For the competitive swimmers with physical disability, an ideal stroke to master has not been fully clarified yet. The objectives of this study were to solve computationally the arm stroke of the crawl swimming that maximized the swimming speed for swimmers with hemiplegia, and to investigate the features of the optimized stroke. For this objective optimizing calculations with the random search, PSO (Particle Swarm Optimization) algorithm, and the swimming human simulation model was conducted. In the optimizing calculation the design variable was the upper limb motion of the unaffected side, represented by five degrees-of-freedom (three at the shoulder joint and two at the elbow joint), and the fastest stroke was obtained as the optimum stroke. For the motions of the other body parts, the legs, trunk and the upper limb of the affected side, the motion of the actual swimmer were used. When the stroke cycle was 1.0 s or 1.1 s, the swimming speed became fastest (1.19 m/s). With the short stroke cycles there were the differences at the end of the stroke, and with the long stroke cycles the swimmer pushed the water deeper in the optimum stroke.
This paper describes the aerodynamic drag acting on the tandem bike. Two full-scale models were employed for the wind tunnel tests. These two models can pedal the tandem bike. It was found that the drag depends on the pilot's helmet angle and the stoker's torso angle. The phase difference between the pilot's pedaling angle and the stoker's pedaling angle was also taken into account. The phase difference reduces the amplitude of the mechanical oscillation and the drag.
The objective of this study was to suggest a method for evaluation of a golf club by estimating the muscle force using a musculoskeletal simulation analysis. A golf swing was represented by prescribing the positional coordinate data of markers attached to the body of subjects (pro and amateur), which were obtained using a 3D motion capture system, into the musculoskeletal model which was scaled based on the body size of subjects. The motion of the club was also represented by introducing the positional data of each marker attached to the grip, shaft and head into the club model with rigid body, which gave the value of mass and moment of inertia. The tendency of the muscle force around the impact was estimated that both subjects mainly used the muscle around the shoulder joint rather than that of the part of large size and that the part of muscle used in the shoulder joint depended on the skill of subjects.
Our goal is to establish a multi objective optimization method of golf shaft to satisfy both with distance and stability. We suggest body burden as a new index for the stability in golf shot. Multi body dynamics and inverse kinetics were used for calculation of the body burden. We defined the body burden as total joint torque of the upper body considering threshold. Club speed was used as an index for the distance. Finite element method and Response surface method are applied for calculation of the club speed and reduction of optimization computing time. From pareto solution, we found out the each best shaft and the each body motion in the case of placing importance on club speed and body burden.
The objective of this study was to construct a finite element (FE) model for a carbon fiber reinforced plastic (CFRP) club shaft with varying torsional stiffness, and to investigate effects of torsional stiffness of the shaft on the dynamic behavior of a golf club during the swing. The FE model of a CFRP shaft with orthotropic elasticity was composed of four-node shell elements. Mechanical properties of a prepreg composites were determined using the rule of mixture which was defined by volume fraction of fiber and resin. The torsional stiffness of shaft was varied with the Young's modulus in the range of a third part of shaft length from the tip end. The constructed shaft models can qualitatively express the torsional angle in a static analysis which loads a torque around the longitudinal axis of the shaft, and swing simulation analyses were conducted using club models which introduced the constructed shaft models. The effect of the torsional stiffness on the clubhead posture at impact tended to be stronger with the impact velocity of the clubhead because of the centrifugal force acting on the head. But, the simulation results of the posture did not necessarily depend on the torsional stiffness. This indicates that the posture of the clubhead at impact tends to be subject to effects of the timing of the impact which depends on the relationship between the ball position and the impact velocity in addition to mechanical properties of the shaft.
It is investigated that how golfers control their arms and clubs for achieving almost the same postures at the impact although they have the various positions at the start of the wrist turn. The golfer's arm and club were modelled with the double pendulum model. Down swing was divided into the two periods, the first period is before the wrist turn in which the arm and club behave together and the second period is during the wrist turn in which the arm and club behave with a joint of the wrist. The effect of swing parameters on the postures of arm and clubs at the impact were investigated by the theoretical and modal analysis, and numerical simulation. It was found, as the results, that the reduction of the low arm and wrist torque during the wrist turn decreases the delay of the club against the arm at the impact. Therefore it is considered that golfers can control their postures of arms and clubs at the impact by appropriately controlling above parameters although they have the various positions at the start of the wrist turn.
For more than 100 years, manufactures have studied on dimple configurations including dimple arrangement, depth, size, shape, surface occupancy ratio and so forth, but in addition to these traditional approaches, a new scientific approach is expected to improve aerodynamic property further. Nike has been exploring micro roughness concept for several years to improve aerodynamic property. Nike has applied a new dimple technology called “Flightsuit” for their new 2016 golf ball, Nike RZN Tour. The “Flightsuit” consists of 13,558 micro dimples on 344 traditional dimple surface. The difference of flow patterns was investigated by PIV in order to confirm the effectiveness of micro dimples. The results showed the lift inclination pattern in the ball of “Flightsuit.”
