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Author: search.filters.author.Ochiai, Yasuzumi

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    New tuning formulas for two-degree of freedom PID controllers and the application to level control systems
    (2007-01-01)
    Benjanarasuth, Taworn
    ;
    Ngamwiwit, Jongkol
    ;
    Komine, Noriyuki
    ;
    Ochiai, Yasuzumi
    This paper presents novel tuning formulas for two-degree of freedom PID-family controllers. The structure of the proposed control system consists of a plant or process to be controlled, P or PI or PID controllers and a pre-filter. The tuning formulas are derived based on the CDM design method by solving CDM algebraic equations obtained from the known controllers' structures and the approximated plant model based on the experimental test. The proposed formulas are summarized in the tuning table and can be used easily. To apply the tuning rules, the plant or process is firstly tested to find the values of critical gain and critical period experimentally in the same manner as Ziegler-Nichols' second method. The parameters of P, PI or PID controller and the associated pre-filter are then obtained by substituting those values in the formulas. The experiments in controlling the level process with long pipeline controlled by the controllers tuned by the proposed rules and the well-known Ziegler-Nichols' formulas are conducted and compared. The proposed control systems result in responses with shorter settling time and considerably smaller or no overshoot. Overall, the proposed formulas are well applicable despite their simplicity.
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    Derivative State Constrained Optimal H2 Control for Oscillatory Systems and its Application
    (2000-01-01)
    Trisuwannawat, Thanit
    ;
    Tirasesth, Kitti
    ;
    lida, Michihiko
    ;
    Komine, Noriyuki
    ;
    Ochiai, Yasuzumi
    The optimal H<inf>2</inf> control of oscillatory systems via the constraints of the derivatives of state variables is discussed and applied to a physical system in this paper. It is shown that the derivative state constrained optimal H<inf>2</inf> control can be reduced into the standard optimal H<inf>2</inf> control problem with modified controlled output equations. The solution to the modified standard problem has salient features for controlling oscillatory systems that have been a tough subject in state space as well as in classical frequency domain controls. The results obtained in the paper suggest the directions how to select the constraining weights in the standard state space control designs of oscillatory systems. The application of this approach to the control of a two-inertia resonance system is shown to demonstrate the proposed schemes. © 2000, The Institute of Electrical Engineers of Japan. All rights reserved.
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    PID × (n-2)/2 Stage PDA Cascade Robust Controllers
    (2000-01-01)
    Tirasesth, Kitti
    ;
    Ngamwiwit, Jongkol
    ;
    Trisuwannawat, Thanit
    ;
    Komine, Noriyuki
    ;
    Ochiai, Yasuzumi
    This paper presents a design technique for the two-degree of freedom control system using PID × (n-2)/2 stage PDA as a cascade robust controller for a class of n<sup>th</sup> order plants. It is intended to satisfy both transient and steady state response specifications based on root locus approach. This controller can be used instead of a conventional PID controller for the higher order plant to obtain better performances. By this design technique, the controlled system is approximated as a second order system, and the desired performances are satisfied. For the plant with stable poles including the case with small dead time, the closed-loop poles are located on the left half of the s-plane and the controlled system become robustly stable. The cascade robust controller gain is adjusted to meet faster responses with a small or no overshoot. Robustness properties given by the controllers proposed in this paper have also been demonstrated by illustrative examples. © 2000, The Institute of Electrical Engineers of Japan. All rights reserved.