• Title/Summary/Keyword: Active Control

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Pole Assignment for Structural Active Control

  • Vongchavalitkul, Sanguan
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.5-7
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    • 2004
  • Significant progress has been achieved in the active control of civil-engineering structures, not only in the control algorithm, but also in control testing of the scaled model and full-scale building. At the present time, most algorithms used in the active control of civil engineering structures are based on the various active control techniques. In this paper represents active control method, by using pole assignment for reducing structural vibration under excited load. Numerical simulations are performed to assess the effectiveness of pole assignment control system. The relative displacement of structure system is significantly reduced.

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The Study of technique to find and prove vulnerabilities in ActiveX Control (ActiveX Control 취약점 검사 및 검증 기법 연구)

  • Sohn, Ki-Wook;Kim, Su-Yong
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.15 no.6
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    • pp.3-12
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    • 2005
  • To provide visitors with the various services, Many web sites distribute many ActiveX controls to them because ActiveX controls can overcome limits of HTML documents and script languages. However, PC can become dangerous if it has unsecure ActiveX controls, because they can be executed in HTML documents. Nevertheless, many web sites provide visitors with ActiveX controls whose security are not verified. Therefore, the verification is needed by third party to remove vulnerabilities in ActiveX controls. In this paper, we introduce the process and the technique to fad vulnerabilities. The existing proof codes are not valid because ActiveX controls are different from normal application and domestic environments are different from foreign environments. In this paper, we introduce the technique to prove vulnerabilities in ActiveX control.

The Study on the Security Model for ActiveX Control Management through Security Authentication (보안 인증을 통한 ActiveX Control 보안 관리 모델에 관한 연구)

  • Park, Sung-Yong;Moon, Jong-Sub
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.19 no.6
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    • pp.113-119
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    • 2009
  • In recent years, to provide visitors with the various and dynamic services, many ActiveX Controls are developed and distributed in most of the web sites such as e-Government Internet banking Portal in Korea. However, unsecure ActiveX Controls may be critical security threats on Internet User. Although hacking incidents increase sharply for these vulnerable ActiveX Controls, there are not enough national security actions or policies. Thus, in this paper we propose the technical method to design 'Security model for ActiveX Control Managemnet through Security Authentication' to be able safe and useful security management in three aspects of development distribution using.

Active Control of External Noise Radiated From Duct Using Sound Intensity (음향 인텐시티를 이용한 관 외부 방사 소음의 능동 제어)

  • 강성우;김양한
    • Journal of KSNVE
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    • v.7 no.3
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    • pp.427-437
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    • 1997
  • Mean active intensity based active control for the cancellation of radiated noise out of the duct exit is studied. The active intensity control strategy is drerived based on the relation of the exterior sound field out of the duct termination and interior sound field of the duct. One of the characteristics of this control strategy is that the control performance can be maintained regardless of the sensor loction, compared with the conventional local pressure control methods at either interior downstream or exterior field positions. It is also suggested that the digital filtering for the active intensity control can be achieved by time-domain filtered-x LMP (Lest-Mean-Product) adaptive algorithm. Experiments for an open-ended duct are performed to compare the active intensity control performance with conventional pressure control one. Active control experiment of local sound pressure is conducted by widely used filtered-x LMS adaptive Algorithm and active intensity control implementaion uses the derived filter d-x LMP algorithm. It is shown that the exterior sound fileds was much better observable by sensing of the active intensity than by just sound pressure. It is also demonstrated that the global control performance of external field by acoustic intensity is superior to the conventional sound pressure control performance.

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A semi-active stochastic optimal control strategy for nonlinear structural systems with MR dampers

  • Ying, Z.G.;Ni, Y.Q.;Ko, J.M.
    • Smart Structures and Systems
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    • v.5 no.1
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    • pp.69-79
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    • 2009
  • A non-clipped semi-active stochastic optimal control strategy for nonlinear structural systems with MR dampers is developed based on the stochastic averaging method and stochastic dynamical programming principle. A nonlinear stochastic control structure is first modeled as a semi-actively controlled, stochastically excited and dissipated Hamiltonian system. The control force of an MR damper is separated into passive and semi-active parts. The passive control force components, coupled in structural mode space, are incorporated in the drift coefficients by directly using the stochastic averaging method. Then the stochastic dynamical programming principle is applied to establish a dynamical programming equation, from which the semi-active optimal control law is determined and implementable by MR dampers without clipping in terms of the Bingham model. Under the condition on the control performance function given in section 3, the expressions of nonlinear and linear non-clipped semi-active optimal control force components are obtained as well as the non-clipped semi-active LQG control force, and thus the value function and semi-active nonlinear optimal control force are actually existent according to the developed strategy. An example of the controlled stochastic hysteretic column is given to illustrate the application and effectiveness of the developed semi-active optimal control strategy.

Experimental Study on the Performance of a Semi-Active Orificed Fluid Damper (반능동형 오리피스 유체댐퍼의 성능 실험)

  • 문석준;김병현;정종안
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2003.09a
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    • pp.387-394
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    • 2003
  • A compromise between passive and active control systems has been developed recently in the form of semi-active control systems. Semi-active control systems maintain the reliability of passive control systems while taking advantage of the adjustability of an active control system. This paper presents the results of an experimental study to evaluate the performance of a semi-active orificed fluid damper. The semi-active orificed fluid damper considered is a two-stage damper with normally open solenoid valve. Through a series of experimental tests, characteristics and performance of the damper is investigated.

