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Parameter identification and hybrid mathematical modelling techniques applied to non-linear control systems

Pislaru, Crinela (2001) Parameter identification and hybrid mathematical modelling techniques applied to non-linear control systems. Doctoral thesis, University of Huddersfield.

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    Abstract

    The study is concerned with the mathematical modelling and parameter identification of nonlinear
    motion control systems. The control systems under review are the axis motion control
    systems for a 3-axis CNC machine tool.

    The modelling process commences with lumped parameter methods applied to each element
    and then to each axis in turn. Comparing the dynamic performance of the simulated axis drive
    with the machine tool axis performance identifies the need for a modular load and the
    introduction of measured non-linear effects.

    In order to achieve a realistic dynamic performance, a hybrid model incorporating a
    distributed load, explicit damping factors and measured non-linear effects was developed. The
    influence of factors like damping coefficients, the moving mass, velocity and positional gains,
    time constants of the servo control system on the servo characteristics of machine tool has
    been determined. Different friction models have been investigated and an effective simulation
    method has been developed for simulation purposes. This model represents to a large extent
    the dynamic behaviour of the drives from the actual machine, a fact proven by the comparison
    between the simulated and measured results.

    For multi-axis control, measured geometric errors at the machine were needed to be included
    in the model in order to achieve realistic contouring performance. The models were validated
    by comparison with measurements at the machine.

    A feature of this work is the developed measurement methods for parameter identification.
    This together with the definition of the stimuli provides a solid base for a universal
    identification process for application to non-linear machine tool axis drives. A novel wavelet
    algorithm for the determination of damping coefficients for CNC machine tools is introduced
    and this together with other developed parameter adjustment routines allows for the
    performance to be optimised.

    Item Type: Thesis (Doctoral)
    Additional Information: EThOS Persistent ID uk.bl.ethos.247405
    Uncontrolled Keywords: Machinery & tools, Machinery Tools, Automatic control, Control theory, Electromechnical devices, Electronic apparatus and appliances, Machinery Automatic control, Electromechnical devices
    Subjects: T Technology > TJ Mechanical engineering and machinery
    Schools: School of Computing and Engineering
    School of Computing and Engineering > Centre for Precision Technologies > Engineering Control and Machine Performance Research Group
    School of Computing and Engineering > Pedagogical Research Group
    School of Computing and Engineering > Diagnostic Engineering Research Centre
    School of Computing and Engineering > Diagnostic Engineering Research Centre > Energy, Emissions and the Environment Research Group
    School of Computing and Engineering > Diagnostic Engineering Research Centre > Measurement System and Signal Processing Research Group
    Depositing User: Graham Stone
    Date Deposited: 03 Jun 2009 14:23
    Last Modified: 25 Nov 2010 12:36
    URI: http://eprints.hud.ac.uk/id/eprint/4616

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