• 제목/요약/키워드: error filter

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칼만필터의 자료동화 활용을 위한 배경오차 공분산의 명시적 시간 진전 제거 (An Affordable Implementation of Kalman Filter by Eliminating the Explicit Temporal Evolution of the Background Error Covariance Matrix)

  • 임규호;서애숙;하지현
    • 대기
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    • 제23권1호
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    • pp.33-37
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    • 2013
  • In meteorology, exploitation of Kalman filter as a data assimilation system is virtually impossible due to simultaneous requirements of adjoint model and large computer resource. The other substitute of utilizing ensemble Kalman filter is only affordable by compensating an enormous usage of computing resource. Furthermore, the latter employs ensemble integration sets for evolving the background error covariance matrix by compensating the dynamical feature of the temporal evolution of weather conditions. We propose a new implementation method that works without the adjoint model by utilizing the explicit expression of the background error covariance matrix in backward evolution. It will also break a barrier in the evolution of the covariance matrix. The method may be applied with a slight modification to the real time assimilation or the retrospective analysis.

강결합 기법을 이용한 WNS/GPS 결합 시스템 (WNS/GPS Integrated System Using Tightly Coupled Method)

  • 조성윤;박찬국
    • 제어로봇시스템학회논문지
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    • 제8권12호
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    • pp.1067-1075
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    • 2002
  • The system error model for the compensation of the low-cost personal navigation system is derived and the error compensation method using GPS is also proposed. The walking navigation system (WNS) that calculates navigation information through walking detection has small error than INS, but the error also increases with time. In order to improve reliability of the system regardless of time, WNS is integrated with GPS. Since WNS is usually used in urban area, the blockage of CPS signal is frequently occurred. Therefore tightly coupled Kalman filter is used for the integration of WNS and GPS. In this paper, the system model for the design of tightly coupled Kかm filter is designed and measurement is linearized in consideration of moving distance error. It is shown by Monte Carlo simulation that the error is bounded even through the number of visible satellite is less than 4.

오일러각 정합방식의 전달정렬 칼만필터 설계 (The Kalman Filter Design for the Transfer Alignment by Euler Angle Matching)

  • 송기원;이상정
    • 제어로봇시스템학회논문지
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    • 제7권12호
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    • pp.1044-1050
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    • 2001
  • This paper presents firstly the method of Euler angle matching designing the transfer alignment using the attitude matching. In this method, the observation directly uses Euler angle difference between MINS and SINS so it needs to describe the rotation vector error to the Euler angle error. The rotation vector error related to the Euler angle error is derive from the direction cosine matrix error equation. The feasibility of the Kalman filter designed for the transfer alignment by Euler angle matching is analyzed by the alignment error results with respect to the roll angle the pitch angle, and the yaw angle matching.

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모델링 불확실성을 갖는 이산구조 비선형 시스템을 위한 유한 임펄스 응답 고정구간 스무딩 필터 및 DR/GPS 결합항법 시스템에 적용 (FIR Fixed-Interval Smoothing Filter for Discrete Nonlinear System with Modeling Uncertainty and Its Application to DR/GPS Integrated Navigation System)

  • 조성윤;김경호
    • 제어로봇시스템학회논문지
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    • 제19권5호
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    • pp.481-487
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    • 2013
  • This paper presents an FIR (Finite Impulse Response) fixed-interval smoothing filter for fast and exact estimating state variables of a discrete nonlinear system with modeling uncertainty. Conventional IIR (Infinite Impulse Response) filter and smoothing filter can estimate state variables of a system with an exact model when the system is observable. When there is an uncertainty in the system model, however, conventional IIR filter and smoothing filter may cause large errors because the filters cannot estimate the state variables corresponding to the uncertain model exactly. To solve this problem, FIR filters that have fast estimation properties and have robustness to the modeling uncertainty have been developed. However, there is time-delay estimation phenomenon in the FIR filter. The FIR smoothing filter proposed in this paper makes up for the drawbacks of the IIR filter, IIR smoothing filter, and FIR filter. Therefore, the FIR smoothing filter has good estimation performance irrespective of modeling uncertainty. The proposed FIR smoothing filter is applied to the integrated navigation system composed of a magnetic compass based DR (Dead Reckoning) and a GPS (Global Positioning System) receiver. Even when the magnetic compass error that changes largely as the surrounding magnetic field is modeled as a random constant, it is shown that the FIR smoothing filter can estimate the varying magnetic compass error fast and exactly with simulation results.

An Extended Scalar Adaptive Filter for Mitigating Sudden Abnormal Signals of Guided Missile

  • Lim, Jun-Kyu;Park, Chan-Gook
    • International Journal of Aeronautical and Space Sciences
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    • 제12권1호
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    • pp.37-42
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    • 2011
  • An extended scalar adaptive filter for guided missiles using a global positioning system receiver is presented. A conventional scalar adaptive filter is adequate filter for eliminating sudden abnormal jumping measurements. However, if missile or vehicle velocities have variation, the conventional filter cannot eliminate abnormal measurements. The proposed filter utilizes an acceleration term, which is an improvement not used in previous conventional scalar adaptive filters. The proposed filter continuously estimates noise measurement variance, velocity error variance and acceleration error variance. For estimating the three variances, an innovation method was used in combination with the least square method for the three variances. Results from the simulations indicated that the proposed filter exhibited better position accuracy than the conventional scalar adaptive filter.

