• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.420-421
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• 2018

본 논문에서는 표면부착형 영구자석 동기전동기(SPMSM)를 위한 센서리스 제어방법을 실험을 통해 검증하고자 한다. 동기전동기의 벡터제어를 위하여 엔코더나 레졸버를 이용하면 비용이 증가할 뿐만 아니라 유지 보수가 필요하기 때문에 동기전동기의 센서리스 모터제어 기법이 요구되고 있다. 또한, 동기전동기의 센서리스 모터 제어를 위해서는 정확한 회전자의 위치와 속도가 필요하므로 본 논문에서는 영구자석 동기전동기의 수학적 모델을 통하여 위치와 속도를 추정한다. 회전 중 발생하는 역기전력을 통해 추정 위치 오차를 얻으며, 추정 오차가 0이 되도록 추정기를 구성하여 이를 실험을 통해 검증하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.199-205
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• 2015

Indoor positioning technology has been developed very actively for the smart phone handheld by most users. Especially, many TDOA positioning systems using acoustic signal have been studied, and it estimates the smart phone position by measuring the distance between the smart phone speaker and the microphones which is installed to receive the acoustic signal from the smart phone, and by calculating the hyperbolic equations. But there are always errors for the distance measurements, and furthermore the microphone installation error produces huge position estimation error. In this paper, the position estimation error due to the position error of acoustic sensor in the 3 dimensional TDOA positioning system, is analyzed by PDOP simulation and experiment.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.2
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• pp.178-185
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• 2011

In this paper, we propose the position estimation algorithm based on the multisensor fusion using equalization of state variables and feedback structure. First, the state variables measured from INS of main sensor with large error and DVL of assistance sensor with small error are measured before prediction phase. Next, the equalized state variables are entered to each filter and fused the enhanced state variables for prediction and update phases. Finally, the fused state variables are returned to the main sensor for improving the position estimation of UUV. For evaluation, we create the moving course of UUV by simulation and confirm the performance of position estimation by applying the proposed algorithm. The evaluation results show that the proposed algorithm is the best for position estimation and also possible for robust position estimation at the change period of moving courses.

• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.173-178
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• 2008

확률도시위치는 주로 도시적 해석을 통한 연최대홍수량 또는 연최대강우량의 초과확률의 추정치 산정에 사용되며 빈도해석을 통해 선정된 적정 확률분포형과 표본자료의 개략적인 적합도를 도시적으로 파악할 수 있도록 해주기 때문에 오래 전부터 널리 이용되어 왔다. 본 연구에서는 Gumbel 분포에 적합한 도시위치공식을 새롭게 추정하기 위해 Gumbel 분포의 order statistic과 확률가중모멘트를 이용하여 다양한 표본크기에 대한 도시위치공식의 기본식을 유도하였고, 최적화 기법 중 하나인 유전자 알고리즘을 이용하여 유도된 도시위치공식의 매개변수를 추정하였다. 또한 본 연구에서 추정된 도시위치공식과 기존에 널리 사용되고 있는 도시 치공식의 정확도를 비교하기 위해 reduced variate 간의 오차를 계산하여 비교 검토하였다. 그 결과, 금회 추정된 도시위치공식은 높은 순위에서는 기존의 도시위치공식에 비해 더 정확도가 높은 것으로 나타났고, 표본크기에 대한 순위를 모두 고려할 경우에는 기존의 도시위치공식에 비해 정확도가 높은 것으로 나타나 Gumbel 분포에 대해서 높은 정확도를 보이는 것으로 나타났다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2745-2752
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• 2014

In recent years, Transport Demand Management has been conducted for the efficient management of transport. In ITS applications in particular, the prerequisite is accurate and reliable positioning. However, the major problems are satellite signal outage, and multipath. This paper proposes that outage and multipath measurement can be detected and estimated using elevation angle and signal to noise ratio data association relation in stand-alone GPS. In order to verify the performance of the proposed method, it is then evaluated by the car test. the evaluation test environment has low accuracy and unreliable positioning because of signal outage or multipath such as steep hill and high buildings. In the evaluation test result, 918times abnormal signal occurred and it was confirmed that the proposed method showed more improved 9.48m(RMS) horizontal positioning error than without proposed method.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.447-448
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• 2017

본 논문은 위치 제어 시스템의 기계 제정수 추정 알고리즘을 제안한다. 추정 대상 제정수는 관성모멘트와 점성 마찰계수, 쿨롱 마찰계수이다. 제정수 추정에 대한 오차를 줄이기 위해, 적분 연산과 정현파의 위치 명령을 사용하였다. 시뮬레이션 및 실험을 통하여 이의 유효성을 입증하였다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.341-342
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• 2015

본 논문에서는 파라미터 오차 보상을 통한 3상 BLDC 전동기의 DC 전류 모델 기반의 센서리스 제어 방식을 제안한다. 기존의 DC 전류 모델 기반의 센서리스 제어 방식은 상 전환 구간마다 발생하는 실제 전류와 모델 전류의 오차로 인해 추정한 역기전력과 속도, 위치에 오차가 그대로 나타난다. 이 오차 성분을 줄이기 위해 본 논문에서는 기계 방정식을 이용하여 개선된 역기전력 추정 식을 제안하였다. 또한 개선된 역기전력 추정 식에 파라미터에 오차가 없다면 센서리스 제어가 가능하지만, 오차가 존재한다면 센서리스 제어가 불안정해진다. 이를 극복하기 위한 파라미터 오차 보상 알고리즘도 제안하였다. 제안한 방법은 시뮬레이션을 통해 검증하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.104-111
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• 2018

The sensorless control of high efficiency air compressors using a permanent magnet type synchronous motor as an oil-free air compressor is quite common. However, due to the nature of the air compressor, it is difficult to install a position sensor. In order to control the permanent magnet type synchronous motor at variable speed, the inclusion of a position sensor to grasp the position of the rotor is essential. Therefore, in order to achieve sensorless control, it is essential to use a permanent magnet type synchronous motor in the compressor. The position estimation method based on the back electromotive force, which is widely used as the sensorless control method, has a limitation in that position errors occur due either to the phase delay caused by the use of a stationary coordinate system or to the estimated back electromotive force in the transient state caused by the use of a synchronous coordinate system. Therefore, in this paper, we propose a method of estimating the position and velocity using a rotation angle tracking observer and reducing the speed ripple through a disturbance observer. An experimental apparatus was constructed using Freescale's MPU and the feasibility of the proposed algorithm was examined. It was confirmed that even if a position error occurs at a certain point in time, the position correction value converges to the actual vector position when the position error value is found.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2D
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• pp.319-327
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• 2009

In order to estimate accurate position by GPS observations, it is prerequisite to define both of the correct function model and the realistic stochastic model. In the case that un-modeled outliers exist in observations, estimates become biased, and their standard deviations are unable to be used as a measure which represents their accuracy. Hence, such outliers should be appropriately removed from the observations before estimating final solutions, so that the accuracy can be maximized with the improvement of the reliability. For this purpose, this research deals with quality control and quality measure computation algorithms for GPS stand-alone positioning. After theoretical studies, all the algorithms have been implemented and tested with real observations. Results of the tests indicate that the reliability of the estimated position is improved by increasing redundancy as well as using good satellite geometry and more realistic stochastic model. Moreover, the adaptation of the quality control procedure enable to improve positioning reliability and accuracy by appropriately excluding outlier in observations.