Electrical and Electronic Engineering - Research Publications

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Author: Mareels, Iven × Type: Journal Article × Start date: 2005 × End date: 2007 ×

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Now showing 1 - 5 of 5
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    On non-local stability properties of extrernum seeking control
    Tan, 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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    Control of large-scale irrigation networks
    Cantoni, M ; Weyer, E ; Li, Y ; Ooi, SK ; Mareels, I ; Ryan, M (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2007-01)
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    Adaptive repetitive learning control of robotic manipulators without the requirement for initial repositioning
    Sun, M ; Ge, SS ; Mareels, IMY (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006-06)
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    Stability and motor adaptation in human arm movements
    Burdet, E ; Tee, KP ; Mareels, I ; Milner, TE ; Chew, CM ; Franklin, DW ; Osu, R ; Kawato, M (SPRINGER, 2006-01)
    In control, stability captures the reproducibility of motions and the robustness to environmental and internal perturbations. This paper examines how stability can be evaluated in human movements, and possible mechanisms by which humans ensure stability. First, a measure of stability is introduced, which is simple to apply to human movements and corresponds to Lyapunov exponents. Its application to real data shows that it is able to distinguish effectively between stable and unstable dynamics. A computational model is then used to investigate stability in human arm movements, which takes into account motor output variability and computes the force to perform a task according to an inverse dynamics model. Simulation results suggest that even a large time delay does not affect movement stability as long as the reflex feedback is small relative to muscle elasticity. Simulations are also used to demonstrate that existing learning schemes, using a monotonic antisymmetric update law, cannot compensate for unstable dynamics. An impedance compensation algorithm is introduced to learn unstable dynamics, which produces similar adaptation responses to those found in experiments.
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    Systems engineering for irrigation systems: Successes and challenges
    MAREELS, I ; WEYER, E ; OOI, S ; CANTONI, M ; LI, Y ; NAIR, GN (Elsevier, 2005)
    In Australia, gravity fed irrigation systems are critical infrastructure essential to agricultural production and export. By supplementing these large scale civil engineering systems with an appropriate information infrastructure, sensors, actuators and a communication network it is feasible to use systems engineering ideas to improve the exploitation of the irrigation system. This paper reports how classical ideas from system identification and control can be used to automate irrigation systems to deliver a near on-demand water supply with vastly improved overall distribution efficiency.