In this study, three dimensional running simulation of unilateral transfemoral amputee with running specific prosthesis was modeled. Based on motion capture data, kinematic and dynamic calculations are carried out to establish inverse dynamic model of human and prosthesis. Finally, prosthesis is optimized by using response surface method of inverse dynamic model.is created.

There are various designs in running-specific prostheses (RSP), and the shape of the RSP load-displacement curve differs by its design. The purpose of this study was to examine the effect of the design of RSP to center of pressure (COP) and ground reaction force (GRF) of prosthetic leg at transfemoral athlete’s sprinting. Four types of RSP were used for this study. These load-displacement curves were measured by compression testing machine. Using the motion capture system, the COP and GRF of one transfemoral amputee athlete at sprinting for each RSP were recorded. Depending on the design, two different load displacement curves were confirmed: one was linear curve with L-RSP, the others were non-linear curves with NL-RSP, which became stiffer at larger deformation. Compared with NL-RSP, a small posterior movement of COP and large anterior and vertical GRF were confirmed with L-RSP. These results suggest that L-RSP enable transfemoral amputee to propel easier and it is suitable for sprinting.

Sports prosthesis for lower extremity amputees has a mechanical structure similar to flat springs, and its elastic energy is expected to improve sports performance. Our research project focuses on a long jump event for track and field, in particular, on the takeoff action. Our previous study established a computer simulation system that derived a comprehensive optimum solution for both the mechanical design parameters of the prosthesis and takeoff action to improve the performance of amputee long jump. The purpose of this study is to improve the mechanical model of the prosthesis based on the flat spring design formulas to represent precise deformation and rolling contact with the ground. The curvature of each element of the prosthesis was modified by the deflection angle of the flat spring model, and the contact point to the ground was calculated by considering deformation and rolling contact. Simulation results showed the deformed shape of the prosthesis and takeoff action qualitatively agreed with the actual phenomena. However, magnitude of the ground reaction force by simulation model were larger than that of measured data.

As the official event of Paralympics in the Tokyo 2020 Games, para-badminton competition population is increasing. Among them, wheelchair tennis and wheel chair badminton are also sports that use wheelchairs, but there are big differences in how to use the wheelchair. There is, however, no big difference between the wheelchair for tennis and the wheelchair for badminton. The research aims of this study were kinematics and physiological measurement that can contribute to the development of new wheelchair for badminton. More specifically, motion capture was used for kinematic measurement, and changes due to differences in movement of the player and wheelchair were evaluated from the viewpoint of acceleration at each joint of player. We used a new wheelchair designed to fit the physique of the player and an old wheelchair that is on the market. Furthermore, strokes and swings were classified according to the flexion angle of the elbow joint. As a result, it was confirmed that the new wheelchair player exceeded the acceleration of the old wheelchair, and the maximum speed of swing motion and the operation time were shortened. Therefore, the usefulness of the new wheelchair was shown.

This research supports is a sit ski player Nonno Nitta, who is from Sapporo City. And the purpose is her participate in 2018 Winter Paralympics. In order to develop a competitiveness-improvement sit ski for her, this study evaluate her perform when using sit ski with diferent settings. In the laboratory experiments we used a force plate to measure the floor reaction force and a motion capture system to measure the movement speed of the sit ski. And she performs rowing motion with a slope of 3 degrees on the force plate. We evaluated her performance with using different settings by impulse FΔt consist of her motion time Δt and pushing force on the ground. Our previous studies have shown that her performance changes while adjusting the seat surface and the backrest of the sit ski. The rowing motion is so greatly affected. For the adjustment of the sit ski, we prepare the parts made of high rebound mat. The cross section of the adjusting is a triangle shape. Adjusting parts with various angles are prepared and attached to seat surface and backrest. Following facts became clear from the experimental results. The difference in length of the time between she pulls and pushes the stocks affects the floor reaction force. As a result of the improvement, she got results at last year's World Cup and participated in the Pyeongchang Paralympic Games.

For competitive swimmers with a physical disability, the ideal stroke for crawl swimming has not been clarified yet. It may be different from that of able-bodied swimmers because of differences in body structure. The objective of this study was to solve computationally the fastest arm stroke of crawl swimming for swimmers with unilateral forearm amputation, and to investigate the features of the optimal stroke. The swimming motion of a swimmer with unilateral forearm amputation was reproduced on the swimming human simulation model SWUM, using the videos obtained by a swimming experiment of the swimmer. The optimal stroke was obtained by the optimization method with Particle Swarm Optimization (PSO) and SWUM. In this method, the design variables were the joint angles of the affected limbs for three degrees-of-freedom at the shoulder joint. The objective function was to maximize swimming speed. The swimming speed of the optimal stroke was 7% faster than that of the actual swimmer's stroke. The optimal stroke was the stroke in which the affected limb moved quickly from the entry position to the finish position, and stopped at the finish position to wait the unaffected limb. In addition, a parameter study was conducted by changing the timing to pull the affected limb. It was found that the timing of the optimal stroke was the best to swim fast.

