• Journal of Institute of Control, Robotics and Systems
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• v.10 no.1
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• pp.22-29
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• 2004

This paper studies the coordinated trajectory control of an excavator as a kind of robotic manipulators driven by hydraulic actuators. Hydraulic robot system has many non-linearity in dynamics and kinematics, and strong coupling among joints(or hydraulic cylinders). This paper proposes a combined controller frame of the adaptive robust control(ARC) and the sliding mode control(SMC) for the trajectory tracking control of the excavator to preserve the advantages of the both methods while overcoming their drawbacks, namely, asymptotic stability of adaptive system for parametric uncertainties and guaranteed transient performance of sliding mode control for both parametric uncertainties and external disturbance. The suggested control technique is applied for the tracking of a straight-line motion of end-effector of manipulators, and through computer simulations, its trajectory tracking performances and the robustness to payload variation and uncertainties are illustrated.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.4
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• pp.347-355
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• 2002

Obstacle avoidance of underactuated robot manipulators using switching computed torque method (SCTM) is presented. One fundamental feature of this novel method is to use partly stable controllers (PSCs) in order to fulfill the ultimate control objective. Here, we use genetic algorithms (GAs) to acquire the optimum switching sequence of the control actions for a given time frame with the available set of elemental controllers, depending on which links/variables are controlled. The effectiveness of the concept is illustrated by taking a three-degrees-of-freedom (DOF) manipulator and showing enhanced performance of the proposed control methodology.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.510-514
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• 1994

This paper deals with an application of neural network to camera calibration with wide angle lens and 2-D range finding. Wide angle lens has an advantage of having wide view angles for mobile environment recognition ans robot eye in hand system. But, it has severe radial distortion. Multilayer neural network is used for the calibration of the camera considering lens distortion, and is trained it by error back-propagation method. MLP can map between camera image plane and plane the made by structured light. In experiments, Calibration of camers was executed with calibration chart which was printed by using laser printer with 300 d.p.i. resolution. High distortion lens, COSMICAR 4.2mm, was used to see whether the neural network could effectively calibrate camera distortion. 2-D range of several objects well be measured with laser range finding system composed of camera, frame grabber and laser structured light. The performance of 3-D range finding system was evaluated through experiments and analysis of the results.

• Journal of Information Display
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• v.5 no.1
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• pp.41-46
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• 2004

In this paper, a new stereo 3D moving-target tracking system using the MSE (mean square error) and BPEJTC (binary phase extraction joint transform correlator) algorithms is proposed. A moving target is extracted from the sequential input stereo image by applying a region-based MSE algorithm following which, the location coordinates of a moving target in each frame are obtained through correlation between the extracted target image and the input stereo image by using the BPEJTC algorithm. Through several experiments performed with 20 frames of the stereo image pair with $640{\times}480$ pixels, we confirmed that the proposed system is capable of tracking a moving target at a relatively low error ratio of 1.29 % on average at real time.

• Journal of Korea Multimedia Society
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• v.21 no.12
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• pp.1379-1386
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• 2018

In this paper, we proposed eyeglass type periorbital wrinkle treatment device for reducing and improving periorbital wrinkles using near infrared LED of 850nm wavelength and galvanic current. The proposed periorbital wrinkle treatment device is equipped with a control system based on F-PCB. It consists of eight near-infrared LEDs and four indicator LEDs for treatment of right and left periorbital wrinkles. The eyeglass frame is coated with conductive material, so galvanic current can flow to the skin of periorbital wrinkle contacted to it. One male adult in the mid-40s was allowed to use the device for 10 minutes every day for 4 weeks. After 4 weeks, image analysis using optical equipment for measuring wrinkles indicated that wrinkle indexes were reduced.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.2
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• pp.100-109
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• 2007

Object recognition of service robots is very important for most of services such as delivery, and errand. Conventional methods are based on the geometric models in static industrial environments, but they have limitations in indoor environments where the condition is changable and the movement of service robots occur because the interesting object can be occluded or small in the image according to their location. For solving these uncertain situations, in this paper, we propose the method that exploits observed objects as context information for predicting interesting one. For this, we propose the method for modeling domain knowledge in probabilistic frame by adopting Bayesian networks and ontology together, and creating knowledge model dynamically to extend reasoning models. We verify the performance of our method through the experiments and show the merit of inductive reasoning in the probabilistic model

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.441-449
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• 2021

With advances in autonomous vehicles, there is a growing demand for more accurate position estimation. Especially, this is a case for a moving robot for the indoor operation which necessitates the higher accuracy in position estimation when the robot is required to execute the task at a predestined location. Thus, a method for improving the position estimation which is applicable to both the fixed and the moving object is proposed. The proposed method exploits the initial position estimation from Bluetooth beacon signals as observation signals. Then, it estimates the gravitational acceleration applied to each axis in an inertial frame coordinate through computing roll and pitch angles and combining them with magnetometer measurements to compute yaw angle. Finally, it refines the control inputs for an object with motion dynamics by computing acceleration on each axis, which is used for improving the performance of Kalman filter. The experimental assessment of the proposed algorithm shows that it improves the position estimation accuracy in comparison to a conventional Kalman filter in terms of average error distance at both the fixed and moving states.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.7
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• pp.838-846
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• 2004

In the case where both a camera and a target are moving at the same time, the image background is successively changed, and the overlap with other moving objects is apt to be generated. The snake algorithms have been variously used in tracking the object, but it is difficult to be applied in the excessive overlap with other objects and the large bias between the snake and the target. To solve this problem, this paper presents an extended snake model. It includes an additional energy function which considers the temporal variation rate of the snake's area and a SSD algorithm which generates the template adaptive to the snake detected in the previous frame. The new energy function prevents the snake from over-shrinking or stretching and the SSD algorithm with adaptively changing template allows the prediction of the target's position in the next frame. The experimental results have shown that the proposed algorithm successfully tracks the target even when the target is temporarily occluded by other objects.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.90-96
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• 2013

As the need of electric motor is increased rapidly throughout our society, the various application fields are created and the service market called robot gets expanded as well as the existing industrial market. Out of those, the joint systems such as humanoid that is servo actuator for position control or all fields which require multi-degree of freedom (multi-DOF) require the development of innovative actuator. It is multi-DOF spherical motor that can replace the existing system in multi-DOF operating system. But, multi-DOF spherical motor that has been researched up to date is at the stage which is insufficient in performance or mechanical practicality yet. Thus, first of all the research results and limitation of the previously-researched guide frame-type spherical motors were analyzed and then the feature of double air-gap spherical motor which was devised to complement that was studied. The double air-gap multi-DOF spherical motor is very suitable spherical motor for system applying which requires the multi-DOF operation due to its simple structure that does not require other guide frame as well as performance improvement due to its special shape which has two air-gaps. So, the validity of the study was verified by designing and producing it with 3D-FEM through the exclusive jig for multi-DOF spherical motor.

• Journal of Bio-Environment Control
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• v.18 no.2
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• pp.95-100
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• 2009

This study was conducted to develop an imaging processing system of inoculation processing of a lily callus. The image processing system was composed of a camera, a image processing board, and etc. And the illuminance always decided by setting up 55W/3 wavelength lamp respectively on all aspects and the side was maintained by the lighting part. The image characteristic was examined according to each frame of RGB,therefore the culture vessel was able to be separated with B frame. The required time was 2.2 seconds in one cycle from the image acquisition to obtaining the result. The recognition rate of the container was 100%, and the result of image processing showed that the recognition success rate of lily callus was 93%.