma (ASDH) caused by the rupture of the veins due to angular accelerations. The angular accelerations also have some influences on the development of the concussion and the Diffuse Axonal Injury (DAI). It is thought that the concussion and ASDH occur from the angular accelerations in the sagittal direction and DAI in the coronal direction respectively. It is reported that the tactic Osoto-gari often involves in the judo accidents. On the angular acceleration, of three directions (sagittal, coronal and horizontal direction), the remarkable change was observed in coronal one in Osoto-gari. So the purpose of the experiment is to examine the generating mechanism of the traumatic brain injury while paying attention to a head angular acceleration which Uke takes comparing the Yoko-ukemi. The both peak of angular velocity and angular acceleration were observed just after the palms made contact with the floor. Since each value was much smaller than the threshold value of a concussion, it can be said that a possibility that DAI is caused is extremely low. Since the waveform change was alike in Osoto-gari and Yoko-ukemi, moreover, it is thought that it is necessary for judo players to master Yoko-ukemi together with Ushiro-ukemi paying due attention not to have a temporal blow besides a occipital one in the practice of Osoto-gari.

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The purposes of this study was to develop a simulator generating a ski board vibration in actual skiing and to clarify the relationship between ski board vibration and a coefficient of kinetic friction. In the simulator developed in this study, the surface on the bottom of the ski was assumed as to be a snowy slope and a mass of snow (snow pack) assuming a skier had slid on this ski bottom surface. A ball vibrator connected to a large-sized compressor was installed onto the ski panel in order to vibrate a ski board. The compressed air from the compressor rotated a steel ball in the vibrator at high speed, causing vibration on the ski. A dynamic friction force (F) was detected by the digital force gauge when the snow pack was sliding on the surface in isokinetic condition using a traction device. A traction velocity was controlled automatically using controller. A coefficient of kinetic friction was calculated using this dynamic friction force. The experiment using this simulator was carried out in the low temperature laboratory conditions. On experimental result, in this study, the higher vibration was, the lower the coefficient of kinetic friction was. From these results, it is clarified that the high frequency of the mechanical dynamic vibration reduces the coefficient of kinetic friction.

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Ski vibration and EMG (Electromyography) measurement have been important in the evaluation of a ski performance or the development of new ski material. The purpose of this study was to measure ski vibration as a physical element and EMG as a physiological element in parallel by a new date logger system. Until now, vibration and EMG could not be measured in parallel using one unit, because the natural frequency of the vibration was different from that of the EMG. In our system, both can be measured electrically over time, in parallel. The skiing experiment using this system led us to following important matters; the vibration of ski board was synchronized with the load to ski board and the vibration over 200Hz on ski board made the high velocity in skiing.

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Ski vibration and EMG (Electromyography) measurement have been important in the evaluation of a ski performance or the development of new ski material. The purpose of this study were to measure the mechanical vibration sand the human EMGs in parallel in skiing and the grandeur driving by a new date logger system, and to investigate the these differences between the skiing and the grandeur driving. Until now, vibration and EMG could not be measured in parallel using one unit, because the natural frequency of the vibration was different from that of the EMG. In our system, both can be measured electrically over time, in parallel. The experiments using this system led us to following important matters; the turning way of grandeur driving was almost equal to that of the skiing, the force output from iEMG (integrated EMG) in grandeur driving was larger than that in skiing. However, the muscle fatigue from MPF (Mean power frequency) was not confirmed. This is the problem of the driving distance in grandeur driving.

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The purpose of this study was to describe instantaneous moment arms of the scapular rotators during arm elevation. Thirteen male subjects performed humeral elevation in the scapular plane. The locations of the origin and insertion of the scapular rotators (trapezius, pectoralis minor, rhomboid and serratus anterior) was determined using the existing skeletal model of the scapula and thorax. Based on the helical axis, the instantaneous scapular rotation axis were computed. Then, the instantaneous moment arms of the scapular rotators relative to the scapular rotation axis were calculated. During humeral elevation, the lengths of the moment arms were changed depending on the muscle fascicles. Only the serratus anterior had muscle fascicles whose moment arms were opposite for the scapular rotation in the same muscle. These results indicate the functions of scapular rotators for scapular rotation during humeral elevation.

