• Computers and Concrete
• /
• 제15권5호
• /
• pp.771-794
• /
• 2015

This paper proposes an innovative method for selection of measurement sets in static parameter identification of concrete or steel bridges. This method is proved as a systematic tool to address the first steps of Structural System Identification procedures by observability techniques: the selection of adequate measurement sets. The observability trees show graphically how the unknown estimates are successively calculated throughout the recursive process of the observability analysis. The observability trees can be proved as an intuitive and powerful tool for measurement selection in beam bridges that can also be applied in complex structures, such as cable-stayed bridges. Nevertheless, in these structures, the strong link among structural parameters advises to assume a set of simplifications to increase the tree intuitiveness. In addition, a set of guidelines are provided to facilitate the representation of the observability trees in this kind of structures. These guidelines are applied in bridges of growing complexity to explain how the characteristics of the geometry of the structure (e.g. deck inclination, type of pylon-deck connection, or the existence of stay cables) affect the observability trees. The importance of the observability trees is justified by a statistical analysis of measurement sets randomly selected. This study shows that, in the analyzed structure, the probability of selecting an adequate measurement set with a minimum number of measurements at random is practically negligible. Furthermore, even bigger measurement sets might not provide adequate SSI of the unknown parameters. Finally, to show the potential of the observability trees, a large-scale concrete cable-stayed bridge is also analyzed. The comparison with the number of measurements required in the literature shows again the advantages of using the proposed method.

• 전자공학회논문지
• /
• 제50권1호
• /
• pp.276-284
• /
• 2013

본 논문에서는 관성항법시스템의 전달정렬시 속도정합 알고리듬에 대하여 지렛대 거리 오차의 가관측성 분석을 수행하였다. 이를 위해 지렛대 거리 오차를 포함한 칼만필터 상태 변수를 모델링하였고 측정 방정식을 구성하였다. 가관측성 분석 방법으로는 SOM을 이용하였고 다양한 항체의 운항 조건들에 대하여 가관측성 분석을 수행하였다. 기존의 지렛대 거리 오차를 포함한 가관측성 분석 기법들은 시뮬레이션을 통한 분석이 주를 이룬 반면에 본 논문에서는 상태 변수들이 완전 가관측하기 위한 항체의 운항 조건을 해석적으로 제시하였다. 그리고 시뮬레이션을 수행하여 분석 결과를 검증하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
• /
• pp.957-962
• /
• 1990

A method to determine nonlinear system observability will be introduced here. For the determination of the deterministic nonlinear system observability two conditions connectedness and univalence, are developed and used. Depending on how the conditions are satisfied, observability is classified in three categories : observability in the strict sense, wide sense, and the unobservable case. Including simple linear and nonlinear system example an underwater acoustical locaization tracking nonlinear system, the bearing-only tracking example is analyzed.

• 대한전기학회논문지
• /
• 제36권11호
• /
• pp.769-776
• /
• 1987

This paper deals with the topological observability analysis and the development of an observable island identification algorithm for state estimation in power systems, by using the incidence matrix and bus voltage grouping. An analogy of the DC power flow method to the DC circuit analysis is introduced, and all the relationships between power flows and phase angles are replaced by the corresponding current-voltage relation. As a result, a set of topological measurement equation expressed in the form of the incidince matrix is derived for the topological analysis, and the observability test is carried out by examining the rand of the measuremint matrix. The integer Gauss elimination method is introduced in the determination of matrix rand, so that the proposed observability test yields a precise observability criterion without any nearly-zero pivot problem encountered in the conventional algorithm. Also, an observable island identification algorithm reduced its computational time in comparision with the conventional algorithms. The proposed algorithms have been tested for sample systems, and their practicability has verified.

• 한국음향학회지
• /
• 제18권6호
• /
• pp.9-16
• /
• 1999

이 논문은 측정잡음이 큰 수동소나체계의 각도정보만을 이용한 표적기동분석(TMA ; Target Motion Analysis) 기법 연구의 일환으로서 표적의 상태변수를 추정하는 순차적 추정자로 수정이득확장칼만필터(MGEKF : Modified Gain Extended Kalman Filter)를 사용하며, 이 MGEKF의 초기화를 위해 비선형 batch estimation 알고리듬을 제안한다. 수동표적추적 시스템의 가관측성(observability) 해석을 바탕으로 시스템의 가관측성의 향상을 통해 TMA 성능을 개선시킬 수 있는 관측자의 기동을 결정하는 실용적이면서도 효과적인 방법을 제안한다. 또한 가관측성 확보가 어려운 초기단계의 TMA를 위해 관측자의 진행방향과 표적의 각도정보와 같은 기하학적 자료와 시스템의 가관측성과의 관계를 나타내는 engagement boundary를 산출하여 가관측성이 큰 기하학적 관계를 갖는 위치로 관측자를 선기동(pre-maneuver) 시키는 방법도 제시한다. 제시하는 TMA 기법의 성능을 시뮬레이션을 통해 입증한다.

