• Journal of the Korean Society for Precision Engineering
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• v.25 no.10
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• pp.122-129
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• 2008

This paper deals with precise positioning of a high-speed positioning stage without inducing residual vibration by using an input shaping technique. Input shaping is well known to be a very effective tool for suppressing the residual vibration of flexible structures. However, the ordinary input shaping for positioning stages is designated mostly for velocity regulation, not for the residual vibration at the target position. The main difficulties in implementing input shaping along with precise positioning are the time delay caused by the servo system characteristics and the s-curve feature often employed in some motor controllers. This paper analyzes the dynamic responses of a single-mode-dominate stage system subjected to input shaping. A theoretical model is developed io investigate the nature of system. In order to overcome the difficulty, this paper proposes an improved input shaper based on modified command profile generation. The proposed method is proved effective through experiments and simulations.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.3
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• pp.255-260
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• 2009

This paper presents an experimental result of virtual mode input shaping for positioning stage. Input shaping is liable to increase the rise time of the system, which often degrades the performance of system. The virtual mode input, shaping is an input shaper design method to improve this problem. Experiments are performed with a precise positioning stage with a flexible beam of which natural frequency is adjustable. The experimental results show that the virtual-mode shaper is useful to reduce the rise time as well as the residual vibration of precise positioning stages.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.11
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• pp.1034-1039
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• 2012

In this paper, a structure of precise positioning based on satellite navigation system is proposed. The proposed system is consisted with three parts, range domain filter, navigation filter and position domain filter. The range domain filter generates carrier phase-smoothed-Doppler and Doppler-smoothed-code measurements. And the navigation filter calculates position and velocity using double-differenced code/carrier phase/Doppler measurements. Finally, position domain filter smooth position error, and it means enhancement of positioning performance. The proposed positioning method is evaluated by trajectory analysis using precise map date. As a result, the position error occurred by multipath or cycle slip was reduced and the calculated trajectory was in true lane.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.1
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• pp.35-41
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• 2017

Precise Point Positioning (PPP) method is based on dual-frequency data of Global Navigation Satellite Systems (GNSS). The recent multi-constellations GNSS (multi-GNSS) enable us to bring great opportunities for enhanced precise positioning, navigation, and timing. In the paper, the multi-GNSS PPP with a combination of four systems (GPS, GLONASS, Galileo, and BeiDou) is analyzed to evaluate the improvement on positioning accuracy and convergence time. GNSS observations obtained from DAEJ reference station in South Korea are processed with both the multi-GNSS PPP and the GPS-only PPP. The performance of multi-GNSS PPP is not dramatically improved when compared to that of GPS only PPP. Its performance could be affected by the orbit errors of BeiDou geostationary satellites. However, multi-GNSS PPP can significantly improve the convergence speed of GPS-only PPP in terms of position accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1239-1244
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• 2004

Precise positioning is an important problem facing motion control systems which usually use electric motor. A motor possesses a nonlinear property which degrades the positioning accuracy. Therefore, a compensator which linearizes the relationship between the angular velocity and input signal of the motor is required to enable precise positioning. In this paper, the design of a Model Reference Adaptive Control System (MRACS) for realizing the precise positioning for a system using a motor including the nonlinear property is described. The designed MRACS is applied to the attitude control problem on a satellite using a DC servomotor to drive its reaction wheel. Experimental results demonstrate the validity of a proposed control method for a positioning control system with an electric motor.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.4
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• pp.476-484
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• 2010

Precise positioning stages are often employed for precise machinery. For the purpose of vibration isolation, these precise positioning stages are mounted on a heavy base structure which is supported by compliant springs. Then the base structure is subjected to residual vibration due to the reactive force and vertical moving load induced by the stage motion. This paper investigates the vibration behavior of a positioning stage base and the associated vibration suppression technique. A dynamic model is developed to investigate the base vibration due to the reactive force and moving load effects by the moving stage. An input shaping technique is also developed to suppress the residual vibrations in base structures. Simulations and experiments show that the developed dynamic model adequately represents the base vibration and that the proposed input shaping technique effectively removes the residual vibrations from the positioning stage base.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.146-146
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• 2000

This paper presents field test results of the GPS precise positioning using carrier phase observable. The Least-squares AMBiguity Decorrelation Adjustment(LAMBDA) method is implemented to resolve integer ambiguity problem for two epoch Ll carrier phase measurement data. Field test results show that the GPS precise positioning of cm-level accuracy is obtainable with conventional low cost, single frequency C/A code GPS receivers.

• Journal of Astronomy and Space Sciences
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• v.29 no.3
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• pp.269-274
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• 2012

Kinematic global positioning system precise point positioning (GPS PPP) technology is widely used to the several area such as monitoring of crustal movement and precise orbit determination (POD) using the dual-frequency GPS observations. In this study we developed a kinematic PPP technology and applied 3-pass (forward/backward/forward) filter for the stabilization of the initial state of the parameters to be estimated. For verification of results, we obtained GPS data sets from six international GPS reference stations (ALGO, AMC2, BJFS, GRAZ, IENG and TSKB) and processed in daily basis by using the developed software. As a result, the mean position errors by kinematic PPP showed 0.51 cm in the east-west direction, 0.31 cm in the north-south direction and 1.02 cm in the up-down direction. The root mean square values produced from them were 1.59 cm for the east-west component, 1.26 cm for the south-west component and 2.95 cm for the up-down component.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.2
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• pp.59-66
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• 2016

The International GNSS Service (IGS) provides the IGS-Real Time Service (IGS-RTS) corrections that can be used in stand-alone positioning in real time. In this study, the positioning accuracy before and after the application of the corrections to broadcast ephemeris by applying the IGS-RTS corrections at code pseudo-range based stand-alone positioning was compared with positioning result using precise ephemeris. The analysis result on IGS-RTS corrections showed that orbit error and clock error were 0.05 m and 0.5 ns compared to precise ephemeris and accuracy improved by about 8.5% compared to the broadcast ephemeris-applied result when the IGS-RTS was applied to positioning. Furthermore, regionally dispersed five observatories were selected to analyze the effect of external environments on positioning accuracy and positioning errors according to location and time were compared as well as the number of visible satellites and position dilution of precision by observatory were analyzed to verify a correlation with positioning error.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.43-48
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• 2021

Most existing studies on the wide-area differential global positioning system (WADGPS) used standard positioning service (SPS) receivers in their observation reference stations which provide the central control station global positioning system (GPS) measurements to generate augmentation data. In the present study, it is considered to apply a precise positioning service (PPS) receiver to an observation reference station which is located in the threatened jamming area. Therefore, the reference station network consists of a PPS receiver based observation reference station and SPS receiver based observation reference stations. In this case, to maintain correction performance P1C1 differential code bias (DCB) should be compensated. In this paper, P1C1 DCB estimation algorithm was applied to the PPS/WADGPS system and performance test results using measurements in the Korean Peninsula were presented.