• Journal of Power Electronics
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• 제14권5호
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• pp.1038-1046
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• 2014

Lithium-ion batteries are widely used in hybrid and pure electric vehicles. State-of-charge (SOC) estimation is a fundamental issue in vehicle power train control and battery management systems. This study proposes a novel model-based SOC estimation method that applies closed-loop state observer theory and a comprehensive battery model. The state-space model of lithium-ion battery is developed based on a three-order resistor-capacitor equivalent circuit model. The least square algorithm is used to identify model parameters. A multi-state closed-loop state observer is designed to predict the open-circuit voltage (OCV) of a battery based on the battery state-space model. Battery SOC can then be estimated based on the corresponding relationship between battery OCV and SOC. Finally, practical driving tests that use two types of typical driving cycle are performed to verify the proposed SOC estimation method. Test results prove that the proposed estimation method is reasonably accurate and exhibits accuracy in estimating SOC within 2% under different driving cycles.

• 제어로봇시스템학회논문지
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• 제20권2호
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• pp.170-174
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• 2014

In this paper, an unknown input estimation method via the optimal FIR smoother is proposed for linear discrete-time systems. The unknown inputs are represented by random walk processes and treated as auxiliary states in augmented state space models. In order to estimate augmented states which include unknown inputs, the optimal FIR smoother is applied to the augmented state space model. Since the optimal FIR smoother is unbiased and independent of any a priori information of the augmented state, the estimates of each unknown input are independent of the initial state and of other unknown inputs. Moreover, the proposed method can be applied to stochastic singular systems, since the optimal FIR smoother is derived without the assumption that the system matrix is nonsingular. A numerical example is given to show the performance of the proposed estimation method.

• 한국통신학회논문지
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• 제13권6호
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• pp.510-520
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• 1988

無限誤長 상태 공간 디지틀 필터를 有限誤長 상태 공간 디지틀 필터로 실현할 때 量子化 誤差인 상태 공간 계수〔ABCD〕의 미소 변동에 기인한, 출력 오차 分散을 $\Delta$〔ABCD〕의 分散으로 正規化하였다. 즉, S=E을 統計的 感度로 정의하고 시스템 구조적 성질을 나타내는 可制御性 Gramian, 그리고 2차 모드 해석 방법을 상태 공간 디지틀 필터에 확장해서 最小 統計的 感度를 갖는 실현 구조를 합성하였으며 시뮬레이션을 통하여 최소 구조 합성의 유효성을 확인하였다.

• 한국정보처리학회논문지
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• 제2권1호
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• pp.119-129
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• 1995

본 논문에서는 분산 실시간 프로그램의 스케줄가능성 분석 방법을 제안한다. 스케 줄가능성 분석을 위한 여러 가지 방법이 개발되었지만, 이 방법들은 가능한 모든 상 태공간을 추적하거나 고정 우선순위 스케줄 방법을 사용했기 때문에 지수적인 시간 과 공간의 복잡성을 야기한다. 따라서 상태 공간을 줄여서 더 이른 시간단위에서 스케 줄가능성을 조사하는 방법이 필요하다. 본 논문에서 제시한 스케줄가능성 분석 방법은 번역시간에 결정될 수 있는 프로세스들의 최대 수행시간, 주기, 마감시간, 동기화 시 간을 고려하여 동기화 동작 이후에 남는 계산시간과 마감시간의 차이를 계산하여 실시 간 프로세스가 마감시간을 지키는가를 판단하는 새로운 알고리즘을 제안하고, 실험을 통하여 그 성능을 평가한다. 실험에 의하여 Fredette의 방법과 비교하면 약 50퍼센트 정도 더 이른 단위시간에 스케줄이 불가능함을 판단할 수 있다.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2007년도 한국음성과학회 공동학술대회 발표논문집
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• pp.29-32
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• 2007

This paper describes a multimodal dialog system that uses Hidden Information State (HIS) method to manage the human-machine dialog. HIS dialog manager is a variation of classic partially observable Markov decision process (POMDP), which provides one of the stochastic dialog modeling frameworks. Because dialog modeling using conventional POMDP requires very large size of state space, it has been hard to apply POMDP to the real domain of dialog system. In HIS dialog manager, system groups the belief states to reduce the size of state space, so that HIS dialog manager can be used in real world domain of dialog system. We adapted this HIS method to Smart-home domain multimodal dialog system.

