• Title, Summary, Keyword: time-delay system

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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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    • 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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Analysis of Response Characteristics of the CAN-Based Feedback Control System Considering the Network Delay Time

  • Jeon, Jong-Man;Kim, Dae-Won
    • 제어로봇시스템학회:학술대회논문집
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    • pp.119.3-119
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    • 2001
  • When building a network-based real-time control system, a network-induced delay time should be surly considered for real time schedulability to be guaranteed. The network delay time on end-to-end communication has been analyzed theoretically and modeled mathematically from many previous works. There also exist any other delay element not considered before. In this paper, the remote feedback control system using the CAN protocol is proposed to control three axes´ manipulator arm and the application layer of CAN is modeled to analyze the delay elements defined by three types of time delay: Software delay time, Controller delay time, and Access delay time, in details. The analyzed results are used as an important component to determine PID gains of the proposed system. The effect of the delay time on the control performance is evaluated by com paring the response characteristics of the control system through simulation.

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Discrete Representation Method of Nonlinear Time-Delay System in Control

  • Park, Ji-Hyang;Chong, Kil-To
    • 제어로봇시스템학회:학술대회논문집
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    • pp.327-332
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    • 2003
  • A new discretization method for nonlinear system with time-delay is proposed. It is based on the well-known Taylor series expansion and the zero-order hold (ZOH) assumption. We know that a discretization of linear system can be obtained with the ZOH assumption and within the sampling interval. A similar line of thinking is available in nonlinear case. The mathematical structure of the new discretization method is explored and under the structure, the sampled-data representation of nonlinear system including time-delay is computed. Provided that the discrete form of the single input nonlinear system with time-delay is derived, this result is easily extended to nonlinear system with multi-input time-delay. For simplicity two inputs are considered in this study. It is enough to generalize that of multiple inputs. Finally, the time-discretization of non-affine nonlinear system with time-delay is investigated for apply all nonlinear system

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A Study on the Measurement Time-Delay Estimation of Tightly-Coupled GPS/INS system (강결합방식의 GPS/INS 시스템에 대한 측정치 시간지연 추정 연구)

  • Lee, Youn-Seon;Lee, Sang-Jeong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.11 no.4
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    • pp.116-123
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    • 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.

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.

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.

Compensation of Time Delay in Induction Motor Vector Control System Using DQ Transformation (유도전동기 벡터제어 시스템에서 DQ변환을 이용한 시간지연 보상)

  • 최병태;권우현;박철우
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.12
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    • pp.1001-1008
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    • 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.

Control of a Flexible Link with Time Delays

  • Choi, Hyoun-Chul;Hong, Suk-Kyo
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1136-1141
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    • 2004
  • This paper presents a control method for time-delay systems and verifies the performance of the designed control system via real experiments. Specifically, the control method is applied to a flexible-link system with time delays. The method combines time- and frequency-domain controllers: linear quadratic optimal controller (or LQR) and lag compensator. The LQR is used to stabilize the system in optimal fashion, whereas the lag compensator is used to compensate time-delay effects by increasing the delay margin of the system. With this methodology, the maximum allowable time delay can be increased significantly. The proposed method is simple but quite practical for time-delay system control as it is based on the conventional loop-shaping method, which gives practical insights on delay-phase relationship. Simulation and experiment results show that the method presented in this paper is feasible and practical.

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Analysis for the Stability of a Haptic System with the Computational Time-varying Delay (가변적인 계산시간지연에 의한 햅틱 시스템에서의 안정성 영향 분석)

  • Lee, Kyungno
    • Journal of Institute of Convergence Technology
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    • v.5 no.2
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    • pp.37-42
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    • 2015
  • This paper presents the effects of the computational time-varying 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 computational time-varying delay model. In this paper, the maximum of the computational time-varying delay is assumed to be as much as the sampling time. Using the simulation, it is analyzed how the sample-hold methods and the computational time-varying delay affect the maximum available stiffness. As the maximum of computational time-varying delay increases, the maximal available stiffness of a virtual wall model is reduced.

Engine torque and engine/automatic trandmission speed control systems using time delay control (시간지연 제어를 이용한 엔진 토크 및 엔진/자동변속기 속도 제어 시스템)

  • Song, Jae-Bok;Lee, Seung-Man
    • Journal of Institute of Control, Robotics and Systems
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    • v.2 no.2
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    • pp.81-87
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    • 1996
  • Time delay control(TDC) law has been recently suggested as an effective control technique for nonlinear time-varying systems with uncertain dynamics and/or unpredictable disturbances. This paper focuses on the applications of the TDC algorithm to torque control of an engine system and speed control of an engine/automatic transmission system. Through the stability analysis of the engien system based on TDC, determination of the appropriate time delay and control factor is investigated. It was revealed that the size of time delay of the TDC law should be greater than that of transport delay of the system for both stability and better control performance. Simulation and experimental results for the engine torque control and engine/automatic transmission speed control systems show both relatively good command following and disturbance rejection properties. However, TDC controller shows rather slow responses when applied to the system with large transport delay.

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