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LQG/LTR Control of Hydraulic Positioning System with Dead-zone (사역대가 포함된 유압 위치 시스템의 LQG/LTR 제어)

  • Kim, Ki-Bum;Kim, Yeung-Shik;Kim, In-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.614-619
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    • 2012
  • A LQG/LTR(Linear Quadratic Gaussian/Loop Transfer Recovery) controller with an integrator is designed to control the electro-hydraulic positioning system. Without considering the nonlinearity in the dead-zone, computer simulations are performed and show good performances and tracking abilities with the feedback controller based on the linear system model. However, the performance of the closed loop hydraulic positioning system shows big steady-state error in real system because of the dead-zone. In this paper, the feedback controller with a nonlinear compensator is introduced to overcome the dead-zone phenomenon in hydraulic systems. The inverse dead-zone as a nonlinear compensator is used to cancel out the dead-zone phenomenon. Experimental tests are performed to verify the performance of the controller.

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LQG/LTR Control of Hydraulic Positioning System with Dead-zone (사역대가 포함된 유압 위치 시스템의 LQG/LTR 제어)

  • Kim, In-Soo;Kim, Yeung-Shik;Kim, Ki-Bum
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.8
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    • pp.729-735
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    • 2012
  • A LQG/LTR(linear quadratic Gaussian/loop transfer recovery) controller with an integrator is designed to control the electro-hydraulic positioning system. Without considering the nonlinearity in the dead-zone, computer simulations are performed and show good performances and tracking abilities with the feedback controller based on the linear system model. However, the performance of the closed loop hydraulic positioning system shows big steady-state error in real system because of the dead-zone. In this paper, the feedback controller with a nonlinear compensator is introduced to overcome the dead-zone phenomenon in hydraulic systems. The inverse dead-zone as a nonlinear compensator is used to cancel out the dead-zone phenomenon. Experimental tests are performed to verify the performance of the controller.

An Upper Bound Analysis of the Shapes of the Dead Metal Zone and the Curving Velocity Distribution in Eccentric Plane Dies Extrusion (평다이를 사용한 편심 압출가공에서의 비유동 영역의 형상과 굽힘 속도 분포에 관한 상계해석)

  • Kim, Jin-Hoon;Jin, In-Tai
    • Transactions of Materials Processing
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    • v.7 no.2
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    • pp.177-185
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    • 1998
  • The kinematically admissible veolcity field is developed for the shapes of dead metal zone and the curving velocity distribution in the eccentric plane dies extrusion. The shape of dead metal zone is defined as the boundary surface with the maximum friction constant between the deformable zone and the rigid zone. The curving phenomenon in the eccentric lane dies is caused by the eccentricity of plane dies. The axial velocity distribution in the plane dies is divided in to the uniform velocity and the deviated velocity. The deviated velocity is linearly changed with the distance from the center of cross-section of the workpiece. The results show that the curvature of products and the shapes of the dead metal one are determined by the minimization of the plastic work and that the curvature of the extruded products increase with the eccentricity.

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A Study on Dead-Zone Turbine Control System (불감대 특성을 지닌 터빈제어 계통에 관한 연구)

  • Hwang, Jae-Ho;Lee, Sang-Hyug;Seo, Jin-Heon
    • Proceedings of the KIEE Conference
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    • pp.332-336
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    • 1989
  • This paper describes the nonlinear analysis and effectual operation methods of thermal power plant turbine control system. When the turbine control governor system has dead-zone characteristic, the effectual frequency development control is difficult, because turbine output does not correspond to frequency deviation in dead-zone. Therefore to obtain effectual correspondance, the turbine dead-zone characteristic must be analyzed by proper method. This paper proposes this nonlinear analysis and effectual plant operating load.

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Rigid Plasticity Finite Element Analysis of the Bending of Extrusion Product Using the Square dies (2차원평원 압출가공의 굽힘에 관한 강소성 유한요소 해석)

  • 박대윤
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.80-83
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    • 1999
  • Rigid Plasticity Finite Element Analysis is developed for the shapes of dead metal zone and the curving velocity distribution in the eccentric square dies extrusion. The shape of dead metal zone is defined as the boundary surface with the maximum friction constant between the deformable zone and the rigid zone. The curving phenomenon in the eccentric square dies is caused by the eccentricity of square dies. The deviated velocity is changed with the distance form the center of cross-section of the workpiece. The results show that the curving of products and the shapes of the dead metal zone are determined by Rigid Plasticity Finite Element Analysis and that the curvature of the extruded products increases with the eccentricity.

