• The Journal of Korea Robotics Society
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• v.18 no.2
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• pp.172-181
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• 2023

This paper presents research on the stability of control for a quadruped robot with two different leg structure designs. The focus of the research is on the design and analysis of the leg structures in terms of their impact on the stability and robustness of the robot's motion. First, a static analysis was performed in the simulation to compare the structural strength of the legs when the same force was applied. Secondly, two quadruped robots were built, each equipped with differently designed legs, and performed trot gait walking in the real world. And the states of the robots and the torques of each joint were analyzed and compared. In conclusion, based on the results of structural analysis in simulation and the actual walking experiments with the robots, it was demonstrated that the legs designed to be structurally robust improved the control stability of the quadruped robot.

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.503-509
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• 2014

The purpose of this study was to investigate the effect of Forest-walking exercise on gait pattern in the elderly. The subjects (n=37) were assigned to 2 groups: Forest-walking exercise (FWE) group (n=19, $66.34{\pm}4.31$ years old) and In-door treadmill-walking exercise (ITWE) group (n=18, $67.18{\pm}2.78$ years old). The subjects participated in FWE program or ITWE program (3 times/week, 80 min/day) for 12 weeks. The subjects were tested on functional fitness (strength, endurance, agility/balance, BMI) and gait pattern (cadence, velocity, and stability) at the beginning and the end of the 12-weeks program. For data analysis, mean and standard deviation scores were calculated, and independent t-test and repeated two-way ANOVA were used. The results of this study were as follow: First, FWE group was significantly more improved than ITWE group on functional fitness(lower-body muscular strength, lower-body flexibility, mobility, cardiorespiratory endurance) after 12-weeks exercise program. But both groups showed equally improvements on functional fitness (upper-body muscular strength, upper-body flexibility, BMI). Second, FWE group was significantly more improved than ITWE group on cadence, gait velocity, and gait stability after 12-weeks exercise program. Therefore, this study may suggest that Forest-walking exercise based on sensory-motor functional integration improves efficiently functional fitness and gait pattern in the elderly, and further becomes an effective exercise method that makes more dynamic life, and prevents from falling.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1210-1216
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• 2004

This paper deals with a human-like gait generation of a biped robot with a balancing weight of an inverted pendulum type by using genetic algorithm. The ZMP (Zero Moment Point) is the most important index in a biped robot's dynamic walking stability. To perform a stable walking of a biped robot, a balancing motion is required according to legs' trajectories and a desired ZMP trajectory. A dynamic equation of the balancing motion is nonlinear due to an inverted pendulum type's balancing weight. To solve the nonlinear equation by the FDM (Finite Difference Method), a linearized model of equation is proposed. And GA (Genetic Algorithm) is applied to optimize a human-like balancing motion of a biped robot. By genetic algorithm, the index of the balancing motion is efficiently optimized, and a dynamic walking stability is verified by the ZMP verification equation. These balancing motion are simulated and experimented with a real biped robot IWR-IV. This human-like gait generation will be applied to a humanoid robot, at future work.

• Journal of Advanced Navigation Technology
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• v.11 no.2
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• pp.209-216
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• 2007

In this paper, we embodied posture-stabilization and dynamic gait in a walking robot. 10 RC servo motors are used to operate joints. And the joints have enough moving ranges suitable in any walking pattern. Each joint trajectory is generated by cubic spline interpolation method and the stability of the trajectory is verified by using Zero Moment Point from the robot modeling. To avoid complex structure and expression, Zero Moment Point of the biped robot used angular acceleration is suggested. To measure the stability of the biped robot, Tilt sensor and gyro sensor are used. Finally, Personal Computer is used computer monitoring and data processing. Most of computation, such as 10 RC servo motor control, joint trajectory generating, ZMP compensation, sense measuring, etc, was used Digital Signal Processor.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.1
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• pp.15-22
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• 2012

Purpose : We investigated the effects of the combined use of FES and over ground walking with partial body-weight support (PBWS) on walking function and balance control in people with chronic strokes. Methods : Twenty-seven people who were ambulatory after chronic strokes were evaluated. The exercise's intervention consisted of the combined use of FES and over ground walking with PBWS and general exercise groups. The FES + PBWS group and general exercise group consisted on a-20-minute session per day, 3 times a week during a 4 week period. The evaluation was carried out before, after, and two weeks after the exercise intervention. Outcome measures were a 6 Minute Walk Test, 6-Meter walk Test, Timed Up and Go Test, and a Balance Test, measured before and after the exercise interventions at a-2 week follow up. Results : The endurance was significantly increased in both the FES+PBWS group and general exercise group (p<0.05). Significant increase on the gait velocity was observed in both the FES+PBWS group and general exercise group (p<0.05). The TUG was significantly different in both the FES + PBWS group and general exercise group (p<0.05). However there were no differences in both the between-group & interaction. The stability index was significantly different in both the FES + PBWS group and general exercise group (p<0.05). Conclusion : In conclusion, the combined use of FES and over ground walking with PBWS led to an improvement in walking function and balance control. Thus, it is possible to combine the use of FES and over ground walking with PBWS for physical therapy intervention to improve walking function and balance control. It is suggested to apply this intervention in the clinical field.

