• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.907-914
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• 2004

In this paper, we present a reduced-order observer for a class of nonlinear systems based on the input output linearization. While the most results in the literature presented full-order nonlinear observer, we proposed a procedure for the design of reduced-order observer far nonlinear systems that are not necessarily observable. Assuming that there exists a global observer fer internal dynamics and that certain functions are globally Lipschitz, we can design a global reduced-order observer An illustrative example is included that demonstrate the design procedure of the proposed reduced-order observer.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1311-1316
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• 1999

A visual servoing method has been proposed based on disturbance observer to eliminate the effect of the off-diagonal component of image feature Jacobian, since performance indices such as measurement sensitivity of visual features, sensitivity of the control to noise and controllability could be improved when an image feature Jacobian was given as a block diagonal matrix. In this paper, experimental results of disturbance observer-based visual servoing are discussed where Samsung FARAMAN-AS1 6-axis industrial robot manipulator is employed. Also, the feature saturator is proposed to stabilize the disturbance observer loop by saturating the differential changes of the image features.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.7
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• pp.637-643
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• 2006

Generally, the tracking performance of optical disk drive(ODD) system can be improved using a disturbance observer(DOB). However, a DOB is not easily applied in an ODD system because an additional microprocessor, such as a digital signal processor(DSP), is needed. This paper shows how a DOB system can be replaced by the error-based modified disturbance observer(EM-DOB) when two mathematical conditions are satisfied. Due to the simplified structure of EM-DOB, the algorithm is easily implemented as an analog circuit, which is suitable for the ODD servo system. Additionally, in these algorithms, disturbances rejection performances can be tuned as Q filter parameters. Similar to a DOB system, three design guidelines of a Q filter can be applied. Experimental results of DOB and EM-DOB are evaluated under forced disturbances.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.232-235
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• 2008

This paper presents an LMI-based method to design reduced order observers by which we can substitute full order sliding mode observers for a class of uncertain time-delay systems. We show that a reduced order observer can be constructed as long as the uncertain system satisfies the previous LMI existence conditions of a full order sliding mode observer. And we give explicit formulas of the reduced order observer gain matrices. Finally, we give a simple LMI-based design algorithm, together with a numerical design example.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2116-2124
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• 2018

Magnetic levitation system with the advantages of non-contact, no friction and no wear can satisfy the requirement of high precision and high speed positioning. In this paper, magnetic levitation positioning stage which mainly consists of planar coil and HALBACH permanent magnet array and its control and driving system are designed. Magnetic levitation system is a highly nonlinear and strongly coupled complex system and its control performance can be influenced by the uncertainty and external disturbance. So exact feedback linearization method is used to realize exact linearization and decoupling, and a strategy of sliding mode control based on disturbance observer is proposed to compensate the uncertainty and external disturbance. Detailed proofs of observer's convergence property and system stability are derived. Both the simulation and experiment results verify the effectiveness of sliding mode control algorithm based on disturbance observer.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.600-604
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• 2000

In this paper authors proposed a new nonlinear rotor flux observer for rotor field oriented control of an induction motor which is designed based on theory of the extended Luenberger observer(ELO) one of a nonlinear state observer. The proposed rotor flux observer is derived from the 2 phase model of induction motor by the theory of ELO. The simulation results taken under the varying condition of rotor resistance and load torque show fast convergence of estimated rotor flux and high performance of IM drive system is achieved 표 experiment.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.125-128
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• 2001

In this paper, We proposed the nonlinear controller and observer design for a ball and beam system. Unfortunately, for the ball and beam system, the control coefficient is zero whenever the angular velocity or ball position are zero. Therefore, the relative degree of the ball and beam system is not well defined. The presented the nonlinear controller and observer design is based on the approximation input-output feedback linearization. And we verified that the proposed nonlinear controller and observer scheme is the feasible through a computer simulation.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.11a
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• pp.341-344
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• 2007

This paper proposes an alternative robust adaptive high-gain fuzzy observer design scheme and its application to synchronization of chaotic systems. The structure of the proposed observer is represented by Takagi-Sugeno fuzzy model and has the integrator of the estimation error. This improves the performance of high-gain observer and makes the proposed observer robust against noisy measurements, uncertainties and parameter perturbations as well. Using Lyapunov stability theory, an adaptive law is derived and the stability of the proposed observer is analyzed. Some simulation result is given to present the validity of theoretical derivations and the performance of the proposed observer.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.803-806
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• 1997

In this paper, a force estimation method is proposed for the sensorless force control. For this, a disturbance observer is applied to each joint of an n degrees of freedom manipulator to obtain a simple equivalent robot dynamics(SERD) being represented as an n independent double integrator system. To estimate the output of disturbance observer in the absence of external force, the observer estimator is designed, where the uncertain parameters of the robot manipulator are adjusted by gradient method to minimize the output between the disturbance observer and the observer estimator. When the external force is exerted, the external force is estimated using the difference between the output of disturbance observer which include the external torque signal and that of observer estimator. And then, a force controller is designed for force feedback control employing the estimated force signal. To verify the effectiveness of the proposed force estimation method, several numerical examples are illustrated for the 2-axis planar type robot manipulator.

• 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.