• Journal of Biomedical Engineering Research
• /
• v.24 no.3
• /
• pp.209-215
• /
• 2003

The goal of this study was to investigate the relationship between kinematic and kinetic characteristics of foot joints resisting ground reaction force. Passive elastic joint moment and angular displacement were obtained from the experiment using 3 cameras and force plate. The relationship between joint angle and moment was mathematically modeled by using least square method. The ranges of motion of joints ranged from 5$^{\circ}$ to 7$^{\circ}$ except metatarsophalangeal joint. In the study, we presented simple mathematical models that could relate joint angle and plantar pressure. From this model, we can got the kinematic data of joints which is not available from conventional motion analysis. Furthermore, the model can be used not only for biomechanical model which simulates gait but also for clinical evaluation.

• Korean Journal of Applied Biomechanics
• /
• v.23 no.3
• /
• pp.201-208
• /
• 2013

The aim of this study was to investigate badminton smash and drop motion depends on player's level. To perform this study, ten male badminton players were participated: five skilled players (SG, age: $21.6{\pm}1.1$ yrs, height: $181.4{\pm}6.8$ cm, body mass: $72.4{\pm}5.7$ kg, career: $11.2{\pm}1.1$ yrs) and five less-skilled players (LSG, age: $21.2{\pm}1.1$ yrs, height: $180.2{\pm}5.6$ cm, body mass: $73.6{\pm}6.7$ kg, career: $10.6{\pm}0.9$ yrs). Three-dimensional motion analysis with 7 infrared cameras was performed with a sampling frequency as 200 Hz. Player's swing motion was divided into four events: starting motion (E1), backswing (E2), impact (E3), following (E4). For all upper joints, LSG showed greater angle differences between drop and smash motions than that of SG at E3 (p<.05). For all upper joints, greater angular velocities were found in SG than that of LSG. For both groups, significantly smaller angular velocities were found in drop motion than that of smash motion (p<.05). The greater sequential angular velocities (proximal to distal) were found in SG than LSG during smash motion. Based on our findings, performing the same motion between drop and smash would be related to enhance performance at badminton competition. It is expected that these results will be useful in developing a training program for enhancing performance of badminton athletes.

• The Journal of Korean Physical Therapy
• /
• v.29 no.3
• /
• pp.145-151
• /
• 2017

Purpose: The purpose of this study was to investigate the validity and reliability of the measurement of shoulder joint motions using an inertial measurement unit (IMU). Methods: For this study, 33 participants (32 females and 1 male) were recruited. The subjects were passively positioned with the shoulder placed at specific angles using a goniometer (shoulder flexion $0^{\circ}-170^{\circ}$, abduction $0^{\circ}-170^{\circ}$, external rotation $0^{\circ}-90^{\circ}$, and internal rotation $0^{\circ}-60^{\circ}$ angles). Kinematic data on the shoulder joints were simultaneously obtained using IMU three-dimensional (3D) angular measurement (MyoMotion) and photographic measurement. Test-retest reliability and concurrent validity were examined. Results: The MyoMotion system provided good to very good relative reliability with small standard error of measurement (SEM) and minimal detectable change (MDC) values from all three planes. It also presented acceptable validity, except for some of shoulder flexion, shoulder external rotation, and shoulder abduction. There was a trend for the shoulder joint measurements to be underestimated using the IMU 3D angular measurement system compared to the goniometer and photo methods in all planes. Conclusion: The IMU 3D angular measurement provided a reliable measurement and presented acceptable validity. However, it showed relatively low accuracy in some shoulder positions. Therefore, using the MyoMotion measurement system to assess shoulder joint angles would be recommended only with careful consideration and supervision in all situations.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.1
• /
• pp.227-234
• /
• 2008

The purpose of this study was to investigate kinematic factors affecting scores of Olympic Round Game during follow through which was basic and important in archery. For this study, 8 male archers($20{\pm}1\;yrs$, $77{\pm}13kg$, $178{\pm}5\;cm$) of K university participated in the experiment. The seven infrared cameras (Qualisys MCU-240) were used to acquire raw data, and analyzed with Matlab6.5 for variables. The results were as follows: First, angular average velocity of shoulder joint affecting scores was a statistical significance (p=.65, p<.10), and the regression equation was y = - 0.0637 x + 17.074, and determinant coefficient $R^2$ = 0.874 respectively. Second, good records was acquired about $120^{\circ}$/sec. of angular average velocity of shoulder joint. Third, as records was lower and lower, a peak-pulse on angular average velocity of shoulder joint was great during follow through. In conclusion, the record was greater as angular average velocity of shoulder joint was smaller and smaller from $110^{\circ}$/sec. to $160^{\circ}$/sec. It is suggested that a lower angular average velocity of shoulder joint and no peak-pulse may obtain good scores during follow through.