• Journal of the Ergonomics Society of Korea
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• v.31 no.2
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• pp.327-336
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• 2012

Objective: The purpose of this study is to find the problems of stability when people use the bassinet as an ambulatory aid for old people. Background: Many aged people use a bassinet as ambulatory aid. But the safety of using the bassinet as ambulatory aid has not been verified yet. Method: The 13 university-students who don't have musculoskeletal disorders volunteered to participate in this study. According to structural analysis of the both tools, we compared the structural stability of an outdoor rollator with the structural stability of a bassinet. And when the participants walked using both tools, the motions were captured and analysed. We measured the angle of shoulder joint and the angle of trunk from the ground when the participants were walking. And we found the distance from participants' pressure cone apex and greater trochanter. Results: Following the structural analysis, the bassinet has the lower structural stability than the outdoor rollator. When the people used the bassinet as ambulatory aid, the angle of the shoulder joint was bigger than to use the outdoor rollator. The angle of trunk wasn't different between the outdoor rollator and the bassinet. And distance from pressure cone apex to greater trochanter was far to use the bassinet than to use the outdoor rollator. Conclusion: Through the structure analysis and gait analysis of the bassinet and the outdoor rollator, we can be aware of that the bassinet has problem of stability. Therefore the people who use the bassinet as an ambulatory aid, especially supporting body weight, may be hurt due to the problems of stability. Application: This research can be used for developing a study of the ambulatory aid and preventing the accident when the aged people use the ambulatory aid.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.103-108
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• 1988

A walking robot must have the ability to change the body direction in order to avoid the obstacles. In this paper, we develop a gait control algorithm that can maintain the stable movement of the robot for three different modes of changing directions. The algorithm makes it possible for the robot to have the larger gait stability margin than the threshold value by the method of changing the body speed.

• The Journal of Korean Physical Therapy
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• v.25 no.6
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• pp.379-385
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• 2013

Purpose: The purpose of this study is to compare kinematics on lower limbs between stair walking with high heel and barefoot in healthy adult women. Methods: 18 healthy adult women were recruited in this study. The subjects performed stair ascent and descent with high heels and barefoot. The experiment was conducted in random order and repeated three times for each stair walking with high heels and barefoot. The movements of lower limb joints were measured and analyzed using a three-dimensional analysis system. Results: The ankle, knee, and hip flexion angles on the sagittal plane exhibited statistically significant differences between stair ascent and descent with high heels and barefoot. The pelvic forward tilt angles showed statistically significant differences only during stair ascent. The ankle inversion, hip abduction and pelvic lateral tilt angles on the frontal plane showed statistically significant differences between stair walking with high heels and barefoot. On the transverse plane, the hip rotation angles showed statistically significant differences between the high-heeled and barefoot gait during stair ascent and descent. However, the pelvic rotation angles showed no statistically significant differences. Conclusion: Therefore, wearing high-heeled shoes during stair walking in daily life is considered to influence lower limb kinematics due to the high heel, and thus poses the risks of pain, and low stability and joint damage caused by changes in the movement of lower limb joints.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.7
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• pp.659-667
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• 2011

The study of bipedal robot is towards similar shape and function with human. In this paper, we propose a human-like walking pattern compatible to the flexible foot with toe and heel structure. The new walking pattern for a bipedal robot consists of ZMP, center of mass (CoM), and ankle trajectory and is drawn by considering human kinesiology. First, the ZMP trajectory moves forward without stopping at a point even in the single support phase. The corresponding CoM trajectory to the ZMP one is derived by solving differential equations. As well, a CoM trajectory for the vertical axis is added by following the idea of human motion. The ankle trajectory closely mimics the rotational motion of human ankles during taking off and landing on the ground. The advantages of the proposed walking pattern are demonstrated by showing improved stability, decreased ankle torque, and the longer step length capability. Specifically, it is interesting to know that the vertical CoM motion is able to compensate for the initial transient response.

• Journal of The Korean Society of Integrative Medicine
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• v.5 no.1
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• pp.19-24
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• 2017

Purpose : The purpose of this study was to find out the difference motion of hip, knee and ankle joint during walking according to using walker on older people. Method : Korean older people of 34 subjects was participated in this study. Participants was measured joint motion on hip, knee and ankle joint during both conditions (walking with walker and without walker). The measured data were analyzed using independent t-test to investigate the difference of joint motion on the both condition. The statistical analyses were performed using Predictive Analytics Soft Ware (PASW) for windows(Ver. 19) and p-value less than .05 were considered significant for all cases. Result : The study showed that more joint motion on hip flexion and ankle pronation is increased by using walker. And hip extension, knee external rotation and ankle plantar flexion is decreased by using walker. Conclusion : This study suggest that using walker on older people was change the motion of the lower limb joint during walking. Therefore, It is necessary to develop a new walker that can reduce dependency and ensure stability on older people during walking.