• 한국소음진동공학회논문집
• /
• 제18권8호
• /
• pp.823-831
• /
• 2008

Since it needs the light computational load and small database, sound source localization method using time delay of arrival(TDOA method) is applied at many research fields such as a robot auditory system, teleconferencing and so on. Researches for time delay estimation, which is the most important thing of TDOA method, had been studied broadly. However studies about factors for time delay estimation are insufficient, especially in case of real environment application. In 1997, Brandstein and Silverman announced that performance of time delay estimation deteriorates as reverberant time of room increases. Even though reverberant time of room is same, performance of estimation is different as the specific part of signals. In order to know that reason, we studied and analyzed the factors for time delay estimation using speech signal and room impulse response. In result, we can know that performance of time delay estimation is changed by different R/D ratio and signal characteristics in spite of same reverberant time. Also, we define the performance index(PI) to show a similar tendency to R/D ratio, and propose the method to improve the performance of time delay estimation with PI.

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

• Structural Engineering and Mechanics
• /
• 제31권5호
• /
• pp.621-624
• /
• 2009

The time delay in active and semi-active controls is an important research subject. Many researches on the time-delay control for deterministic systems have been made (Hu and Wang 2002, Yang et al. 1990, Abdel-Mooty and Roorda 1991, Pu 1998, Cai and Huang 2002), while the study on that for stochastic systems is very limited. The effects of the time delay on the control of nonlinear systems under Gaussian white noise excitations have been studied by Bilello et al. (2002). The controlled linear systems with deterministic and random time delay subjected to Gaussian white noise excitations have been treated by Grigoriu (1997). Recently, a stochastic averaging method for quasi-integrable Hamiltonian systems with time delay has been proposed (Liu and Zhu 2007). In the present paper, a stochastic optimal time-delay control method for stochastically excited nonlinear structural systems is proposed based on the stochastic averaging method for quasi Hamiltonian systems with time delay and the stochastic dynamical programming principle. An example of stochastically excited and controlled hysteretic column is given to illustrate the proposed control method.

• 한국통신학회논문지
• /
• 제37권5B호
• /
• pp.365-369
• /
• 2012

동기식 고속 광전송망에서 망간 delay보상을 통한 동기제어는 매우 중요하다. 본 연구에서는 광선로의 길이에 따른 time delay를 보상하기 위하여 Rayleigh 산란광을 이용한 OTDR방식의 delay 측정장치를 제작하여 평균화 횟수와 광펄스의 peak power에 따른 파형변화를 관찰하고 기존에 활용되고 있는 방식과의 정확도에 대한 비교측정을 통해 실제 시스템에 적용타당성에 대한 검증실험을 실시한 결과 최대 0.06usec 이내의 측정오차와 0.021usec의 측정표준편차로서 이동통신 광중계기와 기지국 장비간 delay 제어에 적용이 가능함을 확인하였다.

• 제어로봇시스템학회논문지
• /
• 제4권3호
• /
• pp.295-300
• /
• 1998

In this paper, we point out the possibility of the divergence of control input caused by the estimation error of delay-time when general iterative learning algorithms are applied to a class of linear dynamic systems with time-delay in which delay-time is not exactly measurable, and then propose a new type of iterative learning algorithm in order to solve this problem. To resolve the uncertainty of delay-time, we propose an algorithm using holding mechanism which has been used in digital control system and/or discrete-time control system. The control input is held as constant value during the time interval of which size is that of the delay-time uncertainty. The output of the system tracks a given desired trajectory at discrete points which are spaced auording to the size of uncertainty of delay-time with the robust property for estimation error of delay-time. Several numerical examples are given to illustrate the effeciency of the proposed algorithm.

• 한국군사과학기술학회지
• /
• 제11권4호
• /
• pp.116-123
• /
• 2008

In this paper we study the performance of the measurement time-delay estimation of tightly-coupled GPS/INS(Global positioning system/Inertial Navigation system) system. Generally, the heading error estimation performance of loosely-coupled GPS/INS system using GPS's Navigation Solution is poor. In the case of tightly-coupled GPS/INS system using pseudo-range and pseudo-range rate, the heading error estimation performance is better. However, the time-delay error on the measurement(pseudo-range rate) make the heading error estimation performance degraded. So that, we propose the time-delay model on the measurement and compose the time-delay estimator. And we confirm that the heading error estimation performance in the case of measurement time-delay existence is similar with the case of no-delay by Monte-Carlo simulation.

• 제어로봇시스템학회논문지
• /
• 제9권12호
• /
• pp.1001-1008
• /
• 2003

A time-delay compensation method for vector control system is proposed that can compensate for voltage and current distortions resulting from a time delay in the overall system due to the low pass filter, hysteresis control inverter, microprocessor program computation time, and so on. The proposed scheme estimates the time delay using the difference between the Q-axis stator current command and the time-delayed actual Q-axis stator current in a synchronous reference frame, then compensates the time delay in the voltage and current using the angular displacement of a DQ transformation. Accordingly, the proposed scheme can accurately compensate for the time delay related to the overall system, thereby significantly improving the performance of the vector control system, as verified by simulation and experiment.

• Journal of Power Electronics
• /
• 제12권5호
• /
• pp.715-722
• /
• 2012

New discrete time domain models for the peak current controlled (PCC) power LED drivers in continuous conduction mode include for the first time the effects of the time delay in the pulse-width-modulator. Realistic amounts of time delay are found to have significant effects on the average output LED current and on the critical inductor value at the boundary between the two conduction modes. Especially, the time delay can provide an accurate LED current for the PCC buck converter with a wide input voltage. The models can also predict the critical inductor value at the mode boundary as functions of the input voltage and the time delay. The overshoot of the peak inductor current due to the time delay results in the increase of the average output current and the reduction of the critical inductor value at the mode boundary in all converters. Experimental results are presented for the PCC buck LED driver with constant-frequency controller.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제51권2호
• /
• pp.43-47
• /
• 2002

Stability conditions of time-varying discrete state delay systems are proposed. The time-varying state delay is assumed that (i) the magnitude is known to lie in a certain interval (ii) the upper bound of the rate of change is known. Under these conditions, new stability conditions are derived based on switched Lyapunov functions. Stability conditions for both fast time-varying and slowly time-varying delay are considered.

• 화약ㆍ발파
• /
• 제41권4호
• /
• pp.41-50
• /
• 2023

본 연구에서는 굴착 물량 증대와 발파공해 저감을 위해서 전자뇌관을 이용한 수직방향 더블 데크 공법을 적용하였다. 더블 데크 공법은 상부 데크 발파 후 자유면이 완전히 형성되지 않은 상태에서 하부 데크 발파가 진행되면 발파 효율이 감소할 가능성이 있다. 이와 같은 이유로 더블 데크 공법은 데크 단차에 따라서 발파 효율이 달라진다. 따라서 본 연구에서는 홀 단차의 1~5배를 적용한 4가지 데크 단차를 제안하였고, 발파 후 파쇄도 분석을 통해 발파 효율을 평가하였다. 파쇄도 평가 결과 패턴 4(데크 단차=홀 단차×5)의 파쇄도가 가장 좋았으며, 패턴 3(데크 단차=홀 단차×3) 이상에서 파쇄효율이 큰 폭으로 증가하는 것을 확인할 수 있었다. 이에 따라 수직방향 더블 데크 발파 시 데크 단차는 최소 홀 단차의 3배 이상이 되어야 효율적인 발파 효과를 얻을 수 있다고 분석되었다.