• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1185-1188
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• 1996

In this paper we present a genetic approach for trajectory control algorithm of balancing weight for IWR biped walking robot. The biped walking robot, IWR that was made by Automatic Control Lab. of Inha University has a trunk which stabilizes its walking by generating compensation moment. Trunk is composed of a revolute and a prismatic joint which roles balancing weight. The motion of balancing weight is determined by the gait of legs and represented by two linear second order ordinary differential equations. The solution of this equation must satisfy some constraints simultaneously to have a physical meaning. Genetic algorithm search for this feasible motion of balancing weight under some constraints. Simulation results show that feasible motion of balancing weight can be obtained by genetic algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.114-117
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• 2000

We developed a motion capture system to get angle data of human joints in walking mode. The data are used to coordinate the biped-walking robot developed in our laboratory. A pair of motion capture system is composed of three links with the ankle, knee, and pelvis joints. The system has six axes attached with potentiometers. We used an A/D converter was used to get digital data from joint angles. We filterd the data using the Butterworth 4th order digital filter, and simulated walking motion based on the data using the Matlab.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.959-964
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• 1992

This study treats the method for kinematic modeling of the biped walking robot, for synthesizing various gait trajectories, and for calculating adequate values of the joint torque inside the stable region. To synthesize various and anthropomorphic walking easily, the gait trajectory is specified by a set of ten walking prameters, and the trunk motion equation is derived by the zero moment point and the gait trajectory. By distributing ground reaction force and moment reduced at the zero moment point to the both feet, the joint torque equation can be derived readily, and according to this equation, the joint torque to stable walking can be computed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.583-586
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• 2000

The conventional actuators with the speed reducer had weakness in supporting the weight of the body and leg itself. To overcome this, a new four bar link mechanism actuated by the ball screw was proposed. The four bar mechanism has higher strength and gear ratio than the conventional actuator to actutate the leg of the biped robot. One leg was designed to have ankle, thigh, and hip joints. The kinematics and dynamics of one leg with four bar link mechanism was analyzed using Euler-Lagrange approach. The dynamics of one leg was expressed in the ball strew frame.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.10
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• pp.907-911
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• 2007

Compliance of joints must be considered when we analyze dynamics of a multi-body system. If the virtual model for CAE(computer aided engineering) analysis does not consider compliance, the result of CAE analysis can be very different from the actual experimental result. Especially in a biped walking robot, the robot may lose walking stability due to the compliance in joints of a walking robot. This paper proposed a method applying a compliance of joints in the biped walking robot to a virtual model. Also, through the 3-D displacement measurement using a laser tracker, it was demonstrated that the virtual model considering the joint compliance could effectively simulate the nonlinear motion of the real model.

• 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.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.9
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• pp.849-857
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• 2015

Although human-sized bipedal humanoid robots have been developed as the ideal form of human-friendly robots, studies of humanoid robots from the user perspective and of actual interaction between humanoid robots and the public in daily environments are few. This paper presents a long-term public demonstration that encouraged interaction between a humanoid robot and unspecified individuals. We have collected a significant amount of subjective evaluation data from the public by performing a storytelling demonstration that enhanced people's empathy towards the robot. The evaluation model consists of the robot's human friendliness, which involves its impression on humans, interaction with humans, and imitation of human motions and the robot's human appearance which involves gender, age, height, and body type. This study shows that there is no significant difference in human-friendliness between gender groups (male and female), while there is a significant difference between age groups (children and adults). In human appearance, it appears that there is no significant difference between either gender groups or age groups, except for the case of the robot's height.

• The Journal of Korea Robotics Society
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• v.8 no.2
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• pp.92-103
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• 2013

Humanoid robot is the most intimate robot platform suitable for human interaction and services. Biped walking is its basic locomotion method, which is performed with combination of joint actuator's rotations in the lower extremity. The present work employs humanoid robot simulator and numerical optimization method to generate optimal joint trajectories for biped walking. The simulator is developed with Matlab based on the robot structure constructed with the Denavit-Hartenberg (DH) convention. Particle swarm optimization method minimizes the cost function for biped walking associated with performance index such as altitude trajectory of clearance foot and stability index concerning zero moment point (ZMP) trajectory. In this paper, instead of checking whether ZMP's position is inside the stable region or not, reference ZMP trajectory is approximately configured with feature points by which piece-wise linear trajectory can be drawn, and difference of reference ZMP and actual one at each sampling time is added to the cost function. The optimized joint trajectories realize three phases of stable gait including initial, periodic, and final steps. For validation of the proposed approach, a small-sized humanoid robot named DARwIn-OP is commanded to walk with the optimized joint trajectories, and the walking result is successful.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.2
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• pp.148-155
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• 2008

This paper proposes a method of adaptively generating a gait pattern of biped robot. The gait synthesis is based on human's gait pattern analysis. The proposed method can easily be applied to generate the natural and stable gait pattern of any biped robot. To analyze the human's gait pattern, sequential images of the human's gait on the sagittal plane are acquired from which the gait control values are extracted. The gait pattern of biped robot on the sagittal plane is adaptively generated by a genetic algorithm using the human's gait control values. However, gait trajectories of the biped robot on the sagittal plane are not enough to construct the complete gait pattern because the biped robot moves on 3-dimension space. Therefore, the gait pattern on the frontal plane, generated from Zero Moment Point (ZMP), is added to the gait one acquired on the sagittal plane. Consequently, the natural and stable walking pattern for the biped robot is obtained, as proved by the experiments.

• 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.