Qing-Guo Wang

Central South University, Changsha, Hunan, China

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Publications (165)248.27 Total impact

  • Binh Nguyen Le, Qing-Guo Wang, Tong Heng Lee
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    ABSTRACT: This paper deals with the problem of determining the stabilizing controller gain and plant delay ranges for a general delay system in feedback configuration. Such a problem admits no analytical solutions in general. Instead, the condition of the loop Nyquist plot's intersection with the critical point is employed to graphically determine stability boundaries in the gain-delay space and stability of regions divided by these boundaries is decided with the help of a new perturbation analysis of delay on change of closed-loop unstable poles. As a result, all the stable regions are obtained and each stable region captures the full information on the stabilizing gain intervals versus any delay of the process. The proposed method is applicable to both stable and unstable processes of any order with or without the right-half plane zeros. Several examples are provided for illustration and comparison with the existing methods.
    Journal of Process Control 01/2015; 25. · 2.18 Impact Factor
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    ABSTRACT: A graphical method is extended to determine the stabilizing gain and delay ranges for a bi-proper delay system.•A bi-proper process is rare but causes great complications for the method because of possibility of infinite intersections of boundary functions within a finite delay range.•The properties of boundary functions from such processes are investigated in great details to show that finite boundary functions are sufficient to determine all stable regions for finite parameter intervals.•The formula is given for calculating this number.•Algorithms are established to find exact stabilizing gain and delay ranges.
    ISA Transactions 10/2014; · 2.26 Impact Factor
  • Qing-Guo Wang, Binh-Nguyen Le, Tong-Heng Lee
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    ABSTRACT: An effective method is presented to find PID stabilizing region in controller parameters plane. The concept of stability boundaries in D-decomposition technique is extended to the parameterized stability boundary, which transforms boundary curves into boundary bands when one of the controller gains varies in a range. This eliminates the difficulty of using 3D graph to solve the problem with 3 parameters while maintaining the advantage of 2D method.
    2014 11th IEEE International Conference on Control & Automation (ICCA); 06/2014
  • 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 07/2010; 41(4):440-445. · 2.64 Impact Factor
  • 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.
    Industrial & Engineering Chemistry Research 06/2008; 47(13). · 2.24 Impact Factor
  • 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

Publication Stats

3k Citations
248.27 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
  • 1993–2009
    • 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