In the running attitude considered to be greatly related to the recording in the wheelchair marathon, it varies depending on the players, and there are not many researches on air resistance due to this difference in posture. Reduction in air resistance during driving also leads to a reduction in physical strength consumption of competitors. On the other hand, disabled people are considered to be a social problem that the risk to the body during competition is very large unlike healthy subjects. In particular, many of the athletes suffering from spinal cord injury are presumed to be difficult due to autonomic dysfunction, various disorders such as perspiration disorder and temperature control dysfunction are caused, and physical condition control during competition becomes difficult. Therefore, in this study, we aimed to visualize the optimal running attitude with less air resistance and the flow of heat around the athlete model using numerical fluid dynamics analysis and consider the running attitude and the heat around the athlete.

We compared motion differences of amputee soccer players and non-amputated player using motion capture system VICON. Participants were Turkey representative amputee soccer player(TUR), Japan representative amputee soccer player(JPN) and collegiate non-amputated player(COL). Participants performed short sprint, place kick and volley kick. As a result, in the sprint, COL showed the largest sprint velocity. It was revealed that acceleration by ground contact of crutches is important to decrease deceleration of body velocity for the amputee player. In the place kick, trend of kinetic chain that expressed by velocity in the direction of displacement of some anatomical landmarks in kicking foot side was not different. However, it was considered that the last step before kick impact without ground contact of crutches can make large body velocity as same as non-amputated player velocity. In the volley kick, amputee player showed ability to raise higher kick impact height. They used crutches to support their center gravity of body. Then it enables to make higher trajectory of kicking foot than center gravity of body till the 2 m for maximum height for amputee player. We confirmed that how to use crutches, pushing ground and supporting center gravity of body or not using in the situation required acceleration were too important for amputee players.

We developed a wearable device that can electrically stimulate muscle and measure the muscle activities simultaneously. This device is composed only of flexible material such as textile electrode printed on cloth and 5μm-thick piezoresistive silicon, polyimide substrate and PDMS. By deploying this device on sportswear, muscle training and motion assist by electrical muscle stimulation become possible, monitoring muscle activity simultaneously.

The purpose of this study is to develop a robust heart rate measurement algorithm in sports, especially cyclic motion like treadmill running and walking using optical sensor and 3-axis accelerometer. The pitch of running was calculated from 3-axis synthetic acceleration, and remove motion frequency peak in the frequency spectrum. When the frequency of motion and heart rate is near, the pulse wave was beaten. The problem was solved by detecting nodes in the beaten waveform and applying the window function around nodes. Results of the experiment compared with chest type heart rate sensor, it was confirmed that the accuracy of this algorithm was high. (MAE = 1.45[bpm], RMSE = 2.00[bpm])

In this research, we focused on the part of the players' ability to exercise their ability by using GPS, depending on the skill level of attacking players. In previous research using GPS, it is often used as a physical aspect that it is important that the numerical values such as the distance traveled and the number of high-speed sprints are high. In order to judge the skill level of individuals. There are no papers using. If we can judge the part there using GPS, we think that we can show new suggestions on the use of GPS. Training of 6 vs 3 ball pitches was conducted with the top team players as the top team and the 4th team player as the lower group of the university. Student 's football team belonging to the Kanto University football league. (15 m x 15 m) 2 min x 5 combinations of combinations of offensive side and defensive side with upper group x upper group, lower group x lower group, upper group x lower group, lower group x higher group. The phase was divided every 15 seconds, GPS values were analyzed, and RPE was measured every 1 minute as heart rate and psychological fatigue degree as physiological fatigue degree. It was found that the numerical values of the GPS of the lower group at the time of attack were significantly lower than those of the other groups, and the upper group had elements that did not increase the speed and strength of the partner compared to the lower group. Although it is definitely a fact that it is better that the physical numerical value is higher, it is thought that the sports such as football is a sport where relative importance is more important. In other words, in football, it is seen that when you jump in vigorously, it is used to take advantage of that power and you are reversed, and if that situation continues, you will not be able to approach the opponent with the momentum. It is inferred that the high level players are equipped with this part, which creates a situation that "I want to go but can not go" by cutting off opponent's momentum, that is, not to show the opponent's ability.

Currently, there are a few sports centers for prosthesis. There are few places where seniors can do exercise. In public places, it is an effective exercise that they walk the appropriate distance. Also they participate in light sports accompany their health care. It is stated in this experiment utilizing Satellite-data gives them places of safe exercise and we analyze exercise load using this data.

Measurement of whole body motion using motion capture play important role in fields of rehabilitation, imitation learning, and human-robot interaction. However, the measurement requires a large number of markers and sensors to be worn and there are many limitation on the measurement environment. In this paper, we propose a novel method to estimate whole body motion from partially observed body motion during walking. We create a deep neural network similar to the Convolutional Neural Network (CNN) auto-encoder to extract features of walking motion from partial motion data and estimate whole body motion from the features. In the experiment, we compare the estimated joint angles and motion data to verify the usefulness of the proposed method.

In previous works, instrumented insoles with a small number of force sensors have been proposed for kinetic gait analysis in small clinics, where costly force plates are not available. However, their calibration, which estimates vertical ground reaction force (vGRF) from their sensors, relied on the use of force plates. Therefore, this paper presents a novel calibration method of the insoles to estimate vGRF during walking using the Wii Balance Board (WBB) as an accessible alternative to force plates. The sensor forces were weighted using linear least-squares regression to fit to the measurements of the WBB during walking or standing. By comparison with force plates, the accuracies of the vGRF estimated by the proposed method using the measurements of walking through the WBB were equivalent to the force plate-based calibration. In addition, the method based on standing on the WBB did not have large deteriorations when compared to the walking-methods. From these results, the proposed calibration methods of the insoles using the WBB were valid for kinetic gait analysis.