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An Upper Bound Analysis of the Shapes of the Dead Metal Zone and the Curving Velocity Distribution in Eccentric Plane Dies Extrusion (평다이를 사용한 편심압출가공에서의 비유동영역의 형상과 굽힘속도분포에 관한 상계해석)

  • 김진훈;진인태
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.250-253
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    • 1998
  • The kinematically admissible velocity field is developed for the shapes of dead metal zone and the curving velocity distribution in the eccentric plane dies extrusion. The shape of dead metal zone is defined as the boundary surface with the maximum friction constant between the deformable zone and the rigid zone. The curving phenomenon in the eccentric plane dies is caused by the eccentricity of plane dies. The axial velocity distribution in the plane dies is divided in to the uniform velocity and the deviated velocity. The deviated velocity is linearly changed with the distance from the center of cross-section of the workpiece. The results show that the curvature of products and the shapes of the dead metal zone are determined by the minimization of the plastic work and that the curvature of the extruded products increases with the eccentricity.

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Performance Analysis of a Cascaded Interference Canceller using Dead Zone Decision for DS/CDMA System (DS/CDMA 시스템에서 Dead Zone 검출방식을 이용한 직렬 간섭제거의 성능분석)

  • Lee, Sang-Hun;Kim, Nam
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.5
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    • pp.689-696
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    • 2000
  • In this paper, the cascaded co-channel interference canceller using the dead zone decision is proposed to reduced the co-channel interference in the DS/CDMA communication with the multipath fading and its performance is analyzed. The cancellation scheme creates the replica of the co-channel interference using the data decision of correlator output and removes it at the next stage. The canceller uses the dead zone decision which is detecting strong signal to obtain a good performance in the mobile communication. The results of performance analysis show that the proposed cancellation scheme has the improved performance and the number of user is increased 4 times compared with the conventional receiver, and increased 17% compared with the hard decision. And also the perfect power control is required along with increasing the number of user.

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Quasi-LQG/$H_{infty}$/LTR Control for a Nonlinear Servo System with Coulomb Friction and Dead-zone

  • Han, Seong-Ik
    • International Journal of Precision Engineering and Manufacturing
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    • v.1 no.2
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    • pp.24-34
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    • 2000
  • In this paper we propose a controller design method, called Quasi-LQG/$H_{\infty}$/LTR for nonlinear servo systems with hard nonlinearities such as Coulomb friction, dead-zone. Introducing the RIDF method to model Coulomb friction and dead-zone, the statistically linearized system is built. Then, we consider $H_{\infty}$ performance constraint for the optimization of statistically linearized systems, by replacing a covariance Lyapunov equation into a modified Riccati equation of which solution leads to an upper bound of the LQG performance. As a result, the nonlinear correction term is included in coupled Riccati equation, which is generally very difficult to thave a numerical solution. To solve this problem, we use the modified loop shaping technique and show some analytic proofs on LTR condition. Finally, the Quasi-LQG/$H_{\infty}$/LTR controller for a nonlinear system is synthesized by inverse random input describing function techniques (ITIDF). It is shown that the proposed design method has a better performance robustness to the hard nonlinearity than LQG/$H_{\infty}$/LTR method via simulations and experiments for the timing-belt driving servo system that contains the Coulomb friction and dead-zone.

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Process Design to Prevent Flow Defect of Piston-Pin for Automobile (자동차용 피스톤-핀의 유동결함 방지를 위한 공정설계)

  • 김동진
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.155-158
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    • 2000
  • Flow defect of a piston-pin for automobile parts is investigated in this study. In cold forging of piston-pin Lapping defect a kind of flow defect appears by the dead metal zone. This appearance evidently happens in products with a thin piercing thickness for the dimension accuracy and the decrease of material loss. The best method that can prevent flow defect is removing dead metal zone. The finite element simulations are applied to analyze the flow defect. This study proposed processes for preventing flow defect by removing dead metal zone. Then the results are compared with the experiments for verification. These FE simulation results are in good agreement with the experimental ones.

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Process Design of Piston-Pin for Automobile by the Flow Control (유동제어를 통한 자동차용 피스톤-펀의 공정설계)

  • 김동진;김병민;이동주
    • Transactions of Materials Processing
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    • v.10 no.2
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    • pp.151-159
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    • 2001
  • Flow defect of a piston-pin for automobile parts is investigated in this study. In combined cold extrusion of piston-pin, lapping defect, which is a kind of flow defect, appears by the dead metal zone. This appearance evidently happens in products with a thin thickness to be pierced for the dimensional accuracy and the decrease of material loss. The flow defect that occurs in piston-pin has bad effects on the strength and the fatigue life of piston-pin. Therefore, it is important to predict and prevent defects in the early stage of process design. The best method that can prevent flow defect is removing or reducing dead metal zone through material flow control. The finite element simulations are applied to analyze the flow defect. This study proposes processes for preventing flow defect by removing dead metal zone. Then the results are compared with the experimental ones for verification. These FE simulation results are in good agreement with the experimental ones.

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