• 한국환경과학회지
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• 제4권1호
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• pp.71-80
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• 1995

생화학적 산소요구량(BOD) 및 용존 산소(DO)을 이용하여 여러구간이 있는 강에 대한 이산 상태공간모델은 설정하였다. 상호작용 예측방법을 이용하여, 상태변수에 시간지연이 존재하는 대규모 시스템에 적용가능한 계층적 최적화 방법을 기술하였다. 정상상태 오차를 해석적으로 구하고, 상수 목표티 추적문제에 있어서 정상상태 오차가 발생하지 않을 필요충분조겆을 규명하였다. 수질오염 모델에 대한 컴퓨터 모사를 통하여 기술한 알고리듬의 타당성을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.408-411
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• 1995

In this paper, we discuss the force control of flexible manipulators. Since the force control of flexible manipulators with planar one or two links using the distributed-parameter modeling has been the subject of a considerable number of publications until now, real time computations of the force control schemes are possible. But, application of those control schemes to multi-link spatial manipulators is fairly complicated. In this paper, we apply a concise hybrid position/force control scheme for a flexible manipulators. We use a lumped-parameter modeling for the flexible manipulators. The Hamilton's principle is applied to derive the equations of motion for the system and then, state-space model is obtained by the Lagrange's method. Finally, comparison of simulation results with experimental results is given to show the performance of our method.

• 대한기계학회논문집A
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• 제24권2호
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• pp.290-302
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• 2000

In this paper, we study on the identification of discrete-time state-space model for robust control of tandem cold mill, using a MOESP(MIMO output-error state-space model identification) algorithm based on subspace method. It is shown that the identified model is well adapted to input-output data sets, which are obtained from nonlinear mathematical equations of tandem cold mill. Furthermore, deterministic H$\infty$ norm bounds on uncertainties including modeling errors and disturbances are quantitatively identified in the frequency domain. Finally, the results give a basic idea to determine weighting functions included in formulating some robust control problems of tandem cold mill.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.560-573
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• 2015

In this paper, a battery charger is introduced for an interleaved DC-DC converter with an LCLC filter. To improve the overall performance of the DC-DC converter for battery charger, a method is proposed. First, the structure of the system is presented. Second, an LC filter is compared to an LCLC filter in terms of the response characteristics and size. Third, the small-signal model of a bidirectional DC-DC converter using a state-space averaging method and the required transfer functions are introduced. Next, the frequency characteristics of the converter are discussed. Finally, the simulation and experimental results are analyzed to verify the proposed state space of the bidirectional converter.

• Structural Monitoring and Maintenance
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• 제1권4호
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• pp.427-449
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• 2014

A hybrid optimization method for the identification of state-space models is presented in this study. Hybridization is succeeded by combining the advantages of deterministic and stochastic algorithms in a superior scheme that promises faster convergence rate and reliability in the search for the global optimum. The proposed hybrid algorithm is developed by replacing the original stochastic mutation operator of Evolution Strategies (ES) by the Levenberg-Marquardt (LM) quasi-Newton algorithm. This substitution results in a scheme where the entire population cloud is involved in the search for the global optimum, while single individuals are involved in the local search, undertaken by the LM method. The novel hybrid identification framework is assessed through the Monte Carlo analysis of a simulated system and an experimental case study on a shear frame structure. Comparisons to subspace identification, as well as to conventional, self-adaptive ES provide significant indication of superior performance.