Analyzation of the rowing motion of a boat is necessary for improving athlete’s rowing technique. In this research, a system is developed to measure the rowing motion only by attached the sensors on the boat and the oars. A distance sensor and two IMU sensors are used to measure the motion of the seat, oar, and boat. From the measured data, the movement of the seat and oar can be calculated on the boat. In the evaluation experiment, we test the measurement system on a rowing machine. The accuracy is evaluated by comparing the measured data that obtained from the developed system and the optical motion capture system.

This paper proposes the estimation method of joint torque in gait analysis using the wearable sensor system installing the inertial sensors and the wearable force plates. In this method, joint torques are calculated by inverse dynamics analysis using the Newton-Euler method, and the joint torques are compensated by using the Unscented Kalman filter and the conditions of the body structure. This method estimates the joint torque compensating the accumulative error by transmission of force and moment in the Newton-Euler method. We conducted the measurement experiment the 5m gait test, and we estimated the compensated joint torques. The results by proposed method showed the same tendency as before the compensation, and the offset error was compensated. This method can be used for the gait analysis using the wearable sensor system.

Motion capture systems are used in various fields such as sports, medical, and robotics. Among the motion capture systems, optical systems are used most commonly, and these are also used in the experiments to obtain swimming motion in many studies. However, their own problems such as marker loss and marker misrecognition induce difficulties in experiments especially for swimming motions. In addition, the optical systems are generally very expensive and large scale. The objective of this study was to develop a new motion capture system for swimming by using inertia motion sensors that swimmers can use in a daily training. In this report, the conversion programs to transform the captured data into the form to analyze in SWUM were constructed by considering standard posture, rotating coordinates, and the direction of the model in the world coordinate. An example of conversion was conducted for a motion on the land. From the results of conversion, it was confirmed that the converted motion generally corresponded to the original motion. In addition, sensor parts were waterproofed by using freezer bags, silicon type fillers, and water-resistant adhesive.

The purpose of this study is to examine the accuracy of the system analyzing pitching data using baseball-type sensor (MAQ) and to measure kinematic parameter (ball velocity, spin rate, and spin axis) of baseball pitches by various pitchers. The accuracy of the developed system using a 3D motion analysis system and the high-speed cameras were examined. The spin axis of pitched ball was calculated from data of 12-axis sensor using the sensor fusion by extended Kalman Filter. The ball velocity and spin rate calculated by MAQ and the 3D motion analysis system showed similar values (ball velocity: r = 0.95 spin rate: r = 0.90). In several data, it was indicated that the spin axis calculated by MAQ, the 3D motion analysis system, and the high-speed camera showed similar values. In addition, there was a correlation between ball velocity and spin rate over the velocity range from 6.7 m/s to 41.0 m/s (n=188). From these results, the developed system can be used to evaluate baseball pitching skill with high accuracy.

In order to measure the kinematics of racing bicycle in indoor track, extended Kalman filter method was implemented. Bicycle model was modeled as symbolic formula by using variables considering the road-tire contact condition and the 3 dimensional track shape. Measurement function is derived as symbolic formula by the variables. To verify the Kalman filter system, simulation data was used as measured data and filter was tried by 9 noise parameter sets. It found to be that The filter could reproduced the true motion with an error within a problem-free range under valid noise parameter setting.

The climbing mountain population in Japan is 6.5 million people in 2016, and elderly people over 60 years old account for 40% of the population, mountain distress is rapidly increasing, due to elderly people with weak physical strength and muscular strength. According to the guidelines of the International and Climbing and Mountaineering Federation. They recommend the use of trekking pole for elderly people and climbers with heavy luggage. They said that using the pole can reduce the burden on the lower body such as the knee. However, there are few objective data on the usage of the pole and the burden reduction. Therefore, we made a detachable sensor that can measure the acceleration and pressure of the pole in order to measure the movement of the pole. Using the pole, we confirmed that the movement of the pole can be measured in detail. In climbing, the pressure of the pole is large, but in down, it is small. In addition, skilled people swung it forward efficiently like the pendulum motion, but beginners lifted it high. We think that can be measured form the prototype sensor the method of using the pole according to circumstances.

This paper proposes the evaluation method for the stabilometer center of gravity feedback system using the inertial sensors and the wearable force plates. This method estimates the PD control parameters and offset value using the ankle joint angle and the ankle joint torque. The ankle joint torque is calculated by inverse dynamics using ground reaction force, moment, inertial sensor output and the joint angle estimated by using the sensor fusion. We conducted the measurement experiment using the stabilometer, the inertial sensors and the wearable force plates, and we estimated the PD feedback control parameter and offset parameter in the experiment. The results indicated the change of parameters before and after use of the stabilometer. The method can be used to evaluation the effect by using the stabilometer.

