• The Journal of Korean Physical Therapy
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• v.34 no.4
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• pp.161-167
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• 2022

Purpose: The purpose of this study was to investigate the effects of regular training on the uneven surface that stroke patients encounter in their daily life on their ankle joint muscle activity and balance ability. They were divided into two groups: the gait training group on uneven surfaces and the gait training group on normal surfaces. Methods: In this study, 30 patients diagnosed with stroke and undergoing rehabilitation were selected. 15 people in the uneven surface gait training group and 15 people in the flat gait training group were selected. The muscle activation of the ankle muscles was measured when walking again on a even surface after walking on an uneven surface and on a flat ground. After each gait training, the limit of stability and Romberg test were performed to evaluate the balance ability. Results: As a result of the experimental results before and after walking by group, the tibialis anterior muscle activity of the paralyzed side was significantly decreased in the uneven surface walking group. As a result of measuring balance ability after training, the limit of stability in all directions was significantly increased in the uneven surface gait training group, and the area and length moved significantly decreased in the uneven surface gait training group in the Romberg test as well (p<0.05). Conclusion: After walking on uneven surface, it was confirmed that the muscle activity of the ankle joint decreased in normal flat walking, and thus the efficiency of muscle activity was increased. In addition, it was possible to confirm the improvement of the balance ability of the gait training on the uneven surface, and in conclusion, it could be confirmed that it had an effect on the improvement of the walking ability.

• Korean Journal of Applied Biomechanics
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• v.20 no.1
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• pp.33-39
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• 2010

The purpose of this study was to investigate the changes in walking pattern of the elderly during inclined walkway with uneven surfaces and level walking. 10 young($26.3{\pm}1.3$ years, $174.3{\pm}5.3\;cm$, $69.5{\pm}9.5\;kg$) and 13 elderly($72.4{\pm}5.2$ years, $164.5{\pm}5.4\;cm$, $66.1{\pm}9.6\;kg$) male subjects were participated in the experiment. Experiment consisted of 2 walking conditions: horizontal and inclined walkway with uneven surfaces. 3D motion capturing system were used to acquire and analyze walking motion data with sampling frequency of 120 Hz. To compare differences between conditions, kinematic variables(walking speed, stance-swing ratio, hip joint angle, knee joint angle, ankle joint angle, pelvic rotation angle) were used. Results showed that there were some changes of elderly walking pattern in inclined walkway with uneven surfaces: hip joint(adduction and rotation) and pelvic movement pattern. These changes by inclination and surface may affect gait pattern of young subjects as well as elderly subjects. However, in case of elderly it revealed more unstable gait than the young. Further study is necessary to clarify changes in walking pattern for elderly by considering various gait variables including head movement and various walkway conditions.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.10
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• pp.47-55
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• 2009

In this study, a robot foot having toes for firm stepping on uneven surface is proposed. The toes are connected to the lower leg by parallel links so that the lower leg can rotate in the rolling and pitching directions during stance phase without ankle joint. The landing performance of the foot on uneven surface was evaluated by relative comparison with that of the most common foot making point contact with the walking surface, since the test conditions considering real uneven surface could be hardly defined for its objective evaluation. Anti-slip margin(ASM) was defined in this study to express the slip resistance of a robot foot when it lands on a projection with half circular-, triangular- or rectangular cross section, assuming that uneven surface consists of projections having these kind of cross sections in different sizes. Based on the ASM analysis, the slip conditions for the two feet were experimentally confirmed. The results showed that the slip resistance of the new foot is not only higher than that of the conventional point contact type foot but also less sensitive to the surface friction coefficient.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1152-1159
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• 2013

This paper proposes an effective walking system for a hexapod robot on uneven terrain. To overcome the deficiencies of two-pair walking systems, which are effective on even terrain, the use of only three legs changes the steps required for movement. The proposed system receives feedback data from switches attached to the bottom of the legs and gyro sensor to carry out stable walking using the Bezier curve algorithm. From the coordinates of the Bezier curve, which guarantees the circular motion of legs, the motor's angle value can be obtained using inverse kinematics. The angle values are sent to each motor though RS-485 communication. If a switch is pushed by the surface during navigation in the Bezier curve pattern, the robot is designed to change its circular course. Through the changed course, each leg can be located on an optimal surface and the wobble phenomenon is reduced by using a normal vector algorithm. The simulation and experiment results show the efficiency of the proposed algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.56-62
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• 2011

