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Publications (10 of 88) Show all publications
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, 104-109 p.Conference 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, 1175-1180 p.Conference 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
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, 563-571 p.Article 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: 2017-05-17Bibliographically approved
Bro, V. & Medvedev, A. (2017). Nonlinear Dynamics of the Human Smooth Pursuit System in Health and Disease: Model Structure and Parameter Estimation. In: : . Paper presented at 56th IEEE Conference on Decision and Control, December 12-15, 2017, Melbourne, Australia (pp. 1-6). .
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)Conference 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.

National Category
Other Medical Engineering Mathematics
Identifiers
urn:nbn:se:uu:diva-334957 (URN)
Conference
56th IEEE Conference on Decision and Control, December 12-15, 2017, Melbourne, Australia
Available from: 2017-11-29 Created: 2017-11-29 Last updated: 2017-12-05Bibliographically approved
Medvedev, A. & Jansson, D. (2016). Capturing age-related alternations in the human smooth pursuit mechanism by Volterra models. In: 2016 AMERICAN CONTROL CONFERENCE (ACC): . Paper presented at American Control Conference (ACC), JUL 06-08, 2016, Boston, MA (pp. 1289-1294). IEEE.
Open this publication in new window or tab >>Capturing age-related alternations in the human smooth pursuit mechanism by Volterra models
2016 (English)In: 2016 AMERICAN CONTROL CONFERENCE (ACC), IEEE , 2016, 1289-1294 p.Conference paper, Published paper (Refereed)
Abstract [en]

A method for quantifying the effects of aging in the human smooth pursuit system is proposed. The dynamical properties of the oculomotor system are characterized by means of a truncated Volterra model that has previously been utilized for distinguishing between patients diagnosed with Parkinson's disease and healthy controls. The orthonormal basis of Laguerre functions is employed for the parameterization of the Volterra model kernels. The Volterra-Laguerre model coefficients are estimated from gaze direction data collected by means of eye tracking from healthy adults of different age responding to specially designed visual stimuli. The experimental results suggest that aging primarily impacts the linear term of the Volterra model through gain and frequency bandwidth reduction. Parameter variability increases with age, both in the linear and quadratic term of the Volterra model. The mean values of the nonlinear term coefficients appear though to be essentially independent of age within the studied population.

Place, publisher, year, edition, pages
IEEE, 2016
Series
Proceedings of the American Control Conference, ISSN 0743-1619
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:uu:diva-320120 (URN)000388376101055 ()978-1-4673-8682-1 (ISBN)
Conference
American Control Conference (ACC), JUL 06-08, 2016, Boston, MA
Funder
VINNOVA
Available from: 2017-04-21 Created: 2017-04-21 Last updated: 2018-01-13Bibliographically approved
Churilov, A. N. & Medvedev, A. (2016). Discrete-time map for an impulsive Goodwin oscillator with a distributed delay. MCSS. Mathematics of Control, Signals and Systems, 28(1), Article ID 9.
Open this publication in new window or tab >>Discrete-time map for an impulsive Goodwin oscillator with a distributed delay
2016 (English)In: MCSS. Mathematics of Control, Signals and Systems, ISSN 0932-4194, E-ISSN 1435-568X, Vol. 28, no 1, 9Article in journal (Refereed) Published
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-294338 (URN)10.1007/s00498-016-0160-y (DOI)000372846500009 ()
Funder
Swedish Research Council, 2012-3153
Available from: 2016-02-19 Created: 2016-05-18 Last updated: 2017-11-30Bibliographically approved
Churilov, A. N., Medvedev, A. & Zhusubaliyev, Z. T. (2016). Impulsive Goodwin oscillator with large delay: Periodic oscillations, bistability, and attractors. Nonlinear Analysis: Hybrid Systems, 21, 171-183.
Open this publication in new window or tab >>Impulsive Goodwin oscillator with large delay: Periodic oscillations, bistability, and attractors
2016 (English)In: Nonlinear Analysis: Hybrid Systems, ISSN 1751-570X, E-ISSN 1878-7460, Vol. 21, 171-183 p.Article in journal (Refereed) Published
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-298831 (URN)10.1016/j.nahs.2015.08.004 (DOI)000377232200014 ()
Available from: 2015-09-26 Created: 2016-07-11 Last updated: 2017-11-28Bibliographically approved
Cubo, R., Medvedev, A. & Åström, M. (2016). Model-based optimization of individualized Deep Brain Stimulation therapy. IEEE Design & Test, 33(4), 74-81.
Open this publication in new window or tab >>Model-based optimization of individualized Deep Brain Stimulation therapy
2016 (English)In: IEEE Design & Test, ISSN 2168-2356, Vol. 33, no 4, 74-81 p.Article in journal (Refereed) Published
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-300550 (URN)10.1109/MDAT.2015.2480705 (DOI)000379598700008 ()
Funder
EU, European Research Council, 247035
Available from: 2016-06-20 Created: 2016-08-09 Last updated: 2016-08-10Bibliographically approved
Cubo, R., Jiltsova, E., Fahlström, M., Andersson, H. & Medvedev, A. (2016). Optimization of deep brain stimulation by means of a patient-specific mathematical model. In: : . Paper presented at XXII Congress of the European Society for Stereotactic and Functional Neurosurgery, Madrid, Spain, September 28 – October 1, 2016. .
Open this publication in new window or tab >>Optimization of deep brain stimulation by means of a patient-specific mathematical model
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2016 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-305222 (URN)
Conference
XXII Congress of the European Society for Stereotactic and Functional Neurosurgery, Madrid, Spain, September 28 – October 1, 2016
Available from: 2016-10-13 Created: 2016-10-13 Last updated: 2017-07-13Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6608-250x

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