The purpose of this study was to examine the possibility of a system which can act immediate feedback of generating mechanism of ball throwing motions in different sports (baseball and handball) using inertial measurement units (IMUs). The IMUs were attached on the upper trunk, upper arm, fore arm and hand segments. The posture of each segment was estimated from the angular velocity outputs of the IMUs. Dynamics contribution analyses were carried out with respect to the estimated motion. The contributions of the individual terms such as, joint torque term, gravitational force term, and motion-dependent term (MDT) to the generation of ball speed were quantified using the equation of the target system with estimated segmental postures. Furthermore, the generating factor of the MDT was considered using a recurrent formula derived from the equation of motion for the target system. The results of this study show that almost good agreements between estimated motions with IMU outputs and measured motions obtained by a motion-capture system in terms of generating mechanism of ball speed. Moreover, dynamic contribution analysis obtained from estimated motion data could show the difference in terms of generating mechanism of ball speed in throwing motion by balls of different sports. Constructing immediate feedback system with respect to the speed generating mechanism using IMUs would be expected to evaluate generating mechanism at sports fields.

Nordic walking, or walking with poles, is an effective aerobic activity that uses the whole body. We consider the information that can be learned from receiving feedback from the poles in real time during use. We developed a compact and portable system using Raspberry Pi, Arduino, Grove sensors, etc. to analyze the use of the poles in Nordic walking. We installed 10 axis IMU sensors at the tips of the poles, and measured the behavior of the poles in the system at the gymnasium and on a hiking course. From the acceleration information in the obtained data, we could study the difference of behavior between experts and beginners. In addition, we investigated the impressions of the colors of LED tape lights attached to the poles. From these data, it is possible to present useful information by changing the LED color in sensor data from the poles.

Visualization of balance evaluation during standing is important issue for diagnosis of disease and determination of training effect. Although there have been many studies of the balance evaluation, these evaluation methods are insufficient in terms of a saving of work and its reliability. This study tries to evaluate the balance characteristics based on a mathematical model from the response of human body to an external stimulus. We applied frequency analysis to the response to horizontal sway of the support surface as the external stimulus, and identified personal balance characteristics by fitting an assumed balance control model to the result. The balance control model assumed in this study is multiple feedback loop system which is composed of the delayed state feedback control system as an inner-loop and posture control system according to the velocity of the support surface as an outer-loop. From the feedback parameters for inner-loop control, we found individual balance characteristics by calculating equivalent damping ratio and natural angular frequency. As a result, the present method can evaluate individual balance characteristics by using the assumed feedback model when external stimulus is acted.

The present study aimed to elucidate the direct relationship between the degrees of freedom (DoF) of embodied systems and postural fluctuation. An embodied system consists of various DoF and can be considered a complex system. Postural fluctuation can be considered a representative of system dynamics and easily measured. Therefore, it is expected to be useful for assessment of fall risk in elderly people. Recently, clinical studies have not only applied linear methods but also nonlinear methods of assessment to evaluate static and dynamic balance abilities. In our presentation, we report the result of our preliminary experiment that examined the effect of joint DoF fixation on postural dynamics. Young healthy male participants were asked to maintain their balance during a single-leg standing task with no fixation or with ankle/knee joint fixation. The time series data of the center of pressure (COP) were collected and analyzed using linear and nonlinear methods. As a result, static measure (COP trajectory length) did not significantly differ across the conditions. On the other hand, the dynamic measurement (the detrended fluctuation analysis scaling exponent) was significantly higher in the ankle-fixation condition in the mediolateral (ML) direction. These results suggest that although static balance ability was not affected, dynamic balance ability (anti-persistent behavior) was reduced under the ankle-fixation condition in the ML direction by constraining the DoF.

Human can learn to move limbs in novel environments by modifying the endpoint trajectories, for example, correcting hand trajectories to accurately throw a ball to a target. However, the complicated modification at multiple joints is needed to correct the limb endpoint, since the endpoint movements are generated by the combination of multi-joint motion. Then, how is the learning response at a limb endpoint distributed among different joints? To answer the question, participants performed horizontal reaching movements to each of 8 targets while holding robotic handle by their right hand. For the training, the reaching movements were performed under the presence of a velocity-dependent curl force field. Learning response of hand force was quantified as the force pushing a randomly-interleaved virtual force channel, in which the movement trajectory of the handle was constrained to a straight path from the start position to the target. During the tasks, the torques in shoulder, elbow and wrist joints were estimated from the kinematic data obtained using a motion capture system. As a result, the hand movements were corrected by exponentially increasing the force against the force field across each training trial. During the training, muscle torques in each joint were gradually modified to generate the corrected force. Interestingly, the learning to the torque after the training trials was faster in the distal joint than in the proximal joints. Accordingly, early in the training the joint motion in the distal joint would be corrected to generate the desired hand movement whereas late in the training the proximal joint was modified to fine-tune the hand motion. Therefore, movements can be learned in novel environments by modifying the multi-joint motion in chains.

This paper proposes the estimation method of gait velocity and position using wearable sensor system installing inertial sensor. This method decides the ground contact using the angular velocity and the posture information. The posture information is estimated from angular velocity and acceleration by the sensor fusion algorithm using the Extended Kalman filter. The gait velocity is calculated by using the angular velocity and the position vector from ground to the inertial sensor attaching on lower thigh in the ground contact states. We conducted the measurement experiment of 10m gait using the wearable sensor system. The gait velocity and position are estimated by using the measurement information. We can decide the ground contact by using the angular velocity and the posture information, and we estimated the gait velocity considering the ground contact and the rotational motion of lower thigh segment. Hence, we could obtain the gait velocity and position indicating the compensated values. Therefore, we indicated the effectiveness of proposed method. This method can be used to gait analysis using the wearable sensor system using inertial sensor.

