R. Barcena
University of the Basque Country
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Publication
Featured researches published by R. Barcena.
IEEE Transactions on Circuits and Systems I-regular Papers | 2001
M. De la Sen; R. Barcena; Aitor J. Garrido
It is rigorously proved that the limiting discrete zeros located at z=1 as the sampling period tends to zero are limiting intrinsic zeros (i.e., they do not appear if the continuous plant is zero-free). To prove that known result, it is not assumed as usual in the literature, that the plant is approximated by an integrator of order equal to its relative degree as the sampling period tends to zero. It Is also proved that limiting zeros at z=1 are present for any fractional zero-order hold (FROH), including the zero-order hold (ZOH) and the first-order hold (FOH), even when the continuous plant is of zero relative degree (i.e., biproper).
Journal of The Franklin Institute-engineering and Applied Mathematics | 2007
R. Barcena; A. Etxebarria
Abstract A connectionist method for autotuning the free parameter of a fractional-order hold (FROH) circuit in order to improve the performance of the digitally controlled systems is proposed. Such a technique employs multilayer perceptrons to approximate the mapping between the sampling period/continuous-time parameters of the estimated plant and the optimal value of the FROH adjustable gain. In this way, adaptive discretization systems to improve the stability properties of the resulting discrete-time zeros are implemented. Simulation results are presented in order to illustrate the properties of the complete system applied to two actual digitally controlled printing devices (HP 7090A and low-cost computer printer).
Automatica | 2012
Unai Ugalde; R. Barcena; Koldo Basterretxea
We present a generalized sampled-data hold function that combines arbitrary z-domain zero-placement ability with zero-order hold behavior under constant input, thus exhibiting minimal intersample ripple by design. Our hold can be regarded as a generalization of the fractional-order hold, with a polynomial instead of a simple linear pattern, and therefore with as many tuning parameters as desired. Moreover, the polynomial approach turns out to provide a simple mechanism of control energy minimization. Among other benefits, all these features help to achieve qualitatively better perfect model referencing, because problematic sampling z-zeros or the intersample issues of the conventional generalized holds need no longer be endured.
american control conference | 2000
Aitor J. Garrido; M. De la Sen; R. Barcena
We present an explicit description of an innovative technique to treat the real sampling and hold method by considering a real finite pulse instead of an ideal one to sample the signal. Fractional-order sampling and hold devices are considered in general while including the zero-order hold and the first-order hold as particular cases. The discrete model obtained leads to an increment of the degrees of freedom. Therefore the proposed technique may be very useful in adaptive control to improve the stability of the discrete plant zeros. This model affords better results than the one based on the traditional ideal sampling. In addition, the use of multirate sampling, with a fast sampling rate being used to approximate the continuous signal during the real sampling pulse, provides a simple technique to deal with other multirate problems.
Applicable Analysis | 2004
M. De la Sen; R. Barcena
This article deals with asymptotic stability and stabilization criteria based on Rouches theorem for variation of zeros of analytic functions within complex domains. Stability criteria consisting of sufficiency conditions for asymptotic stability of time-invariant point delay systems are obtained, provided that an auxiliary delay-free system is globally asymptotically stable, in terms of smallness of the delayed dynamics related to such a free-delay dynamics. A physical insight related to the use of the stability criteria linked with the variations of the auxiliary system are also given. Finally, some extensions related to closed-loop stabilization using such stability criteria are also given.This article deals with asymptotic stability and stabilization criteria based on Rouches theorem for variation of zeros of analytic functions within complex domains. Stability criteria consisting of sufficiency conditions for asymptotic stability of time-invariant point delay systems are obtained, provided that an auxiliary delay-free system is globally asymptotically stable, in terms of smallness of the delayed dynamics related to such a free-delay dynamics. A physical insight related to the use of the stability criteria linked with the variations of the auxiliary system are also given. Finally, some extensions related to closed-loop stabilization using such stability criteria are also given.
international conference on control applications | 2001
R. Barcena; M. De la Sen; A.J. Garrido
A connectionist method for autotuning the free parameter of a fractional order hold (FROH) in order to improve the stability properties of the resulting discrete-time zeros is proposed. Such a technique employs multilayer perceptrons to approximate the mapping between the sampling period/continuous-time parameters of the plant and the optimal values of the FROH parameter. The neural networks are designed to adapt online to changing system structures, parameter values and sampling periods. To achieve this objective, the network weighting coefficients are determined during an off-line training phase. In this training phase, the optimal values of the FROH parameter are obtained by applying the classical generalized root locus procedure. Simulation results are presented in order to illustrate the properties of the complete regression system applied to a digitally controlled printing device.
american control conference | 2001
R. Barcena; M. De la Sen; A.J. Garrido
A connectionist method for autotuning the free parameter of a Fractional order hold (FROH) in order to improve the stability properties of the resulting discrete-time zeros is proposed. Such a technique employs multilayer perceptrons to approximate the mapping between the sampling period/continuous-time parameters of the plant and the optimal values of the FROH parameter. The neural networks are designed to adapt on-line to changing system structures, parameter values and sampling periods. To achieve this objective, the network weighting coefficients are determined during an off-line training phase. In this training phase, the optimal values of the FROH parameter are obtained by applying the classical generalised root locus procedure. Simulation results are presented to illustrate the properties of the complete regression system.
american control conference | 2003
A.J. Garrido; M. De la Sen; R. Barcena
In this paper, we present two different filter-based identification methods to obtain discrete transfer functions for LTI systems under real sampling of finite duration rather than an instantaneous ideal one. The first method is based on a typically used least-squares minimization, while the second one is based on the Leverrier algorithm; that is, using a data series of the impulse response of the system to identify a parametric discrete model. This second method, being also an approximated technique, provides an algebraic result at least for the first computed data of the series. The main idea is to use semi-heuristic techniques of reduced mathematical complexity to derive parametric discrete models from measured input-output data series. These methods are of particular practical interest when the continuous-time system is unknown or when dealing with discrete-time systems whose analytical expression become very complex due, for instance, to the use of finite duration real sampling. This is the case of the problem treated in the application, where the proposed discretization technique allows a simple and accurate description of the discrete system. The identification techniques are also used to improve the discretization process in the context of a bi-estimation scheme that switches to the model that provides a better performance at each considered estimation instant, which is also used to compare the two techniques.
IEE Proceedings - Control Theory and Applications | 2000
R. Barcena; M. De la Sen; I. Sagastabeitia
Cirp Annals-manufacturing Technology | 2013
Jokin Munoa; I. Mancisidor; N. Loix; L.G. Uriarte; R. Barcena; Mikel Zatarain