- Electrical and Electronic Engineering - Research Publications
Electrical and Electronic Engineering - Research Publications
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ItemPoint-wise extremum seeking control scheme under repeatable control environmentTan, Y ; Mareels, I ; Nešić, D ; Xu, JX (IEEE, 2007-01-01)
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ItemA note on the control of a spherical inverted pendulumLiu, 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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ItemOn automatic seeking of optimal steady-states in biochemical processesBastin, 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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ItemOn global extremum seeking in the presence of local extremaTan, 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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ItemOn the choice of dither in extremum seeking systems: A case studyNesic, 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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ItemStability results for networked control systems subject to packet dropoutsKellett, 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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ItemOn non-local stability properties of extrernum seeking controlTan, Y ; Nesic, D ; Mareels, I (PERGAMON-ELSEVIER SCIENCE LTD, 2006-06-01)In this paper, we consider several extremum seeking schemes and show under appropriate conditions that these schemes achieve extremum seeking from an arbitrarily large domain of initial conditions if the parameters in the controller are appropriately adjusted. This non-local stability result is proved by showing semi-global practical stability of the closed-loop system with respect to the design parameters. We show that reducing the size of the parameters typically slows down the convergence rate of the extremum seeking controllers and enlarges the domain of the attraction. Our results provide guidelines on how to tune the controller parameters in order to achieve extremum seeking. Simulation examples illustrate our results.
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ItemOn non-local stability properties of extremum seeking controlTan, Y ; Nešić, D ; Mareels, IMY (Elsevier BV, 2005-01-01)
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ItemWay point tracking of a spherical pendulum invertedLiu, G ; Mareels, I ; Nesic, D (IEEE, 2007)
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ItemModelling and stabilisation of a spherical inverted pendulumLiu, G ; Nešić, D ; Mareels, I (Elsevier BV, 2005-01-01)