|Nominal Model Manipulation for Enhancement of Stability Robustness for Disturbance Observer-Based Control Systems
Kyoungchul Kong and Masayoshi Tomizuka
International Journal of Control, Automation, and Systems, vol. 11, no. 1, pp.12-20, 2013
Abstract : Disturbance observer-based control systems often encounter the stability problem due to modeling un-certainties. In such cases, the disturbance observer (DOB) may have to be re-designed by narrowing the bandwidth of the Q-filter to enhance stability robustness, but this approach to stability enhancement deteriorates the performance of DOB. In order to improve robust stability while main-taining the performance of DOB, this paper proposes a method that manipulates the nominal plant model in the DOB; the parameters of the discretized nominal model are optimized to improve robust stability in the discrete time domain. For the optimization of nominal model, it is assumed that the closed-loop poles of DOB are subjected to multiplicative uncertainties, and the maximum allowable magnitude of uncertainties is utilized as the measure of stability robustness. Then, the proposed method changes the location of closed-loop poles to maximize the robustness margin. This paper pro-vides a case study that includes experimental results.
Disturbance observer (DOB), model uncertainty, nominal model, optimization, robustness.
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