In this paper, we simulate an oblique collision between a golf ball and an elastic body by LS-DYNA which is major FEM software. The body is used in this simulation with changing loft angle of the body, which is 15 degree, 30degree and 45degree, and also changing Young's modulus of the body. The ball is modelized by 3 piece ball, which consist of a core, a mid and a cover, and their Young's modulus are determined from our previous study. The frictional force, the normal force and the slip condition between the ball and the body are simulated by LS-DYNA. As the results, the difference of changing Young's modulus of the body and the loft angle are discussed on the frictional force, the spin rate and slip condition.
In previous study, quantitative relationship between slip magnitude under driver shot impact and back spin rate was analyzed. For confirming the theory, measurement system which can observe the slip magnitude in 0.5msec contact phenomena was constructed. The system could capture the slip phenomena clearly, and by the result, the slip magnitude vary from 0.3mm to 1.5mm by changing contact surface friction property. The difference of back spin rate and the relationship between slip and backspin is roughly correct with proposed mathematical model.
Golfers expect to hit a golf ball with enough distance for golf clubs, especially in the case of driver. Therefore, golf clubs are designed to satisfy golfers' demands. However, not only volume of head of a golf club but also coefficient of a golf club was restricted. Therefore, golf club developers use a variety of methods to customize clubs to individual golfer. One such technique is “database fitting,” established by Sumitomo Rubber Industries, Ltd. (SRI). In the future, golf club developers would like to provide shafts customized to fit each individual golfer. In order to do so, it is necessary to predict shaft movement during a golf swing via simulation. Previous studies simulating shaft movement during a golf swing demonstrate shaft movement using a finite element method (FEM) model with shaft flexibility and the golfer's grip. As a result, there was a difference of deflection value at impact timing. In order to solve this problem, we considered that the deflection torque generated by the cross product of the shaft deflection. Therefore, we made a simulation model in consideration of the deflection torque. To verify the effectiveness of this model, the shaft movement was measured with a 3D motion capture system (VICON). The sampling frequency was 500 Hz and markers were attached to the shaft. Examinees were one average golfer. We compared simulation and experiment. As a result, we reached conclusion that the model in consideration of the deflection torque can reproduce real golf swing.
The aim of this study is to establish the estimation method of body parameter using wearable sensor system. The wearable motion sensor installs gyro sensor, acceleration sensor and magnetic field sensor, and this sensor outputs angular velocity, acceleration and magnetic field. The output of acceleration sensor attached to body segment includes the centrifugal and tangential acceleration components, and these components include the position vector from the joint to the sensor. The proposed method estimates the position vector from the joint to the sensor by using the output of wearable motion sensor. Furthermore, the position vector is focused the component of 1-axis direction. We conducted the measurement experiment of bending exercises by a subject attaching the wearable motion sensors. The position vector from foot joint to the motion sensor attaching to lower thigh is estimated. The position vector indicated the similar result against the length measured using other method. We indicated that the proposed method can use in actual body motion measurement. Therefore, the method can be used for the development of more simply motion measurement method in the motion analysis using wearable motion sensor.
Since kinematic Global Positioning System (GPS) has highly accurate positioning ability, it has been used for sports kinesiology such as 3D movement measurement and analysis. Unlike camcorders, GPS loggers must be attached to measuring subjects, most of which are bodies of athletes and their tools. Therefore we have developed a compact and lightweight GPS logger named AT-H-02 with post-processed kinematic mode. The AT-H-02 is 1/7 more compact and 1/5 less weight than another mobile GPS logger with kinematic mode GCX2 by SOKKIA. The purpose of this report is to validate positioning accuracy of the AT-H-02 during outdoor sports. From experimental results using electric assistant tricycle, we found the positioning accuracy of the AT-H-02 is 5mm in horizontal and 14mm in vertical direction. It can be said that the AT-H-02 has enough positioning accuracy for kinesiology of outdoor sports.
The aim of this study is to establish the gait measurement mehod using the wearable force plates. In this study, we propose the method using the Extended Kalman filter for reducing the error by acceleration integration. The gait velocity is compensated by using the condition of grounding, and the covariance matrix about process noise of Extended Kalman filter was set to coordinate with the final value of position in traveling direction. The measurement experiment was conducted by using the wearable force plates and the motion capture system, and we conducted the measurement experiment in 10m gait supposing the motion measurement of long distance. This method can estimate the gait trajectory corresponding to the final values. This method will be used to gait analysis using the wearable force plate.
