• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.765-768
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• 2000

Linearization of the biped dynamic equations and design of linear controller for the linearized equations are studied in this paper. The biped robot with inverted pendulum type trunk, used to stabilize the dynamic balancing of the biped robot during dynamic walking period, is modelled with 14 DOF and simulated. Despite of well defined linear control theories so far, the linear control methods was limited to the applications for a walking robot, because they have been inherently strong nonlinear properties, such as a modeling parameter uncertainties, external forces as noise, inertial and Coriolis terms by three dimensional modeling and so on. To linearize the nonlinear equations of motion of biped robot on MIMO and time varying linear equations of motion, 1st order Taylor series is used to formulate the linear equation. And a 2nd order numerical perturbation method Is used to approximate partial differential equations. Using the linearized equations of motion, a linear controller is designed by pole placement method with feed forward compensation. Using the obtained linearized equations and linear controller, the continuous walking simulation is performed.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1146-1154
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• 2008

This paper presents a method for the acceleration analysis of multi-legged walking robots in consideration of the frictional ground contact. This method is based on both unified dynamic equation for finding the acceleration of a robot's body and constraint equation for satisfying no-slip condition. After the dynamic equation representing relationship between actuator torques and body acceleration, is derived from the force and acceleration relationship between foot and body's gravity center, the constraint equation is formulated to reconfigure the maximum torque boundaries satisfying no-slip condition from given original actuator torque boundaries. From application of the reconfigured torques to the dynamic equation, interested acceleration boundaries are obtained. The approach based on above two equations, is adapted to the changes of degree-of-freedoms of legs as well as friction of ground. And the method provides the maximum translational and rotational acceleration boundaries of body's center that are achievable in every direction without occurring slipping at the contact points or saturating all actuators. Given the torque limits in infinite normsense, the resultant accelerations are derived as a polytope. From the proposed method, we obtained achievable acceleration boundaries of 4-legged and 6-legged walking robot system successfully.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.3
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• pp.269-276
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• 2011

This paper proposes a novel control method using phase plane for a hydraulic biped humanoid robot. In biped walking control, it is much more difficult to control the posture of a biped robot in the coronal plane because the supporting area formed by the both feet in the coronal plane is much narrower than that of the sagittal plane. When the biped robot walks stably, the phase portrait of the pelvis in the coronal plane makes an elliptical shape. From this point of view, we develop an ankle torque controller and a foot placement controller for tracking the desired phase portrait during walking. We design these controllers by using simulations of a simplified compass gait biped model to regulate the desired phase portrait of pelvis. The effectiveness of the proposed control method is proved through full-body dynamic walking simulations and real experiments of the SARCOS hydraulic biped humanoid.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.5
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• pp.530-537
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• 2009

A graphic simulator can be a useful tool for planning gaits or dynamic behaviors to a walking pet robot. Microsoft describes robotics developer studio (MSRDS) as an end-to-end robotics development platform including simulation engine based on dynamics. In this paper, we propose a pet robot simulator (PRS), based on MSRDS, which supports interactively controlled two walking robots connected over network. To be pet robot simulator, modeling a commercial pet robot is performed and gait planning is also implemented. By using concurrency and coordination runtime (CCR) and decentralized software services (DSS) of MSRDS software platform, we connect two robots which are displayed together but controlled separately over network. The two walking pet robots can be simulated interactively by joysticks. It seems to be an internet game for pet robots.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1440-1443
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• 2004

Most previous robots had used the wheels as means for movement. These structures were relatively simple and easy to control and this is why the method had been used until currently. However, there are many realistic problems to move from one place to another in human life, for instance, steps and edges. So we need to develop the two-legged walking humanoid robot. The 2-legged walking Robot system has been vigorously developed in so many corporations and academic circles of several countries. However, 2-legged walking Robot has been mostly studied in view of the static walk. We design a stable humanoid Robot which can walk in high-speed through the research of the dynamic walk in this paper. Especially, worldwide companies have been interested in developing humanoid robots for a long time to solve the before mentioned problems so that they can become more familiar with the human form. The most important thing, for the novel two-legged walk, is to create a stable and fast walking in two-legged robots. For realization of this movement, an optimal mechanical design of 12 DOFS, a distributed control and a parallel processing control are implemented in this paper. This paper proves that high speed and stable walking can be achieved, through experiments.

