Qing-Guo Wang

Central South University, Changsha, Hunan, China

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Publications (157)212.27 Total impact

  • Zhuo-Yun Nie, Min Wu, Qing-Guo Wang, Yong He
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    ABSTRACT: This paper addresses the problem of loop gain and phase margins of two-input two-output (TITO) systems. A new frequency domain approach is proposed to accurately compute the loop gain and phase margins for TITO systems. With the help of geometry analysis method, the stability boundaries are shown to be the intersection points of some constructed curves. The computational burden is reduced by restricting the frequency range estimated by the norm analysis. The gain and phase margins are determined in the stable region. The method is demonstrated by two examples.
    Journal of the Franklin Institute 04/2013; 350(3):503–520. · 2.42 Impact Factor
  • Zhuo-Yun Nie, Qing-Guo Wang, Min Wu, Yong He
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    ABSTRACT: In this paper, a single-iteration strategy is proposed for the design of a multi-loop PI controller to achieve the desired gain and phase margins for two-input and two-output (TITO) processes. To handle loop interactions, a TITO system is converted into two equivalent single loops with uncertainties drawn from interactions. The maximum uncertainty is estimated for the initial controller design in one loop and single-input and single-output (SISO) controller design is applied. This controller is substituted to other equivalent loop for design, and finally, the first loop controller is refined on knowledge of other loop controller. For SISO controller tuning, a new method is presented to determine the achievable gain and phase margins as well as the relevant controller parameters. Examples are given for illustration and comparison.
    Journal of Process Control 01/2011; 21(9):1287-1295. · 2.18 Impact Factor
  • Control and Intelligent Systems. 01/2011; 39.
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    ABSTRACT: Double integral plants under relay feedback are studied. Complete results on the uniqueness of solutions, existence, and stability of the limit cycles are established using the point transformation method. Analytical expressions are also given for determining the amplitude and period of a limit cycle from the plant parameters.
    Journal of Control Science and Engineering 01/2011; 2011.
  • Qing-Guo Wang, Binh-Nguyen Le, Tong Heng Lee
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    ABSTRACT: Effective graphical methods are presented to exactly compute stabilizer gain ranges for a two-input two-output (TITO) plant. Our approach determines those critical gains which result in pure imaginary roots of the characteristic equation and establish the stabilizing boundaries. For a fixed plant, the gain ranges of a decentralized stabilizer are obtained, whereas, for a parameterized plant, the gain range of central stabilizer is given in terms of the common time delay of the plant. Examples are provided for illustration and comparison with other methods.
    9th IEEE International Conference on Control and Automation, ICCA 2011, Santiago, Chile, December 19-21, 2011; 01/2011
  • Zhuo-Yun Nie, Qing-Guo Wang, Min Wu, Yong He
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    ABSTRACT: This paper describes lead/lag compensators tuning method based on gain and phase margin specifications for two kinds of unstable processes. A simple and effective graphic method is used to solve a set of nonlinear coupled equations. The solutions are determined from the intersections of the two kinds of curves constructed from gain and phase margin specifications. The results are applied to the tuning of the lead/lag compensator. Examples are provided for illustration.
    Control and Automation (ICCA), 2010 8th IEEE International Conference on; 07/2010
  • See Chek Lee, Qing-Guo Wang, Le Binh Nguyen
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    ABSTRACT: The stabilization of unstable first-order plus time-delay processes with a zero by means of simple controllers is investigated in detail. Explicit stabilizability conditions are established. And the computational methods for determining stabilizing controller parameters are also presented with illustrative examples.
    ISA Transactions 07/2010; 49(3):318-25. · 2.26 Impact Factor
  • See Chek Lee, Qing-Guo Wang
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    ABSTRACT: The presence of zero dynamics is not uncommon in industrial chemical processes. For unstable delay processes that exhibit zero dynamics, the stabilizability by simple controllers has not really been addressed before. The paper studies stabilizing control for such processes, and establishes some stabilizability conditions.
    Journal of The Taiwan Institute of Chemical Engineers - J TAIWAN INST CHEM ENG. 01/2010; 41(4):440-445.
  • Zhuo-Yun Nie, Qing-Guo Wang, Min Wu, Yong He
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    ABSTRACT: This paper addresses the problem of loop gain margins of multivariable feedback system. A frequency domain approach is proposed to accurately computing loop gain margins for multivariable feedback systems. With the help of vector mapping method, the loop gain margins problem is converted to some constrained optimization, which is solved numerically by the Lagrange multiplier and Newton–Raphson iteration algorithm. The proposed approach can determine all the stabilizing boundaries and provide exact gain margins in comparison with conservativeness of the linear matrix inequalities (LMI) results reported before.