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In this paper, digital image correlation (DIC) and a multi-camera system are being used to reconstruct 3D shapes of different parts of the human face and then aligning these parts using the Iterative Closest Point (ICP) algorithms to produce the full 3D shape of the human face. A simple method to remove the more sparse 3D point cloud in the overlapping area between two 3D shapes is developed by iteratively using the principal component analysis method (PCA). In addition, displacement measurements on the surface of the skin that are caused by a facial expression are measured. The experiment apparatus and set up are seven DSLR cameras that are mounted on a half circle light metal pipe and three tripods. A practical method for calibrating this system is developed by using a designed double sided calibration board, with check marks on both sides that are aligned with each other. A safe and practical method to apply a random speckle pattern on a human's face is developed by using an air brush make up set.

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In this research, we measured the force acting on tip of the finger when rugby player throwing spin pass. We put five sensors on the fingers. The sensor can measure three axis force (pressure and two axis shear force). Three examinee, which rugby experiences were varied from 13years to none-experience, threw spin passes three times each and the ball moving speed and rotating speed were measured. From the data analysis, 13-years-experienced rugby player threw the ball concentrating the force in 0.04 seconds just before releasing the ball to increase the rotating speed.

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In order to reduce risk of gonalgia at middle age and iliotibial band syndrome, i.e. IT band syndrome, which is called as runner's knee, biomechanics movement of knee at running and jogging is key point. Too big fluctuation in the perpendicular to the running direction might be a source of gonalgia. When a runner can recognize proper movement at running by himself, the risk of runner's knee might be reduced. In the present paper, in order to recognize the proper movement of knee, an evaluation method of the fluctuation of knee was proposed. The movement of knee was evaluated by detecting difference between knee and thigh using a high speed video camera and pattern recognition of image processing. In order to investigate a possibility of reducing method by sole insert, the fluctuation of the knee was measured changing with shoe and sole insert. It was concluded that the fluctuation of the knee could be measured by a high speed video camera and image processing.

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The purposes of this study were to develop the Sport-typed Wheel-chair can driving Straight using either one-handed or both-handed operation and to evaluate this wheel-chair. To perform these purposes, a wheelchair which had two handrims on one side to get to behind both wheels simultaneously by one hand. To be transmitted to the driving force from the handrims side to opposite side wheel, the driving force transmitted axis (DFT) made by author's laboratory was adopted. DFT consisted on three axes, because the sport-typed wheel-chair had the chamber angle. Each axis was combined using universal joint in order to be transmitted the driving force between each chamber. Each chamber angle was set on 16°. The evaluation of this wheelchair led to summarized as follows; Load in driving this wheelchair by one handed operation was almost close to that by both handed operation from point of EMG. The relationship between the wheel position of the specific in wheelchair and the driving force had the large individual equation in case of the wheelchair by one handed operation. The maximum driving force of driver in operation by one handed operation was almost 100N. The torque loaded to the DFT was estimated as almost 37.5M・m. Furthermore, the shearing stress against DFT was calculated as almost 24MP and this stress was thought to be cause of the DFT rupture.

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PIV methods coupled with smoke wire techniques have been studied. The wire arrangements of these methods were perpendicular to the wind tunnel flow until now, however in our new proposal, the arrangements are parallel to the main flow direction of wind tunnel. The former wind speed, which was available to the flow observation, had been restricted only 0〜4.0 m/s. But, according to our new method, the maximum wind speed was ranging 40 m/s with 1 second duration time of smoke, which is available to the image captures by high speed camera of 20000 fps. The increase of wake turbulence behind these wires were measured by PIV method itself. We showed some examples of stream line measurements behind spinning golf balls and baseball balls under 40 m/s wind speed.

