• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.203-208
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• 2001

In this paper, a novel dual-type positioning mechanism using a voice coil motor(VCM) and a piezoelectric actuator is proposed for optical disk drive or near-field recording type drive. The VCM is used for a coarse motion actuator and the piezoelectric actuator, "S" configuration deflection motion when voltage applied, is used for a fine motion actuator with self-sensing technique, which allows it to sense and actuate simultaneously in a closed loop frame work. When the VCM rotates and stops, a position feedback control algorithm is adopted to further control residu vibration. The performance of the control scheme is confirmed through simulations and experiments.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.77-80
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• 1996

In this paper a nonlinear control strategy via feedback linearization and energy based Lyapunov function for underactuated mechanical systems is investigated. Underactuated mechanical system is a system of which the number of actuators is less than the number of degrees of freedom. Developed algorithm is applied to a crane system of grab operation. Positioning of the trolley as well as swing-up of the pendulum to the up-right position including maintaining the sway angle at some desired degree are demonstrated. Simulations are provided.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1060-1063
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• 1996

Remote Cask Grappling and Lid Unbolting Device (RCGLUD) is developed as a dedicated device capable of performing complete procedure of handling nuclear spent fuel transport cask. Since RCGLUD is suspended to an overhead crane, its body should undergo prolonged vibration upon actuation in rotational direction and it becomes difficult to achieve precise grappling of the cask. Therefore, this paper presents an adaptation of input shaping technique to effectively suppress the rotational vibration of RCGLUD and achieve precise positioning in rotational direction. This technique has a practical merit in that it requires only the information on the system natural frequency and the damping ratio. Its performance is verified by both simulation and experimental studies, and revealed that the method is also insensitive to modeling error.

• International Journal of Ocean System Engineering
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• v.1 no.2
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• pp.89-94
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• 2011

Underwater localization is a crucial capability for reliable operation of various types of underwater vehicles including submarines and underwater robots. However, sea water is almost impermeable to high-frequency electromagnetic waves, and thus absolute position fixes from Global Positioning System (GPS) are not available in the water. The use of acoustic telemetry systems such as Long Baseline (LBL) is a practical option for underwater localization. However, this telemetry network system needs to be pre-deployed and its availability cannot always be assumed. This study focuses on demonstrating the validity of terrain-based localization techniques in a GPS-denied underwater environment. Since terrain-based localization leads to a nonlinear estimation problem, nonlinear filtering methods are required to be employed. The extended Kalman filter (EKF) which is a widely used nonlinear filtering algorithm often shows limited performance under large initial uncertainty. The feasibility of using a particle filter is investigated, which can improve the performance and reliability of the terrain-based localization.

• International Journal of Control, Automation, and Systems
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• v.1 no.2
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• pp.229-235
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• 2003

We designed a family of completely autonomous mobile robots with local intelligence. Each robot has a number of on-board sensors, including vision, and does not rely on global positioning systems The on-board embedded controller is sufficient to analyze several low-resolution color images per second. This enables our robots to perform several complex tasks such as navigation, map generation, or providing intelligent group behavior. Not being limited to playing the game of soccer and being completely autonomous, we are also looking at a number of other interesting scenarios. The robots can communicate with each other, e.g. for exchanging positions, information about objects or just the local states they are currently in (e.g. sharing their current objectives with other robots in the group). We are particularly interested in the differences between a behavior-based approach versus a traditional control algorithm at this still very low level of action.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.848-851
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• 2002

Recently, there are lots of concerning on the integration of robot and virtual reality with the trends of the research of intelligent robot and mined reality. In this paper, a 3D GUI system is proposed based on Internet for remote controlling and monitoring of agent robot working for itself. The proposed system is consists of a manager ordering a new position and displaying the motion of robot, an agent robot moving to the destination according to the indication, a positioning module detecting the current position of robot, and a geographical information module. A user can order the robot agent move to a new position in a virtual space and watch the real images captured from the real sites of the robot. Then, the agent robot moves to the position automatically with avoiding collision by using range finding and a path detection algorithm. We demonstrate the proposed 3D GUI system is supporting a more convenient remote control means far the robots.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.61-68
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• 2017

In this paper, the coarse acquisition code (C/A code), for civil navigation, of the ranging codes for Global Positioning System (GPS) is studied, simulated and analyzed by using Matlab. We can see with the simulation results that the correctness of the method and feasibility, which is at simulation platform to further study on the real environment of GPS signal, can be confirmed. With using this results, we think, the complexity of tracking the satellite signal environment can be captured, and the performance of satellite receiver will be improved.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.154-157
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• 2003

Precision displacement of less than a few nm resolution was measured in real-time using fiber optic EFPI sensor. The novel method for real-time processing of analyzing EFPI output signal was developed and verified. Linearity in the mean values of interferometric light intensity among adjacent fringes was shown, and the sinusoidal approximation algorithm that estimates past and coming fringe values was verified through the linearity. Real-time signal processing program was developed, and the intensity signal of the EFPI sensor was transformed to the phase shift with this program. The resolution below 0.4 ~ 10 nm in the displacement range of $0 ~ 300\mu\textrm{m}$ was obtained by reducing the photodetector noise using low-pass filter and signal averaging. The nano-translation stage with a Piezo-electric actuator and the EFPI sensor system was designed and tested. This stage successfully reached to the desired destination in $15\mu\textrm{m}$ range within 1 nm accuracy.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.48-54
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• 2012

This paper introduces the kinematic calibration method to improve the positioning accuracy of a parallel mechanism. Since all the actuators in the parallel mechanism are controlled simultaneously toward the target position, the volumetric errors originated from each motion element are too complicated. Therefore, the exact evaluation of the error sources of each motion element and its calibration is very important in terms of volumetric errors. In the calibration processes, the measurement of the errors between commands and trajectories is necessary in advance. To do this, a digitizer was used for the data acquisition in 3 dimensional space rather than arbitrary planar error data. After that, the optimization process that was used for reducing the motion errors were followed. Consequently, Levenberg-Marquart algorithm as well as the error data acquisition method turned out effective for the purpose of the calibration of the parallel mechanism.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.1051-1059
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• 1992

Two types of digital repetitive control systems are analyzed and designed to reduce the error spectrum including not only harmonic but also non-harmonic components. First, a novel gain scheduling algorithm is suggested for conventional and modified repetitive controller is scheduled to reduce the infinite norm of error in frequency domain. For this, the relative error transfer function is mewly defined as the ratio of the error spectrum for the system with a repetitive controller to the error spectrum for the system with a repetitive controller to the error spectrum for the system without a repetitive controller. Secondly, as an alternative of a repetitive control system with the gain scheduling, a repetitive control system with higher order repetitve function is analyzed and designed, where instead of equal weightings, weightings of the higher order repetitive function is determined in such a way that the infinite norm of relative error transfer function is minimized. To show the validities of proposed methods, computer simulation results are illustrated for a typical disk drive head positioning servo system.