• 융합신호처리학회논문지
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• 제5권4호
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• pp.301-307
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• 2004

본 논문에서는 Takagi-Sugeno(T-S) 퍼지모델에 대한 가변구조제어방식을 제안하며 이를 이용한 바퀴구동 도립 진자의 자세제어를 보인다. 비선형 시스템이 T-S 퍼지모델로 모델링 될 수 있다는 가정 하에서 바퀴구동 도립진자에 대하여 몇 개의 대표 동작점을 기준으로 시스템을 선형화하여 퍼지모델을 얻고 이를 통해 가변구조제어이론을 도입하여 제어기를 설계한다. 제안된 제어법칙은 퍼지모델을 구성하는 각각의 선형 부 시스템의 입력이득 행렬을 동일한 행렬로 단일화하고 그 단일화된 제어이득행렬을 토대로 설계되어진다. 이득행렬의 단일화 과정에서 생성되는 불확실성은 가변구조제어 이론의 입력 외란으로 해석되어질 수 있으며 이러한 단일화 외란은 기존 가변구조제어의 강인성에 의해 해결되어질 수 있다. 바퀴구동 도립진자 시스템 예를 통해 제안된 제어알고리즘의 타당성과 유용성을 보인다.

• 대한인간공학회지
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• 제19권3호
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• pp.39-49
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• 2000

During human-computer interaction(HCI), people typically send inputs to computers through electromechanical pointing devices. Many applied studies have therefore evaluated cursor-positioning movements made with various pointing devices. Though there were so many studies about performance of various pointing devices, it was nearly impossible to compare device performance each other until the Fitts' law was applied. It does appear that Fitts' law may predict performance reasonably well for the one C-D gain level. But in varying C-D gain levels, Fitts' law could not predict movement time. This study investigated the effects of C-D gain in mouse movement time and suggested a revised Fitts' model including C-D gain as an independent variable. The revised Fitts' model may use to measure the performance of various devices in varying C-D gain levels.

• 전자공학회논문지
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• 제51권11호
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• pp.101-106
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• 2014

본 논문에서는 자동 이득 제어 회로를 이용한 와이드 다이나믹 레인지 RF root-mean-square (RMS) 전력 검출기를 소개한다. 제안하는 자동 이득 제어는 voltage gain amplifier (VGA), RMS 변환 블록, 이득 조절 블록으로 구성되어 있다. VGA는 dB-linear한 이득 관계를 갖는 캐스코드 VGA를 사용하였다. 제안하는 RMS 변환은 입력 신호 전 파장의 제곱 변환을 이용하여 RMS에 비례하는 DC 전압을 출력한다. 제안하는 RMS 전력 검출기는 500MHz에서 5GHz에서 작동하며 검출 범위는 0 dBm에서 -70dBm 이상의 신호를 -4.53 mV/dBm의 비율로 검출한다. 제안하는 RMS 전력 검출기는 TSMC 65nm 공정을 사용하여 설계되었으며 1.2V에서 5mW의 전력소비를 갖는다. 칩 레이아웃 면적은 $0.0097mm^2$이다.

• Smart Structures and Systems
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• 제9권4호
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• pp.373-392
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• 2012

Tracking control of systems with variable stiffness hysteresis using a gain-scheduled (GS) controller is developed in this paper. Variable stiffness hysteretic system is represented as quasi linear parameter dependent system with known bounds on parameters. Assuming that the parameters can be measured or estimated in real-time, a GS controller that ensures the performance and the stability of the closed-loop system over the entire range of parameter variation is designed. The proposed method is implemented on a spring-mass system which consists of a semi-active independently variable stiffness (SAIVS) device that exhibits hysteresis and precisely controllable stiffness change in real-time. The SAIVS system with variable stiffness hysteresis is represented as quasi linear parameter varying (LPV) system with two parameters: linear time-varying stiffness (parameter with slow variation rate) and stiffness of the friction-hysteresis (parameter with high variation rate). The proposed LPV-GS controller can accommodate both slow and fast varying parameter, which was not possible with the controllers proposed in the prior studies. Effectiveness of the proposed controller is demonstrated by comparing the results with a fixed robust $\mathcal{H}_{\infty}$ controller that assumes the parameter variation as an uncertainty. Superior performance of the LPV-GS over the robust $\mathcal{H}_{\infty}$ controller is demonstrated for varying stiffness hysteresis of SAIVS device and for different ranges of tracking displacements. The LPV-GS controller is capable of adapting to any parameter changes whereas the $\mathcal{H}_{\infty}$ controller is effective only when the system parameters are in the vicinity of the nominal plant parameters for which the controller is designed. The robust $\mathcal{H}_{\infty}$ controller becomes unstable under large parameter variations but the LPV-GS will ensure stability and guarantee the desired closed-loop performance.