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Soccer balls are constructed with 32 pentagonal and hexagonal panels. More recently Teamgeist 2 and Jabulani balls have 14 and 8 panels, respectively, with dramatically different panel shapes and designs from conventional balls. The latest model called Brazuca, made with 6 panels, has been adopted by 2014 Brazil World Cup. However, there are few studies on the aerodynamic characteristics of these balls. This study examined the trajectory and aerodynamic characteristics of soccer balls constructed with different numbers and shapes of panels. Results of wind tunnel tests indicated that the aerodynamic forces varied significantly according to the number of panels. The results for points of impact showed that the ball trajectory changes dramatically according to panel shape, suggesting that panel shape has significant effects on the flight of the balls.

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It seems that there is a great difference between a wind tunnel test and a flight test about a region of the negative Magnus force. In order to confirm these differences, the flight experiments were conducted. At low spin condition, some strange trajectory that a ball rises to was occasionally observed. The trajectory obtained from the flight experiments and the simulation based on the wind tunnel experiment were compared at about Re=8.5×10^4. Trajectories except SP=0.4 by which negative Magnus force was observed in the wind tunnel experiment are mutually in agreement. The results from flight experiments also suggest that the negative Magnus force does not appear in table tennis game.

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Aerodynamic characteristics of some golf balls whose dimples have different depths were measured. As a result, it was found that the shallower the dimple was, the larger the lift coefficient was. However, when the depth of the dimples was much shallower, the lift coefficient was extremely-little on the slow velocity, i.e. under 28m/s. We searched for a golf ball with dimple patterns that had a high lift coefficient at all velocities. As a result, it was found that a golf ball with a dimple pattern that has extremely small dimples between large shallow dimples has a high lift coefficient at all velocities, including under 28m/s. In order to investigate the cause of the results, a flow visualization experiment was conducted. Visualization of flow around a golf ball was conducted by smoke wire method. Moreover pictures of flow were taken by high-speed video and we analyzed them by PIV (Particle Image Velocimetry). As a result, there was the difference in the streamline distribution between golf balls.

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Computer simulations for the prediction of badminton shuttlecock trajectories have been performed widely. Aerodynamic properties, such as drag, lift and pitching moment coefficients for a simulation are usually measured by a wind tunnel experiment. For the sake of simplicity, it is desirable to measure the aerodynamic properties using images of shuttlecock trajectory experiment captured by a high speed video camera without a wind tunnel experiment. This paper describes a possibility for an identification of shuttlecock aerodynamic properties which depend on Reynolds number and angle of attack from a trajectory analysis. We present a new method to overcome difficulties which arise from variations of velocity and angle of attack during a shuttlecock flight. Fairly good results of shuttlecock aerodynamic properties which depend on Reynolds number and angle of attack are obtained using the present identification method through horizontal projection experiments at a variety of initial velocities and an inclined projection experiment.

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The objective of this study is to simultaneously optimize the design of a discus and the skill with which it is thrown. The main question is whether the size of a discus depends on the wind such as the tail or head wind. In order to answer this question, the dependences of size and the angle of attack on the aerodynamic data are estimated by using CFD (computational fluid dynamics) technique. The optimization is carried out with the aid of a genetic algorithm. It was found that there was little deference of the size for tail or head wind.

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Recently we have enjoyed the sport "Ultimate" using flying disc in the world. The flying discs used in this competition are not made in Japan. Therefore, it is expected to develop an inexpensive and highly efficient flying disc of Ultimate. In this research, we visualized the flow fields by 2D-PIV measurement experiment and CFD analysis to understand the phenomena of flow around spinning and non-spinning flying disc. Compared with these results, the flow field of the calculation agreed with that of the experiment qualitatively. Therefore it was shown that analysis of the flow field was reasonable. In addition, the wingtip vortices arose from the flying disc and we could observe that two wingtip vortices arising from spinning flying disc were asymmetric.

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Curling distance was measured with high precision by use of digital image analysis in order to obtain its relation to the number of rotations. Movement of the curling stone from the release of delivery was recorded in the sequential images with the cameras located on the ceiling. Calibrations to remove lens aberration and to connect the imaging areas of two cameras were done prior to the experiment. The initial directions of the stone in each delivery were calculated as a reference line using the positions of the stone derived from the sequential images. Then the curl distance was measured as a length from the stop position of the stone perpendicular to the reference line, which was corrected as to convert the translation of the stone equivalent to distance between the hog line and the tee line. It was found that the curl distance decreases almost linearly as the number of rotations increases.