• 대한전기학회논문지:전력기술부문A
• /
• 제49권7호
• /
• pp.313-322
• /
• 2000

This paper presents optimal placement of minimal set of Phasor Measurement Units (PMU's) and observability analysis of the network with PMU's. In order to find a observable system, a symbolic method which directly assigns an appropriate symbol for measurement or pseudo-measurement to every entry of node-branch incidence matrix is proposed. It is much simpler and easier to analyze the observability of the network with PMU's than the conventional ones. For the optimal PMU placement problem, two approaches which are based on a modified Simulated-Annealing (SA) method and a Direct Combination method are proposed. Some case studies with IEEE sample system are made to show the performance of the proposed methods are almost alike and more effective than the conventional simulated-annealing method. It is also shown that the Direct Combination method is more effective than the modified simulated-annealing one in the sense of computation burden. The results of this study showed also that the accuracy of power system estimation and system observability can be improved the proposed PMU placements.

• Journal of Electrical Engineering and Technology
• /
• 제10권2호
• /
• pp.474-486
• /
• 2015

This paper proposes a multi-objective optimal placement method of Phasor Measurement Units (PMUs) in large electric transmission systems. It is proposed for minimizing the number of PMUs for complete system observability and maximizing measurement redundancy of the buses, simultaneously. The measurement redundancy of the bus indicates that number of times a bus is able to monitor more than once by PMUs set. A high level of measurement redundancy can maximize the system observability and it is required for a reliable power system state estimation. Therefore, simultaneous optimizations of the two conflicting objectives are performed using a binary coded firefly algorithm. The complete observability of the power system is first prepared and then, single line loss contingency condition is added to the main model. The practical measurement limitation of PMUs is also considered. The efficiency of the proposed method is validated on IEEE 14, 30, 57 and 118 bus test systems and a real and large- scale Polish 2383 bus system. The valuable approach of firefly algorithm is demonstrated in finding the optimal number of PMUs and their locations by comparing its performance with earlier works.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제4권1호
• /
• pp.1-6
• /
• 2004

This paper deals with a balanced model reduction for T-S(Takagi-Sugeno) fuzzy systems with time varying state delay. We define a generalized controllability gramian and a generalized observability gramian for a stable T-S fuzzy delayed systems. We obtain a balanced state space realization using the generalized controllability and observability gramian and obtain a reduced model by truncating states from the balanced state space realization. We also present an upper bound of the approximation error. The generalized controllability gramian and observability gramian can be computed from solutions of linear matrix inequalities. We demonstrate the efficacy of the suggested method by illustrating a numerical example.

• 대한기계학회논문집A
• /
• 제29권6호
• /
• pp.795-803
• /
• 2005

This paper studies the observability of calibration system with a measurement operator. The calibration system needs a simple digital indicator to measure the mobile table movements with respect to the MC coordinate. However, it yields the concern about the poor parameter observability due to measuring only a part of the movements. We uses the QR-decomposition to find the optimal calibration configurations maximizing the linear independence of rows of an observation matrix. The number of identifiable parameter is examined by the rank of the observation matrix, which represents the parameter observability. The method is applied to a 6-axis MC with parallel tilting table and the calibration results are presented. These results verify that all necessary kinematic parameters are observable and the calibration system has robustness to the noise using optimal calibration configurations.

• 대한기계학회논문집A
• /
• 제27권4호
• /
• pp.647-655
• /
• 2003

This paper studies the observability of calibration system with a constraint movement by a constraint operator. The calibration system with the constraint movement need only simple sensing device to check whether the constraint movements are completed within an established range. However, it yields the concern about the poor parameter observability due to the constraint movements. This paper uses the QR-decomposition to find the optimal calibration configurations maximizing the linear independence of rows of a observation matrix. The number of identifiable parameters are examined by the rank of the observation matrix, which represents the parameter observability. The method is applied to a parallel typed machining center and the calibration results are presented. These results verify that the calibration system with low-cost indicators and simple planar table is accurate as well as reliable.