• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1587-1592
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• 2003

There are three kinds of singularity in controlling redundant manipulators. Kinematic, algorithmic and representation singularities are those. If manipulators fall into any singularity without proper action to avoid it, the control system must go away from our desire, and we can meet a dangerous situation. Hence, we have to deal the singularities very carefully. In this paper, we describe an on-line solution for avoiding the occurrence of both algorithmic and kinematic singularities in task-priority based kinematic controllers of robotic manipulators. Representation singularity can be easily avoided by using proper representation algorithm, so, in this paper, we only consider kinematic and algorithmic singularities. The proposed approach uses a desired task reconstruction and a successive task projection in order to maintain the measure for singularity over a user defined minimum value. It shows a gain in performance and a better task error especially when working in proximity of singular configurations. It is particularly suitable for autonomous systems where an off-line trajectory control scheme is often not applicable. The advantage and performance of the proposed controller is verified by simulation works. And, the experiment with real manipulator is remaining for the future works.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2435-2440
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• 2003

Manipulation of the nano/micro scale object has been a key technology in biology as the sizes of DNA, chromosome, nucleus, cell and embryo are within such order. For instance, for embryo cell manipulation, the cell injection is performed manually. The operator often spends over a year to carry out a cell manipulation project. Since the typical success rate of such operation is extremely low, automation of such biological cell manipulation has been asked. As the operator spends most of his time in finding the position of cell in the Petri dish and in injecting bio-material to the cell from the best orientation. In this paper, we propose a new strategy and a vision system, by which one can find, recognize and track nucleus, polar body, and zona pellucida of the embryo cell for automatic biomanipulation. The deformable template matching algorithm has been used in recognizing the nucleus and polar body of each cell. Result suggests that it outperforms the conventional methods.

• International Journal of Control, Automation, and Systems
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• v.5 no.6
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• pp.663-673
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• 2007

This paper presents a new moving obstacle detection method using an optical flow in mobile robot with an omnidirectional camera. Because an omnidirectional camera consists of a nonlinear mirror and CCD camera, the optical flow pattern in omnidirectional image is different from the pattern in perspective camera. The geometry characteristic of an omnidirectional camera has influence on the optical flow in omnidirectional image. When a mobile robot with an omnidirectional camera moves, the optical flow is not only theoretically calculated in omnidirectional image, but also investigated in omnidirectional and panoramic images. In this paper, the panoramic image is generalized from an omnidirectional image using the geometry of an omnidirectional camera. In particular, Focus of expansion (FOE) and focus of contraction (FOC) vectors are defined from the estimated optical flow in omnidirectional and panoramic images. FOE and FOC vectors are used as reference vectors for the relative evaluation of optical flow. The moving obstacle is turned out through the relative evaluation of optical flows. The proposed algorithm is tested in four motions of a mobile robot including straight forward, left turn, right turn and rotation. The effectiveness of the proposed method is shown by the experimental results.

• International Journal of Control, Automation, and Systems
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• v.6 no.5
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• pp.722-730
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• 2008

This paper proposes two novel algorithms enabling mobile robots to cooperate with each other in a reliability-based system and a time-critical system. In the reliability-based cooperative system, the concepts of a mobile ad hoc network (MANET) and an object entropy are adopted in order to coordinate a specific task. A logical robot group is created based on the exchange of request and reply messages in a robot communication group whose organization depends on transmission range. In the time-critical cooperative system, relational entropy is used to define the relationship between mobile robots. A group leader is selected based on optimizing power consumption. The proposed algorithm has been verified based on the computer-based simulation and soccer robot experiment. The performance metrics are defined. The metrics include the number of messages needed to make a logical robot group and to obtain the relationship of robots and the power consumption to select a group leader. They are verified by simulation and experiment.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.145-155
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• 2010

This paper presents a new approach to obstacle avoidance for mobile robot in unknown or partially unknown environments. The method combines two navigation subsystems: low level and high level. The low level subsystem takes part in the control of linear, angular velocities using a multivariable PI controller, and the nonlinear position control. The high level subsystem uses ultrasonic and IR sensors to detect the unknown obstacle include static and dynamic obstacle. This approach provides both obstacle avoidance and target-following behaviors and uses only the local information for decision making for the next action. Also, we propose a new algorithm for the identification and solution of the local minima situation during the robot's traversal using the set of fuzzy rules. The system has been successfully demonstrated by simulations and experiments.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.45-54
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• 2007