    Journal of Process Control 01/2010; 20(6):762-768. · 2.18 Impact Factor
  • See Chek Lee, Qing-Guo Wang, Cheng Xiang
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    ABSTRACT: The stabilization of a class of all-pole unstable delay processes of arbitrary order with single unstable pole by means of simple controllers is investigated in details. Complete stabilizability conditions are established and the computational methods for determining stabilizing controller parameters presented. They provide theoretical understanding of such a stabilization problem and can also serve as practical guidelines for actual controller design.
    Journal of Process Control 01/2010; 20(2):235-239. · 2.18 Impact Factor
  • Zhuo-Yun Nie, Qing-Guo Wang, Min Wu, Yong He
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    ABSTRACT: In this note, the limitations of conventional or separate gain or phase margin are shown. Then, the combined gain and phase margins are introduced to overcome the limitations and suit both stable and unstable systems. A simple method for their computation is presented and their applications in stabilization is demonstrated.
    ISA Transactions 09/2009; 48(4):428-33. · 2.26 Impact Factor
  • Source
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    ABSTRACT: Pole placement is a well-established design method for linear control systems. Note however that with an output feedback controller of low-order such as the PID controller one cannot achieve arbitrary pole placement for a high-order or delay system, and then partially or hopefully, dominant pole placement becomes the only choice. To the best of the authors’ knowledge, no method is available in the literature to guarantee dominance of the assigned poles in the above case. This paper proposes two simple and easy methods which can guarantee the dominance of the two assigned poles for PID control systems. They are based on root locus and Nyquist plot respectively. If a solution exists, the parametrization of all the solutions is explicitly given. Examples are provided for illustration.
    Journal of Process Control 01/2009; 19(2):349-352. · 2.18 Impact Factor
  • Qing-Guo Wang, Zhen Ye, Lihong Idris Lim
    ICINCO 2009, Proceedings of the 6th International Conference on Informatics in Control, Automation and Robotics - Signal Processing, Systems Modeling and Control, Milan, Italy, July 2-5, 2009; 01/2009
  • Chong Lin, Qing-Guo Wang, Tong Heng Lee, Bing Chen
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    ABSTRACT: This paper is concerned with the H<sub>infin</sub> filter design for nonlinear systems with time-varying delay via Takagi-Sugeno fuzzy model approach. Delay-dependent design method is proposed in terms of linear matrix inequalities (LMIs), which forms the main contribution of this paper. The main technique used is the free-weighting matrix method combined with a matrix decoupling approach. The results for rate-independent case, delay-independent case, and delay-free case are also given as easy corollaries. An illustrative example is given to show the effectiveness of the present method.
    IEEE Transactions on Fuzzy Systems 07/2008; · 5.48 Impact Factor
  • Qing-Guo Wang, Min Liu, Chang Chieh Hang
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    ABSTRACT: In this paper, an integral identification method is proposed for continuous-time delay systems in presence of both unknown initial conditions and static disturbances from a step test. The integration limits are specifically chosen to make the resulting integral equation independent of the unknown initial conditions. This enables identification of the process model from a step test by one-stage least-squares algorithm without any iteration. The proposed identification method is demonstrated through numerical simulation and real time testing.
    Industrial & Engineering Chemistry Research - IND ENG CHEM RES. 06/2008; 47(14).
  • Source
    Zhen Ye, Qing-Guo Wang, Chang Chieh Hang
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    ABSTRACT: The loop phase margins of multivariable control systems are defined as the allowable individual loop phase perturbations within which stability of the closed-loop system is guaranteed. This paper presents a frequency domain approach to accurately computing these phase margins for multivariable systems. With the help of unitary mapping between two complex vector space, the MIMO phase margin problem is converted using the Nyquist stability analysis to the problem of some simple constrained optimization, which is then solved numerically with the Lagrange multiplier and Newton−Raphson iteration algorithm. The proposed approach can provide exact margins and thus improves the linear matrix inequalities (LMI) results reported before, which could be conservative.
    06/2008;
  • Qing-Guo Wang, Min Liu, Chang Chieh Hang