In this study, an inverse dynamics analysis method was constructed only by using some wireless motion sensors.(WMS) First, it was confirmed that the acceleration data by the WMS agreed well with the one by the 3-dimensional motion analysis system. Then, the method to estimate the contact period between the foot and ground was constructed by using the vertical acceleration data of the body. Moreover, the method to identify the ground reaction force was constructed, i.e., the top down approach. For the actual running data, the ground reaction force was identified, and it was concluded that the result agreed well with the one by using the force plate. The method constructed in this study, therefore, is concluded to be applicable for the actual application.
In this paper, we propose a novel Attitude and Heading Reference System (AHRS) based analysis method for sport wheelchair propulsion. Wireless inertial measurement units were attached to each wheel and an AHRS calculation was used to obtain the rotation angle of the sensors. The sensor rotation angle from the AHRS contains both the wheel rotation angle and the wheelchair turn angle in the horizontal plane. A coordinate system conversion from global coordinates to viewing coordinates was required to extract the wheel rotation angle. Both the distance travelled and the velocity were calculated using the angle. Four different trials were performed with two inertial sensors on each wheel. Straight-line distance tests gave high agreement among four sensors (28.164±0.028m). The difference between two sensors on the same wheel did not increase even for trials over 10 minutes, which implies a reduction in the effect of gyroscope drift. The velocity curves demonstrate agreement for acceleration and deceleration accompanied by push and traveling resistance.
The disabled sports get a great deal of attention. In fact, almost 40 million people watched the London Paralympic games on TV. Among them, the wheelchair racing has been popular after the first international wheelchair sporting competition for the disabled in 1952 and Japan got a lot of medals in the wheelchair racing. Due to advanced wheelchair quality and technology of analyzing kinematics, the results of record have improved. Previous studies considered the force on a hand rim and the characteristics of strokes. However these studies were confined to consider the driving force and the motion individually. One of the reason is that no measurement instrument of the driving force for a racing wheelchair was developed. Then this study developed the sensor wheel for a racing wheelchair to measure the two-force components on a hand rim plane. The experiment to measure the driving force and the motion at the same time was conducted at wind tunnel facility of JISS (Japan Institute of sports sciences) with the sensor wheel, 7 motion capture cameras and a roller system. The subjects were 3 proficient athletes, two of them have played as Japanese national members. They were asked to play the cruising and acceleration phase. In conclusion, the present study has demonstrated that the driving force could be measured with the sensor wheel and we could discovery the differences of strokes. Further study is needed in order to analyze the characteristic of strokes and indicate the relationship of each parameter in detail.
In recent years, fluid dynamics has been important in the competition to compete for speed .Wheelchair marathon to finish the race in 1 hour 30 minutes about the 42.195 km. For record improvement, they take various invention to change the shape of wheelchair to reduce air resistance. In this research, the air resistance of helmet and posture by the wheelchair marathon by were investigated by using computational fluid dynamics (CFD). Also, ass for the rear wheel of the wheelchair, three types of wheels, such as disk wheel, baton wheel and spoke wheel were investigated on the air resistance. As a result, the appropriate postures, helmets and wheels could be suggested on the air resistance in the wheelchair marathon.
In order to improve the performance in wheelchair racing, it is important for players to use the optimum wheelchair and to propel it in the optimum manner. However, only trial and error is conducted in the present training situation to find them. In order to consider the whole dynamics of player and wheelchair, a simulation model was developed in the present study. In this model, forces were given on joints of upper body, as well as between hand and handrim. Also, the forces between tyres and road were calculated by the magic formula. As a result, the experimental situation was successfully reproduced in this model, and the torque acting on joints were investigated. The developed model enabled to evaluate wheelchair and propelling style.
The purpose of this study indicates necessity of the shearing force measurement in socket for artificial foot. The measurement of force information in socket for artificial foot is difficult, and the force information is complication. Therefore, it is necessary to develop the sensor for measurement of the various force components, and the analysis for identifying the important factors such as shearing force should be conducted. In this study, we conducted the measurement experiment and analysis by hypothetical motion, and this experiment was conducted by using the artificial foot model manufactured by using the 3D printer. The motion was measured by using wireless motion sensors and compact force sensors. We extracted the components of force sensor output against the component of traveling direction. These results indicated the effect of sharing force for generating the force component of traveling direction. Hence, we can indicated the necessarily of the sharing forces sensor in socket for artificial foot.
