• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.12
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• pp.542-548
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• 2002

We consider an unknown linear time invariant plan with static load disturbance. A saturation function nonlinear element is sued to find th one point information in the frequency domain. We analyze an asymmetric self-oscillation caused by static load disturbance with relay feedback and saturation function feedback. We propose a new method to tune a PID controller using a saturation nonlinear feedback element in the presence of asymmetric oscillation. The proposed method does not require the knowledge of plant d.c. gain with an asymmetric oscillation in the plat output.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1103-1106
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• 1996

Disturbance Accommodating Attitude control logic for 3-axis stabilized spacecraft is designed and compared with PIID control logic. PID controller provide the zero steady error for constant disturbances. PIID controller detect and cancel disturbances upto the ramp input. PID control logic is designed as the main control logic. We designed the disturbance observer to detect the effect of disturbance using the sinusoidal function. The detected disturbance are compensated by the additional control logic. The comparison simulation is conducted between PIID and PIID with DAC. The simulation results show that PIID with DAC shows the better attitude pointing accuracy.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.388-391
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• 2003

Disturbance observer(DOB) is effective to enhance the performance of system in the presence of disturbances. Various types of disturbance observer have been proposed to improve sensitivity function of system. However, it has been observed that current DOBs tend to bring poor transient response due to cross-couplings. This paper proposes a new type of disturbance observer to reduce effect of cross-couplings and provide simpler structure than Dual DOB. Finally, we verify the performance of the proposed DOB through numerical simulations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.8 s.251
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• pp.897-905
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• 2006

This study considers an experimental design of disturbance compensation control to improve stabilization performance of main battle tanks. An adaptive non-parametric design technique based on the Filtered-x Least Mean Square(FXLMS) algorithm is applied in the consideration of model uncertainties. The optimal compensator is designed by two-step design procedures: determination of frequency response function of the disturbance compensator which can cancel the disturbance of series of single harmonics by using the FXLMS algorithm and determination of the compensator polynomial which can fit the frequency response function obtained in the first step optimally by using a curve fitting technique. The disturbance compensator is applied to a simple experimental gun-torsion bar-motor system which simulates gun driving servo-system. Along with experimental results, the feasibility of the proposed technique is illustrated. Experimental results demonstrate that the proposed control reduces the standard deviation of stabilization error to 47.6% that by feedback control alone. The directional properties of the FXLMS Algorithm such as the direction of convergence and its convergence speed are also verified experimentally.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.2
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• pp.125-131
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• 2017

2-Axis Pan and Tilt Motion Platform, a complex multivariate non-linear system, may incur any disturbance, thus requiring system controller with robustness against various disturbances. In this study, we designed an adaptive backstepping compensated controller by estimating the disturbance and error using the Radial Basis Function Neural Network (RBF NN). In this process, Uniformly Ultimately Bounded (UUB) was demonstrated via Lyapunov and stability was confirmed. By generating progressive disturbance to the irregular frequency and amplitude changes, it was verified for various environmental disturbances. In addition, by setting the RBF NN input vector to the minimum, the estimated disturbance compensation process was analyzed. Only two input vectors facilitated compensatory function of RBF NN via estimating the modeling and control error values as well as irregular disturbance; the application of the process resulted in improved backstepping controller performance that was confirmed through simulation.

• Journal of Korean Clinical Nursing Research
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• v.14 no.2
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• pp.115-126
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• 2008

Purpose: This study was aimed to develop an aromatherapy hand massage program, and evaluate the effects of aromatherapy hand massage on cognitive function, sleep disturbance and problematic behaviors of elderly with dementia. Method: The research design was a nonequivalent control group non-synchronized quasiexperimental study. Aromatherapy hand massage was administrated to experimental groupI for 2 weeks, jojoba oil massage were administrated to experimental groupII for 2 weeks, and no treatment for control group for 2 weeks. Data were analyzed using the $x^2-test$, ANOVA, ANCOVA and $Scheff{\acute{e}}$ test in the SPSS 12.0 program. Results: Experimental group I showed significant changes in sleep disturbance and problematic behaviors compared to those in experimental groupII or control group. Conclusion: Aromatherapy hand massage program is found effective on sleep disturbance and problematic behaviors of elderly with dementia.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.5
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• pp.339-345
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• 2016

This paper presents a robust speed control of an autonomous vehicle using a disturbance observer. For the purpose, the transfer function of speed dynamics of an autonomous vehicle is identified using step response data. Based on the identified transfer function, model based PID (Proportional-Integral-Derivative) control is designed. In order to design a robust control against load variations on the vehicle, a disturbance observer (DOB) based control is devised. The performance of the designed DOB based control is demonstrated by real experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.447-450
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• 2003

This paper concerns on application of active magnetic bearing(AMB) system to levitate the elevation axis of an electro-optical sight mounted on moving vehicles. In such a system. it is desirable to retain the elevation axis within the predetermined air-gap while the vehicle is moving. A disturbance compensation control is proposed to reduce the base motion response. In the consideration of the uncertainty of the system model, a filtered-x least-mean-square(FXLMS) algorithm is used to estimate adaptively the frequency response function of the feedforward control which cancels disturbance responses. The frequency response function is fitted to an optimal feedforward control. Experimental results demonstrate that the proposed control reduces the air-gap deviation to 27.7% that by feedback control alone.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.2
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• pp.69-77
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• 2019

This study introduces MATLAB Graphical User Interface (GUI)-based software to monitor ionospheric disturbances. This software detects ionospheric disturbances using Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) measurements, and estimates a location of the disturbance source through the detected disturbance. In addition, this software includes a sky plot making function and frequency analysis function through wavelet transform. To evaluate the performance of the developed software, data of 2011 Tohoku earthquake in Japan were analyzed by using the software. The analysis results verified that the ionospheric disturbances were detected through GPS and GLONASS measurements, and the location of the disturbance source was estimated through the detected disturbance.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.11
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• pp.100-107
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• 2003

This paper represents a disturbance compensation control for attenuating disturbance responses. In the consideration of the requirements on the model accuracy in the model based compensator designs, an experimental feed forward compensator design based on adaptive estimation by Filtered-x least mean square (FXLMS) algorithm is proposed. The convergence properties of the FXLMS algorithm are discussed and its conditions for the asymptotic convergence are derived theoretically. The effectiveness of the proposed method and the theoretical proof are verified by computer simulation.