• Title/Summary/Keyword: time-delay

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Stability Analysis of Time Delay Controller for General Plants (일반적인 플랜트에 대한 시간지연을 이용한 제어기법의 안정성 해석)

  • Kwon, Oh-Seok;Chang, Pyung-Hun;Jung, Je-Hyung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.6
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    • pp.1035-1046
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    • 2002
  • Time Delay Control(TDC) is a robust nonlinear control scheme using Time Delay Estimation(TDE) and also has a simple structure. To apply TDC to a real system, we must design Time Delay Controller to guarantee stability. The earlier research stated sufficient stability condition of TDC for general plants. In that research, it was assumed that time delay is infinitely small. But, it is impossible to implement infinitely small time delay in a real system. So, in this research we propose a new sufficient stability condition of TDC for general plants with finite time delay. And the simulation results indicate that the previous sufficient stability condition does not work even for small time delay, while our proposed condition works well.

Extraction of Optimal Time-Delay in Adaptive Command Shaping Filter for Flexible Manipulator Control (유연한 매니퓰레이터 제어를 위한 적응형 명령성형 필터의 최적 시간지연 값 추출)

  • Park, Joo-Han;Rhim, Sung-Soo
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.6
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    • pp.564-572
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    • 2008
  • The performance of the direct adaptive time-delay command shaping filter depends on the select time-delay. In the previously introduced direct adaptive command shaping filter, however, the time-delay value is fixed and only the magnitudes of the impulses are learned. In this paper, the authors introduce a new scheme to adapt the time-delay which is to be used in conjunction with the direct adaptive command shaping for the improved vibration suppression in flexible motion system. In order to formulate the time-delay adaptation scheme, the authors have analyzed the effect of the time-delay value on the performance of the direct adaptive command shaping filter. By modifying the direct adaptation formula based on the analysis result the authors have established a set of equations to adapt the time-delay toward the optimal value. Simulation results show the effectiveness of the proposed time-delay adaptation approach for the improved vibration suppression.

Active control of a nonlinear and hysteretic building structure with time delay

  • Liu, Kun;Chen, Long-Xiang;Cai, Guo-Ping
    • Structural Engineering and Mechanics
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    • v.40 no.3
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    • pp.431-451
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    • 2011
  • Time delay inevitably exists in active control systems, and it may cause the degradation of control efficiency or instability of the systems. So time delay needs to be compensated in control design in order to eliminate its negative effect on control efficiency. Today time delay in linear systems has been more studied and some treating methods had been worked out. However, there are few treating methods for time delay in nonlinear systems. In this paper, an active controller for a nonlinear and hysteretic building structure with time delay is studied. The nonlinear and hysteretic behavior of the system is illustrated by the Bouc-Wen model. By specific transformation and augmentation of state parameters, the motion equation of the system with explicit time delay is transformed into the standard state space representation without any explicit time delay. Then the fourth-order Runge-Kutta method and instantaneous optimal control method are applied to the controller design with time delay. Finally, numerical simulations and comparisons of an eight-story building using the proposed time-delay controller are carried out. Simulation results indicate that the control performance will deteriorate if time delay is not taken into account in the control design. The simulations also prove the proposed time delay controller in this paper can not only effectively compensate time delay to get better control effectiveness, but also work well with both small and large time delay problems.

Active control of a flexible structure with time delay

  • Cai, Guo-Ping;Yang, Simon X.
    • Structural Engineering and Mechanics
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    • v.20 no.2
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    • pp.191-207
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    • 2005
  • Time delay exists inevitably in active control, which may not only degrade the system performance but also render instability to the dynamic system. In this paper, a novel active controller is developed to solve the time delay problem in flexible structures. By using the independent modal space control method, the differential equation of the controlled mode with time delay is obtained from the time-delay system dynamics. Then it is discretized and changed into a first-order difference equation without any explicit time delay by augmenting the state variables. The modal controller is derived based on the augmented system using the discrete variable structure control method. The switching surface is determined by minimizing a discrete quadratic performance index. The modal coordinate is extracted from sensor measurements and the actuator control force is converted from the modal one. Since the time delay is explicitly included throughout the entire controller design without any approximation, the system performance and stability are guaranteed. Numerical simulations show that the proposed controller is feasible and effective in active vibration control of dynamic systems with time delay. If the time delay is not explicitly included in the controller design, instability may occur.

