Electrical and Electronic Engineering - Research Publications

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    Point-wise extremum seeking control scheme under repeatable control environment
    Tan, Y ; Mareels, I ; Nešić, D ; Xu, JX (IEEE, 2007-01-01)
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    A note on the control of a spherical inverted pendulum
    Liu, G ; Mareels, I ; Nešić, D (IFAC, 2007-01-01)
    We carry out extensive numerical simulations of a spherical inverted pendulum with various controllers to verify our theoretical developments. The simulations are useful in quantitatively understanding the operation of the system with different controllers and checking that the theoretical results are consistent with the numerical results. Using the numerical simulations, we also discuss in some detail various important aspects of the performance of the closed loop systems in order to compare the controllers.
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    On automatic seeking of optimal steady-states in biochemical processes
    Bastin, G ; Nešić, D ; Tan, Y ; Mareels, I (IFAC, 2007-01-01)
    It is discussed how the automatic seeking of optimal steady states biochemical reactors can be achieved by using non-model based extremum-seeking control with semi-global practical stability and convergence properties. A special attention is paid to processes with multiple steady-states and multivalued cost functions.
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    On global extremum seeking in the presence of local extrema
    Tan, Y ; Nesic, D ; Mareels, I ; Astolfi, A (IEEE, 2006-01-01)
    We analyze global extremum seeking in the presence of local extrema for static nonlinear maps controlled by a scalar extremum seeking scheme that was recently proposed in [1]. Sufficient conditions are given under which it is possible to tune the controller parameters to achieve convergence to an arbitrarily small neighborhood of the global extremum in the presence of local extrema from an arbitrarily large set of initial conditions. Several examples provide insights and highlight the potential difficulties that one would face when trying to generalize our results.
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    On the choice of dither in extremum seeking systems: A case study
    Nesic, D ; Tan, Y ; Mareels, I (IEEE, 2006-01-01)
    We discuss how the dither (excitation signal) shape affects on the performance of extremum seeking using a benchmark situation: a static scalar map; and a simple scalar extremum seeking scheme. Our comparisons are based on the performance of the system with different dithers in terms of three performance indicators: the speed of convergence, domain of attraction and accuracy (i.e. the ultimate bound on trajectories). Our analysis explicitly shows how the dither shape affects each of these performance indicators. Our study suggests that the practitioners using extremum seeking control should consider the dither shape as an important design parameter. Computer simulations support our theoretical findings.
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    Stability results for networked control systems subject to packet dropouts
    Kellett, CM ; Mareels, IMY ; Nešić, D (Elsevier, 2005-01-01)
    Stability and performance of networked control systems has been a recent area of interest in the control literature. The inclusion of a shared communication network between plant and controller inevitably leads to occasional random data loss. We provide novel results relating to the probability of such a system being globally asymptotically stable or input to state stable.
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    The Gröbner basis method in control design: An overview
    Nešić, D ; Mareels, IMY ; Glad, T ; Jirstrand, M (Elsevier BV, 2002-01-01)
    The paper discusses the usefulness of Gröbner bases methods in a variety of control problems for a class of polynomial systems. Polynomial systems are described by difference or differential equations in which the transition map or vectorfield are polynomials. Gröbner bases methods are useful in both the analysis and the design of polynomial control systems.
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    A virtual laboratory experience based on a double tank apparatus
    Irawan, R ; Ooi, M ; Yeung, G ; Weyer, E ; Nesic, D ; Mareels, I (IEEE, 2001-01-01)
    How can a virtual laboratory experience achieve the typical educational outcomes expected from a normal in situ laboratory experience? The paper deals with this question in the context of a double tank apparatus experimental set up. For this laboratory experiment, a World Wide Web interface was developed to assist students in assimilating control engineering concepts at the University of Melbourne.
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    On non-local stability properties of extremum seeking control
    Tan, Y ; Nešić, D ; Mareels, IMY (Elsevier BV, 2005-01-01)
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    Way point tracking of a spherical pendulum inverted
    Liu, G ; Mareels, I ; Nesic, D (IEEE, 2007)