• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.305-310
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• 1991

In industrial multivariable plants, it is often the case that the plant outputs are detected in a similar components not simultaneously but serially. In this paper, the problem of estimating the state vector of the plant based on the data obtained from such a detecting scheme is considered, and a special type of observer (referred to as a "multiple serial-sampling" type observer) which renews its internal states whenever a new group of data is obtained is proposed. It is proved that such an observer can be constructed for almost every sampling period if the plant is observable as a continuous-time multivariable system, and that the poles of the closed-loop system using the serial-sampling type observer consist of the poles of the observer and those of the state feedback system. The behaviors of the observer and the closed-loop system are studied by simulation. The results of simulation indicate that a multiple serial-sampling type observer can estimate the state of the plant more accurately than the ordinary type observers and improve the closed-loop performance, especially, in the existence of dectecting noise.ing noise.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.39-44
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• 2003

It was shown that the robustness of deterministic observers with respect to modeling errors, measurement bias and round-off errors can be represented by a single performance index the condition number of the observer eigenvector matrix. In this paper, a robust observer for multi-output systems is designed using the left eigenstructure assignment, where the observer gain can not be determined uniquely with respect to the desired observer poles. Utilizing the eigenstructuer assignment for the robustness of the observer, the desired eigenvector matrix is selected to achieve the observer eigenvector matrix with the small condition number. The performance of the designed robust observer is evaluated in a spindle-drive simulation example where the load speed to be estimated based on the measured signals.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.338-339
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• 2018

최근 분산전원 시스템 개발로 인해 계통연계 인버터의 사용이 증가해 왔다. 계통연계 인버터의 주요한 역할은 계통연계 환경에서의 안정적인 운전과 계통 사고 시 중요 부하에 대한 연속적인 전력을 공급하기 위한 독립운전에 있다. 각 모드 전환시의 출력전압의 변동성과 과도응답 특성을 개선하기 위해 최근 다중 루프 및 간접 전류 제어 방식이 계통연계 인버터에 적용되었다. 하지만 이러한 제어 방식은 캐패시터 전압 및 인버터 전류의 측정이 요구되어 시스템의 비용 및 복잡성을 증가시키게 된다. 본 논문에서는 이산시간 상태공간에서의 전상태 관측기를 설계하여 무순단 절체 동작 시 제어기가 요구하는 변수를 추정하고 이를 궤환신호로 사용하여 시스템의 설계 비용 및 복잡성을 줄인다. 또한 계통연계 시 계통유입 고조파 전류를 억제하기 위해 일반적으로 사용되는 기존 공진형 제어기의 과도 응답을 개선하기 위해 이산시간에서 슬라이딩 모드와 공진제어기가 결합된 새로운 제어기 구조를 제안한다. 제안된 기법의 타당성은 PSIM 시뮬레이션을 통하여 입증된다.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.4
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• pp.271-278
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• 2005

In this paper, we present an adaptive observer for multi-output nonlinear systems that include unknown constant parameters and are not necessarily observable. Based on generalized nonlinear observer canonical form, new adaptive observer canonical form is proposed. Sufficient conditions are given for a nonlinear system to be transformed into the proposed adaptive observer canonical form. The existence of the proposed adaptive observer is given in terms of Lyapunov-like condition and SPR condition. An illustrative example is presented to show the design procedure of the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.233-240
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• 2005

In this paper, we have shown the gain recovery time of erbium-doped fiber amplifier(EDFA) in WDM add/drop networks can be reduced to less than $3\mu$sec by employing disturbance observer technique with PID controller which is based on 3-level EBFA model. The $3\mu$sec transient time is the fastest one ever reported and it is about $1\%$ of $250\mu$sec previously obtained from disturbance observer technique with PI controller which was based on 2-level EDFA model and it is also less than $200\mu$sec of commercially available EDFAs for WDM networks. We were able to obtain this result by analyzing various system characteristics as we change the parameters of disturbance observer and PID controller. If this result is applied to a commercial product, the product will do an important role in the future dynamic WDM networks.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.167-168
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• 2011

한반도 및 근해의 지진 지진해일 감시를 위해 지진관측망이 구축되어 있다. 이러한 지진관측망는 향후 조기경보를 위해 보다 조밀하게 설치될 예정이다. 지진계측기의 정보통신망은 대부분 행정망 및 전용회선 단일망으로 운영되고 있으며 지진계측기의 전력체계는 상용전원의 단일 전력체계로 운영되고 있다. 국내 지진관측망 운영상의 문제점으로 단일 정보통신망 운영으로 인한 통신 단절 발생 시 지속적인 자료 수집 불능과 단일 전력체계인 상용전원 단절시 통신장비에 전원공급 단절로 인한 실시간 자료 전송 장애 발생이 있다. 또한 지진관측기의 정보통신망과 전력체계에 대한 원격감시 및 관리 기능이 부재하여 유지 보수 및 안정적 자료수집에 취약점을 가지고 있다. 이러한 취약점을 극복하기 위해서는 각종 재해에 대한 내재해성과 유지보수성을 향상시키는 것이 시급하며 정보통신망과 전력체계의 다중화/이중화가 좋은 대안이 될 수 있다.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.59-70
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• 2022

In this paper, we proposed an active fault tolerant control (AFTC) method for the position control of a quadrotor with complete loss of effectiveness of one motor. We obtained the dynamics of a quadrotor using Lagrangian equation without small angle assumption. For detecting the fault on a motor, we designed a fault detection module, which consists of the fault detection and diagnosis (FDD) module and the fault detection and isolation (FDI) module. For the FDD module, we designed a nonlinear observer that observes the states of a quadrotor based on the obtained dynamics. Using the observed states of a quadrotor, we designed residual signals and set the appropriate threshold values of residual signals to detect the fault. Also, we designed an FDI module to identify the fault location using the designed additional conditions. To make a quadrotor track the desired path after detecting the fault of a motor, we designed a fault tolerant controller based on the multiple sliding surface control (MSSC) technique. Finally, through simulations, we verified the effectiveness of the proposed AFTC method for a quadrotor with complete loss of effectiveness of one motor.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.2
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• pp.215-221
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• 2006

This paper is concerned with the control of multiple nonlinearities included in a humanoid robot system. A humanoid robot has some problems such as the structural instability, which leads to consider the control of multiple nonlinearities caused by driver parts as well as gear reducer. Saturation and backlash are typical examples of nonlinearities in the system. The conventional algorithms of backlash control were fuzzy algorithm, disturbance observer and neural network, etc. However, it is not easy to control the system by employing only single algorithm since the system usually includes multiple nonlinearities. In this paper, a switching Pill is considered for a control of saturation and a dual feedback algorithm is proposed for a backlash control. To implement the above algorithms, the system identification is firstly performed for the minimization of the difference between the results of simulation and experiment, and then the switching Pill gains are determined using genetic algorithm with some heuristic approach. The performance of the switching Pill controller for saturation and the dual feedback for backlash control is investigated through the simulation. Finally, it is shown that the implemented control system has good results and can be applied to the real humanoid robot system ISHURO.