• Title, Summary, Keyword: Nonlinear Control

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Improved Nonlinear Speed Control of PM Synchronous Motor Using Time Delay Control

  • Baik, In-Cheol
    • Journal of Power Electronics
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    • v.3 no.3
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    • pp.197-204
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    • 2003
  • An improved nonlinear speed control of a permanent magnet synchronous motor (PMSM) is presented A quasi-linearized and decoupled model including the influence of parameter variations and speed measurement error on the nonlinear speed control of a PMSM is derived Using this model, to overcome the drawbacks of conventional nonlinear control scheme, the improved nonlinear control scheme which employs time delay control (TDC) scheme is proposed. To show the validity of the proposed control scheme, simulation studies are carried out and compared with the conventional control scheme.

Nonlinear H$\infty$ Control for Linear Systems using Nonlinear Weight

  • Kubota, K.;Samei, M.;Shimizu, E;Koga, M.
    • 제어로봇시스템학회:학술대회논문집
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    • pp.60-63
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    • 1996
  • This study deals with the nonlinear H$_{\infty}$ control problem of linear system using nonlinear weight. Generally the solvable condition of nonlinear H$_{\infty}$ control problem is given by the Hamilton Jacobi equality or inequality, but it is very difficult to solve. In this study, some constraints of nonlinear weight reduce the solvable condition to linear Riccati equation. Some examples of the control system design using nonlinear weight are shown.n.

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Nonlinear Optimal Control of an Input-Constrained and Enclosed Thermal Processing System

  • Gwak, Kwan-Woong;Masada, Glenn Y.
    • International Journal of Control, Automation, and Systems
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    • v.6 no.2
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    • pp.160-170
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    • 2008
  • Temperature control of an enclosed thermal system which has many applications including Rapid Thermal Processing (RTP) of semiconductor wafers showed an input-constraint violation for nonlinear controllers due to inherent strong coupling between the elements [1]. In this paper, a constrained nonlinear optimal control design is developed, which accommodates input constraints using the linear algebraic equivalence of the nonlinear controllers, for the temperature control of an enclosed thermal process. First, it will be shown that design of nonlinear controllers is equivalent to solving a set of linear algebraic equations-the linear algebraic equivalence of nonlinear controllers (LAENC). Then an input-constrained nonlinear optimal controller is designed based on that LAENC using the constrained linear least squares method. Through numerical simulations, it is demonstrated that the proposed controller achieves the equivalent performances to the classical nonlinear controllers with less total energy consumption. Moreover, it generates the practical control solution, in other words, control solutions do not violate the input-constraints.

Temperature control of a batch polymerization reactor using nonlinear predictive control algorithm (비선형 예측제어 알고리즘을 이용한 회분식 중합 반응기의 온도제어)

  • 나상섭;노형준;이현구
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1000-1003
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    • 1996
  • Nonlinear unified predictive control(UPC) algorithm was applied to the temperature control of a batch polymerization reactor for polymethylmethacrylate(PMMA). Before the polymerization reaction is initiated, the parameters of the process model are determined by the recursive least squares(RLS) method. During the reaction, nonlinearities due to generation of heat of reaction and variation of heat transfer coefficients are predicted through the nonlinear model developed. These nonlinearities are added to the process output from the linear process model. And then, the predicted process output is used to calculate the control output sequence. The performance of nonlinear control algorithm was verified by simulation and compared with that of the linear unified predictive control algorithm. In the experiment of a batch PMMA polymerization, nonlinear unified predictive control was implemented to regulate the temperature of the reactor, and the validity of the nonlinear model was verified through the experimental results. The performance of the nonlinear controller turned out to be superior to that of the linear controller for tracking abrupt changes in setpoint.

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An Integral-Augmented Nonlinear Optimal Variable Structure System for Uncertain MIMO Plants

  • Lee, Jung-Hoon
    • Journal of IKEEE
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    • v.11 no.1
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    • pp.1-14
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    • 2007
  • In this paper, a design of an integral augmented nonlinear optimal variable structure system(INOVSS) is presented for the prescribed output control of uncertain MIMO systems under persistent disturbances. This algorithm basically concerns removing the problems of the reaching phase and combining with the nonlinear optimal control theory. By means of an integral nonlinear sliding surface, the reaching phase is completely removed. The ideal sliding dynamics of the integral nonlinear sliding surface is obtained in the form of the nonlinear state equation and is designed by using the nonlinear optimal control theory, which means the design of the integral nonlinear sliding surface and equivalent control input. The homogeneous $2{\upsilon}(\kappa)$ form is defined in order to easily select the $2{\upsilon}$ or even $(\kappa)-form$ higher order nonlinear terms in the suggested sliding surface. The corresponding nonlinear control input is designed in order to generate the sliding mode on the predetermined transformed new surface by means of diagonalization method. As a result, the whole sliding output from a given initial state to origin is completely guaranteed against persistent disturbances. The prediction/predetermination of output is enable. Moreover, the better performance by the nonlinear sliding surface than that of the linear sliding surface can be obtained. Through an illustrative example, the usefulness of the algorithm is shown.

