• The Journal of Korea Robotics Society
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• v.15 no.4
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• pp.323-329
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• 2020

This paper presents a control algorithm for a wearable walking aid robot for subjects with paraplegia after stroke. After a stroke, a slow, asymmetrical and unstable gait pattern is observed in a number of patients. In many cases, one leg can move in a relatively normal pattern, while the other leg is dysfunctional due to paralysis. We have adopted the so-called assist-as-needed control that encourages the patient to walk as much as possible while the robot assists as necessary to create the gait motion of the paralyzed leg. A virtual wall was implemented for the assist-as-needed control. A position based admittance controller was applied in the swing phase to follow human intentions for both the normal and paralyzed legs. A position controller was applied in the stance phase for both legs. A power controller was applied to obtain stable performance in that the output power of the system was delimited during the sample interval. In order to verify the proposed control algorithm, we performed a simulation with 1-DOF leg models. The preliminary results have shown that the control algorithm can follow human intentions during the swing phase by providing as much assistance as needed. In addition, the virtual wall effectively guided the paralyzed leg with stable force display.

• The Journal of Korean Physical Therapy
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• v.24 no.4
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• pp.247-252
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• 2012

Purpose: The purpose of this study was to investigate the change of muscle activities during level walking, stairs and ramp climbing in hemiplegic patients. Methods: Eight hemiplegic patients were recruited and agreed to participate in this study. Muscle activity was measured by MP100 system (BIOPAC System Inc., Santa Barbara, CA, USA). Statistical analysis was used as a one-way repeated measure of ANOVA to know the difference according to the gait conditions (level walking, stairs and ramp ascending). Results: In the swing phase, muscle activity of rectus femoris muscle, with the side lower extremities affected, were generally significantly different in the stair and ramp ascending. In addition, biceps femoris muscle with unaffected side lower extremity was generally significantly different in the ramp ascending. In the swing phase, muscle activity of tibialis anterior muscle with unaffected side lower extremities was generally showed a significant difference in the ramp ascending. In the stance phase, climbing stairs and ramps showed an increase in the muscle activities. Further, climbing the stairs increased muscle activities of the gastrocnemius muscle. Conclusion: These findings indicate that compared with the level walking climbing stairs, ramps and muscle activities of lower extremity during each showed different results. It can be seen that in accordance with the terms of gait are different muscles group recruitment.

• The Journal of Korean Physical Therapy
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• v.34 no.3
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• pp.98-103
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• 2022

Purpose: New therapeutic approaches have emerged to improve gait ability in patients with brain damage, such as action observation learning (AOT), auditory cueing, motor imagery etc. We attempted to investigate the effects of AOT with auditory cueing (AOTAC) on gait function in patients with stroke. Methods: The eighteen stroke patients with a unilateral hemiparesis were randomly divided into three groups; the AOTAC, AOT, and control groups. The AOTAC group (n=8) received training via observing a video that showed normal gait with sound of footsteps as an auditory cue; the AOT group (n=6) receive action observation without auditory stimulation; the control group (n=5) observed the landscape video image. Intervention time of three groups was 30 minutes per day, five times a week, for four weeks. Gait parameters, such as cadence, velocity, stride length, stance phase, and swing phase were collected in all patients before and after each training session. Results: Significant differences were observed among the three groups with respect to the parameters, such as cadence, velocity, stride length, and stance/swing phase. Post-hoc analysis indicated that the AOTAC group had a greater significant change in all of parameters, compared with the AOT and control groups. Conclusion: Our findings suggest that AOTAC may be an effective therapeutic approach to improve gait symmetry and function in patients with stroke. We believe that this effect is attributable to the change of cortical excitability on motor related to cortical areas.

• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.297-302
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• 2013

