• Title/Summary/Keyword: plant uncertainty

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Design of Adaptive Discrete Time Sliding-Mode Tracking Controller for a Hydraulic Proportional Control System Considering Nonlinear Friction (비선형 마찰을 고려한 유압비례제어 시스템의 적응 이산시간 슬라이딩모드 추적 제어기 설계)

  • Park, H.B.
    • Journal of Power System Engineering
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    • v.9 no.4
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    • pp.175-180
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    • 2005
  • Incorrections between model and plant are parameter, system order uncertainties and modeling error due to disturbance like friction. Therefore to achieve a good tracking performance, adaptive discrete time sliding mode tracking controller is used under time-varying desired position. Based on the diophantine equation, a new discrete time sliding function is defined and utilized for the control law. Robustness is increased by using both a recursive least-square method and a sliding function-based nonlinear feedback. The effectiveness of the proposed control algorithm is proved by the results of simulation and experiment.

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$\mu$-Controller Design using Genetic Algorithm (유전알고리즘을 이용한 $\mu$제어기 설계)

  • 기용상;안병하
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.301-305
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    • 1996
  • $\mu$ theory can handle the parametric uncertainty and produces more non-conservative controller than H$_{\infty}$ control theory. However an existing solution of the theory, D-K iteration, creates a controller of huge order and cannot handle the real or mixed real-complex perturbation sets. In this paper, we use genetic algorithms to solve these problems of the D-K iteration method. The Youla parameterization is used to obtain all stabilizing controllers and the genetic algorithms determines the values of the state feedback gain, the observer gain, and Q parameter to minimize $\mu$, the structured singular value, of given system. From an example, we show that this method produces lower order controller which controls a real parameter-perturbed plant than D-K iteration method.

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Robust Input Shaping Controller for Slewing Uncertain Flexible Structures (모델 불확실성에 강인한 유연구조물의 입력설계)

  • 황재혁;공병식;이성춘
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.04a
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    • pp.316-323
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    • 1997
  • This paper compares input shaping techniques for controlling residual vibration of flexible structures. Input shaping generates vibration-reducing shaped commands through convolution of an impulse sequence with the desired command. Both feedforward and feedback control approaches with/without input shaper for uncertain dynamical systems are investigated to evaluate the control performances. The control objective is to achieve a fast settling time and robustness to plant uncertainty, to eliminate residual vibrations. It is shown by a series of simulation that a properly designed feedback controller with input shaper performs well, as compared with open-loop controller with input shaper.

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Uncertainty-Compensating Neural Network Control for Nonlinear Systems (비선형 시스템의 불확실성을 보상하는 신경회로망 제어)

  • Cho, Hyun-Seob
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.5
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    • pp.1597-1600
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    • 2010
  • In this paper, a direct controller for nonlinear plants using a neural network is presented. The composed of the control input by using RBF neural networks and auxiliary input to compensate for effects of the approximation errors and disturbances. In the results, using this scheme, the output tracking error between the plant and the reference model can asymptotically converge to zero in the presence of bounded disturbances and approximation errors. Simulation results show that it is very effective and can realize a satisfactory control of the nonlinear system.

A Robust Controller Design for Robot Manipulators with Hydraulic Actuator Dynamics (유압구동기를 채용한 로봇 매니플레이터에 대한 강인제어기 설계)

  • Park, Gwang-Seok;Hwang, Dong-Hwan
    • Proceedings of the KIEE Conference
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    • 1998.07b
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    • pp.598-600
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    • 1998
  • In this paper, a robust controller is proposed to achieve the accurate tracking for uncertain robot manipulators with hydraulic actuator dynamics. The parameter uncertainty can be quantified by the linear parameterization technique. A switching controller is proposed to guarantee the global asymptotic stability of the plant. In order to eliminate the chattering caused by the switching controller, a smoothing controller is proposed using the boundary layer technique around the sliding surface. It is shown that the smoothing controller guarantees the uniform ultimate boundedness of the tracking, error. The proposed controller shows good better tracking performance.

