• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.6
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• pp.749-754
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• 2009

Two gait generation methods using GP(genetic programming) and CPG(Central Pattern Generator) are compared to develop a fast locomotion for quadruped robot. GP based technique is an effective way to generate few joint trajectories instead of the locus of paw positions and lots of stance parameters. The CPGs are neural circuits that generate oscillatory output from a input coming from the brain. Optimization for two proposed methods are executed and analysed using Webots simulation for the quadruped robot which is built by Bioloid. Furthermore, simulation results for two proposed methods are experimented in real quadruped robot and performances and motion features of GP and CPG based methods are investigated.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.6
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• pp.503-509
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• 2015

In this paper, we designed and tested an ankle joint mechanism for a gait rehabilitation robot. Gait rehabilitation programs are designed to improve the natural leg motion of patients who have lost their walking capabilities by accident or disease. Strengthening the muscles of the lower-limbs and stimulation of the nervous system corresponding to walking helps patients to walk again using gait assistive devices. It is an obvious requirement that the rehabilitation system's motion should be similar to and as natural as the normal gait. However, the system being used for gait rehabilitation does not pay much attention to ankle joints, which play an important role in correct walking as the motion of the ankle should reflect the movement of the center of gravity (COG) of the body. Consequently, we have designed an ankle mechanism that ensures the safety of the patient as well as efficient gait training. Also, even patients with low leg muscle strength are able to operate the ankle joint due to the direct-drive mechanism without a reducer. This safety feature prevents any possible adverse load on the human ankle. The additional degree of freedom for the roll motion achieves a gait pattern which is similar to the normal gait and with a greater degree of comfort.

• The Journal of the Korea Contents Association
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• v.6 no.1
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• pp.31-40
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• 2006

In this paper, we propose a gait recognition method based on gait silhouette sequences. Features of gait are affected by the variation of gait direction. Therefore, we synthesize silhouettes to canonical form by using planar homography in order to reduce the effect of the variation of gait direction. The planar homography is estimated with only the information which exist within the gait sequences without complicate operations such as camera calibration. Even though gait silhouettes are generated from an individual person, fragments beyond common characteristics exist because of errors caused by inaccuracy of background subtraction algorithm. In this paper, we use the Principal Component Analysis to analyze the deviated characteristics of each individual person. PCA used in this paper, however, is not same as the traditional strategy used in pattern classification. We use PCA as a criterion to analyze the amount of deviation from common characteristic. Experimental results show that the proposed method is robust to the variation of gait direction and improves separability of test-data groups.

• Journal of Information Processing Systems
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• v.9 no.2
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• pp.333-348
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• 2013

Mobile authentication/identification has grown into a priority issue nowadays because of its existing outdated mechanisms, such as PINs or passwords. In this paper, we introduce gait recognition by using a mobile accelerometer as not only effective but also as an implicit identification model. Unlike previous works, the gait recognition only performs well with a particular mobile specification (e.g., a fixed sampling rate). Our work focuses on constructing a unique adaptive mechanism that could be independently deployed with the specification of mobile devices. To do this, the impact of the sampling rate on the preprocessing steps, such as noise elimination, data segmentation, and feature extraction, is examined in depth. Moreover, the degrees of agreement between the gait features that were extracted from two different mobiles, including both the Average Error Rate (AER) and Intra-class Correlation Coefficients (ICC), are assessed to evaluate the possibility of constructing a device-independent mechanism. We achieved the classification accuracy approximately $91.33{\pm}0.67%$ for both devices, which showed that it is feasible and reliable to construct adaptive cross-device gait recognition on a mobile phone.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.1
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• pp.21-28
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• 2012

Purpose : The purpose of this study was to examine the gait parameter and plantar foot pressure of adults with Down syndrome(DS) during walking in order to provide data for developing evidence-based deficit or common rehabilitation strategies. Method : 15 participants with DS(12 men, 3 women; age $26.06{\pm}4.47$) and 15 healthy subjects(12 men, 3 women; age $25.33{\pm}3.43$) were matched age. They walked at self selected speeds on a GAITRite system and RS-scan system, and had the following measurements done: cadence, stride length, step width, foot angle, percent stance, percent double support, and plantar foot pressure in 10 areas of the foot. Results : In comparison of gait parameter(cadence, stride length, step width, foot angle, percent stance, and percent double support) between adults with DS and healthy subjects, there was significant differences(p<.05). Regarding plantar foot pressure during gait with or without DS, there were statisically significant differences in the area of Toes 1-5, Metatasal 1-4, Midfoot, and Heel(Medial and lateral)(p<.05). Conclusion : Our data show that DS walk with a less physiolosical gait pattern and plantar foot pressure than healthy subjects. Based on our results, DS patients need targeted rehabilitation and exercise strategies.

