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Robust controller design for lightly damped systems with feedback delay

Hung, Donald Lu-Cheng
http://rave.ohiolink.edu/etdc/view?acc_num=case1055364861

Abstract Details

1991, Doctor of Philosophy, Case Western Reserve University, Electrical Engineering.
Stability analysis based on an idealized robot-stiff environment model shows that for a lightly damped system, a time delay in the feedback may become a critical issue to the system's stability if the delay is nonnegligible with respect to the system's natural frequency. The attention of this thesis focuses on the design of controllers for lightly damped systems with nonnegligible feedback delay. A generalized control system framework is adopted and two major assumptions are made: the plant and the controller are linear, time-invariant (LTI), and the plant is open-loop stable. The time delay in the feedback loop is modeled in the plant. By discretizing, the perturbed plant remains as LTI and the sample-hold effects have been taken into consideration. A closed-loop transfer matrix obtained from the control system framework contains all closed-loop transfer functions of interest. Therefore the closed-loop performance specifications for controller design can be expressed as constraints or objectives for each entry of this transfer matrix. Via a bilinear transformation, all stable closed-loop transfer matrices form a convex set and many performance specifications become convex functions defined on the set. This property allows a convex programming approach for the controller design procedure. Since this has to be done through a numerical approach, the solution space is truncated to form a finite dimensional Euclidean subspace. The designed controllers are robust with respect to time delays in the feedback action. Other robustness considerations, such as unmodeled plant dynamics, can also be taken into the design specifications. Since the convex program is a global optimal technique, once a controller is found, it is optimal in the sense that it meets the design specifications. On the other hand, if no solution is found then there exists no LTI controller which can satisfy the design specifications. Simulation results show that the designed controllers can effectively stabilize the lightly damped system and significantly improve its performance.
Stephen Phillips (Advisor)
137 p.
Robust controller damped systems

Recommended Citations

Citations

  • Hung, D. L.-C. (1991). Robust controller design for lightly damped systems with feedback delay [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1055364861

    APA Style (7th edition)

  • Hung, Donald. Robust controller design for lightly damped systems with feedback delay. 1991. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1055364861.

    MLA Style (8th edition)

  • Hung, Donald. "Robust controller design for lightly damped systems with feedback delay." Doctoral dissertation, Case Western Reserve University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055364861

    Chicago Manual of Style (17th edition)

case1055364861
698
© 1991, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.