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Publications (10 of 96) Show all publications
Cubo, R., Åström, M. & Medvedev, A. (2018). Optimization-based contact fault alleviation in deep brain stimulation leads. IEEE transactions on neural systems and rehabilitation engineering, 26(1), 69-76
Open this publication in new window or tab >>Optimization-based contact fault alleviation in deep brain stimulation leads
2018 (English)In: IEEE transactions on neural systems and rehabilitation engineering, ISSN 1534-4320, E-ISSN 1558-0210, Vol. 26, no 1, p. 69-76Article in journal (Refereed) Published
National Category
Medical Engineering
Identifiers
urn:nbn:se:uu:diva-342456 (URN)10.1109/TNSRE.2017.2769707 (DOI)000422939000008 ()29324404 (PubMedID)
Available from: 2017-11-03 Created: 2018-02-26 Last updated: 2018-03-29Bibliographically approved
Bro, V. & Medvedev, A. (2017). Constrained SPICE in Volterra-Laguerre modeling of human smooth pursuit. In: : . Paper presented at 2017 IEEE Conference on Control Technology and Applications (CCTA).
Open this publication in new window or tab >>Constrained SPICE in Volterra-Laguerre modeling of human smooth pursuit
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The Volterra model is a well-established option in nonlinear black-box system identification. However, the estimated model is often over-parametrized. This paper presents an approach to reducing the number of parameters of a Volterra model with the kernels parametrized in the orthonormal basis of Laguerre functions by estimating it with a sparse estimation algorithm subject to constraints. The resulting parameter estimates are scrutinized for parameter redundancy and functional dependence by principal component analysis. The benefits of this approach are illustrated by identifying the human smooth pursuit system. Previous studies have suggested that the Volterra model structure is suitable for modeling the human smooth pursuit system both in health and disease. The data sets are obtained by eye tracking in a study performed on 7 test subjects diagnosed with Parkinson’s disease and 22 healthy control subjects. In terms of output error, the reduced model has similar performance to that of the full model.

National Category
Other Medical Engineering Mathematics
Identifiers
urn:nbn:se:uu:diva-334955 (URN)
Conference
2017 IEEE Conference on Control Technology and Applications (CCTA)
Available from: 2017-11-29 Created: 2017-11-29 Last updated: 2017-12-12Bibliographically approved
Cubo, R., Medvedev, A. & Andersson, H. (2017). Deep Brain Stimulation therapies: a control-engineering perspective. In: Proc. American Control Conference: ACC 2017. Paper presented at ACC 2017, May 24–26, Seattle, WA (pp. 104-109). American Automatic Control Council
Open this publication in new window or tab >>Deep Brain Stimulation therapies: a control-engineering perspective
2017 (English)In: Proc. American Control Conference: ACC 2017, American Automatic Control Council , 2017, p. 104-109Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
American Automatic Control Council, 2017
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-305221 (URN)10.23919/ACC.2017.7962938 (DOI)978-1-5090-5992-8 (ISBN)
Conference
ACC 2017, May 24–26, Seattle, WA
Available from: 2017-07-03 Created: 2016-10-13 Last updated: 2017-07-12Bibliographically approved
Yamalova, D. & Medvedev, A. (2017). Design of a hybrid observer for an oscillator with an intrinsic pulse-modulated feedback. In: Proc. American Control Conference: ACC 2017. Paper presented at ACC 2017, May 24–26, Seattle, WA (pp. 1175-1180). American Automatic Control Council
Open this publication in new window or tab >>Design of a hybrid observer for an oscillator with an intrinsic pulse-modulated feedback
2017 (English)In: Proc. American Control Conference: ACC 2017, American Automatic Control Council , 2017, p. 1175-1180Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
American Automatic Control Council, 2017
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-316001 (URN)10.23919/ACC.2017.7963112 (DOI)978-1-5090-5992-8 (ISBN)
Conference
ACC 2017, May 24–26, Seattle, WA
Available from: 2017-07-03 Created: 2017-02-23 Last updated: 2017-07-12Bibliographically approved
Churilov, A. N., Medvedev, A. & Zhusubaliyev, Z. T. (2017). Discrete-time mapping for an impulsive Goodwin oscillator with three delays. International Journal of Bifurcation and Chaos in Applied Sciences and Engineering, 27(12), Article ID 1750182.
Open this publication in new window or tab >>Discrete-time mapping for an impulsive Goodwin oscillator with three delays
2017 (English)In: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering, ISSN 0218-1274, Vol. 27, no 12, article id 1750182Article in journal (Refereed) Published
Abstract [en]