Terrain recognition ability is crucial to the performance of legged robots in an outdoor environment. For instance, a robot will not easily walk and it will tumble or deviate from its path if there is no information on whether the walking surface is flat, rugged, tough, and slippery. In this study, the ground surface recognition ability of robots is discussed, and to enable walking robots to recognize the surface state and changes, a central moment method was used. The values of the sensor signals (load cell) of robots while walking were detected in the supported section and were analyzed according to signal variance, skewness, and kurtosis. Based on the results of such analysis, the surface state was detected and classified.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.124-129
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• 2013

Hexapod walking robots are superior to biped or quadruped ones in terms of walking stability. Therefore hexapod robots have the advantage in performing intelligent tasks based on walking stability. In this paper, we propose a hexapod robot that has one fore leg, one hind leg, two left legs, and two right legs and can perform various intelligent tasks. We build the robot by using 26 motors and implement a controller which consists of a host PC, a DSP main controller, an AVR auxiliary controller, and smart phone/pad. We show by several experiments that the implemented robot can perform various intelligent tasks such as uneven surface walking, tracking and kicking a ball, remote control and 3D monitoring by using data obtained from stereo camera, infrared sensors, ultra sound sensors, and contact sensors.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.639-644
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• 2003

An unstructured environment requires a robot to possess outstanding mobility and advanced control algorithms since there exist complicated configurations such as obstacle, uneven surface, etc. Especially, when a quadruped robot walks in these environments, obstacles in the walking route will obstruct the walking or may give rise to a serious trouble. In this paper, we introduce a strategy for the stable walking in unstructured environment. The proposed strategy consists of two control algorithms. One is a collision{free algorithm to avoid obstacles and the other is an algorithm to overcome any obstacle. These are based on the obstacle detection method and a shape reconstruction algorithm, Which algorithms are described in detail. In addition, the validity of these algorithms have been demonstrated through experiments using a quadruped walking robot called "MRWALLSPECT III(Multifunctional Robot for Wall inSPECTion version 3 )".

• The Journal of Korea Robotics Society
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• v.2 no.4
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• pp.353-360
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• 2007

This paper proposes the trot gait pattern generation and online control methods for a quadruped robot to carry heavy loads and to move fast on uneven terrain. The trot pattern is generated from the frequency modulated pattern generation method based on the frequency modulated oscillator in order for the legged robots to be operated outdoor environment with the static and dynamic mobility. The efficiency and performance of the proposed method are verified through computer simulations and experiments using qRT-1/-2. In the experiments, qRT-2 which has two front legs driven by hydraulic linear actuators and two rear casters is used. The robot can trot at the speed up to 1.3 m/s on even surface, walk up and down the 20 degree inclines, and walk at 0.7 m/s on uneven surface. Also it can carry over 100 kg totally including 40 kg payload.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.4
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• pp.72-81
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• 2009

The purpose of this paper is to accomplish the stable humanoid robot walking on the soft terrains. The goal of the humanoid robot development is to make the robotic system perform some tasks in human living environment. However, human dwelling environments are very different from those of laboratories, where varied experiments are performed by the robot. In many cases, the ground is soft or elastic unlike the floor of a laboratory. When a robot walks on the soft ground, the sole of robot contacts the uneven ground. This results in unstable walking or walking may be impossible according to the degree of softness. Therefore, the algorithm that facilitates stable walking on the soft ground surface is required. In this paper, we suggest an algorithm that controls the ankle to help the robot walk stably on the soft ground using the humanoid robot (ISHURO-II) as a real model. A humanoid robot walking on the soft ground was simulated to verify that the proposed algorithm results in stable walking.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.387-397
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• 2009

Physical activity has been increased with increased leasure time. Specifically, due to our mountainous geographical benefits, people actively participate in hiking and climbing as regular daily activities. Thus, more stable and comfortable hiking boots are required to walk on uneven and sloped rocky surface for a long period of time. 5 male subjects were recruited for testing planter pressure patterns of four different conditions(barefoot, classic hiking boot, stiffness 60 and stiffness 65). Tested hiking boots(stiffness 60 and stiffness 65) consists of the multiple pieces of outsoles as they are designed for a better shock absorption. In the results, some positive aspects of stiffness 60 and stiffness 65 such as wide contact area and powerful propulsive patterns at take off was observed compared to the classic hiking boots. Therefore, biomechanical development of hiking related clothes and footwear as well as equipment would be beneficial for people who enjoy hiking to maximize their quality of activities.