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Nonlinear Attitude Control for Uncertain Quad-rotors Using a Global Approximation-Free Control Scheme (GAFC 비선형 제어기법을 적용한 쿼드로터의 자세 및 고도제어)

  • Kim, Young-Ouk;Park, Seong-Yong;Leeghim, Henzeh
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.10
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    • pp.779-787
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    • 2016
  • A nonlinear control law for the quad-rotor of a low-complexity, global approximation-free from system uncertainties and external disturbances are described in this paper. The control law guarantees convergence to a small bounded error using a prescribed performance function. The stability of the proposed nonlinear control system is also proven by the Lyapunov stability theorem. The advantage of this technique is that it has a simpler form than any other nonlinear compensators and is applicable to any nonlinear systems without precise knowledge of the systems. In this paper, the proposed approach is applied to attitude/altitude control of a quad-rotor. Numerical simulations are performed to investigate the proposed nonlinear attitude control law by applying it to an uncertain quadcopter system with external disturbances.

A simple method for treating nonlinear control systems through state feedback

  • Han, Kyeng-Cheng
    • 제어로봇시스템학회:학술대회논문집
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    • pp.931-933
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    • 1989
  • If the nonlinear term in a nonlinear control system equation can be deleted by state feedback control, the original system becomes a linear system. For this linear control system, many well known methods may be used to handle it, and then reverse it back to nonlinear form. Many problems of nonlinear control systems can be solved in this way. In this paper, this method will be used to transfer the identification problem of nonlinear systems into a linear control problem. The nonlinear observer is established by constructing linear observer. Then the state control of nonlinear systems is realized. Finally, the technique of the PID controller obtained by using bang-bang tracker as a differentiator provides a stronger robust controller. Even though the method in this paper may not theoretically perfect, many numerical simulations show that it is applicable.

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Improved Nonlinear Speed Control of PM Synchronous Motor using Time Delay Control (시간지연 제어를 이용한 영구자석형 동기전동기의 개선된 비선형 속도제어)

  • 백인철
    • Proceedings of the KIPE Conference
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    • pp.299-304
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    • 1998
  • An improved nonlinear speed control of a permanent magnet synchronous motor(PMSM) is presented. A quasi-linearized and decoupled model including the influence of parameter variations and speed measurement error on the nonlinear speed control of a PMSM is derived. Using this model, to overcome the drawbacks of conventional nonlinear control scheme, the improved nonlinear control scheme that employs time delay control(TDC) is proposed. To show the validity of the proposed control scheme, simulation studies are carried out and compared with the conventional control scheme.

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Advances in Nonlinear Predictive Control: A Survey on Stability and Optimality

  • Kwon, Wook-Hyun;Han, Soo-Hee;Ahn, Choon-Ki
    • International Journal of Control, Automation, and Systems
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    • v.2 no.1
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    • pp.15-22
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    • 2004
  • Some recent advances in stability and optimality for the nonlinear receding horizon control (NRHC) or the nonlinear model predictive control (NMPC) are assessed. The NRHCs with terminal conditions are surveyed in terms of a terminal state equality constraint, a terminal cost, and a terminal constraint set. Other NRHCs without terminal conditions are surveyed in terms of a control Lyapunov function (CLF) and cost monotonicity. Additional approaches such as output feedback, fuzzy, and neural network are introduced. This paper excludes the results for linear receding horizon controls and concentrates only on the analytical results of NRHCs, not including applications of NRHCs. Stability and optimality are focused on rather than robustness.

Nonlinear Adaptive Control based on Lyapunov Analysis: Overview and Survey (리아프노브 분석법 기반 비선형 적응제어 개요 및 연구동향 조사)

  • Park, Jin Bae;Lee, Jae Young
    • Journal of Institute of Control, Robotics and Systems
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    • v.20 no.3
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    • pp.261-269
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    • 2014
  • This paper provides an overview of the basics and recent studies of Lyapunov-based nonlinear adaptive control, the aim of which is to improve or maintain the performance and stability of the closed-loop system by cancelling out the presumable uncertainties in the nonlinear system dynamics. The design principles are essentially based on Lyapunov's direct method. In this survey, we provide a comprehensive overview of Lyapunov-based nonlinear adaptive control techniques with simplified effective design examples, which are to be elaborated as related recent results are gradually shown. The scope of the survey contains research on singularity problems in adaptive control, the techniques to deal with linearly and nonlinearly parameterized uncertainties, robust neuro-adaptive control, and adaptive control methodologies combined with various nonlinear control techniques such as sliding-mode control, back-stepping, dynamic surface control, and optimal/$H_{\infty}$ control.