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Fault Detection and Isolation System for DC motor driven Centrifugal Pump-Pipe Systems: Parity Relation Approach (직류전동기 구동 원심펌프-파이프 계통의 고장검출진단시스템: 등가관계 접근법)

  • Park, Tae-Geon;Ryu, Ji-Su;Lee, Kee-Sang
    • Proceedings of the KIEE Conference
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    • 1998.07b
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    • pp.819-821
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    • 1998
  • This paper deals with a method or a residual generation for fault isolation in a centrifugal pump with a water circulation system, driven by a speed controlled dc motor. It is based on parity relations derived from the moving-average model of the system and is used to identify sensor faults and two possible brush and impeller faults, where the former is dealt with additive faults, while the latter characterized as discrepancies between the nominal and actual plant parameters of the system is modelled by multiplicative faults. We will represent the propagation of this uncertainty to the model matrices by the approximate handling of partial derivatives of polynomials. With multiplicative faults, the transformation matrix implemented in the residual generator are calculated on-line. The simulation studies demonstrate that small changes of the system can be detected and diagnosed by using the method.

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Evaluation of Reference Temperature on Pressurized Thermal Shock for Domestic Pressurized Water Reactors (국내 가압경수형 원자로에 대한 가압열충격 기준온도 평가)

  • Choi, Young Hwan;Park, Jeong Soon;Jhung, Myung Jo
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.6 no.2
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    • pp.42-46
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    • 2010
  • The evaluation method for the failure frequency of reactor vessel under pressurized thermal shock(PTS) is developed using probabilistic fracture mechanics. The probabilistic reactor integrity evaluation code, named R-PIE code, is developed. The validity and uncertainty of the R-PIE code is investigated. The reactor failure frequencies under PTS for Kori-1 nuclear power plant and other type of domestic nuclear power plants are evaluated. The reference PTS temperature for domestic nuclear power plants is obtained for the rule making against PTS failure.

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Adaptive Fuzzy Control of Helicopter (헬리콥터의 적응 퍼지제어)

  • 김종화;장용줄;이원창;강근택
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2001.05a
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    • pp.144-147
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    • 2001
  • This paper presents adaptive fuzzy controller which is uncertainty or unknown variation in different parameters with nonlinear system of helicopter. The proposed adaptive fuzzy controller applied TSK(Takagi-Sugeno-Kang) fuzzy system which is not only low number of fuzzy rule, and a linear input-output equation with a constant term, but also can represent a large class of nonlinear system with good accuracy. The adaptive law was designed by using Lyapunov stability theory. The adaptive fuzzy controller is a model reference adaptive controller which can adjust the parameter $\theta$ so that the plant output tracks the reference model output. First of all, system of helicopter was considered as stopping state, and design of controller was simulated from dynamics equation with stopping state. Results show that it is controlled more successfully with a model reference adaptive controller than with a non-adaptive fuzzy controller when there is a modelling error between system and model or a continuous added noise in such unstable system.

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A Study on the Torque Ripple Reduction in Brushless DC Motors using Disturbance-Observer Controller (BLDC 모터의 토크리플을 줄이기 위한 외란 관측기 기반 제어기 설계에 관한 연구)

  • Jang, So-Hyun;Jo, Nam-Hoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.8
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    • pp.1217-1223
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    • 2015
  • In this paper, we study the problem of torque ripple minimization in Brushless DC Motors (BLDC) and proposes a disturbance observer (DOB) based controller in order to efficiently reduce the torque ripple. In the DOB based control system, an equivalent disturbance (plant disturbance and effect of modelling error) is cancelled by its estimate. When the DOB controller is applied to BLDC motors, the effect of inverter switching is considered as an equivalent disturbance and to be cancelled by the DOB controller. Through computer simulations, it is shown that the performance of the proposed DOB controller is superior to that of the conventional PI controller. In the case where the numerical values of resistance and inductance are not known exactly, it is shown that the proposed DOB controller achieves better performance than the PI controller.

Robust Trajectory Control of a Hydraulic Excavator using Disturbance Observer in $H_\infty$Framework ($H_\infty$구조의 외란 관측기를 이용한 유압 굴삭기의 강인한 궤적 제어)

  • 최종환;김승수;양순용;이진걸
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.10
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    • pp.130-140
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    • 2003
  • This paper presents an $H_\infty$controller synthesis based on disturbance observer for the trajectory control of a hydraulic excavator. Compared to conventional robot manipulators driven by electrical motors, hydraulic excavator have more nonlinear and coupled dynamics. In particular, the interactions between an excavation tool and the materials being excavated are unstructured and complex. In addition, its operating modes depend on working conditions, which make it difficult to not only derive the exact mathematical model but also design a controller systematically. In this study, the approximated linear model obtained through off-line system identification is used as nominal plant model for a disturbance observer. A disturbance observer based tracking controller which considers the effect of disturbance and model uncertainty is synthesized in $H_\infty$frameworks. Simulation results are used to demonstrate the applicability of the proposed control scheme.