A popular biomathematics model of the Goodwin oscillator has been previously generalized to a more biologically plausible construct by introducing three time delays to portray the transport phenomena arising due to the spatial distribution of the model states. The present paper addresses a similar conversion of an impulsive version of the Goodwin oscillator that has found application in mathematical modeling, e.g. in endocrine systems with pulsatile hormone secretion. While the cascade structure of the linear continuous part pertinent to the Goodwin oscillator is preserved in the impulsive Goodwin oscillator, the static nonlinear feedback of the former is substituted with a pulse modulation mechanism thus resulting in hybrid dynamics of the closed-loop system. To facilitate the analysis of the mathematical model under investigation, a discrete mapping propagating the continuous state variables through the firing times of the impulsive feedback is derived. Due to the presence of multiple time delays in the considered model, previously developed mapping derivation approaches are not applicable here and a novel technique is proposed and applied. The mapping captures the dynamics of the original hybrid system and is instrumental in studying complex nonlinear phenomena arising in the impulsive Goodwin oscillator. A simulation example is presented to demonstrate the utility of the proposed approach in bifurcation analysis.

National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-339710 (URN)10.1142/S0218127417501826 (DOI)000418277700010 ()
Available from: 2017-11-30 Created: 2018-01-26 Last updated: 2018-01-29Bibliographically approved
Yamalova, D., Churilov, A. & Medvedev, A. (2017). Hybrid observer for an intrinsic impulsive feedback system. In: : . Paper presented at IFAC 2017, 20th IFAC World Congress, July 9–14, Toulouse, France (pp. 4570-4575). , 50
Open this publication in new window or tab >>Hybrid observer for an intrinsic impulsive feedback system
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This paper deals with continuous plants subject to intrinsic pulse-modulated feedback, thus exhibiting hybrid closed-loop dynamics. The system structure implements a hybrid oscillator and arises in living organisms, e.g. when episodically firing neurons control the production of hormones in endocrine glands. Hybrid observers reconstructing both the continuous and discrete states of the hybrid plant from only continuous measured outputs are considered. They excel over the existing solutions through the introduction of two co-ordinated feedbacks of the output estimation error: one correcting the continuous state estimates and another adjusting the discrete ones. Different types of the feedback operator to the discrete estimates are analyzed. The observer design problem is reduced to synchronization of the observer solution with that of the plant. The synchronous mode of the observer is rendered locally stable by the selection of the feedback gains. Numerical illustration of the design procedure and observer performance with respect to a pulse-modulated model of testosterone regulation is provided.

Series
IFAC-PapersOnLine, ISSN 2405-8963 ; 50:1
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-342175 (URN)10.1016/j.ifacol.2017.08.733 (DOI)
Conference
IFAC 2017, 20th IFAC World Congress, July 9–14, Toulouse, France
Available from: 2017-10-18 Created: 2018-02-19 Last updated: 2018-04-06Bibliographically approved
Yamalova, D. & Medvedev, A. (2017). Hybrid observers for an impulsive Goodwin’s oscillator subject to continuous exogenous signals. In: 2017 IEEE 56Th Annual Conference on Decision and Control (Cdc): . Paper presented at CDC 2017, IEEE 56:th Annual Conference on Decision and Control, December 12–15,2017, Melbourne, Australia (pp. 2396-2401). Piscataway, NJ: IEEE
Open this publication in new window or tab >>Hybrid observers for an impulsive Goodwin’s oscillator subject to continuous exogenous signals
2017 (English)In: 2017 IEEE 56Th Annual Conference on Decision and Control (Cdc), Piscataway, NJ: IEEE, 2017, p. 2396-2401Conference paper, Published paper (Refereed)
Abstract [en]

