• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.115-124
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• 2001

In this paper, authors propose a new nonlinear rotor flux observer for rotor field oriented control of an induction motor which is designed based on the extended Luenberger Observer theory. Extended Luenberger Observer requires minimal solution of nonlinear partial differential equation on its coordinate transformation and linearization needed on a nonlinear observer design in general. The proposed rotor flux observer is derived from the 2 phase model of induction motor on the orthogonal coordination and it has the reduce gain matrix. Simulation and experimentation were performed under the conventional indirect vector control and direct vector control with the proposed observer at different rotor resistance. Simulation results show that the convergence of the proposed observer is influenced by the chosen eigenvalues. Experimentation results on load operation show the direct vector control with the proposed observer is better than the indirect vector control to maintain the characteristics of the vector control.

• Composites Research
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• v.28 no.6
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• pp.383-388
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• 2015

Ionic Polymer-Metal Composite (IPMC) consisting of soft membrane plated by platinum electrode layers on both surfaces generates electric energy when subjected to various mechanical stimuli. The paper proposes a circuit model that describes the physical composition of IPMC to predict the voltage generation characteristic corresponding to bending motion. The parameter values in the model are identified to minimize the RMS error between the real and simulated outputs. Following the design of IPMC circuit model, the state observer of the model is designed by using pole placement technique which improves the model accuracy. State observer design technique is also applied to find the inverse model which estimates the input bending angles from the output voltage data. The results show that the inverse model estimates input bending angles fairly well enough for the further applications of IPMC not only as an energy harvester but also as a bending sensor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1543-1549
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• 2012

This study focuses on the state space model and the design of a state observer for the slip dynamics between rolls in STS cold cluster mills. First, a mathematical model of the roll slip is given as a nonlinear differential equation. Then, by using a Taylor series expansion, it is linearized as a state space model. Next, by using Gopinath's algorithm, a minimal-order state observer based on the state space model is designed to estimate the angular speed of all idle rolls except for an actuated roll that is measureable. Finally, a computer simulation is used to validate that the proposed state space model very well describes slip dynamics between, and moreover, the state observer very well estimates the angular speed of the idle roll.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.2
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• pp.185-190
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• 2009

In this paper, an observer-based intelligent controller for the nonlinear networked control systems with packet loss is proposed for wireless sensor network. For the intelligent control of the nonlinear system, it uses the fuzzy system with Takagi-Sugeno (T-S) fuzzy model. The observer is designed for the fuzzy networked control system, and the output feedback controller is proposed for the stability of estimates and errors. The stability condition of the closed-loop system with the proposed controller is represented to the linear matrix inequality (LMI) form, and the observer and control gain are obtained by LMI. An example is given to show the verification discussed throughout the paper.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.183.1-183.1
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• 2005

• Journal of the Korean Society of Industry Convergence
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• v.7 no.2
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• pp.187-192
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• 2004

본 논문에서는 시간지연 제어기와 관측기를 사용하여 산업용 로봇을 위한 고속 제어 방법을 설계하였다. 설계된 방법은 로봇의 매개변수 변화나 비선형이 존재하는 상황에서도 강인한 제어성능을 보이게끔 개발되었으며, 실제구현을 하였을 때도 계산량이 적으면서 동시에 구현이 쉬운 방법이다. 평면 2 자유도 스카라 로봇의 적용을 통하여 실험을 하였는데, 그 결과 실제 시스템에 효과적으로 적용될 수 있음 확인하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.437-441
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• 1999

In this paper, a fault diagnosis method using unknown-input proportional integral (PI) observers including the magnitude of actuator failures is proposed. It is shown that actuator failures are detected and isolated perfectly by monitoring the integrated error between the actual output and the estimated output using an unknown-input PI observer. Also in presence of complex actuator and sensor failures, these failures are detected and isolated by multiple unknown-input PI observers perfectly.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.51-52
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• 2007

이 논문에서는 다중입출력 선형 시스템에 대한 외란 관측기설계 방법을 제안하고자 한다. 제안된 방법을 특이 섭동(Singular Perturbation) 이론을 사용하여 해석하며, 그 결과 Q 필터의 상수가 매우 작다면 외란 제거와 시스템 불확실성에 대한 보상을 통하여 실제 시스템을 공칭 시스템으로 근사화 시켜주는 것을 볼 수 있다.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.5
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• pp.360-368
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• 2008

A lumped parameter model of Li-ion battery in hybrid electric vehicle(HEV) is constructed and system parameters are identified by using recursive least square estimation for different C-rates, SOCs and temperatures. The system characteristics of pole and zero in the frequency domain are analyzed with the parameters obtained from different conditions. The parameterized model of a Li-ion battery indicates highly dependent of temperatures. To estimate SOC and polarization voltage, a Luenberger state observer is utilized. The P- or PI-gains of observer based on a suitable natural frequency and damping ratio is adopted for the state estimation. Satisfactory estimation accuracy of output voltage and SOC is especially obtained by a PI-gain. The feasibility of the proposed estimation method is verified through experiment under the conditions of different C-rates, SOCs and temperatures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1029-1040
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• 1993

Recently the Time Delay Control (TDC) method has been proposed as a promising technique in the robust control area, where the plants have nonlinear dynamics with parameter variations and substantial disturbances are present. TDC method, however, requires the measurements of all the state variables, together with their derivatives. This requirement imposes a severe limitation on the applications to most real systems. In order to solve this measurement problem, we proposed an observer design method that can stably reconstruct the state variables and their derivatives. the stability of the overall system has been analyzed and proved. Then, for a simulation study, the controller/observer based on our design method has been applied to a nonlinear plant, the result of which confirmed that the controller/observer performs satisfactorily as predicted, Finally we made experimentations on a DC servo motor that is substantial amount of inertia variations and external disturbances. the results showed that the controller/observer performs quite robustly under those variations and disturbances, and is much less sensitive to sensor noise than the controller using numerical differentiations.