A sensor using pressure-sensitive conductive rubber was developed, however this sensor could only measure normal loads and was unable to detect the shearing load and moment. Thus, a flexible contact sensor for three-axis load measurement using an elastic body and a pressure-sensitive conductive material has been developed in a previous study. The sensor has a load detection layer composed of multiple zones. It is possible to separately measure the shear component and components of the load based on the relationship among the voltage changes in each zone. However, the thickness of the sensor was over 5mm. In the present study, a sensor using a prismatic elastic body and a load measurement layer was developed for the normal and shearing force measurement in socket for prosthesis. The sensor is capable of determining the applied normal load, shearing load. To investigated the effectiveness of this sensor, the dependence of the voltage change on the normal force, shearing force. In the result, the thickness of developed thin sensor was 1.2mm.
In cycling motion analysis, a reaction force applying to each of the thigh from a saddle should be measured to calculate the hip joint torque. For this, a saddle type sensor that is split bilaterally has been developed in this study. This sensor measures a loading point in the error of 2 mm at most. From the measurement of a pedaling motion, the path of contact point between the sensor and the thigh was observed in lateral edge of the saddle surface. This result could not be obtained from a non-split saddle sensor, and the bilateral split sensor should be useful to analyze the pedaling performance kinetically.
Para-cyclists that use below-knee prosthesis in both legs do not have the healthy characteristic information of their feet. To decide the cleat position, they have to consider the relation between the position and pedaling performance. In this study, angular velocity and kinetic energy were evaluated when the cleat position was changed. Two dimensional lower extremity model was used in this study. The joint torque was generated using a central pattern generator (CPG), and the parameters of CPG at a certain cleat position were optimized by a genetic algorithm. As a result, there were some conditions where higher angular velocity and lower work were obtained. Therefore, an adequate cleat position could be decided to suit to a physical characteristic of a para-cyclist, and consider the other kinematic or kinetic quantities in pedaling performance.
We present a method for estimating the aerodynamic coefficients of balls in flight by using position data on its trajectory. Since this approach is the inverse problem of solving the motion equation, it is possible to obtain instantaneous values of the aerodynamic coefficients along trajectories. Considering the motion equation of a particle including aerodynamic forces such as drag, lift and sideways force, and applying space-curve geometry to it, general expressions for the aerodynamic coefficients are derived. In order to validate the present approach, we apply the method to trajectory data of golf and soccer balls in flight. In the former data, time series of drag, lift and sideways force coefficients are estimated by using three dimensional data measured with TrackMan, and the results on drag and lift show good agreement with those of TrackMan's output. The 12 data in two dimensional ball trajectory are used in the latter, and also time series of drag and lift coefficients are estimated. The results reveal qualitative behaviour of the drag and lift coefficients in the Reynolds number.
Many studies have examined the aerodynamics of soccer balls, focusing on groove depth, length, and so on. This study aimed to clarify the influence of aerodynamic characteristics for various groove volumes of various balls by conducting a wind tunnel experiments. Firstly, the drag coefficient of balls supported by piano wire is higher than that of balls supported by wire support in the supercritical region for smooth balls. However, there is no difference in drag coefficient for balls supported by wire support and piano wire in all regions for balls having panels or grooves. Secondly, in a case of without rotation, the critical Reynolds number becomes smaller as the ratio of the groove volume and the volume to ball volume increase, regardless of the size of the ball. Moreover, regarding official balls, the separation point in critical Reynolds number is constant regardless of the ratio of the groove volume and the ball volume increase. This tendency is as same as that of in supercritical region.
The generation of the three-dimensional twins vortices behind soccer balls wake was confirmed by 3D-Dynamic PIV measurement and the fluid forces occurred on the balls were measured simultaneously. As a result, it was confirmed that the direction of the jet flow between the three-dimensional twin vortices was opposite to the direction of fluid forces.
Spinning serve or shot exist as a technique in tennis. For a correct competition to hit across the net. The batted ball of the high turn is shot by friction with the gut. So it is necessary to elucidate the aerodynamic characteristics of a spinning ball. In addition, it is necessary to compare various balls. In this study performed fluid force measurement and two-dimensional dynamic PIV with high number of rotation. We was confirmed that felt fuzzed a race by the PIV measurement.
This paper describes the validity of the fastest speed gait analysis system using tiptoe-mounted inertial sensor. Recent studies have suggested that the change in walking speed may indicate mild cognitive impairment. Hirosaki University has conducted a survey of 10 m fastest speed walking for local residents. However, the conventional method was a big burden to the staff because they need to measure the walking time with a stopwatch by following subjects. To solve this problem, we have studied the system for calculating the walking speed from top toe-mounted inertial sensor. Further, it may be found the index to find the disease by analyzing the gait parameters of each step. However, it is difficult to analyze the very fast speed walking such as of young people because the acceleration or the angular velocity exceeds the measuring range of the high sensitivity sensor. To solve this problem, the low sensitivity inertial sensors which can measure up to 120 G and 6000 deg/s are used in addition to the high sensitivity sensor which can measure up to 16 G and 2000 deg/s. In addition, integration duration is decided by using the synthetic angular velocity. 135 young subjects participated in the experiments and experimental results showed that the estimation error of walking distance is about - 1.14 ± 6.85 %. It is suggested that the tip-toe mounted inertial sensor can be used for analysis of the gait parameters of the 10 m fastest speed walking.