Feasibility assessment was performed about a gait pattern analysis based on the temporal relationships in the multidimensional data obtained from inertial measurement units (IMUs). Temporal delays between time-series data of three 6-axes accelerometer and gyroscope sensors on the left and right forefoot and over the sacrum, under normal and fast 10 m walk by 35 elderly participants. Nine temporal delay parameters were estimated in terms of maximum and significant cross-correlation in the 2-second window between all possible combinations of the time-series data, including inter-sensor parameters, suggesting applicability of the method to the whole-body analysis. One parameter successfully predicted fall history. Other parameters successfully predicted levels of need for care (AUC=0.78, accuracy=82.4% for normal walk, AUC=0.66, accuracy=76.5% for fast walk). Future studies should address whether the analysis of the detailed temporal relationships enables more accurate estimation of gait kinematics as well as gait characterization directly.

The importance of rehabilitation in the treatment for walking disorders due to such illnesses as strokes continues to increase. When physical therapists instruct a patient during rehabilitation, information about joint moment of lower limb is very useful. Joint moment of lower limb has been calculated by inverse dynamics applied to data obtained from a force plate and three-dimensional motion analysis system and their use conditions and measurable number of steps are limited because they must be installed at a purpose-built structure. Therefore, the wearable gait motion analysis system using mobile force plate and attitude sensor has been developed. However, structural optimization of the mobile force plate based on the ground reaction force during gait as the biomechanical evidence has not been investigated yet. In this paper, we showed a new optimum design example of the mobile force plate by applying the multi-objective structural optimization technique using finite element analysis based on strains, response surface method and desirability function. As a result of inputting each load condition by using the ground reaction force during gait, we could optimize the structure of the mobile force plate as the minimization of several dimensions based on the maximization of strains to each axis direction of the elements and nodes of maximum principle stresses. We applied optimum design variables to the finite element model and validated the effectiveness of the proposed design example. Finally, optimization of the mobile force plate for the improvement based on structure and arrangement of three-axis force sensors was attempted.

In this research, a flexible contact sensor for triaxial load measurement was placed in the insole, and a system for measuring the load applied to the soles of the foot during walking was prototyped. For measuring the load distribution of the sole at the walking, the effectiveness of the system by measuring on walking was confirmed on the treadmill. As a result, it was possible to measure the angles of vertical load, shear load, and shear load in all sensors. It was possible to confirm the usefulness of the measurement system that can easily measure the load distribution during walking.

Rosin powder, which consists mainly of magnesium carbonate powder and pine rosin, has been used empirically as an anti-slip agent in baseball pitching. However, it is unclear whether the rosin powder increases friction between baseball ball and a finger. In this study, the effect of rosin powder on the frictional characteristic between baseball ball and a finger was investigated by sliding friction test using a force plate. A leather sheet of baseball ball was adhered to the force plate. Ten young adult male participated and they were asked to slide their right index finger on the leather sheet of baseball ball under various normal load and sliding velocity conditions. The test condition of the interface between the ball and the finger were varied as follows: dry without powder, dry with rosin powder, wet without powder, and wet with rosin powder. The results indicated that the powder tended to rather reduce the friction coefficient under dry and wet conditions. The powder also reduced the effect of normal load and sliding velocity on the friction coefficient under dry and wet conditions, suggesting that rosin powder stabilizes friction between a finger and a baseball ball.

The purpose of this study was to verify the precision of different simulation methods to extrapolate vertical pitch location with the use of some dynamic parameters at ball release measured by TrackMan, and to determine dynamic parameters to predict pitch location. Ball trajectory was calculated by the equation of motion with three different numerical analysis methods (Euler, Runge-Kutta, Dormand Prince) and the vertical pitch location was compared with the measured values. The total number of pitches was 137 pitches. Dormand Prince method showed the smallest errors (5.8 ± 1.4 cm) compared with Euler (6.8 ± 1.4 cm) and Runge-Kutta (6.7 ± 1.4 cm) methods, indicating Dormand Prince was the highest precision method to extrapolate pitch location, but all methods could extrapolate it below the size of ball. Simulation with Dormand Prince method and multiple regression analysis revealed that elevation pitching angle and ball velocity more predicted vertical pitch location rather than other parameters. Furthermore, regression equation structured by these parameters could predict the pitch location with error by less than 10.0 cm (9.5 cm). These results indicate that the elevation pitching angle and ball velocity, i.e. velocity vector of ball, affected the determination of pitching location.

The purpose of this study was to test the validity of using a one- and a two-segment models for determining elbow joint valgus stress during baseball pitching. The one-segment model consisted of a single segment representing the ball, hand and forearm together as a rigid segment. The two-segment model consisted of a distal segment representing the ball, hand and forearm together as a rigid segment and a proximal segment representing the upper arm. In addition, a three-segment model, which is the most widely and frequently used model for determining the valgus stress of baseball pitching, was defined to provide a reference value for testing the validity of the fewer segment models. The three-segment model was comprised of a distal segment representing the ball and hand together as a rigid segment, a mid-segment representing the forearm and the proximal segment representing the upper arm. Fourteen university students with the baseball experience were asked to throw a baseball with their maximum effort and a motion capture analysis system (VICON, Oxford Metrics) was used to measure the motions of the segments. The result showed that the maximum values of the valgus stress determined with one- and two-segment models (approx. 64 Nm for fast balls) were significantly greater than the corresponding value determined with three-segment model (47 Nm), but the correlations among the three models were found to be significantly high (r > 0.83, p < 0.01). These findings suggest that the fewer segment models can be used to compare the magnitude of valgus stress among subjects and among pitches for evaluation of risk of elbow injuries.