오프라인 항법을 위한 비선형 고정구간 스무더 설계 (Design of Nonlinear Fixed-interval Smoother for Off-line Navigation)

  • 유재종;이장규;박찬국;한형석
    • 제어로봇시스템학회논문지
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    • 제8권11호
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    • pp.984-990
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    • 2002
  • We propose a new type of nonlinear fixed interval smoother to which an existing nonlinear smoother is modified. The nonlinear smoother is derived from two-filter formulas. For the backward filter. the propagation and the update equation of error states are derived. In particular, the modified update equation of the backward filter uses the estimated error terms from the forward filter. Data fusion algorithm, which combines the forward filter result and the backward filter result, is altered into the compatible form with the new type of the backward filter. The proposed algorithm is more efficient than the existing one because propagation in backward filter is very simple from the implementation point of view. We apply the proposed nonlinear smoothing algorithm to off-line navigation system and show the proposed algorithm estimates position, and altitude fairly well through the computer simulation.

INS/GPS 통합 항법 시스템의 위치 오차 개선을 위한 IMM 필터 설계 (A Design of the IMM Filter for Improving Position Error of the INS / GPS Integrated System)

  • 백승준
    • 한국항행학회논문지
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    • 제23권3호
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    • pp.221-227
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    • 2019
  • 본 논문에서는 위성 항법 해를 이용하여 INS의 순수항법을 보상하는 INS / GPS 통합 항법 알고리즘을 구성할 때 불안정한 위성 항법 위치 해 출력에도 안정적인 항법 성능을 보장할 수 있는 IMM (interacting multiple model)필터를 설계하였다. INS / GPS 통합 항법 시스템 구조 내에 칼만필터를 서브 필터로 하는 IMM 필터 구조를 정의하였다. IMM필터 구성시 서브필터는 2개로 구성하였으며, 각각의 칼만필터는 INS의 오차 방정식으로부터 위치, 속도, 자세, 센서 오차 등으로 구성한 16차의 상태를 정의하고 추가로 위성항법의 유색 잡음(coloured measurement noise)영향으로 2차를 확장하였다. 제안한 IMM 필터의 성능을 확인하기위해 위성 항법에 임의의 오차를 위도와 경도에 삽입하고 필터의 추종성을 확인하는 것으로 성능을 비교 분석하였다. 몬테카를로 시뮬레이션을 100회 수행하여 결과를 RMS로 비교한 결과 제안한 필터 방식이 오차에 대해 안정적이며 빠른 수렴결과를 보이고 있음을 확인할 수 있었다.

큰 초기 자세 오차를 가진 관성항법장치의 운항중 정렬을 위한 비선형 필터 연구 (Nonlinear Filtering Approaches to In-flight Alignment of SDINS with Large Initial Attitude Error)

  • 유해성;최상욱;이상정
    • 제어로봇시스템학회논문지
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    • 제20권4호
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    • pp.468-473
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    • 2014
  • This paper describes the in-flight alignment of SDINS (Strapdown Inertial Navigation Systems) using an EKF (Extended Kalman Filter) and a UKF (Unscented Kalam Filter), which allow large initial attitude error uncertainty. Regardless of the inertial sensors, there are nonlinear error dynamics of SDINS in cases of large initial attitude errors. A UKF that is one of the nonlinear filtering approaches for IFA (In-Flight Alignment) are used to estimate the attitude errors. Even though the EKF linearized model makes velocity errors when predicting incorrectly in case of large attitude errors, a UKF can represent correctly the velocity errors variations of attitude errors with nonlinear attitude error components. Simulation results and analyses show that a UKF works well to handle large initial attitude errors of SDINS and the alignment error attitude estimation performance are quite improved.

최소계수 양자화 오차를 갖는 2차 디지틀 필터의 설계 (Design of the 2nd order Digital Filter with Minimum Coefficient Quatization Error)

  • 문용선;박종안
    • 한국통신학회논문지
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    • 제15권5호
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    • pp.364-373
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    • 1990
  • 디지틀 필터를 전용 하드웨어나 범용 계산기에 의해서 實現할 때 有限 語長 實現에 기인해서 量子化 誤差(演算, 誤差, 係數 量子化 誤差)가 필연적으로 발생하며, 또한 이러한 量子化 誤差의 最小化를 위한 等價 變換 行列이 연구되었다. 본 논문에서는 演算 誤差 最小 實現과 係數 量子化 誤差 最小 實現과의 상호 등가 변환할 수 있는 等價 變換行列을 유도하고 유도된 等價 變換 行列의 유효성을 나타내기 위해서 演算 誤差 最小型 2차 디지틀 필터로부터 係數 量子化 誤差 最小型 2차 디지틀 필터를 설계하고 시뮬레이션하였다.

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Order Statistic-Median Hybrid(OMH)필터 (Order Statistic-Median Hybrid(OMH) Filter)

  • 백수현;황유모;류동기
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1992년도 하계학술대회 논문집 A
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    • pp.434-436
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    • 1992
  • In this paper, we propose a new multilevel nonlinear filter for simultaneous edge detection and noise suppression, which we call a order statistic-median hybrid(OMH) filler. The median-related filters cause an edge shift in the presence of an impulse near the edge. The proposed filter reduces such edge shifting while suppressing impulsive as well as nonimpulsive noise. We show that at the noisy edge point the OMH filter is substantially superior to the median filter, the $\alpha$-TM filter and the STM filter[I] in two respects: (a) the output bias error and (b) the output mean square error. Test results confirm that the OMH filter is robust in preserving sharp edges, inhibiting edge shifting, and suppressing a wide variety of noise. The structure for the OMH filter integrated circuit is also described.

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