The purpose of this study was to develop the analysis algorithm that is able to estimate the baseball bat trajectory from swing beginning to follow-through phase in the practice swing motion and to examine the accuracy of the proposed method using the 3D motion capture system. The measurement system in this study, which consists of inertial sensor system, measured 3-axis angular velocity and 3-axis acceleration. To compensate the error of velocity during follow-through phase, the backward direction integration from the instance of swing stop was performed. The sensor fusion using the Adaptive Kalman filter by compensating velocity compensated the error of acceleration integration during follow-through phase, and it estimated the 3D bat trajectory in a global coordinate by combining the sensor fusion and the compensation using motion characteristics. The measurement experiment was conducted to indicate the accuracy of the proposed method using 3D motion capture system. The 3D bat trajectory from swing beginning to follow-through phase estimated by the proposed method corresponded with the 3D bat trajectory obtained by the 3D motion capture system. This result indicates that the error by acceleration integration during follow-through phase is compensated. Therefore, the effectiveness of the proposed method was indicated and the proposed method can be used to evaluate baseball swing include follow-through phase with high accuracy.
As the expectations of wearable technologies for personalised health and lifestyle continues to expand, it becomes increasingly important to reduce the power demands placed on the hardware where possible. For applications such as activity recognition, particularly in fitness, there are a number of options available for identifying and classifying these activities but it is not always clear which particular method should be implemented. This paper explores a variety of classification models provided by the MATLAB numerical analysis software and describes a training and testing outline using a previously validated dataset. Each model is trained prior to testing with a consistent training accuracy of > 99% for the given data. The results showed that for the same test data, decision tree models outperformed discriminant analysis, k-nearest-neighbour, support vector machine by a factor of 1.91, 8.37, and 36.15 respectively. Finally, the considerations of appropriate classification model selection are discussed in the context of light-weight, low power wearable devices where processing hardware and battery limitations are key factors.
This study deals with the application to gait analysis of the established method in the previous studies. This method estimates the position vector from the joint to the sensor. We extended the estimation method using the output of the wearable force plates. The condition contacting to ground and the stationary condition are detected by using the resultant force and the resultant angular velocity in the wearable force plate. The estimation method is performed by limiting to between implementing the conditions. We conducted the measurement experiment the gait measurement by the subject attaching the wearable sensor system, and we apply the method to the measurement information. The estimation results indicated the position vector from the knee joint to the sensor attached to the lower thigh. The proposed method can extend to parameter estimation in total body. Therefore, the method can be used to the development of more simply motion measurement method by wearable sensor system.
We aim to clarify dynamics of the wrist turn of golf swing and the effect of the parameters on dynamic behavior at the wrist turn using the double pendulum model and modal analysis. Eigenvalue analysis was carried out for the linearized two-degree-of-freedom system and natural frequency and mode were calculated. We found out that the first mode is a rigid mode and the second one is the vibration mode of the double pendulum, and mode shapes are constant during the wrist turn even though natural frequency changes. By applying the modal analysis method we obtained equations of motion for the rigid mode and vibration mode separately. Furthermore, using the theory of linear superposition, the equation of motion for the vibration mode was separated again into 3 equations which can help to understand the mechanism of the wrist turn. Calculation results for shallow cock angle by the proposed modal separation method and the exact solution using numerical integration for the double pendulum compared well and showed the validity of the proposed method. The effect of the parameters of the arm torque and the wrist torque on the dynamic behavior of the wrist turn were examined by the parameter survey using the proposed method and the mechanism of the wrist turn was clarified.
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. However, it is hard to solve inverse dynamics problem of this system without measuring each right and left arm or each grip force. In this study, the manipulating forces which act at both grips during golf swing were measured using a 6 axis force/moment sensors and points of application of forces at each hand were identified.
