Electrical and Electronic Engineering - Research Publications

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    A UNIFYING FRAMEWORK FOR ANALYSIS AND DESIGN OF EXTREMUM SEEKING CONTROLLERS
    Nesic, D ; Tan, Y ; Manzie, C ; Mohammadi, A ; Moase, W (IEEE, 2012-01-01)
    We summarize a unifying design approach to continuous-time extremum seeking that was recently reported by the authors. This approach is based on a feedback control paradigm that was to the best of our knowledge explicitly summarized for the first time in this form in our recent work. This paradigm covers some existing extremum seeking schemes, provides a direct link to off-line optimization and can be used as a unifying framework for design of novel extremum seeking schemes. Moreover, we show that other extremum seeking problem formulations can be interpreted using this unifying viewpoint. We believe that this unifying view will be invaluable to systematically design and analyze extremum seeking controllers in various settings.
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    Extremum seeking methods for online optimization of spark advance in alternative fueled engines
    Mohammadi, A ; Manzie, C ; Nešić, D (Elsevier, 2012-01-01)
    Alternative fueled engines offer greater challenges for engine control courtesy of uncertain fuel composition. This make optimal tuning of input parameters like spark advance extremely difficult in most existing ECU architectures. This paper proposes the use of greybox extremum seeking techniques to provide real-time optimization of the spark advance in alternative fueled engines. The ability and flexibility of the proposed framework is demonstrated through simulation examples. The approaches demonstrated may be extended to other engine inputs requiring online optimization.
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    A Systematic Approach to Extremum Seeking Based on Parameter Estimation
    Nesic, D ; Mohammadi, A ; Manzie, C (IEEE, 2010-01-01)
    We present a systematic approach for design of extremum seeking (ES) controllers for a class of uncertain plants that are parameterized with unknown parameters. First, we present results for static plants and show how it is possible to combine, under certain general conditions, an arbitrary optimization method with an arbitrary parameter estimation method in order to obtain extremum seeking. Our main results also specify how controller needs to be tuned in order to achieve extremum seeking. Then, we consider dynamic plants and separate our results into the stable plant case and unstable plant case. For each of these cases, we present conditions on general plants, controllers, observers, parameter estimators and optimization algorithms that guarantee semi-global practical convergence to the extremum when controller parameters are tuned appropriately. Our results apply to general nonlinear plants with multiple inputs and multiple parameters.
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    Emulation Design for a Class of Extremum Seeking Controllers: Case Studies in ABS Design and Spark Timing Calibration
    Mohammadi, A ; Nesic, D ; Manzie, C (IEEE, 2013-01-01)
    The vast majority of extremum seeking designs in the literature are in continuous-time, however their practical implementation is typically done using digital technology. In this paper, a sampled-data implementation of extremum seeking controllers using emulation design methods is studied to address this gap. The conditions under which the emulated controller preserves the performance of the continuous-time plant are investigated. The main result also provides a guideline on how to tune the controller parameters including sample period in order to achieve the desired performance. The examples of anti-lock braking and spark timing calibration are used to illustrate the proposed design method through simulation and experimental tests.