Purpose: This study was conducted in order to investigate the kinematic gait parameter of lower extremities with different gait conditions (level walking, stair, ramp) in hemiplegic patients. Methods: Ten hemiplegic patients participated in this study and kinematic data were measured using a 3D motion analysis system (LUKOtronic AS202, Lutz-kovacs-Electronics, Innsbruk, Austria). Statistical analysis was performed using one-way repeated measure of ANOVA in order to determine the difference of lower extremity angle at each gait phase with different gait conditions. Results: Affected degree of ankle joint in the heel strike phase showed significant difference between level walking and climbing stairs, and toe off phase showed significant difference between level walking and climbing stairs, ramps, and climbing stairs. Affected degree of knee joint showed no significant difference in all attempts. Affected degree of hip joint in the toe off phase showed significant difference between level walking, ramps and stairs, and climbing ramps. Swing phase showed significant difference between sides for level walking and stairs, climbing ramps. Affected ankle joint of heel strike and toe off, and affected hip joint of toe off and the maximum angle of swing phase in the angle was increased. Unaffected side of the ankle joint, knee joint, and hip joint showed a significant increase in walking phase. Conclusion: These findings indicate that compared with level walking, different results were obtained for joint angle of lower extremity when climbing stairs and ramps. In hemiplegia patient's climbing ramps, stairs, more movement was observed not only for the non-affected side but also the ankle joint of the affected side and hip joint. According to these findings of hemiplegic patients when climbing stairs or ramps, more joint motion was observed not only on the unaffected side but also on the affected side compared with flat walking.

• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.85-94
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• 2008

The purpose of this study is to provide basic materials for amateur golf players or golf maniacs to learn desirable iron swing motions. This study compared and analyzed the swing motions of iron clubs(3, 6, 9) by using 3-D in three elite golf players. 1. There was no a great difference in the total of swing time by club and the time by phase was nearly similar. 2. There was no a difference in the change in a head location at address and impact by club. 3. The angle change in a right knee joint was similar by club except the difference according to the length of the club. 4. There was a subtle difference in hip rotation angle by club. 5. In each club, the same rotation angle of shoulder joint at address and impact motions contributed to accurate swing, and the maintenance of more than $90^{\circ}$ of shoulder rotation angle in top swing increased swing rotation. 6. Although subtle, the forward angle of upper body was increased with a shorter club. $30-36^{\circ}$ of forward angle of upper body was maintained at address, top swing, and impact motions.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.283-289
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• 2021

Objective: The aim of this study was to analyze the pattern of Kolman technique by five Korean top gymnasts including the three national athletes on horizontal bar. Method: Two digital high-speed camcorders were used with 90 frames/sec and their Kolman motions were filmed in sports science secondary school gymnasium at U city. After the kinematic and kinetic variables were carried out by Kwon3D 3.1 motion package during the whole phase, the optimized release motion was investigated by simulating the body COG path during the aerial phase. Results: Firstly, it was revealed that the average changes of hip, shoulder joint angle were 84 deg, 53 deg respectively during the functional sub-phase and the average swing phaseal time was 1.21 s. Secondly, it was revealed that the average body COG positions and velocities (Y, Z) at release were -0.65 m, 0.48 m, 1.65 m/s, 3.97 m/s respectively and the average release angle, peak height and flight time were 67 deg, 1.29 m, 0.79 s respectively. Thirdly, it was revealed that the directions of somersault of whole and lower body, tilt of lower body were counterclockwise, whereas the directions of tilt of whole body, twist of whole and lower body were clockwise at the ready for re-grasp. Lastly, it was revealed that the body COG paths were different from each other during the aerial phase followed by the different body COG velocities. Conclusion: Korean gymnasts of this study controlled their motions well in terms of the timing of hip·shoulder joint, body position, body angular momentum especially during the functional sub-phase, but their motions were different during the aerial phase. Nonetheless most of them made the adequate body position at the instant of re-grasp. It would be suggested that Korean gymnasts except S3 should increase the vertical velocity.

• Korean Journal of Applied Biomechanics
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• v.25 no.4
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• pp.483-488
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• 2015

Objective : The purposes of this study was to analyze the locomotive movement of forelimbs according to changes in velocities in the quadruped cadence of horses. Methods : Horses selected as subjects consisted of Jeju pony horses (heights of withers: $1.23{\pm}0.51$). Two camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) were used to capture the movement of the horses' forelimbs at a rate of 60 frames/sec. Additionally, raw data was collected from Kwon3D XP motion analysis package ver 4.0 program (Visol, Korea) with DARTFISH (DFKREA., Korea) video software solution. The variables analyzed consisted of 1 step lengths, 1 stride lengths, stance time, swing time, 1 stride time, velocity while walking, and trot of the horses. A two-way ANOVA and paired t-test of the variables by velocity and phase were treated at .05 level of significant difference, statistically. Results : The time elapsed of walk(stance: 0.63 sec[63.86%], swing: 0.35 sec[36.14%], 1 stride time: 0.99 sec respectively) showed significant difference with more delay than that of trot(stance: 0.29 sec[45.73%], swing: 0.34 sec[54.27% ], 1 stride time: 0.63 sec respectively), and also showed significant difference at trot in interaction (stance time>tort swing>walk swing>walk stance). The 1 step lengths and stride lengths in trot showed significant difference with longer than that of walk. Velocity of Trot showed significant difference statistically with higher than that of walk Conclusion : The horses' velocity during 1 step lengths and 1 stride lengths showed a proportional relationship, but the correlation between the horses' velocity and stance time showed a negative relationship during the quadruped cadence.

