• Title, Summary, Keyword: Open-loop control

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The Implementation and Experiments of Open-Loop Cylindrical Vibratory Gyroscope (개루프 제어의 실린더 진동형 자이로 구현 및 실험)

  • 공형직;김정엽;홍성경
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.8
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    • pp.669-672
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    • 2004
  • This paper considers the implementation and experiments of an open-loop Cylindrical Vibratory Gyroscope(CGV). An open-loop CGV composed of thin cylindrical vibrating element, electromagnetic drive and pick-off element with open-loop control was designed and fabricated. The experimental performance tests of the open-loop CGV were done using a temperature chambered rate table. Also, the limitations of open-loop CGV were analyzed and the solution for the limitations was proposed.

Open-Loop Control of Combustion Instability in Hot-Firing Test Using Gaseous Hydrocarbon Fuel (기체 탄화수소 연료 연소시험에서 연소불안정의 개루프 제어)

  • Hwang, Donghyun;Ahn, Kyubok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.6
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    • pp.28-36
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    • 2018
  • A study was conducted to apply open-loop control to the combustion instability in a dump combustor using gaseous hydrocarbon fuels. Control power and frequency were varied by employing a loudspeaker under combustion conditions with similar characteristic chemistry times of the fuels. In the case of open-loop control where the frequency was identical to the combustion instability frequency, the open-loop control power affected the control performance. Results obtained from conducted open-loop control tests, where the frequency was different from the combustion instability frequency, show that setting the open-loop control frequency similar to the combustion instability frequency is effective.

Development of a full-scale magnetorheological damper model for open-loop cable vibration control

  • Zhang, Ru;Ni, Yi-Qing;Duan, Yuanfeng;Ko, Jan-Ming
    • Smart Structures and Systems
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    • v.23 no.6
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    • pp.553-564
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    • 2019
  • Modeling of magnetorheological (MR) dampers for cable vibration control to facilitate the design of even more effective and economical systems is still a challenging task. In this study, a parameter-adaptive three-element model is first established for a full-scale MR damper based on laboratory tests. The parameters of the model are represented by a set of empirical formulae in terms of displacement amplitude, voltage input, and excitation frequency. The model is then incorporated into the governing equation of cable-damper system for investigation of open-loop vibration control of stay cables in a cable-stayed bridge. The concept of optimal voltage/current input achieving the maximum damping for the system is put forward and verified. Multi-mode suboptimal and Single-mode optimal open-loop control method is then developed. Important conclusions are drawn on application issues and unique characteristics of open-loop cable vibration control using MR dampers.

The Implementation of Train Diagram Modeling in the Open-loop Metro Line (Open-loop Metro Line에서의 열차 운전도 모델링의 구현)

  • Hong, H.S.;Yoo, K.K.;Lee, T.S.;Moon, Y.H.
    • Proceedings of the KIEE Conference
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    • pp.527-530
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    • 1995
  • In this paper, traffic modeling and control design was considered to analyze and improve the stability of train diagram in the open-loop Metro line. A complete discrete-event traffic model describing the natural instability of open-loop metro line is analyzed. The traffic stability properties are introduced and easy-to-implement state feed back traffic control algorithms are designed, which satisfied with system stability.

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Design formulas for vibration control of taut cables using passive MR dampers

  • Duan, Yuanfeng;Ni, Yi-Qing;Zhang, Hongmei;Spencer, Billie.F. Jr.;Ko, Jan-Ming;Fang, Yi
    • Smart Structures and Systems
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    • v.23 no.6
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    • pp.521-536
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    • 2019
  • Using magnetorheological (MR) dampers in multiswitch open-loop control mode has been shown to be cost-effective for cable vibration mitigation. In this paper, a method for analyzing the damping performance of taut cables incorporating MR dampers in open-loop control mode is developed considering the effects of damping coefficient, damper stiffness, damper mass, and stiffness of the damper support. Making use of a three-element model of MR dampers and complex modal analysis, both numerical and asymptotic solutions are obtained. An analytical expression is obtained from the asymptotic solution to evaluate the equivalent damping ratio of the cable-damper system in the open-loop control mode. The individual and combined effects of the damping coefficient, damper stiffness, damper mass and stiffness of damper support on vibration control effectiveness are investigated in detail. The main thrust of the present study is to derive a general formula explicitly relating the normalized system damping ratio and the normalized damper parameters in consideration of all concerned effects, which can be easily used for the design of MR dampers to achieve optimal open-loop vibration control of taut cables.