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In the long history of curling varieties of information and experience have been accumulated on the technique, strategy, coaching and others. However, scientific or quantitative investigations have rarely been made especially on the stone dynamics so that there still remain fundamental problems unsolved. This report summarizes the previous theoretical and experimental studies of stone dynamics and aims at making clear the assignments to be solved.

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In this study, we have studied aiming to develop curling robot which can win the game with a human. In this paper, motion model of curling which consist on stone and ice sheet was proposed. A strategy simulator constructed by using a motion simulator that based on using the motion model. The detail of both motion and strategy simulator are reported. The motion simulator calculates position and velocity of stone. The results of these physical variables indicate the usefulness of the friction model and motion simulator. Then strategy simulator is evaluated by simulated game with virtual enemy. The ranges of parameters for stone delivery were decided from actual curling games. The results of simulated games show usefulness of the simulator and the validity of the evaluation function was observed.

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In this study, curling robot that can win in curling game with human has been developed. In previous papers, a stone delivery robot, strategy and motion simulator were developed. This paper deals with the game result of human and robot. A strategy simulator constructed by using a motion simulator that based on using the motion model. The strategy simulator evaluates the placement of stone and condition on the ice sheet, than determine the delivery parameter to the robot. Curling robot played and won one end game on irregular rules such as human team contained only one person and no time limits. This system was evaluated by the skilled coach and player after the game. Details and results of the game and evaluation result of the system were reported in this paper.

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The purpose of this investigation was to develop a method for calculating contributions of the force-couple system applied to the baseball bat to the orientation of the bat at ball impact. A collegiate baseball player was asked to perform tee-batting in a direction toward the center field. A motion capture system operating at 500 Hz was used to determine three-dimensional coordinates of reflection markers attached to the bat. The resultant force and the resultant moment exerted on the bat by the batter's hands were determine with the inverse dynamics approach and their contributions to the orientation of the bat were computed with the forward dynamics approach. Horizontal angles and vertical angles of the bat calculated with the forward approach were in excellent agreement with the kinematically measured angles of the bat. A sample analysis of collegiate baseball player indicated that the horizontal and vertical angles were produced by the positive contributions of the couple moment that exceeds the negative contributions of the moment of resultant force.

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In baseball batting, it's important to send a high speed ball. To do it, batters are required to accelerate bat head hugely and to hit a ball accurately in space and in time. This study focused on mistimed batting. Four hypotheses are tested: mistimed batting occurs due to (1) the influence of the ball image thrown previously, (2) delayed start of the swing, (3) delayed arrival of the bat at the ideal impact position because the bat head speed didn't increase enough before impact, and (4) delayed arrival of the bat at the ideal impact position because swing trajectory was longer. Six collegiate baseball players were asked to hit pitched balls of three different speeds (120km/h, 130km/h, 140km/h) toward the center field in 2 conditions. In the first condition, they hit several balls of a given speed repeatedly until they think they hit the ball in the way they evaluate best. In the second condition, they hit 35 balls thrown at various speeds without being informed of the ball speed. Ball projection order was pre-determined by the examiner to include five patterns: (1) 10km/h up (2) 20km/h up (3) 10km/h down (4) 20km/h down (5) Speed keep. The results showed that mistimed batting occurred most frequently at 140km/h fast ball and the factor 2 was most common reason for it. This result supports the instruction that baseball coaches often says "you should swing early."

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A front-court forehand lift of badminton is known that the sports injuries occur frequently for applying the high load to the lower-extremity joint. In order to prevent the lower-extremity joint injury caused by the high load, the purpose of this study was to analyze the kinetic effect on the lunge landing leg during front-court forehand lift. Subject was eight male high school badminton players. The three-dimensional angle of the lower-extremity joint, ground reaction force and center of pressure (COP) on the lunge landing sole were obtained from the motion capture of the front-court forehand lift. As kinetic parameter of the lunge landing leg, the joint reaction force and joint moment were estimated by using the inverse dynamics technique. Lunge landing time was average 0.524s. During the lunge landing time, so as to decelerate the whole body which reached the maximum velocity and to achieve the proper racket swing, the stability of the lunge landing leg was maintained by the hip- and knee-flexion moments, hip adduction moment and knee varus moment. The large anterior shear force was affected on the knee joint, and therefore the muscular strength training around the knee joint was essential to prevent the knee-joint injury. Because the COP was located on lateral compartment of the lunge landing sole, the grip performance on lateral compartment of the badminton shoes was important to maintain the whole-body stability during the front-court forehand lift.

