• The Journal of Korea Robotics Society
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• v.8 no.1
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• pp.8-19
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• 2013

One of the important issues for structural and electrical specifications in developing a robot is to determine lengths of links and motor specifications, which need to be appropriate to the purpose of robot. These issues become more critical for a gait rehabilitation robot, since a patient wears the robot. Prior to developing an entire gait rehabilitation robot, designing of a 1DOF assistive knee joint of the robot is considered in this paper. Human gait motions were used to determine an allowable range of knee joint that was rotated with a linear type actuator (ball-screw type) and links. The lengths of each link were determined by using an optimization process, minimizing the stroke of actuator and the total energy (kinetic and potential energy). Kinetic analysis was performed in order to determine maximum rotational speed and maximum torque of the motor for tracking gait trajectory properly. The prototype of 1 DOF assistive knee joint was built and examined with a impedance controller.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.579-585
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• 2010

In this paper, an assistive device for a knee joint to help a disabled person to stand up by supporting power is presented. The device is designed and controlled by using damping characteristics of the MR (Magneto-Rheological) damper. The MR damper helps the person to sit slowly and safely. A DC motor supports muscle power in the case of standing motion. Thus the device helps the disabled person to sit down and stand up. Through the experiments, it is feasible that an assistive device can help the disabled person to standup according to the foot pressure change.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.6 no.2
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• pp.9-14
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• 2012

In this study, an advanced knee joint for active prosthesis leg driven by a linear actuator is suggested. The structure of knee joints of existing active prosthesis legs consists of three links. This kind of linkage requires large torque to drive the active prosthesis legs. Thus a new linkage structure is suggested to solve such problem in this paper. Motion characteristics of the suggested linkage are examined in the simulation. The motion simulation results show that the proposed linkage is able to imitate human gait cycles with the half of linear actuator speed in existing linkages.

• Journal of the Ergonomics Society of Korea
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• v.29 no.3
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• pp.357-364
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• 2010

This study proposes a lower-limb exoskeleton system that is controlled by a wearer's muscle activity. This system is designed by following procedure. First, analyze the muscle activation patterns of human leg while walking. Second, select the adequate actuator to support the human walking based on calculation of required force of knee joint for step walking. Third, unit type knee and ankle orthotics are integrated with selected actuator. Finally, using this knee-assistive system (KAS) and developed muscle stiffness sensors (MSS), the muscle activity pattern of the subject is analyzed while he is walking on the stair. This study proposes an operating algorithm of KAS based on command signal of MSS which is generated by motion intent of human. A healthy and normal subject walked while wearing the developed powered-knee exoskeleton on his/her knees, and measured effectively assisted plantar flexor strength of the subject's knees and those neighboring muscles. Finally, capabilities and feasibility of the KAS are evaluated by testing the adapted motor pattern and the EMG signal variance while walking with exoskeleton. These results shows that developed exoskeleton which controlled by muscle activity could help human's walking acceptably.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.1
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• pp.65-72
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• 2016

In this study, a fully active transfemoral prothesis with a knee joint is designed considering stair walking conditions. Since the torque at the knee joint required for stair walking condition is relative high compared with the one in normal walking condition, the proposed design has high torque generating mechanism. Moreover, the transfemoral prothesis is designed in compact size to reduce its weight, which is related to comfortable fit and fatigue of patients. Flat type BLDC motor is used for simple and compact structure and various components are used to generate required torque with target working angle and speed. The weight reduction of structure is carried out using optimization method after the initial design process is complete. The optimization is conducted under the load conditions of stair walking. The optimized design is validated via finite element analysis and experiments. As a result, the weight is reduced using topology and shape optimization but maintaining the safety of structure. Also the space efficiency is improved due to its compact size.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.139-144
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• 2013

Various types of disease in the nervous and musculoskeletal system can change gait, and the gait analysis is very important in determining the progression of the disease. Most methods of analyzing gait are subject to high-priced equipment and spatial restrictions. This study used smart phone images and the walking track analysis program to make a comparative analysis with the existing gait analysis on the basis of the stride length measurements and the changes in the knee joint angle for walking. The test necessary to analyze gait was conducted in seven healthy men, and data about the angle of right and left knee joints and stride length were used to analyze gait. The gait analysis in this study obtained the similar results to the existing ones. The use of the methods suggested in this study will enable gait analysis to be made without high-priced equipment and spatial restrictions.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.4
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• pp.259-265
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• 2014

The aims of this study are to investigate the walking intention detection of a rollator based on Infraed (IR) sensor measuring knee joint anterior displacement and leg muscle activities. We used Active Walker attached IR sensor to measure the knee joint anterior displacement and EMG signal of leg muscles(rectus femoris, biceps femoris, tibialis anterior, gastrocnemius) were taken by Delsys bagnli-8ch. Subjects were eight healthy males(age $23.7{\pm}0.5years$, height $175.4{\pm}2.3cm$, weight $70.6{\pm}5.6kg$) and they were involved in experiments which had been proceeded 30 minutes a week, during 3 weeks. This system indicates that the knee joint anterior displacement had the distinction increases according to the gait slope and velocity. We showed the increase of the femoral muscle activities along the anterior tilt and the increase of the crural muscle activities along the posterior tilt.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.101-107
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• 2013

In this paper, we were to investigate effect of correction to muscle imbalance in lower limbs according to reduction of weight bearing methods of four point of horizontal shaft using two-belt treadmill. Participants were divided to two group according to each ten peoples who have difference of muscle function in left and right legs over 20%. Experiment progressed forty minutes a day three days a week, total four weeks and we estimated the maximal peak torque and average power for testing joint torque in hip, knee and ankle. The results showed that the correction effect of muscle imbalance to the maximal muscle strength was the most effective in hip joint. Also in knee joint, correction effect of muscular reaction was the most effective too. We thought that reduction of weight bearing methods could be positive effect to correct muscle imbalance in lower limbs.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.41-46
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• 2013

IIn this paper, active trasfemoral prosthesis leg is designed for the handicapped who lost their legs upon knee. It is important to design proper knee joint to mimic walking motion of hyman. 1 degree-of-freedom active trasfemoral prosthesis leg is designed with knee joint. Operating angle and torque have been calculated using kinematics of three linkages in prosthesis leg. Finite element analysis of major components is performed to evaluate the safety under operating condition and to reduce weights. Minimum volumes of components are obtained by optimization as satisfying safety requirements. The results show that about 35% of weight of components is reduced.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.3
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• pp.177-185
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• 2014

In this study, the exoskeleton orthosis for the assistance of dorsiflexion torque in ankle joint to prevent foot-drop was developed. It was consist of three part; 1) the power part using artificial pneumatic actuator, 2) wearing part of ankle and knee joints to fix the orthosis, and 3) control part to detect the gait phase using physiological signal. The dorsiflexion torque was generated by the artificial pneumatic actuator connected with wearing part between ankle and knee joint. The accurate timing to assist dorsiflexion torque is made up of physiological signal in foot sole part that detect the gait phase, that is, stance and swing phase in each foot. We conduct the experiment to investigate the effect of exoskeleton orthosis to the 7 elderly people and 10 healthy people. The result showed that the muscular activities in tibialis anterior muscle were reduced because of the assistance of dorsiflexion torque in ankle joint using the exoskeleton orthosis.