• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.422-425
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• 1997

We consider the robust control problem for nonminimum phase(NMP) systems with parametric uncertainty which appear often in aircraft and missile control. First, a new method that makes such an uncertain NMP system to be factored as a interval minimum phase(MP) transfer function and a time delay term in the Pade approximation form has been presented. The controller to be proposed consists of a compensator $C_{Q}$(s) with Smith predictor in the internal model control(IMC) structure, so that it can have good robustness and performance against the structured uncertainty and the time delay behaviour due to NMP plant the $C_{Q}$(s) is designed on the MP model by using QFT. The stability and performance of overall system has been evaluated by the generalized Kharitonov theorem.rem.

• 제어로봇시스템학회논문지
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• 제3권2호
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• pp.162-168
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• 1997

Digital variable structure controller(DVSC) is implemented to control the temperature for the hot water heating circulating pump control system. For the DVSC, a control algorithm is suggested, which using a nonlinear sliding surface and a PID sliding surface outside and inside of steady state error boundary layer, respectively. Smith predictor algorithm is used for the compensation of long dead time. The DVSC of the suggested algorithm yields improved control performance compared with the one of existing algorithm. The system responses with the suggested DVSC shows good responses without overshoot and steady state error inspite of heating load change. By decreasing sampling time, dead time and rise time are increasing, and system output noise by flow dynamics is amplified.

• 전기학회논문지
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• 제59권6호
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• pp.1179-1185
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• 2010

This paper deals with a robust controller design problem for a small one-link robot arm system subject to input time delay and load variations. The uncertain parameters of the system are considered as a disturbance input. A disturbance observer(DOB) has been designed to alleviate disturbance effects and to compensate performance degradation owing to the time-delay. This paper employs a new DOB structure for non-minimum phase systems together with the Smith predictor. We propose a new controller for reducing the both effects of disturbance and time-delay. In order to test the performance of proposed controller, four different other control laws are compared with the proposed one by computer simulations. The simulation results show the effectiveness of the proposed control method.

• Journal of Mechanical Science and Technology
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• 제15권6호
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• pp.699-708
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• 2001

This paper presents a new approach to the AFR (Air-to-Fuel Ratio) control problem, which is based on the wide-band oxygen sensor output. The dedicated nonlinear controller is based on the feedback lineaization technique. It is well known that the feedback linearizing control technique requires an exact model of the plant for the cancellation of plant nonlinearities. A sliding mode control scheme is applied which can effectively compensate the modeling uncertainties. The measurement time delay of an oxygen sensor limits the gain of the feedback controller. Hence, time delay compensation procedure is necessary for the improvement of control performance. The Smith predictor is adopted to compensate the effects of time delay. The simulation and experimental results show that the proposed controllers can effectively reduce the transient peaks of AFR in spite of fast tip-in and tip-out maneuvers of the throttle.

• 조명전기설비학회논문지
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• 제18권2호
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• pp.49-54
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• 2004

공정제어에 있어서, 긴 시간지연은 시스템의 효과적인 제어성능을 기대하기 어렵기 때문에 공정의 모델을 이용한 스미스 예측기와 이를 이용한 PPI 제어기 등이 제안되었다. 그러나, 이들 제어기는 실 플랜트와 모델간에 존재하는 오차 때문에 실제 플랜트에서는 원하는 제어성능을 보장할 수 없다. 따라서, 본 논문에서는 이러한 모델 불일치에 의해 발생되는 오차를 보상할 수 있도록 새로운 제어변수 추정전략을 제시하였다. 또한, 이러한 추정전략은 다양한 사례를 통하여 유용한 결과를 얻었다.

• 대한전기학회논문지
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• 제41권2호
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• pp.199-208
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• 1992

MIESF(Modified Integral Error and State Feedback) controller suggested in order to control the processes with time delay is the control scheme that combines Smith predictor and IESF(Integral Error and State Feedback). This control scheme has better performance than the conventional PID controller incorporating Smith predictor with respect to the robustness and control performance for the modelling error. MIESF controller can be simply designed by pole assignment algorithm. BUT in such a case, it is difficult to find proper poles which gurantee robustness with respect to process parameter uncertainties. In order to solve the aforementioned difficulties, we suggest a new design method for MIESF controller and show the validity of the proposed design method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.518-520
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• 1999

The practical control problems for the time-delay system is considered. The delay-free characteristics of the Smith Predictor is available only when both the process and it's model are exactly matched. So it does not used widely in practical industrial processes. In this paper, using the 2nd-order plus deadtime model in place of the plant model of the Smith predictor, the proposed controller shows the improved performance in case of the very long time delay. And the range of integral constant of the PI controller is also proposed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.930-932
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• 1999

Recently a new modified Smith predictor is proposed for a time-delay system with an integrator. It is shown that the approximate model yields the zero-steady state error and the disturbance compensator improved the transient response. But in case of mismatch between the plant's time-delay and model's time-delay, the overall response is not satisfactory. In this paper, it is proposed that the proper pole is added to the new modified smith predictor to improve the overall response.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.68.1-68
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• 2001

This paper discusses tracking position control of linear actuator that has a time delay. The time delay happens when the process reads the sensor data and sends the control input to the plant located at a remote site in distributed control system. In this thesis, the time delay between the linear actuator and the discrete PID controller has constant value due to buffer device so the time delay can be modeled by Pade approximation but the large position error of the linear actuator is generated by the time delay. Therefore, the Smith predictor is used for tracking position control of the linear actuator with the time delay in order to minimize the effect of the time delay. The experimental and simulation results show that the ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.62.3-62
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• 2002

In this paper, we proposed a control technique that can be applied to various processes. The most of the process can bereduced to second order plus time delay (SOPTD) model. And we proposed improved model reduction algorithm using geneticalgorithm. This method considered four points to reduce the error between original model and reduced model in the Nyquistcurve. And, to compensate time delay, the Smith predictor plus PID controller is adopted. And a new PID tuning algorithm wasproposed, which got from numerical analysis and can be obtained the optimal performance. The PID parameters are obtainedfrom the coefficients and time delay of reduced model. The simulation results show the validity.