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The purpose of this study was to quantify the dynamical role of joint torques in control of racket face orientation during badminton smash motion. The human body was modeled as a multi-linked segment model consisting of 17 rigid segments with 38 DOFs of joints. The racket shaft was divided into a set of rigid segments connecting to its adjacent segments via virtual joints with rotational springs and damper. The joint angle and angular velocity of the shaft joints were calculated using generalized velocity vectors and the time integration of the velocity vector. The contributions of joint axial torques to the angular velocity of racket face were calculated from the equation of motion for a racket-human combined system. In order to realize stable numerical calculation for stiff system, the Newmark-beta method was used at the computation of recurrent equation. From the results, shoulder horizontal adduction/abduction and sternocleidal horizontal adduction/abduction joint torques significantly contributed to the racket face angular velocity. These torques were the great contributor for controlling racket orientation during badminton jump smash motion.

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A continuous rolling motion around a body axis to switch the front side of a body facing upside to downside or vice versa when performing a double-leg circle on a pommel horse has been presented as another skill instead of conventional skill of twisting the hips. An analysis was made of the time history data of spatial coordinates of several selected points of a body acquired with a motion capture presented in a previous paper for three gymnasts, who are different in the amount of rolling motion training from well-trained to no-trained. In comparison of the rolling motion with the twist of the hips, it is shown that the rolling motion has an advantage to keep a body higher and straighter with less bend at the waist, giving more impressive performance.

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This paper studies on operability evaluation for steering mechanism of pleasure boats. Although some evaluation methods has been already proposed by our group and can show the evaluation results on the effectivity and efficiency for a simulation task, it is hard to say that those methods give the intuitive understanding for the evaluation results. And the questionnaire results to investigate the subject satisfaction are not quantitatively included in the final operability evaluation. Therefore, this paper proposes an operability evaluation method to lead the total evaluation result, which is easy to understand intuitively. Also, the total evaluation result of the proposed evaluation method includes the user satisfaction quantitatively.

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The objective of this study was to develop a comprehensive dynamic model of the paddler, paddle and hull for a simulation analysis of the paddling motion in a single kayak. In the development of the model, a similar simulation model, not for the kayak, but for human swimming was utilized. The paddler, paddle and hull in the model were connected by means of virtual springs and dampers. The geometries of the paddler, paddle and hull were acquired based on the experiments that measured them. The joint motion of the paddler was measured by means of motion analysis as well. By inputting the acquired data, simulation of the paddling motion was conducted. From the results, it was confirmed that the paddler, paddle and the hull were successfully connected by the virtual springs and dampers. In the simulation, the averaged velocity of the hull in the propulsive direction was 3.4 m/s, which was 11% lower than the actual value of 3.8 m/s.

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This paper analyzes stability of pleasure boats controlled by human in order to develop an electronic control steering system of those boats. At first, the equation of motion of pleasure boats in the global coordinate is derived. This equation of motion is used to compute a man-machine system model for controlled pleasure boats. Stability of pleasure boats controlled by proportional action of human is analyzed based on the man-machine system model. It can be seen that stability region can be enlarged when a forward gazing point is long. To keep such long gazing point, electronic control steering system should give adequate reaction force through the helm into captains so that they can grasp their input for the helm without any instruments.

