• Structural Engineering and Mechanics
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• v.54 no.5
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• pp.937-953
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• 2015

This paper investigates the load model for single footfall trace of human walking. A large amount of single person walking load tests were conducted using the three-dimensional gait analysis system. Based on the experimental data, Fourier series functions were adopted to model single footfall trace in three directions, i.e. along walking direction, direction perpendicular to the walking path and vertical direction. Function parameters such as trace duration time, number of Fourier series orders, dynamic load factors (DLFs) and phase angles were determined from the experimental records. Stochastic models were then suggested by treating walking rates, duration time and DLFs as independent random variables, whose probability density functions were obtained from experimental data. Simulation procedures using the stochastic models are presented with examples. The simulated single footfall traces are similar to the experimental records.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.1-5
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• 2013

In this paper, we proposed how to estimate the walking state in the knee disarticulation prosthesis's knee angle control. In control of the knee disarticulation prosthesis, we can estimate walking state that measurement of knee angle using absolute encoder and measurement of load on the soles using strain gage. We suggested a method of estimating the current walking states which can be divided into four cases and showed the effectiveness of the method via a series of experiments.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.344-351
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• 2014

In order to accomplish complex navigational commands, humanoid robot should be able to modify its walking period, step length and direction independently. In this paper, a novel walking pattern generation algorithm is proposed to satisfy these requirements. Modification of the walking pattern can be considered as a transition between two periodic walking patterns, which follows each navigational command. By assuming the robot as a linear inverted pendulum, the equations of motion between ZMP(Zero Moment Point) and CM(Center of Mass) state is easily derived and analyzed. After navigational command is translated into the desired CM state, corresponding CM motion is generated to achieve the desired state by using simple ZMP functions. Moreover, when the command is not feasible, feasible command is alternated by using binary search algorithm. Subsequently, corresponding CM motion is generated. The effectiveness of the proposed algorithm is verified by computer simulation.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.3
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• pp.37-44
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• 2021

PURPOSE: This study examined the effects of functional electrical stimulation (FES) on temporal-spatial gait and the activities of daily living in hemiplegic stroke patients. METHODS: The subjects were 29 hemiplegic stroke patients (57.7 ± 10.3). The patients walked at a self-controlled speed in four states: (1) walking without FES (non-FES), (2) walking with FES on the gluteus medius in the stance phase (GM), (3) walking with FES on the common peroneal nerve and tibialis anterior in the swing phase (PT), (4) walking with both GM and PT. A GAITRite system, Timed-Functional Movements battery, and Timed UP and Go test were used to measure the variables. RESULTS: Significant improvements were observed in all variables of the GM+PT, GM, and PT states compared to the non-FES state (p < .05). There were significant improvements in the GM+PT state compared to GM and PT states (p < .05). Moreover, significant improvements were noted in the single support time on the affected side, backward walking 10ft, and side stepping 10ft on the affected side of the GM state compared to the PT state (p < .05). There were significant improvements in the stride length on the affected side and side stepping 10ft on the unaffected side of the PT state compared to the GM state (p < .05). CONCLUSION: FES is effective in improving the temporal-spatial gait and activities of daily living in hemiplegic stroke patients.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.751-758
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• 2016

The modifiable walking pattern generation (MWPG) algorithm can handle dynamic walking commands by changing the walking period, step length, and direction independently. When an infeasible command is given, the algorithm changes the command to a feasible one. After the feasibility of the navigational command is checked, it is translated into the desired center of mass (CM) state. To achieve the desired CM state, a reference CM trajectory is generated using predefined zero moment point (ZMP) functions. Based on the proposed algorithm, various complex walking patterns were generated, including backward and sideways walking. The effectiveness of the patterns was verified in dynamic simulations using the Webots simulator.

• Journal of People, Plants, and Environment
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• v.22 no.1
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• pp.109-118
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• 2019

Physical activities in the forest environment stimulate the parasympathetic nervous system of humans and have positive effects on the autonomic nervous system as well as moods and emotions. However, there are almost no studies on the benefits of exercise in the forest environment for patients with myocardial infarction. The aim of this study was to investigate the effects of 15-minute single session walking by myocardial infarction patients in the forest and urban environment on the physiological and psychological states. The heart rate variability was measured in 10 patients with myocardial infarction to assess physiological state after single session walking for 15 minutes in the forest environment and urban environment. In order to evaluate the psychological state, a profile of mood scale (POMS) and semantic differential (SD) questionnaire were used. The results of this study showed that 15-minute single session walking in the forest environment activated the parasympathetic nervous system of adult myocardial infarction patients more than 15 minutes of single session walking in the urban environment, and also made them feel more positive in terms of the POMS and SD. Therefore, this study suggests that even single session walking in the forest environment can positively influence the physiological and psychological states of adult heart disease patients and may also contribute to health care.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.249-251
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• 2005

For walking patterns of biped robots, knee-bent patterns are used in most cases. However, humans are mostly walking with their knees nearly stretched. In this paper, a human-like walking algorithm using hybrid system is proposed for biped robots, The hybrid system consists of the logically constituted discrete system, in which the discrete states are defined by considering the walking characteristics, and the continuous state system used for motor control. It is shown that the proposed algorithm is effective by experimental studies.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.530-532
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• 2006

In this paper, we propose stable walking algorithm using ZMP for the biped robot in the slope-way. At first, we define discrete state variables that classified stable area and unstable area by center of mass from ZMP during slope-way walking. For the stable walking gait, the discrete state controller for determining the high-level and low-level decision making are designed. The high-level decision making is composed of the discrete state variables; left foot support phase, right foot support phase, flat-way, and slope-way. Then the continuous state controller is implemented for the low-level decision making using ZMP.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2368-2375
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• 2015

To accommodate various navigational commands, a humanoid should be able to change its walking motion in real time. Using the modifiable walking pattern generation (MWPG) algorithm, a humanoid can handle dynamic walking commands by changing its walking period, step length, and direction independently. If the humanoid is given a command to perform an infeasible movement, the algorithm substitutes the infeasible command with a feasible one using binary search. The feasible navigational command is subsequently translated into the desired center-of-mass (CM) state. Every sample time CM reference is generated using a zero-moment-point (ZMP) variation scheme. Based on this algorithm, various complex walking patterns can be generated, including backward and sideways walking, without detailed consideration of the feasibility of the navigational commands. In a previous study, the effectiveness of the MWPG algorithm was verified by dynamic simulation. This paper presents experimental results obtained using the small-sized humanoid robot platform DARwIn-OP.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.548-552
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• 2015

In this paper, we describe the quadruped walking-control algorithm of the complete full-size humanoid DARPA Robotics Challenge-HUBO (DRC-HUBO) robot. Although DRC-HUBO is a biped robot, we require a quadruped walking function using two legs and two arms to overcome uneven terrains in the DRC. We design a wave-type quadruped walking pattern as a feedforward control using several walking parameters, and we design zero moment point (ZMP) controllers to maintain stable walking using an inverted pendulum model and an observed-state feedback control scheme. In particular, we propose a switching algorithm for ZMP controllers using supporting value and weighting factors in order to maintain the ZMP control performance during foot switching. Finally, we verify the proposed algorithm by performing quadruped walking experiments using DRC-HUBO.