Softball is a very popular sport among people irrespective of age or gender in Japan. In the present work, by adding a holding device to the arm-type pitching machine for throwing softball, we develop a prototype machine to realize a real pitcher's windmill throwing (i.e. the one arm revolution is performed as well as windmill rotation). We carry out pitching experiments to verify the pitching performance of the developed machine, and investigate the shape influence of the curve hand that can throw curveballs with small eccentricity of the spin axis and large change of arrival position by pitching simulation using finite element analysis. In special, we design the optimal shape of the curve hand according to the finite element simulation and evaluate the pitching performance by pitching experiment at last. As a result, we confirm that the machine can pitch softball as a real pitcher's windmill throwing that can be utilized in batting practice.

Joint constraint axial torques such as valgus/varus axial torques at knee and elbow joints are crucial factor of joint injury during several sports motions. The purpose of this study was to propose a method which quantifies the generating mechanism of the constraint torque using the induced constraint torque analysis based on dynamic equation with respect to the constraint axial torque. Three-dimensional coordinate data of markers attached to rugby players during place kick motions were measured with a motion capture system with one force plate. The kicking-side leg was modelled as three rigid segment linked model consisting of thigh, shank and foot segments. The equation of motion and dynamic equation with respect to the constraint axial force were obtained. The dynamic contributions of individual terms such as joint torque term, motion-dependent term and gravitational force term to the constraint axial torque was derived from these equations. The results show that 1) active joint torques contributed mainly to the constraint axial torque during the rugby kicking motion and 2) the contribution of joint torque cancelled with the contribution of the gravitational term when considering generating factors of the motion-dependent term during the kicking motion with respect to an example.

In order to design a comfortable bathtub to soak, it is important to evaluate the biomechanical load in the soaking posture. In the previous researches, joint torques as the biomechanical load were calculated. However, in these researches, biomechanical models in the sagittal plane were used and therefore only two dimensional joint torques were calculated. The objective of this study was to calculate the joint torques in three dimensional soaking posture in the bathtub. In order to calculate the joint torques, the soaking posture and reaction forces from the bathtub were obtained by an experiment. Marker coordinates were obtained in the experiment. From the marker coordinates, the directions of the body segments as well as joint angles were calculated. These data were used to calculate the joint torques in the biomechanical model with considerations of gravity, buoyancy, reaction forces from the bathtub, and passive elastic joint torques. From the results, it was confirmed that the components of the joint torques which were not calculated in the previous researches of the sagittal model had certain values.

In this research, we conducted an image analysis from the imprint in shoe insoles. This measurement method is thought to be meaningful because it does not prevent the subject’s natural motion and allows for the capture of a long-term imprint. The subjects were 10 university student (badminton players). Images of insoles ( Dominant Leg group : DL, No-Dominant Leg group : NDL ) were obtained using a camera. The luminance value ( LV ) for each insole was converted to a normalized luminance ( NLV ) value with the minimum value of the insole set to "0" and the maximum value set to "100". NLV was used to calculate the mean for all items with in pixel coordinates and produce a mean luminance value ( MLV ). MLV was divided into 6 regions ( each group ). When a significant difference was recognized, Tukey's multiple comparison test was performed. The occupancy ratio was calculated. The results showed a strong imprint at the big toe, ball of the foot, and calcaneal region. The imprint in the arch of the foot was extremely weak. The imprint of toes other than the big toe in NDL tended to be weak. The center of gravity had the same wave form as the center of pressure. MLV by region showed significant differences mainly between the big toe, fore-foot, and calcaneal region. The occupancy ratio showed significant differences in dominance in the fore-foot, metatarsal medial part, and metatarsal lateral part.

Patients with knee osteoarthritis (OA) have biomechanical alterations in multiple joints during level walking, possibly due to efforts made to avoid pain and minimize knee stress. These biomechanical alterations accompany gait asymmetry, which provides important information about the locomotor mechanism. This cross-sectional study (n = 131; age: 74.2 ± 5.81 y; 71.8 %female) found that patients with severe knee OA had greater gait asymmetry in the medio-lateral axis, evaluated using inertial measurement unit (IMU), and the increased gait asymmetry was associated with a greater knee pain and disability. Furthermore, we proposed “GAIT” (Gait Asymmetry Improving Therapy) concept which supports decision making of therapeutic target in knee OA patient (77 years old; female) with coexisting gait asymmetry and contralateral knee pain. Six weeks physical therapy based on the GAIT concept resulted in improved patient’s clinical outcomes. IMU-based gait assessment could provide us deeper understanding of pathomechanics of OA-related symptom and disability and would support decision making of patients treatment.

People lose knee joint when above knee is severed because of disease or accident. Losing knee joint makes people difficult to walk and to go up/down. Therefore, the range of activities of prosthetic wearers are decreased and the quality of life (QOL) for these people is lost. The walking gait obtained by almost all existing above-knee joint prosthesis are greatly different from healthy people because those prosthesis have no function of fixing/extending the knee joint at an arbitrary angle. This research develops an above knee developed which can fix and extend the knee with a compact and lightweight mechanism without using an external driving source for example batteries. In the proposed fixing mechanism, the wire is towed by the deformation of the arch type foot, and the brake-caliper clamps the brake disk fixed at knee joint, whereby the braking force is generated. In the knee extension mechanism, the input cylinder installed on the instep of the foot is pushed in, and extension torque around the knee joint is generated by extension of output cylinder connected by the hydraulic hose. In this paper, the gait stabilization is evaluated by forcusing on the ground reaction force and knee joint angle while using the developed above-knee prosthesis fix/extension.

