• 대한교통학회지
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• 제13권1호
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• pp.125-152
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• 1995

The purposes of this study are twofold ; (1) to investigate the accuracy of estimation power of the individual models. such as those of Highway Capacity Nanual (HCM), Korea Highway Capacity Manual (KHCM), and NationalCooperative Highway Research Program(NCHRP) Report339 ; and (2) to develop an adjusted delay model which can be applied to the signal control system in urban areas. The study is mainly focused on four subjects related to the research purposes, which are as follows ; (1) characteristecs of exsisting delay models ; (2) inherent problems in exsisting delay models : (3) validation of the proposed model by the comparison of observed delay with estimated delay :and (4) a method which can be applied to develop an appropriate delay model for actrual signal control systems by the adjusted fact of the proposed model.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.425-428
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• 2000

A new dead time compensation method using time delay control approach is presented. The dead time in switching pattern cause the voltage distortion and it can be considered as the disturbance voltage. In this paper the disturbance voltage is estimated using time delay control and the estimated disturbance voltage is summed with voltage command in predictive current control by a feed-forward. The proposed scheme is implemented on a PMSM and the effectiveness is verified through comparative simulation.

• 대한임베디드공학회논문지
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• 제4권2호
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• pp.97-102
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• 2009

In this paper, the problem of stability analysis for networked control systems with norm-bounded parameter uncertainties is investigated. By construction Lyapunov's functional, a new delay-dependent stability criterion for uncertain networked control system is established in terms of LMIs (linear matrix inequalities) which can be easily by various convex optimization algorithms. One numerical example is included to show the effectiveness of proposed criterion.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.157-160
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• 2002

When the teleoperation system has a signal transmission time delay between slave system and control system, the position tracking performance of the slave system and system stability are likely to be deteriorated. This paper proposes a force reflecting position control scheme for teleoperation system with signal transmission time delay. The proposed scheme not only satisfy the system internal stability but also improves the position tracking performance with disturbance rejection capability. The simulation results show that the proposed control method provides excellent performances.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1173-1177
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• 2006

Using an inner P controller, a tuning rule useful for processes with wide ratios of time delay over time constant is proposed. Internal model control method and pole assignment method are utilized. It can be used for processes with wide range of the ratio of time delay to time constant without incovenience to choose different tuning rules.

• 대한전기학회논문지:전력기술부문A
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• 제49권7호
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• pp.345-349
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• 2000

This paper presents an extended integral control with the PI controller by introducing the delay and decaying factors. The extended integral control scheme is developed by substituting the proportional convolution integral control for the PI(Proportional Integral) control. So far, the integral part of PI controller produces a signal that is proportional to the time integral of the input signal to the controller. The steady-state operation points are affected forever by errors in the past due to the input signal containing the information of the error in the past. These phenomena may cause some disturbances for other control purposes related to the given PI control. Introduction of forgetting factors to the error in the past can resolve the disturbance problems. Various forgetting factors are developed using the delay elements, the decaying factors, and the combination of the delay and decaying factors. The proposed various extended integral control schemes can be applicable to the corresponding PI control designs in which the error in the past may badly affect the current steady-state operation points and may cause some disturbances for other control purposes.

• Structural Engineering and Mechanics
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• 제40권2호
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• pp.233-243
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• 2011

This paper presents a theoretical study of a model predictive control (MPC) strategy employed in semi-active control system with magnetorheological (MR) dampers to reduce the responses of seismically excited structures. The MPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an objective function, which can compensate for the effect of time delay that occurred in real application. As an example, a 5-story building frame equipped with two 20 kN MR dampers is presented to demonstrate the performance of the proposed MPC scheme for addressing time delay and reducing the structural responses under different earthquakes, in which the predictive length l = 5 and the delayed time step d = 10, 20, 40, 60, 100 are considered. Comparison with passive-off, passive-on, and linear quadratic Gaussian (LQG) control strategy indicates that MPC scheme exhibits good control performance similar to the LQG control strategy, both have better control effectiveness than two passive control methods for most cases, and the MPC scheme used in semi-active control system show more effectiveness and robustness for addressing time delay and protecting structures during earthquakes.

• 한국음향학회지
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• 제34권6호
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• pp.463-469
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• 2015

본 논문에서는 수중 전파 지연을 고려한 매체 접근 제어 프로토콜을 제안하고 제안하는 프로토콜의 성능을 평가한다. 제안하는 수중 전파 지연을 고려한 매체 접근 제어 프로토콜은 한 슬롯 시간 내에 여러 개의 RTS(Request-To-Send) 프레임들이 싱크 노드에 수신되는 경우에 RTS 프레임들이 겹치지 않게 수신되면 이들을 복원할 수 있다. 본 논문에서는 제안하는 수중 전파 지연을 고려한 매체 접근 제어 프로토콜의 성능 평가를 다양한 환경에서 수행하고 기존의 매체 접근 제어 프로토콜과도 성능을 비교 분석한다.

• Smart Structures and Systems
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• 제31권5호
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• pp.437-454
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• 2023

Real-time hybrid simulation (RTHS), which has the advantages of a substructure pseudo-dynamic test, is widely used to investigate the rate-dependent mechanical response of structures under earthquake excitation. However, time delay in RTHS can cause inaccurate results and experimental instabilities. Thus, this study proposes a model-based adaptive control strategy using a Kalman filter (KF) to minimize the time delay and improve RTHS stability and accuracy. In this method, the adaptive control strategy consists of three parts-a feedforward controller based on the discrete inverse model of a servohydraulic actuator and physical specimen, a parameter estimator using the KF, and a feedback controller. The KF with the feedforward controller can significantly reduce the variable time delay due to its fast convergence and high sensitivity to the error between the desired displacement and the measured one. The feedback control can remedy the residual time delay and minimize the method's dependence on the inverse model, thereby improving the robustness of the proposed control method. The tracking performance and parametric studies are conducted using the benchmark problem in RTHS. The results reveal that better tracking performance can be obtained, and the KF's initial settings have limited influence on the proposed strategy. Virtual RTHSs are conducted with linear and nonlinear physical substructures, respectively, and the results indicate brilliant tracking performance and superb robustness of the proposed method.

• 제어로봇시스템학회논문지
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• 제10권3호
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• pp.273-279
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• 2004

This research is concerned with the development of an Internet-based robot system, which is insensitive to the unpredictable internet time delay. For this purpose, a simple mobile robot system that moves in response to the user s direct control on the internet has been developed. The time delay in data transmission is an important problem for the construction of this kind of system. Therefore, the PPS (Position Prediction Simulator) is suggested and implemented to compensate for the time delay problem of the internet. The simulation and experimental results show that the distance error can be reduced using the developed PPS.