• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.683-693
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• 2010

In this paper, we propose a new parallel mechanism for the legs of biped robots and the control of the robot's locomotion. A leg consists of two 3-DOF parallel platforms linked serially: one is an orientation platform for a thigh and the other is the 3-DOF asymmetric parallel platform for the shank. The desired locomotion trajectory is generated on the basis of the Gravity-Compensated Inverted Pendulum Mode (GCIPM) in the sagittal direction and the Linear Inverted Pendulum Mode (LIPM) in the lateral direction, respectively. In order to simulate the ground reaction force, a 6-DOF elastic pad model is used underneath each of the soles. The performance and effectiveness of the proposed parallel mechanism and locomotion control are shown by the results of computer simulations of a 12-DOF parallel biped robot using $SimMechanics^{(R)}$.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.3
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• pp.353-358
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• 2011

This paper presents a virtual-legged walking model for bipedal robots and analyzes its fundamental RPY(Roll, Pitch, and Yaw) motion effects by simulation. For the purpose of identifying the motion effects of the bipedal walking, we assign some arbitrary trajectories both at the center of mass and at the center of pressure of the robot based on human walking. And then we verify the major moments to the roll, pitch, and yaw directions of the robot. As a result, it is shown that those motions are natural in the process of bipedal walking and they are deeply dependent on the step distance, the vertical level of the center of mass, and the acceleration of the robot. The importance of trajectory planning for the footstep location during a bipedal walking is finally addressed in terms of balance.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.1
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• pp.56-64
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• 2013

We propose an efficient minimum-time cornering motion planning algorithms for differential-driven wheeled mobile robots with motor control input constraint, under piecewise constant control input sections. First, we established mobile robot's kinematics and dynamics including motors, divided the cornering trajectory for collision-free into one translational section, followed by one rotational section with angular acceleration, and finally the other rotational section with angular deceleration. We constructed an efficient motion planning algorithm satisfying the bang-bang principle. Various simulations and experiments reveal the performance of the proposed algorithm.

• International Journal of Control, Automation, and Systems
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• v.4 no.2
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• pp.217-226
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• 2006

Grasping and manipulation by hands can be considered as one of inevitable functions to achieve the performances desired in humanoid operations. When a humanoid robot manipulates an object by his hands, each finger should be well-controlled to accomplish a precise manipulation of the object grasped. So, the trajectory of each joint required for a precise finger motion is fundamentally necessary to be planned stably. In this sense, this paper proposes an effective joint motion planning method for humanoid fingers. The proposed method newly employs a bio-mimetic concept for joint motion planning. A suitable model that describes an interphalangeal coordination in a human finger is suggested and incorporated into the proposed joint motion planning method. The feature of the proposed method is illustrated by simulation results. As a result, the proposed method is useful for a facilitative finger motion. It can be applied to improve the control performance of humanoid fingers or prosthetic fingers.

• ETRI Journal
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• v.40 no.4
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• pp.522-530
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• 2018

In this study, we developed a robotic walker that actively controls its speed and direction of movement according to the user's gait intention. Sensor fusion between a low-cost light detection and ranging (LiDAR) sensor and inertia measurement units (IMUs) helps determine the user's gait intention. The LiDAR determines the walking direction by detecting both knees, and the IMUs attached on each foot obtain the angular rate of the gait. The user's gait intention is given as the directional angle and the speed of movement. The two motors in the robotic walker are controlled with these two variables, which represent the user's gait intention. The estimated direction angle is verified by comparison with a Kinect sensor that detects the centroid trajectory of both the user's feet. We validated the robotic walker with an experiment by controlling it using the estimated gait intention.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.177-180
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• 2006

In this paper we proposed a method of automatic point segmentation acquired by 2D laser scanner to recognize moving objects. Recently, Laser scanner is noticed as a new method in the field of close range 3D modeling. But the majority of the researches are pointed on precise 3D modeling of static objects using expensive 3D laser scanner. 2D laser scanner is relatively cheap and can obtain 2D coordinate information of moving object's surface or can be utilized as 3D laser scanner by rotating the system body. In these reasons, some researches are in progress, which are adopting 2D laser scanner to robot control systems or detection of objects moving along linear trajectory. In our study, we automatically segmented point data of 2D laser scanner thus we could recognize each of the object passing through a section.

• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.2-7
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• 2003

Laser welding application for car body manufacturing has many advantages in the stiffness and the lightness of vehicle, the productivity of assembly line, and the degree of freedom in design. This presentation will express the innovation of car body manufacturing including parameter optimization, process modeling, and system integration. In this application the investment for systems was cut down dramatically by real time switching over the laser path between two welding stations. Points of technical discussion are as follows; optimization of parameters such as laser power, robot speed and trajectory, compact and useful design of jig & fixture to assure welding quality for 3 sheet-layer zinc-coated steel, system integration between 4㎾ Nd:YAG laser device and the other systems, on-line real time welding quality monitoring system, perfect safety standards for high power laser, minimization of consumption costs such as arc lamp, protective glass for optic, etc. This application was successfully launched mass production line in 2001. The laser-welded line of side panel consists of 122 stitches totally. And the length is about 2.4m.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.301-305
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• 2001

Conventionally, robot control algorithms are divided into two stages, namely, path or trajectory planning and path tracking(or path control). This division has been adopted mainly as a means of alleviating difficulties in dealing with complex, complex, coupled manipulator dynamics. The minimum-time manipulator control problem is solved for the case when the path is specified and the actuator torque limitations are known. In path planning, DP is applied to applied to find the shortest path form initial position to final position with the assumptions that there is no obstacle and that each path is straight line. In path control, the phase plane technique is applied to the minimum-time control with the assumptions that the bound on each actuator torque is a function of joint position and velocity or constant. This algorithm can be used for any manipulator that has rigid link, known dynamics equations of motion, and joint angles that can be determined at a given position on the path.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.11a
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• pp.155-159
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• 1991

This paper is a study on the Inverse dynamics of a one-1ink flexible robot arm which is control led by the transiational base motion. The system is composed of the flexible arm, the mobil stage, a DC servomotor, and a computer. The arm base is shifted so that the tip follows a desired path function. The tip Rotten is measured by the laser displacement sensor. The governing equations are based on the Bernoullie-Euler beam theory and solved by applying the Laplace transform method and then the numerical inversion method to the resulted equations. Tip responses obtained both theoretically and experimentally are in good agreement with the desired trajectory, which shows that the scheme of inverse dynamics is effective for the open-loop endpoint positioning of the flexible am driven by the translation stage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.12
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• pp.2626-2631
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• 2011

CST(C-shape sharp turn) represented the motion whereby fish bend their tail quickly in a C-shape to achieve an emergent changing of its swimming direction on fish swimming. But there is not yet the general motion trajectory functions related to CST. In this paper, we proposed the very simple motion functions related to CST sequence recorded from a real fish by biologists. Through the computer simulations, we confirmed the usefulness of the proposed function.