- 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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ItemDecentralized control design of interconnected chains of integrators: A case studyLiu, G ; Mareels, I ; Nesic, D (PERGAMON-ELSEVIER SCIENCE LTD, 2008-08-01)We develop a constructive decentralized control design procedure for a class of systems that may be loosely described as chained integrators which are dynamically coupled. The design method is inspired by nested saturation control ideas and formulated by applying the singular perturbation theory. We demonstrate that the proposed design provides a Lyapunov function for an associated closed loop system from which semi-global stability may be deduced. Using the proposed idea, we design a semi-globally stabilizing control law for a four degree of freedom spherical inverted pendulum.
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ItemOn the choice of dither in extremum seeking systems: A case studyTan, Y ; Nesic, D ; Mareels, I (PERGAMON-ELSEVIER SCIENCE LTD, 2008-05-01)We discuss how the choice of dither (excitation signal) affects 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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ItemNon-local stabilization of a spherical inverted pendulumLiu, G ; Nesic, D ; Mareels, I (TAYLOR & FRANCIS LTD, 2008)We design a non-linear stabilizing control law for a four degree of freedom spherical inverted pendulum. The pendulum is a slim cylindrical beam attached to a horizontal plane via a universal joint; the joint is free to move in the plane under the influence of a planar force. The upright position is an unstable equilibrium of the uncontrolled system because of gravity. The objective is to design a controller so that it stabilizes the upright position starting from any position in the upper hemisphere with arbitrary velocity. We achieve this by first transforming the original system to an appropriate upper triangular form and then designing a controller which incorporates a high gain design with the method of non-linear forwarding. The control law is evaluated through computer simulations.
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ItemNon-linear stable inversion-based output tracking control for a spherical inverted pendulumLiu, G ; Nesic, D ; Mareels, I (TAYLOR & FRANCIS LTD, 2008)We design an exact output tracking control law for a four degree of freedom spherical inverted pendulum based on the non-linear stable inversion tool proposed by Devasia et al. (1989). The pendulum is a slim cylindrical beam attached to a horizontal plane via a universal joint; the joint is free to move in the plane under the influence of a planar force. The upright position is an unstable equilibrium of the uncontrolled system because of gravity. The objective is to design a controller so that the pendulum can be steered to track some smooth desired translational trajectories while keeping the pendulum tightly around the upright position. The design proceeds in three steps: 1. identification of the internal dynamics; 2. feedforward control design for achievable trajectories; 3. feedback design to stabilize the achievable trajectories. The computer simulations show that the proposed controller can deliver excellent tracking performance.
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ItemA 40 GHz power efficient static CML frequency divider in 0.13-μm CMOS technology for high speed millimeter-wave wireless systemsMo, Y ; Skafidas, E ; Evans, R ; Mareels, I (IEEE, 2008-09-05)
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ItemWay point tracking of a spherical pendulum invertedLiu, G ; Mareels, I ; Nesic, D (IEEE, 2007)
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ItemControl of large-scale irrigation networksCantoni, M ; Weyer, E ; Li, Y ; Ooi, SK ; Mareels, I ; Ryan, M (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2007-01)