Title page for ETD etd-09272009-103725


Document Type Doctoral Thesis
Author Coetzee, Lodewicus Charl
Email lccoetzee@gmail.com
URN etd-09272009-103725
Document Title Robust nonlinear model predictive control of a closed run-of-mine ore milling circuit
Degree PhD
Department Electrical, Electronic and Computer Engineering
Supervisor
Advisor Name Title
Prof I K Craig Supervisor
Keywords
  • ROM
  • RNMPC
  • Robust Nonlinear Model Predictive Control
  • run-of-mine ore milling circuit
Date 2009-09-02
Availability unrestricted
Abstract
This thesis presents a robust nonlinear model predictive controller (RNMPC), nominal nonlinear model predictive controller (NMPC) and single-loop proportional-integral-derivative (PID) controllers that are applied to a nonlinear model of a run-of-mine (ROM) ore milling circuit. The model consists of nonlinear modules for the individual process units of the milling circuit (such as the mill, sump and cyclone), which allow arbitrary milling circuit configurations to be modelled easily.

This study aims to cast a complex problem of a ROM ore milling circuit into an RNMPC framework without losing the flexibility of the modularised nonlinear model and implement the RNMPC using open-source software modules.

The three controllers are compared in a simulations study to determine the performance of the controllers subject to severe disturbances and model parameter variations. The disturbances include changes to the feed ore hardness, changes in the feed ore size distributions and spillage water being added to the sump.

The simulations show that the RNMPC and NMPC perform better than the PID controllers with regard to the economic objectives, assuming full-state feedback is available, especially when actuator constraints become active. The execution time of the RNMPC, however, is much too long for real-time implementation and would require further research to improve the efficiency of the implementation.

2009, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Coetzee, LC 2009, Robust Nonlinear Model Predictive Control of a closed run-of-mine ore milling circuit, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-09272009-103725/ >

D676/ag

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