• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.468.1-468.1
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• 2004

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.75-83
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• 1998

This paper presents a low cost and high accuracy integrated Global Positioning System (GPS)/dead reckoning (DR) system. The integrated GPS/DR system is capable of providing highly accurate position data in real-time or in post processing. Based on the analysis of the main error source affecting the DR measurements, an eight-state mathematical model for the integrated system has been developed to represent these errors. This eight-state model has been used to build a nonlinear filter for the estimation of the state vector at every epoch when DR measurements are available. The accuracy of the system has been evaluated using 1Hz DR measurements and 3Hz continuous GPS position estimates. Through numerical simulation the system performance during periods with GPS outage has been investigated by comparing two different noise models. While one model is the position estimation filter containing a single noise model, the other filter includes two-level noise model. The simulation results have shown that the estimation filter containing two-level noise model for computing the position error of the integrated GPS/DR system yields better performance than that the filter including the single-level noise model does.

• Journal of Advanced Navigation Technology
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• v.26 no.5
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• pp.319-324
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• 2022

If radio interference occurs or there is no navigation device, radio navigation of high-speed moving object becomes impossible. Nevertheless, if there are multiple ground stations and precise range measurement between the high-speed moving object and the ground station can be secured, it is possible to estimate the position of moving object. This paper proposes a position estimation method using high-precision TDOA measurement generated using TLM signal. In the proposed method, a common error of moving object is removed using the TDOA measurements. The measurements is generated based on TLM signal including SOQPSK PN symbol capable of precise timing synchronization. Therefore, since precise timing synchronization of the system has been performed, the timing error between ground stations has a very small value. This improved the position estimation performance by increasing the accuracy of the measured values. The proposed method is verified through software-based simulation, and the performance of estimated position satisfies the target performance.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.226-231
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• 2011

This research was done to prove the optimal position to detect a train reader when using a multiple fusion sensor. The experiment was done using four Train installed RFID Readers located on the train. These readers were read by sensors installed at intervals of 50 meters on the up and down sections of the Line 8, from Amsa station to Moran station. We analyze errors in the recognition range according to the Tag's number of recognition due to RFID of train speed, and propose a method of estimation for an accurate estimation of the position of train At this the Least-Squares Method is applied to judge the position of train accurately from the error because of Tag's number of recognition and RFID of train speed. also It is verified through simulation.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.1121-1124
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• 1999

Linear motor is able to produce line movement without rotary-to-line converter at the system required line moving. Thus Linear motor has no gear, screw, belt for line movement. Therefore it has some advantage which decrease friction loss, noise, vibration, maintenance effort and prevent decay of control performance due to backlash. This paper proposes the estimation method of unknown parameters from the BLDC Linear motor and determine the PI controller gain through this estimation. Each control movement that is current, speed, position control, and PWM wave generation is performed on Processor, which is DSP(Digital Signal Processor), having high speed performance. PI theory is adopted to each for controller for control behavior More fast convergence to command position is accomplished by applying the new velocity locus which derived from position error.

• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.221-226
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• 2007

A robust position-sensing system is proposed in this paper for ubiquitous mobile robots which move indoor as well as outdoor. The Differential GPS (DGPS) which has position estimation error of less than 5 m is a general solution when the mobile robots are moving outdoor, while an active beacon system (ABS) with embedded ultrasonic sensors is selected as an indoor positioning system. The switching from the outdoor to indoor or vice versa causes unstable measurements on account of the reference and algorithm changes. To minimize the switching time in the position estimation and to stabilize the measurement, a robust position-sensing system is proposed. In the system, to minimize the switching delay, the door positions are stored and updated in a database. The reliability and accuracy of the robust positioning system based on DGPS and ABS are verified through the real experiments using a mobile robot prepared for this research and demonstrated.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.1
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• pp.84-90
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• 2012

Various methods have been proposed to identify the flux position in an interior permanent magnet synchronous motor (IPMSM) without the use of mechanical sensors. To achieve this, a method that uses both the back electromotive force (EMF) and the saliency to identify the flux position in the IPMSM without the injection of high-frequency components at low speeds has been reported. This method was then extended in order to drive the motor with no load to a light load. We propose a combination of these methods with different proportional-integral (PI) controllers for controlling $di_{dest}$/dt and $di_{qest}$/dt. We also introduce compensation values $F_L$ and $F_H$ to reduce the position error when the estimation rule is being selected.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1915-1923
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• 2011

For automated guidance control of a magnetically guided-all wheel steered vehicle, it is necessary to have information about position and orientation of the vehicle, and deviations from the reference path in real time. The magnet reference system considered here consists of three magnetic sensors mounted on the vehicle and magnetic markers, which are non-equidistantly buried in the road. This paper presents an observer to estimate such position and orientation at the center of gravity of the vehicle. This algorithm is based on the simple kinematic model of vehicle and uses the data of wheel velocity, steering angle, and the discrete measurements of marker positions. Since this algorithm requires the exact values of initial states, we have also proposed an algorithm of determining the initial position and orientation from the 16 successive magnet pole data, which are given by the magnetic measurement system(MMS). The proposed algorithm is capable of continuing to estimate for the case that the magnetic sensor fail to measure up to three successive magnets. It is shown through experimental data that the proposed algorithm works well within permissible error range.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.147-149
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• 2004

This paper presents a new velocity estimation strategy of a non-salient permanent magnet synchronous motor(PMSM) drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system which has the information of rotor position error. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error to zero. For zero and low speed operation, the PI gains of rotor position tracking controller have a variable structure. The PI tuning formulas are derived by analyzing this control system using the frequency domain specifications such as phase margin and bandwidth assignment.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.3
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• pp.174-180
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• 1996

The friction is one of the nonlinearities to be considered in the precise position control of a system which has electromechanical components. The friction has complicated nonlinear characteristics and depends on the velocity, the position and the time. The conventional fixed friction compensator and the controller based on linear control theory may cause the steady state position error or oscillation. The plant to be controlled in this study is a positioning system with a linear brushless DC motor(LBLDCM). The system behaves like a 4th-order model including the compliance and the friction. In this study, the plant model is simplified to a 2nd-order model to reduce the computation in on- line estimation. Also, to reduce the computation time, only the friction is estimated on-line while the mass and the viscous damping coefficient are fixed to the values obtained from off-line estimation. The validity of the proposed scheme is illustrated with the computer simulation and the experiment where the friction is compensated by using the estimation.