Extremum Seeking Control and its Application to Process and Reaction Systems: a Survey.
Event details
| Date | 25.03.2011 |
| Hour | 10:15 |
| Speaker | Pr. D. Dochain, Center for Systems Eng. and Applied Mechanics, Universite Catholique de Louvain, Belgium |
| Location |
MEC2405
|
| Category | Conferences - Seminars |
Most adaptive control schemes documented in the literature are developed for regulation to known set-points or tracking known reference trajectories. Yet in some applications the control objective could be to optimize an objective function, which can be a function of unknown parameters, or to select the desired states to keep a performance function at its extremum value. Extremum seeking control is one of the methods to handle these kinds of optimization problems. Extremum seeking control allows the solution of the optimization problem as a control problem with the advantages related to sensitivity reduction and disturbance rejection. In the past few years, Krstic et al. have presented several schemes for extremum-seeking control of nonlinear systems. First the system is perturbed using an external excitation signal in order to numerically compute the gradient.
Although this technique has been proven useful for some applications, the lack of guaranteed transient performance of the black-box schemes remains a significant drawback in its application. Alternatively an adapted model of the system is used for analytical evaluation of the gradient. The extremum seeking framework proposed by Guay and Zhang assumes that the objective function is explicitly known as a function of the system states and uncertain parameters from the system dynamic equations. Parametric uncertainties make the on-line reconstruction of the true cost impossible such that only an estimated value based on parameter estimates is available. The control objective is to simultaneously identify and regulate the system to the lowest cost operating point, which depends on the uncertain parameters. The main advantage of this approach is that one can guarantee some degree of transient performance while achieving the optimization objectives when a reasonable functional approximation of the objective function is available. The objective of this seminar is to present a survey on extremum seeking control methods and their applications to process and reaction systems. Two important classes of extremum seeking control approaches are considered: perturbation-based and model-based methods.
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