• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.1
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• pp.9-15
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• 2003

To improve the performance of PID controller of high order systems by model reduction, we proposed two model reduction methods. One, Original model with two point $({\angle}G(jw)=\;-{\pi}/2,\;-{\pi})$ in Nyquist curve used gradient base method and genetic algorithm. The other, Original model without two point$({\angle}G(jw)=\;-{\pi}/2,\;-{\pi})$in Nyquist curve used to add very small dead time. This method has annexed very small dead time on the base model for reduction, and we remove it after getting the reduced model, and , we improved Smith-predictor for a dead-time compensator using genetic algorithms. This method considered four points$({\angle}G(jw)=0,\;-\pi/2,\;-\pi,\;-3\pi/2)$ in the Nyquist curve to reduce steady state error between original and reduced model. It is shown that the proposed methods have more performance than the conventional method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1447-1453
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• 2008

In this paper, we proposed to improve performance of the design of a cascade controller with the smith-predictor structure. The parameters of controller in the inner loop are determined to minimize the integral of time multiplied by the absolute value of error (ITAE) value of performance Index. The controller of outer loop and parameters of Smith-Predictor can be obtain using reduction model. The model reduction is considered that it is the transient response and the steady-state response through the use of nyquist curve. Simulation examples are given to show the better performance of the proposed method than conventional methods.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.10
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• pp.1023-1029
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• 2014

In this paper, we propose an SPDR (Smith Predictor for Disturbance Reduction) scheme to improve the temperature control by reduction of the disturbance in ROT process with measurement delay. The proposed controller is a combination of Astrom's modified Smith predictor with a disturbance reduction controller and a grey predictor. The grey prediction is used to calculate the inverse of the measurement delay and to predict future variations and tendencies of system output. The simulation results demonstrate the successful performance of the proposed disturbance reduction controller and enhance the robustness of the proposed control scheme.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.65-68
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• 1997

溜is paper is concerned with the controllers for time-delay systems which has an integrator. It is known that high performance can be obtained for the systems response and load disturbance rejection by adjusting the only three parameters of the modified Smith predictor. In the case of the time-delay systems with repeated poles, good performance cannot be obtained with the modified Smith predictor. But superior performance can be obtained through the intentional delay parameters mismatch. The calculating method for the approximation delay parameter values is proposed. Simulation results show the improved response characteristics with the proposed delay parameter values.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1687-1688
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• 2008

The steam superheater and the steam pressure systems are time delay systems that have poles near the origin in the left half plane or a pure integrator. Smith predictor can't be applied to these systems any more, because of occurring the steady state error for the step disturbance. In this paper, a new Smith predictor controller for the steam superheater and the steam pressure is proposed. A disturbance observer to estimate an input disturbance and a new controller to eliminate an effect of a disturbance are proposed. The computer simulation results are shown the efficiency of the proposed system.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.4
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• pp.449-455
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• 2011

In this paper, a time-delay problem of a tele-operated control system is investigated and compensated by neural network. The smith predictor requires an exact system model to deal with a time-delay in the system. To compensate for modeling errors in the configuration of the Smith predictor, a neural network approach is presented. Based on forming the Smith predictor structure, the radial basis function(RBF) neural network estimator is used. Simulation and experimental studies are conducted to show the functionality of the proposed method.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.170-182
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• 1999

In this paper, we present a tracking accuracy enhancement method by compensating the time delay of the video tracker in an EOTS. The proposed method has two functional parts, which can cope with the time delay of LOS and maneuvering target informations by Smith predictor and Kalman filter. So it can dramatically reduce the tracking error over conventional PI control or Smith predictor control. To verify the proposed method, various and extensive simulation and experimental results are given.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.396-406
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• 2007

In this paper, we proposed development of improved model reduction and design of hierarchical controller using reduction model. The model reduction is considered that it is the transient response and the steady-state response through the use of nyquist curve. The hierarchical controller selected tuning of PID controller to ensure specified gain and phase margin and hybrid smith-predictor fuzzy controller using reduction model. Simulation examples are given to show the better performance of the proposed method than conventional methods.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.2
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• pp.103-109
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• 2020

This paper finds solutions for using ZigBee in wireless networked control system (WNCS). The round trip time delay and packet loss rate of the WNCS are measured. On the basis of these measured data, a playback buffer is used to solve the variable time delay in WNCS, and a Smith predictor is introduced to compensate for the time delay. The WNCS was able to be actually constructed to perform DC motor position control with 40 Hz sampling frequency.

• International Journal of Control, Automation, and Systems
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• v.6 no.2
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• pp.186-193
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• 2008

The Internet's low cost and ubiquity present an attractive option for real-time distributed control of processes on the factory floor. When integrated with the Internet, the LonWorks open control network can give ubiquitous accessibility with the distributed control nature of information on the factory floor. One of the most important points in real-time distributed control of processes is timely response. There are many processes on the factory floor that require timely response. However, the uncertain time delay inherent in the network makes it difficult to guarantee timely response in many cases. Especially, the transmission characteristics of the LonWorks/IP network show a highly stochastic nature. Therefore, the time delay problem has to be resolved to achieve high performance and quality of the real-time distributed control of the process in the LonWorks/IP Virtual Device Network (VDN). It should be properly predicted and compensated. In this paper, a new distributed control scheme that can compensate for the effects of the time delay in the network is proposed. It is based on the PID controller augmented with the Smith predictor and disturbance observer. Designing methods for output feedback filter and disturbance observer are also proposed. Tracking position control experiment of a geared DC Servo motor is performed using the proposed control method. The performance of the proposed controller is compared with that of the Internal Model Controller (IMC) with the Smith predictor. The result shows that the performance is improved and guaranteed by augmenting a PID controller with both the Smith predictor and disturbance observer under the stochastic time delay in the LonWorks/IP VDN.