In the context of auto-landing containers from a container ship to a truck or automatic guided vehicle and vice versa, this research investigates three schemes, one in Part I and two in Part II, for measuring the absolute position of a container. Coordinate transformations between the reference-coordinate, sensor-coordinate, and body-coordinate systems are briefly discussed. The scheme explored in Part I aims the use of three laser-slit sensors, which are relatively inexpensive. In this case, nine nonlinear equations are formulated for six unknown variables (three for orientation and three for position), so a closed-form solution is not available. Instead, an approximate solution through linearization was derived. An advantage of the method in Part I is its ability to measure an absolute position in 3D space, while a disadvantage is the computation time required to obtain pseudo-inverses and the approximate nature of the obtained solution. Numerical examples are provided.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.55-60
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• 2007

In contrast to the method in Part I, which is considered to be the general approach, Part II pursues a closed-form solution. However, this closed-form solution is available only in the 2D situation under the assumption that the moving object is restricted to a 2D space, and also requires the use of only two laser-slit sensors. Since the motion of the container loaded on top of an AGV is restricted to a plane parallel to the ground, it can be considered a 2D motion. As a simple method, but with a high cost, the use of a laser scanner is also discussed. Since the approach in Part I already uses three laser-slit sensors, it is desirable to use the schemes presented in Part II for supplementary purposes.

• Journal of Mechanical Science and Technology
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• v.17 no.10
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• pp.1411-1422
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• 2003

The detection of free spaces between obstacles in a scene is a prerequisite for navigation of a mobile robot. Especially for stereo vision-based navigation, the problem of correspondence between two images is well known to be of crucial importance. This paper describes multi-range approach of area-based stereo matching for grid mapping and visual navigation in uncertain environment. Camera calibration parameters are optimized by evolutionary algorithm for successful stereo matching. To obtain reliable disparity information from both images, stereo images are to be decomposed into three pairs of images with different resolution based on measurement of disparities. The advantage of multi-range approach is that we can get more reliable disparity in each defined range because disparities from high resolution image are used for farther object a while disparities from low resolution images are used for close objects. The reliable disparity map is combined through post-processing for rejecting incorrect disparity information from each disparity map. The real distance from a disparity image is converted into an occupancy grid representation of a mobile robot. We have investigated the possibility of multi-range approach for the detection of obstacles and visual mapping through various experiments.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.3-9
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• 2009

When washing machine is rotated in the laundry, it tends to lean toward one side. This tendency causes a serious vibration. The balance of washing machine plays an important role in order to reduce the vibration by injecting the sand or the salt water into the balance of washing machine. The hot plate welder is used to prevent from outflow of contents. The hot plate welder brings about many problems which is concerned with accidents. The direction recognition and location information of the balance are required in this system. In this paper, the recognition direction of balance in washing machine using machine vision system is studied. The template matching algorithm compares sub-image with original image acquired in real-time to obtain a center point of balance image. The mid points and the edges of balance are estimated by the edge detection and gauging algorithms. The data acquired by these results is used for recognition direction of balance. The automation software for image processing is developed by using LabVIEW.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.1
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• pp.74-81
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• 2017

A crane is typically used as a means to lift and load equipment or materials. A surface vessel uses a towed object for underwater activity. Such a mechanism for dropping and lifting of equipment is necessary, and is called an overboarding unit. The present study is focused on the overboarding unit used for a crane structure. This paper deals with new overboarding mechanism design and GA-based $MATLAB^{(R)}$ optimization. By using a quadrilateral link mechanism, it is possible to set the constraint function for optimizing the GA method. The optimization with $MATLAB^{(R)}$ is followed by the $SolidWorks^{(R)}$ simulation and verification. When applying the proposed mechanism, the operator is expected to have a big advantage in safety and efficiency of operations. Furthermore, the technology developed in this study will be helpful in similar circumstances and in the proposed mechanism.