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Even in these days, when the safety of automobile has been improved, the number of automobile accidents is numerous. Among automobile accidents, Whiplash Injury has the highest occurrence rate, however the mechanism of Whiplash injury has not been clear. Therefore, we need to clarify the cause of Whiplash injury and to prevent the occurrence of it. The aim of this research is to develop the physical neck model reproducing biological neck structures. In this research, first we chose substitute materials whose mechanical property is close to the element of biological neck. Then we developed the physical neck model and conducted the validity evaluation test. Finally we investigated the mechanism of Whiplash injury by using our model. In order to evaluate the validity of the model, we measured the head rotational angle and compared it with volunteer's. The results showed that the head rotational angle of the model is completely within the corridor of volunteer's. Thus, it is obvious that the model we developed sufficiently reproduces the behavior of biological neck. Using this model, we measured the elongation of neck which couldn't be gotten from previous dummies and we compared it for with and without sternocleidomastoid. From these results, the drastic increase and decrease of elongation induces the neck damage and causes Whiplash injury.

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Skin laceration accidents caused by the penetration of curvature edge frequently occur in daily life. However, little attention to skin laceration was paid due to minor injury, thus only few studies regarding the prevention and mitigation of skin laceration can be found. Considering that a fundamental study on skin laceration mechanism and threshold is necessary, in this study, drop weight penetration test device was developed in order to simulate skin laceration accident. The device was then used for evaluating the dynamic responses of skin simulant against several blades with different tip curvature radii. As a result, load and penetration depth at rupture increased with the increase of tip curvature radius of the blades. In addition, drop weight test result showed larger responses compared to quasi-static test result which might be due to the viscous effect and polymer characteristics such as cross-linking.

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In this study, a wooden javelin that conformed to the current length and weight regulations for javelin throw competitions was produced, and various characteristics were measured and compared with those for javelins of three other materials measured in a previous study. The reproduced wooden javelin was confirmed to not differ from the other javelins in shape, weight, position of the center of gravity, or relative size of each part, thus meeting current regulations for javelin throw competitions. The moment of inertia about the short axis through the center of gravity for the wooden javelin was much smaller than that for the other javelins. The resonant frequency of the wooden javelin at the first mode was much lower than that of the other javelins, but the compliance at the loop and the tail and the position of the node were not dramatically different between the wooden javelin and the other javelins. Compared with the other javelins, the wooden javelin had much lower static bending stiffness and bent more than the others by far, by approximately 3-fold. Furthermore, in javelins used for competitions, the relationship where the resonant frequency at the first mode is low such that the static bending stiffness is large was applicable to the wooden javelin.

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Coordination of the whole body movement is important for improvement of front crawl performance. The arm pull, body rolling and flutter kick are characteristic motions in the coordination of the front crawl. In addition, it is difficult to master the appropriate kick timing because the rhythm of flutter kick is quicker than the other motions. However, the training to achieve the appropriate coordination is generally conducted empirically. Therefore, it is useful for swimmers to develop a bio-feedback training system which indicates the appropriate leg kick timing estimated from the rolling motion. In this report, the algorithm which estimates kick timing from roll motion using a CPG network with neural oscillators were constructed. The roll and hip joint angles could be generated by the proposed CPG network. In addition, roll angular velocity during six beat front crawl measured in an experiment were put into the CPG network. The CPG network could generate the roll and hip joint angles synchronized with the swimmer's roll motion.

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For sports players, coaches and trainers are supportive persons who give them some appropriate advice for practicing. They can observe players from broader perspectives, and then evaluate their forms and figure out what the players should adjust in order to achieve better performance. This paper presents a support system for sports practice, which aims at working like coaches and trainers. Displaying the difference between your form and a model one, the system provides you with instructive information for improving your playing forms. Microsoft Kinect was employed as a device capturing your form during practice because the device is comparatively inexpensive and can be used even in your private room. In addition, Kinect never require you to put some markers for capturing on your body. A marker often interferes with your movement. Therefore it is important that the device in the support system is markerless. We have experimentally applied the practice support system to a three ball juggling practice to demonstrate that it works as expected. The experimental results showed that the practice support system effectively assisted several persons in acquiring a model throwing form of three ball juggling.