• Journal of Korea Entertainment Industry Association
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• v.14 no.6
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• pp.221-230
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• 2020

The purpose of this study was to investigate the effect of resistance exercise with vibration stimulation methods on static balance and gait parameters in experienced back pain adults. This study was Three group pretest-posttest design. A total of 30 experienced back pain adults voluntarily participated in the study. Subjects were randomly assigned to the resistance exercise with 8 Hz vibration stimulation(n=10), resistance exercise with 30 Hz vibration stimulation(n=10), and lumbar stabilization exercise groups(n=10). The static balance and the gait parameters, as such stance phase, swing phase, stride length and cadence, were measured using balance measuring equipment and gait analysis treadmill at before and after 6 week. Intervention of each group were performed, three times a week for 6 weeks, and 30 minutes a day. The effect of intervention on static balance, stance phase, swing phase, stride length and cadence were significantly differences after 6 weeks in each group(p<.05). In the comparison of the effects between the groups, static balance and stance phase were significantly difference after 6 weeks(p<.05), but in the swing phase, stride length and cadence, there were no significant differences. As a result, it is considered that resistance exercise with vibration stimulation improved leg muscle strength by a mechanism causing muscle contraction, and the strengthened leg muscle enhanced had a positive effect on balance ability. And improved balance ability was considered a more positive effect on walking ability by allowing the body to stably control posture while moving.

• Physical Therapy Korea
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• v.12 no.1
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• pp.111-119
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• 2005

The purpose of this study was to compare the differences of hip and thigh muscle activities between subjects with increased and decreased femoral anteversion during stair ascent. Twelve healthy female volunteers participated in this study. The subjects were divided into two groups (group 1 with increased anteversion of the hip, group 2 with decreased anteversion of the hip). This study analyzed differences in each mean peak gluteus maximus (GM), gluteus medius (GD) and tensor fascia lata (TLF) EMG amplitude: composite mean peak hip muscles (GM, GD, TFL) EMG amplitude ratios and in each mean peak vastus medialis oblique (VMO), vastus lateralis (VL), biceps femoris (HM) and semitendinosus (HL) EMG amplitude: composite thigh muscles (VMO, VL, HM, HL) EMG amplitude ratios among subjects with decreased or increased relative femoral anteversion. EMG ratios were compared in the stance and swing phase of stair ascent. Group 1 showed an increased standardized mean GM and GD EMG amplitude and decreased standardized mean TFL to composite mean hip muscles EMG amplitude ratios in stair ascent during both stance and swing phase. Also, group 1 showed an increased standardized mean HL EMG amplitude and decreased standardized mean VL and HM to composite mean thigh muscles EMG amplitude ratios in stair ascent during both stance and swing phases. There was no statistically significant difference in vastus medialis oblique between subjects with increased or decreased relative femoral anteversion. In order to provide rehabilitation professionals with a clearer picture of the specific requirements of the stair climbing task, further research must be expanded to include a wider range of age groups that represent the general public, such as including middle-aged healthy persons.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.10
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• pp.1021-1028
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• 2011

The objective of this paper is to optimize the design parameters of a novel mechanism for a robotic knee orthosis. The feature of the proposed knee othosis is to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The quadriceps device operates in five-bar links with 2-DOF motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking. However, the proposed orthosis must use additional linkages than a simple four-bar mechanism. To maximize the benefit of reducing the actuators power by using the developed kinematic design, it is necessary to minimize total weight of the device, while keeping necessary actuator performances of torques and angular velocities for support. In this paper, we use a SGA (Simple Genetic Algorithm) to minimize sum of total link lengths and motor power by reducing the weight of the novel knee orthosis. To find feasible parameters, kinematic constraints of the hamstring and quadriceps mechanisms have been applied to the algorithm. The proposed optimization scheme could reduce sum of total link lengths to half of the initial value. The proposed optimization scheme can be applied to reduce total weight of general multi-linkages while keeping necessary actuator specifications.