Compensation Technique of Measurement Time Delay in Transfer Alignment Using the Double Moving Window Buffer (이중 Moving Window 버퍼 기반 전달정렬 측정치 시간지연 보상기법)

  • Kim, Cheon-Joong;Lyou, Joon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.4
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    • pp.684-693
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    • 2011
  • Measurement time delay in the transfer alignment is very important. It has been well known that the time delay degrades the alignment performance and makes some navigation errors on the transfer alignment of slave INS(SINS). Therefore there are many schemes to eliminate that time delay but the compensation technique through the estimation by Kalman filter through modeling the time delay as a random constant is generally used. In the case of change over measurement time delay or the large measurement time delay, estimation performance in the existing compensation technique is degraded because model of time delay is not correct any more. In this paper, we propose the method to keep the time delay almost constant even though in the abnormal communication state and very small through feedback compensation using double buffer. Double buffer consists of two moving window to temporarily store measurements from master INS and slave INS in real time.

Loop transfer recovery design for input-delayed systems (입력 시간지연 시스템의 루우프 전달복구 설계 기법)

  • 박상현;이상정
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.1201-1204
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    • 1996
  • The previous results on LTR methods for time delay systems need the solution of the operator-type Riccati equation. In addition, it can be difficult to make the target loop shape representing the design specification. This paper proposes a new LTR method for input-delayed systems using well-established LTR method for non-delay systems. For doing this, a time delay margin is derived and the time delay of the input-delayed systems is assumed less than equal to the time delay margin. A simple example is presented for illustrations.

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Analysis of Effects of Time-Delay in an Inverted Pendulum System Using the Controller Area Network

  • Cho, Sung-Min;Hong, Suk-Kyo
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.1474-1479
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    • 2004
  • In this paper, the design of the network system using the CAN and the analysis of effects of time delay in the system are presented. A conventional implementation technique induces many problems because of the amount and complexity of wiring and maintenance problems. The network system reduces these problems, but it cause another problem; time delay. Time delay in a sampling time does not have much effects on the system, but time delay over the sampling time changes the control frequency and ended up makes the system unstable. It is verified that time delay between each parts has different effects on the entire system. The results from this paper will be a base for studying algorithms to reduce effects of time delay in the system using the CAN.

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A stochastic optimal time-delay control for nonlinear structural systems

  • Ying, Z.G.;Zhu, W.Q.
    • Structural Engineering and Mechanics
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    • v.31 no.5
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    • pp.621-624
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    • 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.

Adaptation of Time-Belay in Command Shaping Filter for Vibration Suppression in Flexible Motion System (유연체 모션시스템의 진동억제를 위한 명령성형필터의 시간지연 값 학습)

  • Park J.H.;Rhim S.S.;Lee S.G.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.43-44
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    • 2006
  • The performance of the direct adaptive time-delay filter depends on the select time-delay. In this paper, the authors introduce a new scheme to adapt the time-delay which is to be used in conjunction with the direct adaptive command shaping for the improved vibration suppression in flexible motion system. In order to formulate the time-delay adaptation scheme, the authors have analyzed the effect of the time-delay value on the performance of the direct adaptive command shaping filter. By modifying the direct adaptation formula based on the analysis result the authors have established a set of equations to adapt the time-delay toward the optimal value. Simulation results show the effectiveness of the proposed time-delay adaptation approach for the improved vibration suppression.

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Effects of the time delay on the stability of a virtual wall model with a first-order-hold method (시간지연에 의한 일차홀드 방식을 포함하는 가상벽 모델의 안정성 영향 분석)

  • Lee, Kyungno
    • Journal of Institute of Convergence Technology
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    • v.4 no.2
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    • pp.17-21
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    • 2014
  • This paper presents the effects of the time delay on the stability of the haptic system that includes a virtual wall and a first-order-hold method. The model of a haptic system includes a haptic device model with a mass and a damper, a virtual wall model, a first-order-hold model and a time delay model. In this paper, the time delay is considered as the computational time delay that is assumed to be as much as the sampling time. As the time delay increases, the maximal available stiffness of a virtual wall model is reduced reversely. The relation among the time delay and the maximum available stiffness, the mass and the damper of the haptic device are analyzed using the MATLAB simulation.