Feedback Control for Expanding Range and Improving Lineraity of Microaccelerometers (가속도계의 동작범위 확장와 선형성 향상을 위한 피드백 제어)

  • Park, Yong-Hwa;Park, Sang-Jun;Choi, Byung-Doo;Ko, Hyoung-Ho;Song, Tae-Yong;Lim, Genu-Won;Huh, Kun-Soo;Park, Jahng-Hyon;Cho, Dong-il
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.11
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    • pp.1082-1088
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    • 2004
  • This paer presents a feedback-controlled, MEMS-fabricated microaccelerometer($\mu$XL). The $\mu$XL has received much commercial attraction, but its performance is generally limited. To improve the open-loop performance, a feedback controller is designed and experimentally evaluated. The feedback controller is applied to the x/y-axis $\mu$XL fabricated by sacrificial bulk micromachining(SBM) process. Even though the resolution of the closed-loop system is slightly worse than open-loop system, the bandwidth, linearity, and bias stability are stability are significantly improved. The noise equivalent resolution of open-loop system is 0.615 mg and that of closed-loop system is 0.864 mg. The bandwidths of open-loop and closed-loop system are over 100Hz. The input range, non-linearity and bias stability are improved from $\pm10\;g\;to\;\pm18g$, from 11.1%FSO to 0.86%FSO, and from 0.221 mg to 0.128 mg by feedback control, respectively.

Feedback Control for Expanding Range and Improving Linearity of Microaccelerometers

  • Park, Yong-Hwa;Shim, Joon-Sub;Park, Sang-Jun;Kwak, Dong-Hun;Ko, Hyoung-Ho;Song, Tae-Yong;Huh, Kun-Soo;Park, Jahang-Hyon;Cho, Dong-Il
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1706-1710
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    • 2004
  • This paper presents a feedback-controlled, MEMS-fabricated microaccelerometer (${\mu}$XL). The ${\mu}$XL has received much commercial attraction, but its performance is generally limited. To improve the open-loop performance, a feedback controller is designed and experimentally evaluated. The feedback controller is applied to the x/y-axis ${\mu}$XL fabricated by sacrificial bulk micromachining (SBM) process. Even though the resolution of the closed-loop system is slightly worse than open-loop system, the bandwidth, linearity, and bias stability are significantly improved. The noise equivalent resolution of open-loop system is 0.615 mg and that of closed-loop system is 0.864 mg. The bandwidths of open-loop and closed-loop system are over 100 Hz. The input range, non-linearity and bias stability are improved from ${\pm}$10 g to ${\pm}$18 g, from 11.1 %FSO to 0.86 %FSO, and from 0.221 mg to 0.128 mg by feedback control, respectively

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Electrically-induced actuation for open-loop control to cancel self-excitation vibration

  • Makihara, Kanjuro;Ecker, Horst
    • Smart Structures and Systems
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    • v.9 no.2
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    • pp.189-206
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    • 2012
  • This paper focuses on the actuation system combined with a piezoelectric transducer and an electric circuit, which leads to a new insight; the electric actuation system is equivalent to mechanical variable-stiffness actuation systems. By controlling the switch in the circuit, the electric status of the piezoelectric transducer is changed, and consequently a variable-stiffness mechanism is achieved on the electric actuator. This proposed actuator features a shift in the equilibrium point of force, while conventional electrically-induced variable-stiffness actuators feature the variation of the stiffness value. We intensively focus on the equilibrium shift in the actuation system, which has been neglected. The stiffness of the variable-stiffness actuator is periodically modulated by controlling the switch, to suppress the vibration of the system in an open-loop way. It is proved that this electric actuator is equivalent to its mechanical counterpart, and that the electrical version has some practical advantages over the mechanical one. Furthermore, another kind of electrically-induced variable-stiffness actuator, using an energy-recycling mechanism is also discussed from the viewpoint of open-loop vibration control. Extensive numerical simulations provide comprehensive assessment on both electrically-induced variable-stiffness actuators employed for open-loop vibration control.

Constraint handling optimal PI control of open-loop unstable process: Analytical approach

  • Tchamna, Rodrigue;Lee, Moonyong
    • The Korean Journal of Chemical Engineering
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    • v.34 no.12
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    • pp.3067-3076
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    • 2017
  • This paper proposes the closed-form analytical design of proportional-integral (PI) controller parameters for the optimal control of an open-loop unstable first order process subject to operational constraints. The main idea of the design process is not only to minimize the control performance index, but also to cope with the constraints in the process variable, controller output, and its rate of change. To derive an analytical design formula, the constrained optimal control problem in the time domain was transformed to an unconstrained optimization in a parameter space associated with closed-loop dynamics. By taking advantage of the proposed analytical approach, a convenient shortcut algorithm was also provided for finding the optimal PI parameters quickly, based on the graphical analysis for the optimal solution of the corresponding optimization problem in the parameter space. The resulting optimal PI controller guarantees the globally optimal closed-loop response and handles the operational constraints precisely.

Feedback Loop Design for Micro Gyroscope

  • Sung, Woon-Tahk;Song, Jin-Woo;Lee, Jang-Gyu;Taesam Kang
    • 제어로봇시스템학회:학술대회논문집
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    • pp.39.4-39
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    • 2002
  • This paper presents a design and implementation of a PID feedback control loop for micro gyroscope. The feedback control loop improves the gyroscope performance such as linearity, bandwidth, and bias stability for micro gyroscope which is basically a high-Q system and exhibits a low performance with an open loop control. The designed and implemented feed-back control loop is applied to the SNU-Bosch MEMS gyroscope to demonstrate the improvement with the feedback control loop. The bandwidth is improved to 60Hz from 25Hz of open loop control. The linearity becomes 0.5% from 1%. The bias stability is improved to 0.03 deg/sec from 0.06 deg/sec.

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