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    ABSTRACT: It is well known that a continuous-time feedback system with time delay has infinite spectrum and it is not possible to assign such infinite spectrum with a finite-dimensional controller. In such a case, only the partial pole placement may be feasible and hopefully some of the assigned poles are dominant. But there is no easy way to guarantee dominance of the desired poles. In this paper, an analytical PID design method is proposed for continuous-time delay systems to achieve approximate pole placement with dominance. Its idea is to bypass continuous infinite spectrum problem by converting a delay process to a rational discrete model and getting back continuous PID controller from its discrete form designed for the model with pole placement. Simulation results are included to illustrate the effectiveness of this method.Il est bien établi qu'un système de rétroalimentation continu dans le temps avec retard a un spectre infini et qu'il n'est pas possible d'assigner un tel spectre à un contrôleur à dimensions finies. Dans un tel cas, seul le placement de pôles partiels peut être réalisable, et heureusement, certains des pôles assignés sont dominants. Mais il n'y a pas de manière facile de garantir la dominance des pôles désirés. Dans cet article, on propose une méthode de conception PID analytique pour les systèmes avec retard continu dans le temps, afin d'effectuer le placement de pôles approximatif avec dominance. L'idée est de contourner le problème des spectres infinis continus en convertissant le procédé de retard en un modèle discret rationnel et de récupérer le contrôleur PID continu de sa forme discrète conçue pour le modèle avec placement de pôles. Les résultats des simulations sont inclus pour illustrer l'efficacité de cette méthode.
    The Canadian Journal of Chemical Engineering 05/2008; 85(4):549 - 557. · 1.00 Impact Factor
  • Qing-Guo Wang, Chang Chieh Hang, Min Liu, Wei Tang
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    ABSTRACT: In this paper, a robust identification method is proposed for multiple-input and multiple-output (MIMO) continuous-time processes with multiple time delays. Suitable multiple integrations are constructed and regression equations linear in the aggregate parameters are derived with the use of the test responses and their multiple integrals. The multiple time delays are estimated by solving some algebraic equations without iteration and the other process model parameters are then recovered. Its effectiveness is demonstrated through simulation and real-time testing.On propose dans cet article une méthode d'identification robuste pour les procédés continus dans le temps à entrées et sorties multiples (MIMO) avec des retards multiples. Des intégrations multiples adéquates sont construites et des équations de régression linéaires par rapport aux paramètres regroupés sont établies à partir des réponses des tests et leurs intégrales multiples. Les retards sont estimés en résolvant certaines équations algébriques sans itération et les autres paramètres de modèles de procédés sont alors récupérés. L'efficacité de la méthode est démontrée par la simulation et l'expérimentation en temps réel.
    The Canadian Journal of Chemical Engineering 05/2008; 85(4):399 - 407. · 1.00 Impact Factor
  • Zhiping Zhang, Qing-Guo Wang, Yong Zhang
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    ABSTRACT: This paper investigates the relationship on stabilizability of linear time-invariant (LTI) systems by P and PI controllers. Elementary tools such as the Routh stability criterion and Root-Locus method are employed in the analysis. It is found that PI can stabilize all the systems that P stabilizes but in general the converse is not true. The cases with the equivalence of stabilizability by P and PI are established and they are in general low-order systems with few zeros. The cases with non-equivalence are also identified.On étudie dans cet article la relation sur la stabilité des systèmes invariants en temps linéaire (LTI) par des contrôleurs P et PI. Des outils élémentaires tels que le critère de stabilité de Routh et la méthode de Root-Locus sont employés dans l'analyse. On a trouvé que le PI peut stabiliser tous les systèmes que P stabilise, mais en général l'inverse n'est pas vrai. Les cas d'équivalence de stabilité entre P et PI sont établis et s'avèrent en général des systèmes de faible ordre avec peu de zéros. Les cas de non-équivalence sont également déterminés.
    The Canadian Journal of Chemical Engineering 05/2008; 85(3):374 - 377. · 1.00 Impact Factor
  • Chong Lin, Qing-Guo Wang, Tong Heng Lee, Yong He
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    ABSTRACT: This paper addresses the problem of observer-based H<sub>infin</sub> control for nonlinear systems with time-varying delay represented by Takagi-Sugeno (T-S) fuzzy model. It presents a single-step linear matrix inequality (LMI) method for the fuzzy control design, which overcomes the drawback of the two-step LMI approach often encountered in the literature. The derivation relies mainly on a proposed matrix decoupling technique using which a resultant matrix inequality can be equivalently converted to strict LMIs. When restricted to delay-free fuzzy systems, the present results improve or reduce to existing ones. Illustrative examples show the effectiveness and merits of the present results.
    IEEE Transactions on Fuzzy Systems 05/2008; · 5.48 Impact Factor

Publication Stats

3k Citations
212.27 Total Impact Points

Institutions

  • 2005–2009
    • Central South University
      • School of Information Science and Engineering
      Changsha, Hunan, China
    • University of Western Sydney
      Penrith, New South Wales, Australia
  • 1996–2009
    • National University of Singapore
      • Department of Electrical & Computer Engineering
      Singapore, Singapore
  • 2007–2008
    • Qingdao University
      • Institute of Complexity Sciences
      Tsingtao, Shandong Sheng, China
    • University of Alberta
      • Department of Chemical and Materials Engineering
      Edmonton, Alberta, Canada