• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.11
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• pp.760-767
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• 2004

In this paper, we propose sufficient conditions under which nonlinear systems can be transformed into nonlinear observer canonical form in the extended state space by virtue of dynamic system extension. The proposed scheme weakens two major restrictions of observer error linearization technique. Once a nonlinear system is transformed into nonlinear observer canonical form using dynamic system extension, a state observer can be easily designed. Two illustrative examples are included in order to compare the proposed scheme and observer error linearization method.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.7
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• pp.613-616
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• 2012

This paper proposes the state observer design for nonlinear systems with delayed output. It is shown that by considering a nonlinear term of error dynamics as an additional state variable, the nonlinear error dynamics with time delay can be transformed into the linear one with time delay. Sufficient conditions for existence of a state observer are characterized by linear matrix inequalities. Finally, an illustrative example is given in order to show the effectiveness of our design method.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.891-897
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• 2012

In this paper, the observer based nonlinear state feedback controller has been developed to control the pressures of the oxygen and the hydrogen in the PEM(Proton Exchange Membrane) fuel cell system. Nonlinear model of the PEM fuel cell system was introduced to study the design problems of the state observer and model based controller. A cascade observer using the filtering technique was used to estimate the pressure derivatives of the cathode and the anode in the system. In order to estimate the pressures of the cathode and the anode, the sliding mode observer was designed by using these pressure derivatives. To estimate the oxygen pressure and the hydrogen pressure in the system, the nonlinear state observer was designed by using the cathode pressure estimates and the anode it. These results will be very useful to design the state feedback controller. The validity of the proposed observers and the controller has been investigated by using the Lyapunov's stability analysis strategy.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.328-328
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• 2000

In this paper, An inverted pendulum system is typical of a nonlinear model. We propose a stable the inverted pendulum with fuzzy controller and state observer of nonlinear system. we represent the fuzzy system as a Takagj-Sugeno fuzzy model in addition, full-order state observer of inverted pendulum. As the result show fuzzy controller of inverted pendulum with nonlinear model of full-order state observer.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.8
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• pp.837-841
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• 2008

This paper presents a robust reduced order state observer for a class of Lipschitz nonlinear systems with external disturbance. Sufficient conditions on the existence of the proposed observer are characterized by linear matrix inequalities. It is also shown that the proposed observer design can reduce the effect on the estimation error of external disturbance up to the prescribed level. Finally, a numerical example is provided to verify the proposed design method.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.289-297
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• 2014

This paper proposed a novel high performance sensorless control scheme for IPMSM based on an extended nonlinear state observer. The gain-matrix of the observer has been derived by using state linearization method. Steady state errors in estimated rotor position and speed due to parameter inaccuracy have been analyzed, and an equivalent flux error is defined to represent the overall effect of parameter errors contributing to the wrong convergence of the estimated rotor speed as well as rotor position. Then, an online compensation strategy was proposed to limit the estimation errors in rotor position and speed. The effectiveness of the extended nonlinear state observer is validated through simulation and experimental test.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2292-2297
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• 2010

To improve the performances of Sawyer motors and to regulate yaw rotation, various feedback control methods have been developed. Almost all of these methods require information on the position, velocity or full state of the motor. Therefore, in this paper, a nonlinear observer is designed to estimate the full state of the four forcers in a Sawyer motor. The proposed method estimates the full state using only positional feedback. Generally, Sawyer motors are operated within a yaw magnitude of several degrees; outside of this range, Sawyer motors step out. Therefore, this observer design assumes that the yaw is within ${\pm}90^\b{o}$. The convergence of the estimation error is proven using the Lyapunov method. The proposed observer guarantees that the estimation error globally exponentially converges to zero for all arbitrary initial conditions. Furthermore, since the proposed observer does not require any transformation, it may result in a reduction in the commutation delay. The simulation results show the performance of the proposed observer.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.592-597
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• 2003

In this paper, some differential geometric conditions for the observer using a recurrent neural network are provided in terms of a stochastic nonlinear system control. In the stochastic nonlinear system, it is necessary to make an additional condition for observation of stochastic nonlinear system, called perfect filtering condition. In addition, we provide a observer using a recurrent neural network for the observation of a stochastic nonlinear system with the proposed observation conditions. Computer simulation shows that the control performance of the stochastic nonlinear system with a observer using a recurrent neural network satisfying the proposed conditions is more efficient than the conventional observer as Kalman filter

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.2
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• pp.28-36
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• 1996

By utilizing the interinsic structure of the underlying continous-time nonlinear system, one can design an approximate sampled-data observer improved with respect ot the sampling-time for the systems. In this paper, we characterize the conditions for the solvability of the improved approximate sampled-data nonlinear observer design problem. In particular, it is shown that when the dimension of the state space is two, the nonlinear systems for which it is possible ot desing 3rd or higher order approximate sampled-data nonlinear observer are locally state-equivalent to an observable bilinear system. The practical implication is that seeking higher order approximate sampled-data nonlinear observer for nonlinear systems is very restricted.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.284-284
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• 2000

In adaptive fuzzy control systems. fuzzy systems are used to approximate the unknown plant nonlinearities. Until now. most of the papers in the field of controller design for nonlinear system using fuzzy systems considers the affine system with fixed grid-rule structure based on system state availability. This paper considers observer-based nonlinear controller and dynamic fuzzy rule structure. Adaptive laws for fuzzy parameters for state observer and fuzzy rule structure are established so that the whole system is stable in the sense of Lyapunov.