• 제어로봇시스템학회논문지
• /
• 제10권2호
• /
• pp.125-130
• /
• 2004

This paper describes an approach for synthesizing a Fuzzy Logic Controller(FLC) that combines the benefits of fuzzy logic control and fuzzy logic gain scheduling for the F/A-18 aircraft. Specially, fuzzy rules are utilized on-line to determine the denoralization factor(Κ) of a feedback fuzzy controller based on the dynamic pressure(Q) indicateing the region of the flight envelop the aircraft is operating in. Simulation results demonstrate that the proposed FLC provides excellent compensation for time-varying and/or nonlinear characteristics of the aircraft, and that it also exhibits satisfactory robustness with noisy air data sensors.

• International Journal of Control, Automation, and Systems
• /
• 제4권2호
• /
• pp.178-186
• /
• 2006

We propose and analyze a robust adaptive fuzzy controller for nonlinear systems without a priori knowledge of the sign of the input gain function. No assumptions are made about the type of nonlinearities of the system, except that such nonlinearities are smooth. The uncertain nonlinearities are captured by the fuzzy systems that have been proven to be universal approximators. The proposed control scheme completely overcomes the singularity problem that occurs in the indirect adaptive feedback linearizing control. Projection in the estimated parameters and switching in the control input are both not required. The stability of the closed-loop system is guaranteed in the Lyapunov viewpoint.

• 제어로봇시스템학회논문지
• /
• 제15권6호
• /
• pp.573-580
• /
• 2009

In this paper, we develop a functional test model for magnetic bearing wheels. The functional test model is an electromagnetic levitation system that has three degree of freedom, which consists of one axial suspension from gravity and two axes gimbaling capability to small angels. A nonlinear controller with high-gain observers is proposed and the real-time experiment results show that the rotor is accurately levitated at the desired position and well-balanced, which is a suitable result for the potential use an magnetic bearing wheels. Also, the proposed scheme exhibits better performance when it is compared with the conventional PID control method.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
• /
• pp.88-91
• /
• 2000

An MMIC oscillator operating at the 24.55 GHz has been designed using 0.2 ${\mu}{\textrm}{m}$AlGaAs/InGaAs/GaAs Pseudomorphic HEMT technology. The active device used in the oscillator design has a 0.2 ${\mu}{\textrm}{m}$ gate length PHEMT with 4$\times$80 ${\mu}{\textrm}{m}$ gate width. We obtained 4.08 dB of S$_{21}$ gain and 317 mS/mm of transconductance, and extrapolated unit current gain cut-off frequency (f$_{T}$) and maximum oscillation frequency (fmax) were 62 GHz and 120 GHz, respectively. The circuit are based on a series feedback and negative resistance topology. Microstrip line open stub is used to terminating. The oscillator circuits has designed for delivering maximum power to load and conjugated matching. The simulated small signal negative resistance was 50 Ω. We obtained 1.002 of loop gain and 0.0005$^{\circ}$angle from the simulation by HP libra 6.1. The layout for oscillator is 1.2$\times$1.8 $\textrm{mm}^2$.>.

• 전기학회논문지
• /
• 제56권9호
• /
• pp.1648-1654
• /
• 2007

In this paper, we consider the design of $H_\infty$ high-gain state feedback control for time-delayed linear systems with limited actuator capacities. The high-gain control means that the control permits the predetermined degree of saturation. Based on new Lyapunov-Krasovskii functional, we derive a result in the form of matrix inequalities. The matrix inequalities are consisted of LMIs those confirm the positive definiteness of Lyapunov- Krasovskii functional, satisfaction of predetermined degree of saturation, reachable set and $L_2$ gain constraint. The result is dependent on the bound of time-delay and its rate, predetermined degree of saturation, actuator capacity, and the allowed size of disturbances. Finally, we give a numerical example to show the effectiveness and usefulness of our result.

• 한국전자파학회지:전자파기술
• /
• 제3권1호
• /
• pp.11-19
• /
• 1992

본 연구에서는 초광대역증폭기를 설계하고자 GaAs MESFET 소신호 동가회로에 인덕터 피킹소자를 첨가하여 캐패시턴스의 영향을 감소시키는 주파수 피킹현상에 대하여 분석하였다. GaAs MESFET의 소신호 둥가회로의 전달함수로 부터 인턱터 피킹소자의 최적값을 유도하였으며, 매 우 균일이득을 갖는 귀환증폭모듈을 실현하였다. 실 주파수법에 의하여 입력과 출력단의 엄피던스정합회로를 설계하여 초광대역 마이크로파증폭기를 구현하였으며 컴퓨터 시률레이션에 의하여 셜계된 증폭기의 이득의 오차는 O.lGHz-12GHz에서 O.56dB의 매우 균일한 이득을 얻을 수 있었다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
• /
• pp.360-362
• /
• 2006

This paper proposes a new track-following control method using disturbance observer with the freedom of gain and frequency adaptation in optical disk drive system. Recent ODDs use smaller track pits, higher rotation speed and broader rotational speed variations to increase the data capacity and data transfer rate. This cause the degradation of track-following performance by increasing the disturbance of the rotary system. In this paper, we discussed on a DOB structure that efficiently attenuate the disturbance without effecting the overall feedback loop characteristics on CLV type ODD which uses a higher and broader range of rotational speed. DOB structure uses two band pass filter. We analyzed the track-following performance sensitivity on rotational frequency variance and gain changes. This analysis is done on a computer simulation environment and actual ODD product.

• 소음진동
• /
• 제5권1호
• /
• pp.59-65
• /
• 1995

In this study, we investigated the operational limit of magnetic bearing-rotor system due to the maximum force limit and slew rjate limit of the electromagnetic actuator as a function of the time dependent control characteristics. The feedback gain of the controller varies the current of the electromagnet coil with the motion of the rotor. The distorsion of magnetic force due to the slew rate limit is not occurred jup to 30, 000 rpm in the magnetic bearing that we have a close relation with the rotational speed and vibration level of the rotor and the proportional gain of the controller. Therefore the maximum force limit determines the maximum allowable orbit radius of the magnetic bearing-rotor system. The maximum allowable vibration levels are exponentially decreased according to the increment of rotational speed and proportional gain of the controller.

• 오토저널
• /
• 제13권5호
• /
• pp.73-80
• /
• 1991

Air/fuel ratio control system for gasoline engines has been analyzed to determine the control gain of the system. In this analysis the engine is modelled to be a simple time delaying element and the ramp-and-jump method is used to control air/fuel ratio. The result shows that it is necessary to measure the air flow rate accurately to enhance the control performance. And also it is shown that the control gain must be determined in some bounded region to meet the fast dynamic response and high catalyst conversion efficiency together.

• 전기학회논문지
• /
• 제62권3호
• /
• pp.401-406
• /
• 2013

The mobile robot is one of the widely-used systems in service industry. We propose a gain-scheduling feedback controller for the tracking control of the mobile robot. The benefit of our proposed controller is that it avoids the singularity issue occurs with the controllers suggested in [4], [10]. Moreover, we show the stability analysis of the controlled system via a Lyapunov stability approach such that the exponential convergence of tracking error to zero is analytically provided. The simulation results show the validity of the proposed controller and improved control performance over the conventional controller.