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A Robust Semi-active Suspension Control Law (반능동 현가시스템의 Robust 제어 법칙)

  • Yi, K.S.;Suh, M.W.;Oh, T.I.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.6
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    • pp.117-126
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    • 1994
  • This paper deals with a robust semi-active control algorithm which is applicable to a semi-active suspension with a multi-state damper. Since the controllable damping rates are discrete in case of a multi-state semi-active damper, the desired damping rate can not be produced exactly even if force-velocity relations of a multi-state semi-active damper is completely known. In addition, damping characteristics of the semi-active dampers are different from damper to damper. A robust nonlinear control law based on sliding control is developed. The main objective of the proposed control strategies is to improve ride quality by tracking the desired active force with a multi-state damper of which the force-velocity relations are "not" completely known. The performance of th proposed semi-active control law is numerically compared to those of the control law based on a bilinear model and a passive suspension. The proposed control algorithm is robust to nonlinear characteristics and uncertainty of the force-Velocity relations of multi-state dampers.

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Design of Semi-Active Tendon for Vibration Control of Large Structures (대형 구조물의 진동제어를 위한 반능동형 댐퍼의 설계)

  • Kim, Saang-Bum;Yun, Chung-Bang;Gu, Ja-In
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.282-286
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    • 2000
  • In this paper, magneto-rheological(MR) damper is studied for vibration control of large infra structures under earthquake. Generally, active control devices need a large control force and a high power supply system to reduce the vibration effectively. Large and miss tuned control force may induce the dangerous situation such that the generated large control force acts to amplify the structural vibration. Recently, to overcome the weaknesses of the active control, the semi-active control method is suggested by many researchers. Semi-active control uses the passive control device of which the characteristics can be modified. Control force of the semi-active device is not generated from the actuator with power supply. It is generated as a dynamic reaction force of the device same as in the passive control case, so the control system is inherently stable and robust. Unlike the case of passive control, control force of semi-active control is adjusted depending on the measured response of the structure, so the vibration can be reduced more effectively against various unknown environmental loads. Magneto-rheological(MR) damper is one of the semi-active devices. Dynamic characteristics of the MR material can be changed by applying the magnetic fields. So the control of MR damper needs only small power. Response time of MR to the input voltage is very short, so the high performance control is possible. MR damper has a high force capacity so it is adequate to the vibration control of large infra structure. Because MR damper has a nonlinear property, normal control method used in active control may not be effective. Clipped optimal control, modified bang-bang control etc. have been suggested to MR damper by many researchers. In this study, sliding mode fuzzy control(SMFC) is applied to MR damper. Genetic algorithm is used for the controller tuning. To verify the applicability of MR damper and suggested algorithm, numerical simulation on the aseismic control is carried out. Simulation model is three-story building structure, which was used in the paper of Dyke, et al. The control performance is compared with clipped optimal control. The present results indicate that the SMFC algorithm can reduce the earthquake-induced vibration very effectively.

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Active Vibration Control Experiment of Cantilever Using Active Linear Actuator for Active Engine Mount (능동 엔진 마운트 제어용 Active Linear Actuator를 이용한 외팔보 능동진동제어 실험)

  • Yang, Dong-Ho;Kwak, Moon-K.;Kim, Jung-Hoon;Park, Woon-Hwan;Sim, Ho-Seok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.12
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    • pp.1176-1182
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    • 2010
  • Vibrations caused by automobile engine are absorbed mostly by a passive-type engine mount. However, user specifications for automobile vibrations require more stringent conditions and higher standard. Hence, active-type engine mount have been developed to cope with such specifications. The active-type engine mount consists of sensor, actuator and controller where a control algorithm is implemented. The performance of the active engine mount depends on the control algorithm if the sensor and actuator satisfies the specification. The control algorithm should be able to suppress persistent vibrations caused by the engine which are related to engine revolution. In this study, three control algorithms are considered for suppressing persistent vibrations, which are the positive position feedback control algorithm, the strain-rate feedback control algorithm, and the modified higher harmonic control algorithm. Experimental results show that all the control algorithms considered in this study are effective in suppressing resonant vibrations but the modified higher harmonic controller is the most effective controller for non-resonant vibrations.

Hydraulically Actuated of Half Car Active Suspension System

  • Sam, Yahaya Md.;Osman, Johari Halim Shah
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.1721-1726
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    • 2004
  • The studies of the half active suspension have been performed using various suspension models. In the early days, the modeling considered the inputs to the active suspension as the linear forces. Recently, due to the development of new control theory, the forces input to the half car active suspension system has been replaced by an actual input to the hydraulic actuators. Therefore, the dynamic of the active suspension system now consists of the dynamic of half car suspension system plus the dynamic of the hydraulic actuators. This paper proposed a new modeling technique in integrating both dynamic models. The proportional integral sliding mode control technique is utilized to control the hydraulically actuated of the half car active suspension system. The performance of the half car hydraulically actuated active suspension system is simulated with a bump input. The results show that the proposed modeling technique and the proportional integral sliding mode controller are improved the ride comfort and ride handling of the half car active suspension system.

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