Motion-dependent term (MDT), which consists of centrifugal force, Coriolis force and gyroscopic effect moment expressed in the equation of motion for a multi-link system, plays significant roles in the generation of bat head speed through not instantaneous effect but cumulative effect of the exerting joint torques in baseball batting. According to our previous studies that calculate dynamics contributions of the whole-body joint torques considering generating factor of the MDT, the forward/backward rotational torque (FBR torque) at torso joint plays a significant role in the generation of bat head speed. These studies, however, show that the lower limb joint torques do not contribute directly to the bat head speed. Therefore, the purpose of this study was to make clear the functional roles of the lower limb joint torques considering the cumulative effect of exerting joint torques. The whole-body with bat was modelled as a system of sixteen-rigid linked segments. The contributions of the lower limb joint torques to the exerting FBR torque at torso joint were quantified through dynamic contribution equation, which relates lower limb joint torques to the torso FBR torque, derived from both dynamics joint force contribution equation of whole-body system and equilibrium balance equation with respect to rotational movement of the lower trunk segment. The results obtained in this study show 1) lower limb joint torque, especially flexion/extension torque at both hip joints, is a large contributor to the generation of the torso FBR torque, and 2) lower trunk inertial force term and other terms are small contributors to the FBR torque. The development of this analytical method would enable us to quantify the contribution of the lower limb joint torques.
In 2011, baseball was designated as a required subject at the elementary and junior high school in Japan. Thus, as teachers, teaching baseball skill would be important to instruct required baseball skill for students. Batting is one of the most difficult skill and kinetic chain is very important to achieve ideal batting form. In the present study, we developed auditory cue based biofeedback device that could induce desirable batting form (i.e., ideal kinetic chain). The device gives the player auditory cue that related to their body motion. Pre-posttest found that beginners trained with the device increased the swing speed than that trained with the no device.
We previously proposed a training system that helps inexperienced athletes to acquire skills through a repeated comparison of their biological signals measured in real time to that of the signals produced by the optimization calculation using a musculoskeletal model considering the physical characteristics of each subject. We call this training system “cybernetic training” that refers to a feedback based signal produced artificially by optimization of the model calculations. However, using a model with many muscles, it is very difficult to calculate the optimal muscle activation signals to produce the desired motion. In this paper, we propose a three-dimensional rigid link model using the ODE with a reputation for high-speed computation, was studied for its optimization method.
In recent years, the care costs and insurance premium increasing in Japan. Because, we thought that increase of the number of care-need certificated persons. So, we would like to increase the self-supporting persons in daily-life. Therefore, we thought that we need to analyze about the standing-up/sitting-down motions. And, we thought that the individual difference of physical cause difference of burden for muscles and joints. In the present study, First, we quantitatively analyzed the standing-up/sitting-down motions by using the driving power and the angular momentum. Driving power is considered to be a value for evaluating actual kinematic performance around a joint motion as energy per unit of time. And, angular momentum exerted by each muscle expresses the intensity of motion of that muscle. Second, the individual difference of burden around a joint considered by using the driving power around the joint. Finally, individual difference of burden to muscles considered by using the angular momentum. In this result, we knew that the burden of knee joint and muscles generated by the person of heavy weight are bigger than those generated by the person of light weight. In addition, the burden of knee joint and muscles generated by the dominant foot are bigger than those generated by the non-dominant foot.
Dynamic mechanical model of human body with Muscle-Tendon Unit (MTU) is considered by Bond Graph. This model is based on the principle of lever mechanism, in which the pivot is on the end of the foot, i.e. the toe, instead of the pivot on the ankle joint. Based on this new model we have calculated the tension and the displacement of the tendon by use of the identify of stiffness of tendon and experimental data (Kawakami et al. 2002). The results of the simulation have good agreement with experimental results (Kawakami et al. 2002). So the validation of this new model is considered exactly collect. We have also the tendon extensive speeds and the power through it. This result are visualized that how tendon is behaved with respect to time.
In recent years, the proportion of elderly people is increased. And people who enjoy the sports is increased. To keep fit for elderly people, to enjoy playing sports without injuries and to raise exercise performance, exercise must be done effectively. Previous research is being carried out methods for estimating muscle torque and muscle tension on the basis of a musculoskeletal model. As a result, it has become possible to quantitatively identify the extent of fatigue in each muscle during motion. Therefore, to evaluate muscle fatigue more quantitatively, driving power and angular momentum are focused on. Driving power is considered to be a value for evaluating actual kinematic performance around a joint motion as energy per unit of time, and angular momentum exerted by each muscle expresses the intensity of motion of that muscle. This method is applied to analysis of extension and flection around elbow joint with dumbbell and without dumbbell.
Running form with pronation characteristic is an important key to choose suitable footwear and running gear. This paper describes development of a three-dimensional foot behavior measurement system with low-cost and small-footprint, and formulation of an evaluation parameter to identify runner's pronation characteristic accurately. The measurement system has SngleCamera3D (Photron Co., Ltd.) based on AR technology. In this system, subjects run on a treadmill with four AR markers attached on their heels and calves, while their running forms are recorded from behind by a single video camera. From a sequence of 2D images, three-dimensional orientation matrices of the heel and the calf during running are obtained by modified OpenCV image processing. We also proposed “pronation score” which took into account subtalar joint, heel inclination and tibial rotation angles during stance phase. As a result, the score showed good agreement with runner's pronation type evaluated by specialists. By using the proposed system, we evaluated 216 recreational runners in a major marathon event in Japan, and found that 22%, 40% and 38% of runners were underpronators, neutral pronators and overpronators, respectively.