• 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 Institute of Control, Robotics and Systems
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• v.10 no.4
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• pp.350-356
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• 2004

This paper presents a farce manipulability analysis of multi-legged walking robots, which calculates force or acceleration workspace attainable from joint torque limits of each leg. Based on the observation that the kinematic structure of the multi-legged walking robots is basically the same as that of multiple cooperating robots, we derive the proposed method of analyzing the force manipulability of walking robot. The force acting on the object in multiple cooperating robot systems is taken as reaction force from ground to each robot foot in multi-legged walking robots, which is converted to the force of the body of walking robot by the nature of the reaction force. Note that each joint torque in multiple cooperating robot systems is transformed to the workspace of force or acceleration of the object manipulated by the robots in task space through the Jacobian matrix and grasp matrix. Assuming the torque limits are given in infinite norm-sense, the resultant dynamic manipulability is derived as a polytope. The validity of proposed method is verified by several examples, and the proposed method is believed to be useful for the optimal posture planning and gait planning of walking robots.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.35-41
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• 2019

PURPOSE: This study examined the effects of a vestibular stimulation training program on the walking ability of chronic stroke patients over a six month period. METHODS: Forty stroke patients were enrolled in this study. The patients were divided randomly into a control group (n=20) and experimental group (n=20). A general exercise program was applied to Group I and vestibular stimulation training was applied to Group II(30 min, three times a week for six weeks). The changes in straight walking ability, curved walking ability, and functional walking ability were measured using a 10 m walking test figure-of-eight-walking test, and dynamic gait index, respectively. The measures before and after the program were compared using a paired t-test for a comparison of each group and an independent t-test for a comparison between groups. RESULTS: The changes in each group were examined according to the measurement period. The Experimental group showed significant functional improvement in all three tests after the vestibular stimulation training program, but the control group did not show significant improvement in any of the tests after the general exercise program. A comparison of the changes between groups revealed the experimental group to show significantly higher improvement than the control group in all tests. CONCLUSION: The vestibular stimulation training program helps improve the gait function of stroke patients. Based on the results of this study, it is expected that various vestibular stimulation training programs will be developed and applied in a range of places.

• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.252-259
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• 2013

Purpose: The aim of this study was to evaluate the effect of progressive body weight decrease combined with increasing level of overground walking speed training for patients with chronic stroke. Methods: Eighteen subjects with chronic stroke were composed of the control group (5% body weight support combined with increasing speed training) and the experimental group (progressive body weight decrease with increasing speed training); three sets, three times per week over a period of four weeks. Results: Significant differences in terms of comfortable gait speed (CGS) and the rate of change of CGS were observed between the control and experimental groups (p<0.05). However, no significant difference in the dynamic gait index was observed between the control and experimental groups (p>0.05). A significant difference in the 6 minute walking test (6MWT) was observed for the experimental group, and a significant difference in the rate of change for the 6MWT was observed between the control and experimental groups (p<0.05). Conclusion: The progressive body weight decrease combined with increasing in level of overground walking speed training may be a better and more effective method for community walking and reintegration.

• Journal of Korean Medicine Rehabilitation
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• v.21 no.2
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• pp.227-238
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• 2011

Objectives : This study was to investigate the effects on using Virtual reality exercise program($Wii-Fit^{TM}$) for dynamic balance and walking ability in patients with stroke. Methods : The 22 subjects were randomly selected from the patients of the S hospital who met the study conditions. They were divided into a $Wii-Fit^{TM}$ balance game group of 12 patients and a conventional physical therapy group of 10 patients. The $Wii-Fit^{TM}$ balance game group received $Wii-Fit^{TM}$ balance game group general physiotherapy for 5 days a weeks, 30 minutes a day, for a 4 weeks and the conventional physical therapy group received general physiotherapy for the same period. The subjects were measured and compared for Brunel balance assessment, functional gait assessment, 6 minute walk test, GAITRite system before and after the program. Results : The experimental group tend to improve more than control group in shifting the weight to the affected side(p=0.040) and tap test(p<0.001). The experimental group tend to improve more than control group in FGA(p=0.016). The experimental group improved significantly more than control group in 6MWT(p=0.008). The experimental group improved significantly more than control group in gait speed, cadence, stride length. Conclusions : Virtual Reality program($Wii-Fit^{TM}$) with conventional physical therapy shows the benefits on dynamic balance and gait parameters in patients with stroke.