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The purpose of this study was to elucidate techniques for kicking along various trajectories in direct free kicks from various point in soccer. The subjects were the four skilled soccer players belonging to a university soccer club. The subjects were required to hit each of 4 targets at various combinations of heights and positions in the goal (3.5 m left, and 3.5 m right from the center of goal aria; 1.2 m, and 2.2 m from the ground) behind a screen positioned 9.15 m in front of the kicker. The performances were recorded by six normal-speed video cameras. The behavior of the kicked ball was recorded by two normal-speed video cameras placed behind the kicker and two other normal-speed video cameras placed beside the kicker and analyzed using the three-dimensional direct linear transformation method. The fifth video camera was placed facing the kicker to capture variables related to ball rotation. The sixth video camera was placed beside the kicker to capture when the ball was kicked. The results were as follows: 1) In X-axis, initial direction of the ball just after being kicked is the most important parameter for every subjects and conditions to hit the target. 2) In Z-axis, not only initial direction of the ball just after being kicked but also other parameters about rotation are the important parameter for some subjects and conditions to hit the target.

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Previous studies had demonstrated that the aerodynamic forces of the knuckling shot in a wind tunnel, and/or the irregular in ball flight path. However, there are still unclear parts how to achieve the knuckling shot on the kicking motion analyses. The aim of this study was to estimate the swing leg coordinated motion during knuckling shot compared with those of instep kicking using motion analysis system. Patients performed knuckling shot and instep kick to target. From result of the comparison, we found difference in pelvis motion between knuckling shot and instep kick. Then, it is suggested that the accomplishment of knuckling shot needs adding redundancies by pelvis compared with instep kick.

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We proposed an improved measurement system of 3-axis stress distribution at a human sole by using small and thin 3-axis force sensors. These sensors were placed on the left shoe's insole at 8 points where are the thenar, hallux, the root of middle toe, hypothenar, the base of fifth metatarsal bone, both sides of heel, and the rear end of heel. By using the improved measurement system, the 3-axis stress distribution was measured in level walking and going up and down the slopes. Measured stresses around the heel at the heel striking in going up and down the slopes were smaller and bigger than those in level walking, respectively. In contrast, measured stresses at the forefoot except the hallux at the toe off in going up and down the slopes were bigger and smaller than those in level walking, respectively. Measured normal stresses at the hallux at the toe off were almost the same value in spite of the angle of the road surface.

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The purpose of this study is to develop the portable measurement system for running and sprint motions. This system is composed of acceleration, gyro and magnetic sensors for three directions. By using this system, stride length, step frequency and speed are estimated during acceleration and constant speed phases. Through the comparison with the conventional measurement system, it was continued that this system can precisely estimate stride length, step frequency and speed during constant speed phase. In the case of acceleration phase, step frequency and running speed also gave good agreement with the conventional measurement system. Furthermore, the effects of contact pattern and sensor positions are quantitatively discussed.

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The purpose of this study is to investigate the shock attenuation properties of long pile synthetic turf by modeling and simulation method. Three types of specimens which have different hardness were used for comparing the shock attenuation properties. The hardness was controlled by the composite ratio of infill material, i.e. normal type specimen was formed by mixing the sand and the rubber chip for volume ratio at 1:1, 2:1 for hard and 1:2 for soft. And five types of test feet were used for incorporating the area parameter to the model. To identify the model parameters, multi-intensity multi-area impact tests were performed in various impact intensities and various impact areas. Because of the structure of long pile synthetic turf, the acquired data from the impact tests were unstable. Therefore, ten trials were performed in each condition for reducing the variation of measurements. As a result, the impact forces could be reproduced by the model and the shock attenuation properties of long pile synthetic turf in various conditions were estimated by simulation. However, it may be necessary to rebuild the model for improving the accuracy.

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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. The two-dimensional impact forces acquired from the sensor unit were compared with the data from the force plate for confirming the accuracy of the sensor unit with various initial angles and dropping heights and then the accuracy was ensured by the results. In this study, three different hardness of surfaces were examined for calculating the FR(Force Reduction) values not only the vertical component but also the horizontal component. As the results, both of vertical and horizontal impact forces which varied with initial impact angle and drop height were well represented by quadratic surface. By using these values, vertical and horizontal FR value of three kinds of surface were calculated from the experimental maximum force and estimated impact force with the same height and initial angle. Vertical FR values were increased with increasing the initial angle and dropping height in all surfaces. And the different patterns of horizontal FR values were observed in these surfaces.

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