There are many study to measure shoe motion as foot motion. However, these may not measure exact foot motion. It is known that insole formed pressure sensors are useful to measure in-shoe foot dynamics, but relationship between in-shoe foot kinematics and plantar pressure is unclear. The aim of this study was to examine relationship between in-shoe foot kinematics by using multi-segment foot model defined by jig-attached cluster markers and plantar pressure. Two males were recruited for this study. Foot kinematic variables and plantar pressures collected during static, walking and running inserting a foot arch support insole in shoe were compared to not inserting insole condition. Foot arch support insole reduced plantar pressure acting in medial part of foot bottom and pronation angle of each segment during static stand position in each subject. Moreover that insole reduced pronation angle of rearfoot in subject A during walking and running. Nevertheless, there were not so much change between subjects for hallux plantarflexion angle during walking and running, plantar forces were changed. In conclusion, this study suggests that there is relationship between in-shoe foot kinematics by using multi-segment foot model defined by jig-attached cluster markers and plantar pressure.
We have developed a flexible impact force sensor using a piezoelectric film. The sensor is distribution type in which sensor elements with 30mm square are arranged in a matrix with regular intervals. Each sensor element is a rigid plate structure. Flexibility of the sensor is achieved by the flexible leather connections between adjacent sensor elements. There is no electrical wiring in the sensor. The output signal of the sensor element is obtained from the conductive cloth via upper and lower metal plate of the elements. The authors are challenging to make smaller the size of sensor element, make thinner of the sensor thickness and to remove perfectly the electrostatic effects. In order to realize these, we are in the current situation of repeated prototype testing. In this study, we have conducted three experiments using the prototype sensors, that is, boxing punching test of sandbag, the seating impact test of an office chair, and bamboo sword beating test of kendo forearm.
The International Tennis Federation measures the effect of ball-surface interaction through the coefficients of friction and restitution. The combination of both parameters results in the court pace rating which is used for classifying a tennis court. These coefficients are affected by the surface type, moisture content, level of wear and weather degradation. The result can be an uneven surface which degrades tennis performance and leads to player injuries. Two portable and low-cost devices were developed to measure horizontal and vertical components of force between the ball and the surface, and bounce height using acceleration profiles. Different tennis surfaces were surveyed in dry conditions using 20 distributed sample points. The error obtained for both the coefficient of friction and restitution was less than 5%, which lies within the International Tennis Federation approval test requirements. Variations across the surfaces and between surfaces of two different tennis courts were lower than 15%.
The purpose of this study was to investigate the influence of the difference of step directions on the pitching motion. Eight collegiate baseball players performed pitching under five kinds of conditions including the normal step, two kinds of closed steps and two kinds of open steps. The angular velocities of rotation of trunk, hip and upper limb were measured with accelerometers and gyroscope sensors, and the state of ball-release on the nails of index finger and middle finger were recorded with strain gauges during pitching under above conditions. As the results, there were no significant differences in the strains of nails of index finger and middle finger among the pitching trials under the five conditions of step direction. There were also no significant differences in the angular velocities of rotation of the trunk, the hip and the upper limb. However, there were tendency that the angular velocities of the upper-arm swing and the counterclockwise rotation of hip of closed step pitching were larger than those of other cnoditions. On the other hand, the peak time of the angular velocity of trunk counterclockwise rotation of open step pitching was significantly nearer to the ball-release than that of other conditions. The peak time of trunk and hip movements varied among step directions, but the peak time of upper-arm swing and forearm swing were constant in spite of step direction.
Launch condition parameters of thrown ball, such as linear and angular velocities, speed and direction, are crucial factors to evaluate the performance of pitching motion. Although previous studies have dealt with speed of pitched ball in the induced speed analysis based on equation of motion for pitching side upper limb and trunk model, the mechanism in the generation of angular velocity has been still not clear. Therefore, the purposes of this study were to propose a modelling method of fingers and to derive a formula for dynamic contributions of joint torques, gravitational force, and motion-dependent term (e.g. centrifugal force, Coriolis force, and Gyroscopic effect moment) to the generation of not only ball speed but also angular velocity of ball. Individual finger is modelled with two segments such as, base segment and an instantaneous virtual rigid segments consisting of distal and middle segments. The center of pressure on the ball, at which inertia force exerted on ball surface can cause translational and rotational movement of ball, is calculated through inverse dynamics for ball motion, and then is distributed into COPs at individual fingers through equilibrium equations about exerting force and moment with respect to ball COP location. Time-curves of joint torques at individual joint of pitching side upper limb including finger joints were obtained in this study. Furthermore, dynamic contributions to the ball velocities were derived from the combination of 1) the equations of motion for the individual segments, 2) the equations for constraint conditions arising from the connection of adjacent segments at joints, and 3) the equations for anatomical constraint axes at certain joints.
