• Journal of Institute of Control, Robotics and Systems
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• v.15 no.9
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• pp.959-966
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• 2009

An essential consideration when analyzing the gait of walking robots is their ability to maintain stability during walking. Therefore, this study proposes a vertical waist-jointed walking robot and gait algorithm to increase the gait stability margin while walking on the slope. First, the energy stability margin is compared according to the posture of the walking motion on slope. Next, a vertical waist-jointed walking robot is modeled to analyze the stability margin in given assumption. We describe new parameters, joint angle and position of a vertical waist-joint to get COG (center of gravity of a body) in walking. Finally, we prove the superiority of the proposed gait algorithm using simulation and conclude the results.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.118-126
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• 2005

There are many types of walking robots in the world. For dynamic walking of the robots it is necessary to keep its dynamic stability. The dynamic stability is influenced by the position of ZMP (zero moment point). In this paper we study the control of the ZMP position of walking robot. For experiment we developed a quadruped robot and analyzed the dynamic stability of the robot. Developed robot has 2 joints at each leg and WBO (weight balancing oscillator) on the body of the robot. The WBO is designed to move linearly from side to side when the robot walks dynamically. Walking test was performed to verify the validity of the proposed methods. Especially we showed that the dynamic stability of the robot can be improved without sacrifice of the walking speed by control the WBO.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.4
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• pp.310-318
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• 2008

This paper presents a parallel typed walking robot to improve walking space and stability region. The robot is designed by inserting an intermediate mechanism between upper leg mechanism and lower leg mechanism. The leg mechanism is composed of three legs and base, which form a parallel mechanism with ground. Seven different types of walking robot are invented by combining the leg mechanisms and an intermediate mechanism. Topology is applied to design the leg mechanism. A motor vector is adopted to determine Jacobian and a wrench vector is used to analyze dynamics of the robot. We explore the stability region of the robot from the reaction force of legs and compute ZMP including the holding force to contact the foot to a wall. This investigates a walking stability when the robot walks on the ground as well as on the wall. We examine the walking space generated by support legs and by swing legs. The robot has both a large positional walking space and a large orientational walking space so that it can climb from a floor up to a wall.

• The Journal of Korea Robotics Society
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• v.6 no.4
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• pp.301-307
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• 2011

Based on the stability criteria of ZMP (Zero Moment Point), this paper proposes an adjusting algorithm that modifies walking trajectory of a bipedal robot for stable walking by analyzing ZMP trajectory of it. In order to maintain walking balance of the bipedal robot, ZMP should be located within a supporting polygon that is determined by the foot supporting area with stability margin. Initially tilting imposed to the trajectory of the upper body is proposed to transfer ZMP of the given walking trajectory into the stable region for the minimum stability. A neural network method is also proposed for the stable walking trajectory of the biped robot. It uses backpropagation learning with angles and angular velocities of all joints with tilting to get the improved walking trajectory. By applying the optimized walking trajectory that is obtained with the neural network model, the ZMP trajectory of the bipedal robot is certainly located within a stable area of the supporting polygon. Experimental results show that the optimally learned trajectory with neural network gives more stability even though the tilting of the pelvic joint has a great role for walking stability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.446-449
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• 2002

Quadruped walking robot requires dynamic control to keep its stability in high speed walking. To keep its walking stability by control of only legs' Joint angle lowers energy efficiency. It is known that an animal or a human use the moving of the mass center of one's upper body to keep the stability. We have developed a quadruped walking robot with weight balancing oscillator that have high energy efficiency. In this study, walking tests are performed for the robot to verify the validity of the weight balancing oscillator.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.989-992
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• 2004

In general, it is known that walking stability of a quadruped is determined by its COG(Center of Gravity). In this paper, in order to know whether our virtual quadruped robot is applicable to the real quadruped robot, we simulated our virtual model using the data from the real robot‘s walking. We were able to evaluate the stride of quadruped based on direct and inverse kinematics and compared the stride of the simulation with real robot’s it. During the simulation we calculated the COG of the virtual model and evaluated the walking stability of real model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.11a
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• pp.146-154
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• 1991

As the application of robotic systems expand its scope, more research efforts are given in providing mobility to the robotic systems so that they can travel across various paths including those with formidable obstacles such as stairways or rough terrains. Legged locomotion is mainly concerned because the walking motion, like that of animal behavior, has many advantages over wheel type or track type locomotion especially in rough terrain. Walking robot, in general, having a discrete number of legs, have inherently low static stability. Static stability can be increased to a certain degree, by improving walking method, but it has many limitations such as reduced travel speed. A very promising possibility lies in the use of balancing weight, nevertheless its actual implementation is very rare. In this study, a 4-legged walking machine is developed and the static stability margin is increased with the balancing weight. In the future, this robot will be used to take an experiment on the walking in mush terrain.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.539-541
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• 2006

Biped locomotion is a popular research area in robotics due to the high adaptability of a walking robot in an unstructured environment. When attempting to automate the motion planning process for a biped walking robot, one of the main issues is assurance of dynamic stability of motion. This can be categorized into three general groups: body stability, body path stability, and gait stability. A zero moment point (ZMP), a point where the total forces and moments acting on the robot are zero, is usually employed as a basic component for dynamically stable motion. In this rarer, learning based neuro-fuzzy systems have been developed and applied to model ZMP trajectory of a biped walking robot. As a result, we can provide more improved insight into physical walking mechanisms.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.8
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• pp.675-679
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• 2001

This paper presents walking algorithm for a quadruped robot that does not have an upper body. Tilting motion is added to the planned walking trajectory instead of using an extra body segment that is independent on walking trajectory. Area and tracking algorithms are proposed as tilting method and compared with that of off-line tilting and that of no tilting. Computer simulation shows that stability of tilted walking is more improved than that of the usual walking algorithm for general walking paths. It also shows that the tracking method guarantees stability and best mobility.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.301-306
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• 2001

In this paper, we developed a quadruped walking robot, FRAMIX-T, with insectile leg mechanism and we inspected the efficiency of it in detail. In robotics, the legs of insect type are appropriate for the stability and the agile movement. So we first performed a gait analysis using duty factor, stride, phase etc., and analyzed the stability margin to improve the stability of robot. On the basis of this research, we planned the wave gait suitable for FRAMIX-T and performed a walking experiment. From this result, we proved the high efficiency using insectile leg mechanism and the possibility of walking with improved stability and mobility.