• Annals of Clinical Neurophysiology
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• v.7 no.1
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• pp.13-16
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• 2005

Background: The purpose of this study is to investigate the effect of the intensive functional electrical stimulation(FES) on the improvement of the gait pattern of the chronic hemiplegic patients. Method: Six hemiplegic patients, who could walk independently but have equinovarus deformity during the gait cycle, participated in this study. The affected peroneus longus and tibialis anterior muscles of all subjects were stimulated for 2 weeks period (20 minutes duration, 6 times/day). We measured the activities (mean voltage) of those muscles during the walking, using dynamic EMG. Results: After treatment, there were significant improvements in the strength of peroneus longus and tibialis anterior muscles and the gait speed, but there was no interval change of the spasticity of plantar flexor. The mean voltages of two muscles are significantly increased in all the patients (p<0.05). Conclusion: The results showed that the intensive FES on affected peroneus longus and tibialis anterior muscles in chronic hemiplegic patients could be useful for the improvement of functional gait.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.2 s.245
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• pp.194-201
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• 2006

Gait analysis is essential to identify accurate cause and knee condition from patients who display abnormal walking. Traditional linear tools can, however, mask the true structure of motor variability, since biomechanical data from a few strides during the gait have limitation to understanding the system. Therefore, it is necessary to propose a more precise dynamic method. The chaos analysis, a nonlinear technique, focuses on understand how variations in the gait pattern change over time. Eight healthy eight subjects walked on a treadmill for 100 seconds at 60 Hz. Three dimensional walking kinematic data were obtained using two cameras and KWON3D motion analyzer. The largest Lyapunov exponent from the measured knee angular displacement time series was calculated to quantify local stability. This study quantified the variability present in time series generated from gait parameter via chaos analysis. Knee flexion-extension patterns were found to be chaotic. The proposed Lyapunov exponent can be used in rehabilitation and diagnosis of recoverable patients.

• The Journal of Korean Physical Therapy
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• v.16 no.1
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• pp.183-207
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• 2004

The purpose of this study was to describe and compare the temporo-spatial gait characteristics of healthy elderly people with those osteoarthritis patients. 100 patients reported knee osteoarthritis, diagnosed at the hospital or clinic located in Daegu and Kyungbuk province and 100 normal elderly subjects were participated in this study. Temporal and spatial parameters of gait were analysed for using the computerized GAITRite system. The system integrates specific components of locomotions to provide a single, numerical representation of gait, the Functional Ambulation Performance score. Differences in gait characteristics between the two groups were examined using a correlated t-test and Pearson Correlation(p<.05). Significant differences were observed between the groups for temporal parameters(step time, double support time, stance phase, mean velocity) and spatial parameters(step length, step/extremity ratio)(p<.05). Also there was difference in the functional ambulation performance score between normal elderly subjects and knee osteoarthritis patients(p<.05). Consequently, it may help detect the abnormal gait pattern indicated the main problem in degenerative knee osteoarthritis patients as well as provide data analysing the pathokinesiologic components by comparing normal elderly.

• PNF and Movement
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• v.9 no.2
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• pp.1-7
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• 2011

Purpose : The purpose of this research was to determine the effects of Proprioceptive Neuromuscular Facilitation(PNF) and Functional Electrical Stimulation(FES) of combined on gait ability in hemiplegic gait. Methods : The subjects of this study were 13 hemiplegic patients. Each subjects was taken PNF pattern and FES of combined with 5 times per week for 4weeks. Pre- and Post-intervention change in gait ability were measured using an Timed up and Go test, stride length of the affected side, step length of the affected side. The data were analyzed using the paired t-test. Results : The results of this study were showed significantly improvement in TUG, stride length of the affected side, step length of the affected side after intervention. Conclusion : These results suggest that the Proprioceptive Neuromuscular Facilitation(PNF) and Functional Electrical Stimulation(FES) of combined exercise is an effective way of improving gait ability for hemiplegic patients.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.147.5-147
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• 2001

This paper describes a gait algorithm and a velocity limitation method for a Leg-Wheel Robot. The gait algorithm enables the robot to preserve continuous locomotion even if the velocity command varies extensively. The velocity limitation method restricts the commanded velocity when it exceeds the mechanical limitation of the robot. Combined use of the velocity limitation method with the gait algorithm ensures the continuity of locomotion, and makes the gait pattern efficient with a long step length and low frequency of leg phase change. These methods can be applied to locomotion on unexplored rough terrain even if the range of roughness is unknown.