This paper proposes a motion estimation method using an inertial measurement unit (IMU) for sports measurement. Although motion capture systems using infrared cameras and high-speed cameras provide accurate motion measurement, they are typically expensive and they require time and effort for installation. Therefore, such motion capture systems are not something that anyone can use easily and daily. IMU-based motion estimation technologies can enable handy and inexpensive motion capture systems. The problem we tackle is accumulated errors caused by integration of IMU data, which need to be corrected to achieve practical estimation accuracy. One of the existing approaches for correcting the errors is to use the constrained initial and final states. The accumulated errors are uniformly distributed and canceled throughout the trajectory. We have previously proposed a generalized method that can incorporate measurements of intermediate states; however, the method requires a long processing time. In this paper, we propose an accelerated extension of the previous method based on a different formulation. The experimental results using simulated dataset indicate that the proposed method exhibited approximately six times faster than the previous method. We also report a measurement result of a 19 seconds table tennis play.

We aim to develop a method to measure a table tennis service stroke using an inertial measurement unit (IMU). In table tennis coaching, the orientation of the racket face and the velocity of the racket in a stroke is considered to be important. The mainstream approach to giving real-time technical skills instructions is to have athletes gain technical senses and knacks by having them observe model movements and giving appropriate advice from the coach. It is expected that the quality of on-site coaching can be increased by adding numerical data that serves as objective indicators to back those instructions. However, quantitative data of the racket is usually unavailable in field without using expensive motion capture systems. IMU-based motion estimation methods can enable cheap and handy table tennis stroke measurement. In this paper, we discuss how such methods can be applied to table tennis and we propose a method to measure a service stroke. Accumulated errors in IMU data integration are corrected using a constraint of predefined initial and final states. We measured six types of service strokes 10 times each. The estimated racket trajectories exhibited practical accuracy for the purpose of table tennis coaching.

The purpose of this study was to quantify the mechanism of side-step cutting maneuvers during acceleration phase usually observed in ball games. Four male participants were instructed to perform anticipated 90-degree side-step cutting maneuvers (SS) with the approaching speed of 3.0m/s. In order to reduce the influence of their kinematical differences, they performed SS under restricted track-width condition. Forty-seven reflective markers attached to the body and ground reaction force (GRF) of support legs were measured with a motion-capture system (VICON-MX) and a force platform, respectively. The dynamic contributions of support leg joint torques, during the SS and the next step cutting maneuver (NS), to the generation of GRF and the angular momentum of the HAT (i.e. hat, arms, and trunk) segment through the foot segment of the support leg were quantified by using dynamical force equation regarding 15-segment-linked wholebody system. The results obtained in this study show 1) the extension torque at hip joint play a role in maintaining the upper body posture by controlling forward rotation and side inclination of the HAT segment, 2) individual support leg joint torque maintains the posture of the body on the frontal plane by cancelling the angular momentum of the HAT segment about the axis pointing medial to lateral direction through the foot segment of the support leg, and 3) contribution of the hip joint extension torque to the reduction of body forward rotation in the NS was higher than that in the SS.

Kyudo is a martial art which attaches importance to the operation process, and it is necessary to understand the sequence operation of the shooting method called the Shaho-Hassetsu according to the guidance person and the Kyudo textbook. The Shaho-Hassetsu refers to the Shajutsu procedure law when you have a bow and arrow in Kyudo. It is said that it Shichido the form of the shooting method from old times, and it is called Gomi Shichido. A series of processes to shoot a single arrow is dividing to seven items, This alone is not a Shaho-Hassetue of the shooting method, and in recent years it was added to the Shichi Fushi in addition to the remaining body (Zanshin) Shaho-Hassetsu. The discipline of Shajutsu is related to the Shaho-Hassetsue of the shooting method, and there must be no separation between them. That is, it is possible to smoothly synchronize the movement of the Shaho-Hasstue, Shajutsu technique is said to be Shaho-Hassetue. Among them, there are a lot of points and advanced technologies that should be noted in the "Kai "(association) and "Hanare"(away) which directly connects to Nakari. In fact, when you look at the contest in Kyudo magazine, you can see many comments about the association and the distance, and it is often pointed out to all the players, so in this research,Focusing on these two behaviors, we compare the differences between the high school students from Kyudo beginner to the expert, and the ideal shot form.

At the opening of a match, a skilled Judo referee’s focus is on the upper body of the two contenders. After that, the referees point of reference changes when the contestants skill is displayed, and focus is increased to the lower body. This is done to catch the movement of the thrown combatant.

In this experiment, the referee’s line of sight was confirmed to act according to the above. This was observed by recording a video of the referees line of sight, through use of specialized equipment. Furthermore the referees were interviewed. From this data, the following three observations were made.

1) At the opening of the match, before the competitors have come together, the referees focus is on the half way point between the competitors. I believe this may be to ensure the referee can maintain visual contact on the two opponents until they come together. When the two competitors come together, the viewpoint switched to the middle of the lower back. This is to increase visibility and understanding of the entire body of the two competitors.