• 전기전자학회논문지
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• 제13권1호
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• pp.30-35
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• 2009

입력 상수에 불확실성이 있는 최소위상 비선형시스템에 대해 경로추적 오차가 없는 제어기 설계를 제안하였다. 모델링 불확실성이 존재하는 비선형 시스템에 대해 상태 변수를 예측하기 위해 고 이득 관측기를 사용하였다. 적분형 가변 구조 제어 방식을 이용하여 점근적으로 경로추적오차가 0 되는 새로운 제어기를 제안하여 기존의 경로 추적오차를 감소시켰다. 제어기 설계의 정당성은 폐루프 시스템을 Lyapunov 분석 방법을 통해 보였다. 또한 제어기의 성능을 모의시험을 통해 보였다.

• 한국통신학회논문지
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• 제21권1호
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• pp.67-79
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• 1996

This paper presents a composite luminance signal processing system for NTSC, PAL and SECAM standards. Eaxh of the three standards employs its own specifications of subcarmier bandwidth and luminance signal waveform. The proposed system, compatible to the specifications of the three standard and B/W TV, implements variable freqneucy characteristics by controlling filter coefficients. The major features of the system are a luminance/chroma separation unit and an aperture compensation unit. The luminance/chroma separation unit employes a notch filter selection a trap freqneyc to atenuate unwanted color signals in luminance signal bands. The aperture compensation unit comprises two subunits, to provide clear color definition for each of the three standards: a primary compensation circuit and a variable compensation circuits. The proposed system yields a 40 dB gain from the chroma/luminance separation and a 10 dB gain from the aperture compensation unit.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권3호
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• pp.107-113
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• 2001

This paper deals with speed control of DC servo motor using a PID controller with a gain tuning based on a Back-Propagation(BP) Learning Algorithm. Conventionally a PID controller has been used in the industrial control. But a PID controller should produce suitable parameters for each system. Also, variables of the PID controller should be changed according to environments, disturbances and loads. In this paper described by a experiment that contained a method using a PID controller with a gain tuning based on a Back-Propagation(BP) Learning Algorithm, we developed speed characteristics of a DC servo motor on variable loads. The parameters of the controller are determined by neural network performed on on-line system after training the neural network on off-line system.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.375-382
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• 2001

This paper deals with the compensation method of AMD stroke by adopting variable gain feedback control strategy. The gains, generally known to be constant, are designed to have variable values according to the structural responses and the AMD stroke. This strategy has the advantage of compensating AMD stroke under any kind of loadings, on the other hand the conventional strategies work only under the specific loading. The strategy shows that the AMD stroke is compensated to prevent the stroke saturation and the control force is found not affected by the compensating operation while the control force is reduced and the control efficiency is decreased during the compensating operation in the conventional strategies.

• 한국통신학회논문지
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• 제39C권3호
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• pp.282-288
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• 2014

최근 GPS 안테나 성능개선에 관한 연구가 활발히 진행되고 있다. 이 논문에서는 GPS 대역에 사용가능한 초소형 패치 안테나를 제안하였다. 제안된 안테나의 공진 주파수는 접지면과 가변형 캐패시터를 이용하여 조정하였다. 안테나 제작은 제작 난이도와 경제성을 고려하여 FR4 기판을 사용하였다. 안테나 측정결과 GPS 대역 중심 주파수 1575.42 MHz에서 정재파비(VSWR) 1.2, 수동형 안테나 이득 -0.6 dBi, 능동형 안테나 이득 29 dB의 우수한 특성을 얻었다.

• 대한전기학회논문지:전력기술부문A
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• 제48권8호
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• pp.1014-1021
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• 1999

PID controllers with constant gains have been widely used in various control systems. But it is difficult to have uniformly good control performance in all operating conditions. In this paper, we propose a variable PID controller for robot manipulators. We divide total workspace of manipulators into several subspaces. PID controllers in each subspace are optimized using evolution strategy which is a kind of global search algorithm. In real operation, the desired trajectories may cross several subspaces and we select the corresponding gains in each subspace. The gains may have large difference on the boundary of subspaces, which may cause oscillatory motion. So we use artificial neural network to have continuous smooth gain curves to reduce the oscillatory motion. From the experimental results, although the proposed variable PID controller for robots should pay for some computational burden, we have found that the controller is more superior to the conventional constant gain PID controller.