Browsing by Subject "Robust controller design"

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    On the robust controller design for Hard Disk Drive servo systems with time delays
    (IEEE, 2013) Yan, P.; Özbay, Hitay
    Due to the existence of various sources of delays, the dynamical model of HDD (Hard Disk Drive) servo systems is actually infinite dimensional, although most of the control algorithms simplified the model with Padé expansions or other finite dimensional approximations. In this paper, a robust loop shaping algorithm is developed for the HDD model with delays by using an h ∞ synthesis approach for infinite dimensional systems. The h∞ controller is derived with a structure of an internal feedback loop including an FIR (Finite Impulse Response) filter and an IIR (Infinite Impulse Response) filter, which facilitates non-fragile implementations. Comparisons to other robust control methods are given and the advantages of this approach are demonstrated in terms of improvement of TMR (track misregistration) and tracking TPI (Track-per-Inch) capability.
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    Robust controller design for AQM and H∞-performance analysis
    (Springer, 2005) Yan, P.; Özbay, Hitay
    Active Queue Management (AQM) has recently been proposed in [1] to support the end-to-end congestion control for TCP traffic regulation on the Internet. For the purpose of alleviating congestion for IP networks and providing some notion of quality of service (QoS), the AQM schemes are designed to improve the Internet applications. Earliest efforts on AQM (e.g. RED in [2]) are essentially heuristic without systematic analysis. The dynamic models of TCP ([9, 12]) make it possible to design AQM using feedback control theory. We refer to [11] for a general review of Internet congestion control.