2) Focus is on the equal height of both competitors’ lower backs. When one competitor moves into a dominant position, focus is shifts to the lower back of the dominant competitor. I think this is to be able to predict when to change focus as indicated below in (3).

3) When a sign of skill from the dominant postured competitor shows, focus immediately shifts to that competitors feet.

I think that because this moment may decide the match, the referee wants to judge this movement carefully.

In this paper, eye tracking of a referee in a Kendo match was conducted to gather the information on his eye movement and visional field. The kendo match with referees was performed to characterize the eye movement of the referee and to investigate the influence of his eye movement to his judge. A calibration-free eye tracker device, EMR-ACTUS, and a wearable camera, HX-A1H, were employed to correct the information on visual field of the referees and to record their eye movement. The number of strikes in the match was counted, and the strikes were categorized into three stages for evaluation. It was found that the umpire watched the middle part between players during the whole match. The gaze point did not vary depending on the number of effective strikes and regular strikes. Additionally, it was found that the gaze rate to a player decreased in the case of a low-rated evaluation regarding strikes.

Knee is one of the most frequent-injured joints in the human body, in which anterior cruciate ligament (ACL) rupture is common serious and frequent injury. However, since it is difficult to measure the ACL loading during motion in vivo, it is still not clear which muscles generate ACL loading and what roles of these muscles playing in cutting maneuvers. Therefore, the purpose of this study was to quantify the dynamic contribution of the muscle forces to the ACL loading and ground reaction forces (GRF) generated during sidestep-cutting maneuvers based on multi-body dynamics using a musculoskeletal modelling method. Three-dimensional movement analysis was carried out to investigate five female participants performing anticipated 90° sidestep-cutting maneuvers. Trajectories of 49 marker on the body and GRF of the support leg were measured with VICON-MX system and a force plate, respectively. ACL forces were estimated by optimizing calculation to be equal to the horizontal component of the tibia force generated by muscles during the first 50ms of the contact phase. The results indicate that 1) quadriceps muscles mainly contributed positively to the ACL tension, and it contributed to braking in the approaching direction, and 2) hamstrings muscles mainly contributed negatively to the ACL tensions and positively to the ground reaction force in the cutting direction.

Rowing power moving a competitive boat is generated by coordinating action among leg, trunk, and arm. Their temporal and/or spatial coordination is critical to determine the efficiency of moving a boat. Although a wide variety of rowing style has been proposed, it has not been fully elucidated which technique is superior and if the optimal technique exists. In order to approach this issue, we have developed a system to measure the handle force and position, the seat position and the force exerted against the foot-stretcher (foot plate) during performing rowing movement on Concept 2 rowing ergometer. This system enabled both athletes and us to check how they row in a real time fashion and to see the analyzed data immediately after several rowing strokes. The data collected using this system from the athletes with various competitive levels revealed several characteristics that superior athletes possessed. Firstly, contrary to the expectation that the superior athletes should have faster knee extension velocity (i.e., backward seat velocity), they had slower seat velocity. Secondly, the direction of force exerted on the foot-stretcher was more horizontal for the superior athletes. We speculated that the superior athletes had the ability to control the force direction on the foot-stretcher, which might contribute to reduce the seat velocity because the greater effort of knee joint extension torque was needed for the more horizontal force exertion. The ability to control the force direction is likely to be associated with more efficient rowing power generation in completive rowing athletes.

In a golf swing, a player is acted an inertial force due to the movement of the arm and the club during a swing. On the other hand, if countermeasures are not taken, the equilibrium of forces cannot be taken, and as a result, the player staggers. Therefore, this report examines how to balance a player from measurement experiments. In this research, we consider the balance mechanism by using the trajectory center of pressure, actual golf swings were measured using a three-dimensional motion analysis system and two force plates. And we analyzed for the hitting direction or the anteroposterior direction to evaluate mechanism of balance. From the measurement results, the inertial force caused by the swing motion and the inertial force due to the other motion are separated and estimated, and it is clarified how the respective forces affect the trajectory of center of pressure. As results, it was shown that movement of the trunk acts as an action to balance a player.

Techniques called ”Fitting”, which considers the individual swing characteristics and suggests a golf club optimal for the player, have attracted attention. In the system developed by the authors so far, we can find optimally designed the golf clubs for the individual swing by swinging nine clubs of different characteristics. In this study, for researching relationship with golf swings and club characteristic, we measured four golfer’s swings by motion capture system. Subjects swung two clubs that differ the shaft kick point, and we composed observance matrix from positional data. We conducted SVD to this observance matrix, and conducted Three-way ANOVA to each club motion. As a result, we can decompose golf swing into simple motion combination, and clarify the timing to be affected by the difference in shaft kick point.

Golf club is manipulated by both hands and arms which consist closed link structure. Since the closed link structure can move fast the club and transfer the energy of trunk and lower body into the club directly, it is important to understand how golfer manipulates the golf club using both arm forces and torques acting at each grip. In this study, the manipulating forces which act at both grips during golf swing were measured using a 3D forces and torques sensors and motion capture system with high accuracy for understanding how human utilize force redundancy to control the golf swing. The results revealed that a golfer utilize high internal forces acting on the grips which does not contribute the movement of golf club in order to manipulate the golf club.