This paper deals with the state estimation problemin an impulsive model of Goodwin’s oscillator forced by acontinuous exogenous signal. The continuous linear part of themodel is controlled by an intrinsic impulsive feedback thatcontributes discrete dynamics to the closed-loop system. Theimpacting pulsatile feedback signal is not available for mea-surement and, therefore, has to be reconstructed. To estimateall the elements of the hybrid state vector, an observationproblem is considered. Two hybrid observer structures areproposed and evaluated: one based on reconstructing both thestates of the Goodwin’s oscillator and those of the exogenoussystem and another assuming that the exogenous signal, or afunction of it, is known. The observer design is reduced to aproblem of synchronizing the impulsive sequence produced bythe observer with that of the plant. It utilizes a local approach ofassigning a guaranteed convergence rate to the local dynamicsof a synchronous mode through output error feedback. Thedynamics of the proposed observer schemes are analyzed bymeans of pointwise discrete (Poincar ́e) maps and illustrated bynumerical simulation for a case of bistability in the oscillator.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE, 2017
Series
Proceedings / IEEE Conference on Decision and Control, ISSN 0743-1546
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-342163 (URN)10.1109/CDC.2017.8264000 (DOI)000424696902052 ()978-1-5090-2873-3 (ISBN)
Conference
CDC 2017, IEEE 56:th Annual Conference on Decision and Control, December 12–15,2017, Melbourne, Australia
Funder
Swedish Research Council, 2015-05256
Available from: 2018-01-23 Created: 2018-02-19 Last updated: 2018-04-25Bibliographically approved
Cubo, R. & Medvedev, A. (2017). Individualization of a surrounding tissue model in Deep Brain Stimulation. In: Proc. 56th Conference on Decision and Control: . Paper presented at CDC 2017, December 12–15, Melbourne, Australia (pp. 5919-5924). Piscataway, NJ: IEEE
Open this publication in new window or tab >>Individualization of a surrounding tissue model in Deep Brain Stimulation
2017 (English)In: Proc. 56th Conference on Decision and Control, Piscataway, NJ: IEEE, 2017, p. 5919-5924Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Piscataway, NJ: IEEE, 2017
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:uu:diva-348327 (URN)10.1109/CDC.2017.8264555 (DOI)000424696905113 ()978-1-5090-2873-3 (ISBN)
Conference
CDC 2017, December 12–15, Melbourne, Australia
Available from: 2018-01-23 Created: 2018-04-20 Last updated: 2018-04-26Bibliographically approved
Senek, M., Aquilonius, S.-M., Askmark, H., Bergquist, F., Constantinescu, R., Ericsson, A., . . . Nyholm, D. (2017). Levodopa/carbidopa microtablets in Parkinson’s disease: A study of pharmacokinetics and blinded motor assessment. European Journal of Clinical Pharmacology, 73(5), 563-571
Open this publication in new window or tab >>Levodopa/carbidopa microtablets in Parkinson’s disease: A study of pharmacokinetics and blinded motor assessment
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2017 (English)In: European Journal of Clinical Pharmacology, ISSN 0031-6970, E-ISSN 1432-1041, Vol. 73, no 5, p. 563-571Article in journal (Refereed) Published
National Category
Neurology
Identifiers
urn:nbn:se:uu:diva-320487 (URN)10.1007/s00228-017-2196-4 (DOI)000399175100006 ()28101657 (PubMedID)
Funder
VINNOVA
Available from: 2017-01-18 Created: 2017-04-20 Last updated: 2018-02-28Bibliographically approved
Bro, V. & Medvedev, A. (2017). Nonlinear Dynamics of the Human Smooth Pursuit System in Health and Disease: Model Structure and Parameter Estimation. In: IEEE 56th Annual Conference on Decision and Control (CDC): . Paper presented at 56th IEEE Conference on Decision and Control, December 12-15, 2017, Melbourne, Australia (pp. 4692-4697). IEEE
Open this publication in new window or tab >>Nonlinear Dynamics of the Human Smooth Pursuit System in Health and Disease: Model Structure and Parameter Estimation
2017 (English)In: IEEE 56th Annual Conference on Decision and Control (CDC), IEEE, 2017, p. 4692-4697Conference paper, Published paper (Refereed)
Abstract [en]

Oculomotor tests (OMT) are administered to quantify symptoms in neurological and mental diseases. Eye movements in response to displayed visual stimuli are registered by an digital video-based eye tracker and processed. Stimuli of simple signal form, e.g. sine waves, are traditionally used in medical practice to test the performance of the oculomotor system in smooth pursuit (SP). The calculated SP gain and the phase shift at the frequency in question are then presented as the test outcome. This paper revisits the problem of quantifying the SP dynamics from eye-tracking data by means of nonlinear system identification. First, a sparse Volterra-Laguerre (VL) model is estimated from an OMT with sufficiently exciting (in frequency and amplitude) stimuli. Then the structure and initial parameter estimates of a polynomial Wiener model (WM) are obtained from the kernel estimates of the VL model. Finally, the parameter distributions of the WM are inferred by a particle filter (PF). In the proposed approach, the performance of the PF is improved by the individualized sparse model structure. Experimental data show that the latter captures the alternations in the SP dynamics due to aging and in Parkinson’s disease.

Place, publisher, year, edition, pages
IEEE, 2017
Series
IEEE Conference on Decision and Control, ISSN 0743-1546
National Category
Other Medical Engineering Mathematics
Identifiers
urn:nbn:se:uu:diva-334957 (URN)10.1109/CDC.2017.8264352 (DOI)000424696904084 ()978-1-5090-2873-3 (ISBN)
Conference
56th IEEE Conference on Decision and Control, December 12-15, 2017, Melbourne, Australia
Funder
VINNOVA
Available from: 2017-11-29 Created: 2017-11-29 Last updated: 2018-04-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6608-250x

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