- Mechanical Engineering - Research Publications
Mechanical Engineering - Research Publications
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ItemA UNIFYING FRAMEWORK FOR ANALYSIS AND DESIGN OF EXTREMUM SEEKING CONTROLLERSNesic, 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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ItemOn a Shubert Algorithm-Based Global Extremum Seeking SchemeNesic, D ; Nguyen, T ; Tan, Y ; Manzie, C (IEEE, 2012)This paper adapts the so-called Shubert algorithm for Extremum Seeking Control (ESC) to seek the global extremum (in presence of local extrema) of general dynamic plants. Different from derivative based methods that are widely used in ESC, the Shubert algorithm is a good representative of sampling optimization methods. With knowledge of the Lipschitz constant of an unknown static mapping, this deterministic algorithm seeks the global extremum. By introducing “waiting time” the proposed Shubert algorithm-based global extremum seeking guarantees the semi-global practical convergence (in the initial states) to the global extremum if compact sets of inputs are considered. Several numerical examples demonstrate how proposed method may be successfully deployed.
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ItemMultidimensional global extremum seeking via the DIRECT methodKhong, SZ ; Manzie, C ; Nesic, D ; Tan, Y (IEEE, 2012-01-01)This paper adapts the DIRECT method with a modified termination criterion for global extremum seeking control of multivariable dynamical plants - DIRECT is a sampling type global optimisation method for Lipschitz-continuous functions defined over compact multidimensional domains. Finite-time semi-global practical convergence is established based on a deadbeat sampled-data control law, whose sampling period is a parameter which determines the region and accuracy of convergence. A crucial part of the development is dedicated to a robustness analysis of the DIRECT method against bounded additive perturbations on the objective function. A numerical example of global extremum seeking in the presence of local extrema based on DIRECT is presented at the end.
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ItemExtremum seeking methods for online optimization of spark advance in alternative fueled enginesMohammadi, 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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ItemA methodology for minimising emissions constrained cold start fuel consumptionAndrianov, DI ; Manzie, C ; Brear, MJ (SAE International, 2012-01-01)
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ItemNear-time-optimal tracking controller design for an automotive electromechanical brakeLee, CF ; Manzie, C (SAGE PUBLICATIONS LTD, 2012-04)A state-constrained, robust near-time-optimal clamp force tracking controller for an automotive electromechanical brake is presented. The proposed hybrid control structure consists of two switching control laws that handle tracking of rate-bounded references in the presence of state constraints. The responsive tracking utilizes an approximated time-optimal switching curve as a sliding manifold, while state constraints are handled by a linearizing–stabilizing feedback controller. The hybrid controller is proven to asymptotically track the reference in the presence of unknown but bounded time-varying disturbances and modelling errors. Implementation and validation of the proposed controller on a prototype electromechanical brake enables favourable performance comparisons with existing servo control architectures to be obtained.