In this study, throwing experiments were conducted with the participation of six javelin throwers using a wooden javelin produced to conform to the current regulations for javelin throw competitions and a normal javelin made by duralumin. In the experiments, the wooden javelin and duralumin javelin were thrown and the following release parameters were measured: initial velocity, release height, release angle, attitude angle, and angle of attack). The distances of the throws were measured and the effects of the release parameters were assessed. As a result, it was found that the thrown distance of the wooden javelin was slightly shorter than that of the duralumin javelin, but the difference was not significant. Similarly, no significant difference was observed in each release parameter. The standard deviation of each release parameter was relatively large, and individual differences between the throwers were considered to be one of the causes.
The purpose of this study was to analyze the influence of rackets on human motion in badminton smash motion. To analyze it, we made an experiment using three badminton rackets. The smashes of 12 males were selected for the analysis, and were digitized. Performances were recorded by twelve motion capture cameras. In this study, we analyzed a position in the vertical direction of each marker and angle of joints and considered a characteristic of the smash motion at the time of using each rackets. The results showed that there were characteristics of the smash motion, such as take-back. And we calculated a standard deviation to analyze a difference in the motion between using the rackets. As a result of this analysis, a difference in dispersion of the smash motion was observed depending on using the rackets by the standard deviation. In addition, some inexperience persons could be close to motions of experience by changing the rackets. Therefore, the result showed that it was very important to select a racket suitable for them. And we analyzed the influence of the athletic ability and skill in using the rackets. As a result of this analysis, ranking of the number of hits in the target and velocities of the wrist joint was consistent with ranking of sum of the standard deviation. Thus, the result showed that the athletic ability and skill was improved by using racket of the standard deviation with smaller value. Moreover, we analyzed the influence of psychological evaluation of rackets in using the rackets. As a result of this analysis, ranking of sum of the standard deviation was consistent with preference ranking of rackets. Therefore, the result showed that the standard deviation of smash motion provided one of indications of evaluation of rackets.
This study carried out an evaluation experiment of yoga wear on eight adult males in order to clarify required performance of yoga wear for males. The participants were asked to wear three kinds of yoga wear, selected from the products of popular yoga wear brands, and do a 15-minute yoga program three times, including yoga poses and exercises. An investigator conducted an interview survey with each participant using the evaluation grid method after he finished the programs wearing all kinds of yoga wear. At first, the investigator asked the participant to rank three kinds of yoga wear according to preference, and questioned each subject about differences between them. As a result, six evaluation items of yoga wear were acquired from their answers. After that, the investigator extracted both generic concepts and more specific concepts from the evaluation items by laddering. The evaluation structure of yoga wear was created by illustrating the relationship between all the evaluation items extracted from the interviews with the participants. In addition, fuzzy cluster analysis about the participants was carried out based on frequencies of their usages of keywords (Sense of pressure, Shape around the neck, Tactile properties, Elasticity, Presence of stitches or tags, Permiability) about the six evaluation items during interviews. The eight participants were classified into three clusters (small build, standard build, large build) according to their body type. The analysis results of data from these interviews showed that the required performance of yoga wear was mainly “not to be conscious of wearing them,” “not being painful wearing them” and “being easy to move while wearing them.” The designing of yoga wear with focus on the sense of pressure, elasticity, and shape around the neck of the clothing was required to realize this performance. Moreover, it is necessary to consider the tactile properties of clothes and the presence of stitches or tags on them for designing yoga wear, depending on the shape and needs of each individual body.
To keep the quality of life, a motion assistive cloth that unloads muscle activation is promising. However, the unloading effect of muscle activation would be different depending on the physical size and mass of a wearer, and the attachment position of the assistive equipment. In this study, we evaluate unloading effect of muscle activation depending on the attachment positions of a muscle assistive cloth, which we newly developed, by using a three-dimensional musculoskeletal model and the estimation of the muscle activation.
The comfort provided by clothes is a key element that directly affects the human psychology as well as physiology in all environmental conditions. The authors have presented the development of knitted fabric models for finite element analysis to simulate the large deformation behavior of garments and clothing pressure distribution on the human body in a stationary position. This paper describes an extension of the investigation to a study of the human body in motion. The study accomplished a fully automatic simulation of the clothing pressure change in T-shirts during jogging. The analysis technique is expected to be utilized in the development of a stabilized electrocardiographic measurement for a person during exercise.