• Korean Journal of Applied Biomechanics
• /
• v.12 no.2
• /
• pp.159-177
• /
• 2002

The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle and the angular velocity of the air born phase and understand the control mechanism of the high-bar movement, the somersault, the double somersault, the double somersault with full twist. For this study seven well trained university gymnastic volunteered, Zatsiorky and Seluyanov(1983, 1985)'s sixteen segment system anatomical model was used for this study. For the movement analysis three dimensional cinematographical method(Arial Performance Analysis System : APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 5.1 graphical profromming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and angular velocity were defined. As a result of this study 1. As the rotation of the body increased in the air born phase the projection angle of the CM of the total increased, this resulted the increased of the max hight of the CM. 2. In three dimensional angular velocity the Z axis(vertical direction) projection angular velocity increased as the rotation of the body increased in the airborn phase, but the Y axis and the X axis projection angular velocity did not show significant differences. 3. As the rotation of the body increased in the air born phase the angular movement of the shoulder and the hip showed significant change. These movement act as the starter in the preparation phase. 4. The somersault angle, the twist angle, the tilt angle of the upper body related to the global reference frame in the releas phase the average somersault angle of the three types of high-bar movement was $57.7^{\circ}$, $38.8^{\circ}$, $39.7^{\circ}$, the average tilt angle was $-1.5^{\circ}$, $-5.4^{\circ}$, $-8.4^{\circ}$, the average twist angle was $13.4^{\circ}$, $10.6^{\circ}$, $23.3^{\circ}$. This result showed that the somersault with full twist had the largest movement.

• Journal of information and communication convergence engineering
• /
• v.8 no.2
• /
• pp.145-149
• /
• 2010

In this paper, we propose a kinematic approach to estimating the real-time moving object. A new scheme for a mobile robot to track and capture a moving object using images of a camera is proposed. The moving object is assumed to be a point-object and projected onto an image plane to form a geometrical constraint equation that provides position data of the object based on the kinematics of the active camera. Uncertainties in the position estimation caused by the point-object assumption are compensated using the Kalman filter. To generate the shortest time path to capture the moving object, the linear and angular velocities are estimated and utilized. The experimental results of tracking and capturing of the target object with the mobile robot are presented.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.8 no.2
• /
• pp.75-86
• /
• 2004

In this study, a recursive algorithm for generating the equations of motion of a chain of rigid rods is presented. The methods rests upon the idea of replacing the rigid body by a dynamically equivalent constrained system of particles. The concepts of linear and angular momentums are used to generate the rigid body equations of motion without either introducing any rotational coordinates or the corresponding transformation matrices. For open-chain, the equations of motion are generated recursively along the serial chains. For closed-chain, the system is transformed to open-chain by cutting suitable kinematic joints with the addition of cut-joints kinematic constraints. An example of a closed-chain of rigid rods is chosen to demonstrate the generality and simplicity of the proposed method.

• Journal of Mechanical Science and Technology
• /
• v.17 no.12
• /
• pp.1977-1985
• /
• 2003

In the present study, the dynamic modelling of planar mechanisms that consist of a system of rigid bodies is carried out using point coordiantes. The system of rigid bodies is replaced by a dynamically equivalent constrained system of particles. Then for the resulting equivalent system of particles, the concepts of linear and angular momentums are used to generate the equations of motion without either introducing any rotational coordinates or distributing the external forces and force couples over the particles. For the open loop case, the equations of motion are generated recursively along the open chains. For the closed loop case, the system is transformed to open loops by cutting suitable kinematic joints with the addition of cut-joints kinematic constraints. An example of a multi-branch closed-loop system is chosen to demonstrate the generality and simplicity of the proposed method.

• Korean Journal of Applied Biomechanics
• /
• v.19 no.2
• /
• pp.337-345
• /
• 2009

The purpose of this study were to find out the differences in kinematic variables of racket movement by performing the tennis serve. Three top male tennis players participated in this study. Three synchronized high-speed cameras were used to record the service action of top players for Three dimensional video analysis. The results of this study showed that (1) the velocity of the tennis racket at impact is important to the generation of racket velocity to Y-axis. This result indicates that forward motion and upward movement of the racket; (2) with respect to racket angular velocity at impact, the fast angular momentum of X-axis is important to generate the velocity of the tennis ball. This result indicate upward movement of the racket with a strong flexor of wrist joint; (3) the velocity of the tennis ball was influenced by the change of angular linking the Z-axis to -X-axis. This result indicates that the high velocity of the tennis ball is obtained from having the racket unitedly moving to the direction of the bill's flight at the acceleration interval and acquiring the distance of acceleration with the racket head vertically to the ground at the back scratching.

• Korean Journal of Applied Biomechanics
• /
• v.13 no.3
• /
• pp.181-197
• /
• 2003

The Purpose of this study was to examine the kinematic analysis of the upper-limb motion of wheelchair basketball free throw shooting. Three-dimensional kinematic data were obtained from 8 male wheelchair basketball players performing a successful free throw. Players were divided into three groups, according to their IWBF classification(Group 1: 1 point players, Group 2: 2-2.5point players and Group 3:3.5-4 point players) Wheelchair basketball free throw motions were taken by video camera. The three-dimensional coordinates was processed by DLT. Players from Group 1 and 2 tended to release the ball from a lower height, with greater velocity and release angle. Players from Group 1 showed greater shoulder horizontal adduction and horizontal abduction angle, wrist ulnar flexion and radial flexion angle, and trunk angle. but players from Group 2 appeared lower shoulder abduction. Upper limb angular velocity showed most greatly in hands from Group 1, upperarm from Group 2, and forearm from Group 3.