• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.1-3
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• 2006

This paper deals with a novel utilization method of the predicted current in the high performance PI current controller with a control time delay. The inevitable error of the predicted current in the linear servo drive using a permanent magnet linear synchronous motor is analyzed and a modified cross-coupling decoupling synchronous frame PI current controller is proposed in order to improve the current control response under the control time delay. Simulation and experimental results show that the proposed current controller has an improved current control performance under both the electrical uncertainties of a servo drive system and the control time delay.

• International Journal of Control, Automation, and Systems
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• v.2 no.4
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• pp.530-535
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• 2004

This paper deals with the unknown input observer (UIO) design problem for a class of linear time-delay systems. A case in which the observer error can completely be decoupled from an unknown input is treated. Necessary and sufficient conditions for the existences of such observers are present. Based on Lyapunov stability theory, thedesign of the observer with internal delay is formulated in terms of linear matrix inequalities (LMI). The design of the observer without internal delay is turned into a stabilization problem in linear systems. Two design algorithms of UIO are proposed. The effect of the proposed approach is illustrated by two numerical examples.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.1
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• pp.1-8
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• 2005

A new discretization algorithm for nonlinear systems with delayed input is proposed. The algorithm is represented by Taylor series expansion and ZOH assumption. This method is applied to the sampled-data representation of a nonlinear system with the time-delay input. Additionally, the delay in input is time varying and its amplitude is bounded. The maximum time-delay in input is assumed to be two sampling periods. The mathematical expressions of the discretization method are presented and the ability of the algorithm is tested for some of the examples. The computer simulation proves the proposed algorithm discretizes the nonlinear system with the variable time-delay input accurately.

• Proceedings of the IEEK Conference
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• 2002.06e
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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.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.140-145
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• 1994

In this paper, we consider a problem to estimate process parameters using input-output data collected from the process operating in closed-loop control system. When orders and delay-time of the process are known correctly, under some conditions of identifying experiments, it is reported that accurate identification results can be obtained by applying prediction error method. To get accurate estimates, it is necessary to know orders and delay-time of the process. It is difficult to determine them in closed-loop identification, because ill-condition for identification are easily caused by selection of unsuitable order or delay time. Furthermore, the procedures to select orders and delay-time in open-loop identification aren't always available in closed-loop identification. The purpose of this paper is to determine a delay-time under suitable assumption that order of the process are known as the first step.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.3
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• pp.149-156
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• 2000

Time delay observer (TDO), thanks to the time delay control (TDC) concept, requires little knowledge of a plant model, and hence is easy to design, robust to parameter variation and computationally efficient, yet can reconstruct states rather reliable for nonlinear plant. In this paper, we propose an improved version of TDO that solves two problems inherent in TDO as follows: TDO displays large reconstruction errors due to low-frequency uncertainty and has some restrictions on selecting its gains. By introducing a low pass filter and a state associated with it, we obtain an enhanced time delay observer (ETDO). This observer turns out to have smaller reconstruction errors than those of TDO and not to have any restriction on selecting its gains, thereby solving the problems. Through performance comparison by transfer function and simulation, we validate the analysis results of two observers (TDO and ETDO) and evaluate the performances. Finally, through experiments on BLDC motor system, the analysis results are clearly conformed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.11
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• pp.503-510
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• 1986

A new algorithm based on the concept of prediction error minimization is suggested to estimate the time varying delay in discrete processes. In spite of the existence of the stochastic noise, this algorithm can estimate time varying delay accurately. Computation time of this algorithm is far less than that of the previous extended parameter methods. With the use of this algorithm, generalized minimum variance control shows good control behavior in simulations.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.246-248
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• 2006

This paper is concerned with non-fragile guaranteed cost state feedback controller design algorithm for descriptor systems with time-varying delay and static state feedback controller with multiplicative uncertainty. The considered uncertainties are norm-bounded and time delay is time-varying. Under the condition of controller gain variations, conditions for the existence of controller satisfying asymptotic stability and non-fragility and controller design method are derived via LMI approach. Moreover, the measure of non-fragility and the upper bound to minimize guaranteed cost function are given.

• 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.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.3
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• pp.286-292
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• 2010

In this paper, we investigate the relationship between the performance of telerobotic systems and the two independent time-delay on different modality, which are haptic and video. Especially, we try to find some performance improvement when the amount of delay of haptic and video is synchronized. Experiments were conducted with 10 subjects by scanning the amount of video and haptic delay independently. It is rather interesting to note that the teleoperation performance was not that sensitive to video delay, and the synchronized video and haptic delay doesn't show better performance than the case when haptic delay is lower than video delay.