• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.3
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• pp.9-16
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• 2004

This paper provides an observer-based Η$\infty$ output feedback controller design method for descriptor systems with time-varying delay by just one LMI(linear matrix inequality) condition. The sufficient condition for the existence of controller and the controller design method are presented by perfect LMI approach which can be solved efficiently by convex optimization. The design procedure involves solving an LMI. Since the obtained condition can be expressed as an LMI form all variables including feedback gain and observer gain can be calculated simultaneously by Schur complement changes of variables, and singular value decomposition. Moreover, The proposed controller design algorithm can be extended to the observer-based robust Η$\infty$ output feedback controller design method for descriptor systems with parameter uncertainty and time delay. An example is given to illustrate the results.

• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.325-335
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• 2018

Limited access to state information in the design of a feedback controller has brought out a significant amount of research on the design of an output feedback controller. Despite its long endeavor to find an optimal one, it is still an open problem. Thus, we focus on the comparison of existing states of arts in the design of a static output feedback controller in terms of stability and complexity so as to find further research direction in this field. To this end, we present eight design methods in a unified presentation. We also provide the complete description of algorithms which can be applicable to any system configuration. Stability performance and complexity in terms of processing time are evaluated through numerical simulations. Simulation results show that the algebraic controller (AC) algorithm [20] has the smallest complexity while the scaling linear matrix inequality (SLMI) algorithm [18] seems to achieve the best stability in most cases with much higher complexity.

• The Journal of the Acoustical Society of Korea
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• v.24 no.5
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• pp.238-247
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• 2005

In this Paper. we Presents subband design techniques of a compensating filter and adaptive feedback canceller for the digital hearing aid. The sensorineural hearing loss has a hearing threshold that shows a nonlinear characteristic in frequency domain. and its compensation suffers from an echo that produced by an undesired time varying feedback path. Therefore. the digital hearing aid requires the compensator that can adjust gains nonlinearly in frequency bands and eliminate the echo rapidly In the Proposed digital hearing aid. the compensating filter is designed by the adaptive system identification method in subband structure, and the adaptive feedback canceller is designed by the subband affine projection algorithm. The designed compensation filter can control the nonlinear gain in each subband respectively, therefore precise compensation is possible. And the feedback canceller using the subband adaptive filter achieves fast convergence rate. The Performances of the Proposed method are verified by computer simulations as comparing with the behaviors of the previous trials.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1249-1256
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• 2019

In this paper, we propose a new algorithm to remove acoustic feedback and noise in hearing aids. Instead of using the conventional FIR structure, this algorithm is a deep learning algorithm using neural network adaptive prediction filter to improve the feedback and noise reduction performance. The feedback canceller first removes the feedback signal from the microphone signal and then removes the noise using the Wiener filter technique. Noise elimination is to estimate the speech from the speech signal containing noise using the linear prediction model according to the periodicity of the speech signal. In order to ensure stable convergence of two adaptive systems in a loop, coefficient updates of the feedback canceller and noise canceller are separated and converged using the residual error signal generated after the cancellation. In order to verify the performance of the feedback and noise canceller proposed in this study, a simulation program was written and simulated. Experimental results show that the proposed deep learning algorithm improves the signal to feedback ratio(: SFR) of about 10 dB in the feedback canceller and the signal to noise ratio enhancement(: SNRE) of about 3 dB in the noise canceller than the conventional FIR structure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.4
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• pp.361-370
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• 1992

A controller of the hovering VTOL aircraft with four fan is constructed by SRFIMF(State Rate Feedback Implicit Model-Following)theory, in which feedback state are angle acceleration, angle velocity and angle position of the aircraft during hover With yaw control of the system, characteristics of the hovering aircraft can be analyzed by changing states feedback gain and sponse provides robust stable hovering system.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.159-160
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• 2011

일반적인 엘리베이터 시스템에서는 로드셀이라고 하는 센서가 설치되어 탑승자를 포함한 모터에 걸리는 전체부하를 측정한다. 그리고 이 무게 정보는 브레이크가 풀리고 엘리베이터가 움직이기 시작하기 전에 토크 전향보상을 하는데 사용되고, 엘리베이터는 브레이크 개방 과정에서 정지상태를 유지하여 엘리베이터가 부드럽게 출발하도록 한다. 안티롤백은 로드셀없이 브레이크가 열리는 동안에 위치 편차를 억제하는 기능이다. 다른 회사에서는 이 기능을 기존의 PI 제어기를 사용하여 개발하였다. 반면에 이 논문에서는 안티롤백 기능을 위하여 상태궤환 위치제어기를 사용하였으며 그 적절성을 논의한다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.3 s.108
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• pp.283-290
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• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.91-99
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• 2011

Several repeater systems are used to enhance the cell coverage to location such as shadow and rural areas in mobile systems. But the general RF repeater solutions are not suitable for high power outdoor environment because it has the weakness such as self oscillation problem With adoption of a adaptive digital filter technology, feedback interference cancellation repeater prevents oscillation by detecting and canceling the unwanted feedback signal between transmission and receiver antenna. In this paper, dual NLMS based interference cancellation method is proposed and the step size adaptation can be implemented by the estimation of the feedback channel Doppler frequency characteristics. The performance of the proposed algorithm is quantified via analysis and simulation for the static and multipath fading feedback channels.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.1
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• pp.55-62
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• 2008

This paper proposes a feedback linearization control scheme of AC/DC PWM converters with LCL input filters using no damping resisters. This feedback linearization scheme can eliminate the non-linearity of the system. So, the controller of the system can be designed by using linear control theory, which gives a good transient response. The cascade structure of the controller makes the converter current be controlled within a certain limit. To reduce the number of sensors, the source voltage and current is estimated. The validity of the proposed control algorithm is verified by simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.272-273
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• 2017

계통연계 인버터 시스템은 기존 L 필터보다 낮은 THD를 가지며 저가격의 작은 부피로도 효율적으로 고조파를 저감할 수 있는 LCL 필터를 많이 사용하고 있다. LCL 필터를 가지는 계통연계 인버터의 제어를 위해서는 PI 제어기가 사용되고 있으며 일반적으로 다수의 PI 제어기가 사용되고 있어 많은 제어기 이득을 동시에 설계해야 하는 한계를 지닌다. 본 논문에서는 LCL 필터를 갖는 3상 계통연계 인버터의 상태공간 모델을 이용하여 상태공간에서의 상태 궤환 제어기의 설계기법을 제시한다. 상태 궤환 제어기를 적용함으로서 다수의 PI 제어기 이득을 설계하는 번거로움을 줄일 수 있으며 체계적인 과정으로 제어기가 설계될 수 있다. 제안된 기법의 타당성과 성능이 PSIM 시뮬레이션을 통하여 입증된다.