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Publications (10 of 114) Show all publications
Yamalova, D. & Medvedev, A. (2019). Attractivity of the synchronous mode in hybrid observers for the impulsive Goodwin's oscillator subject to harmonic exogenous excitation. In: Proc. American Control Conference: ACC 2019. Paper presented at ACC 2019, July 10–12, Philadelphia, PA. American Automatic Control Council
Open this publication in new window or tab >>Attractivity of the synchronous mode in hybrid observers for the impulsive Goodwin's oscillator subject to harmonic exogenous excitation
2019 (English)In: Proc. American Control Conference: ACC 2019, American Automatic Control Council , 2019Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
American Automatic Control Council, 2019
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-382413 (URN)
Conference
ACC 2019, July 10–12, Philadelphia, PA
Note

to appear

Available from: 2019-04-25 Created: 2019-04-25 Last updated: 2019-05-07Bibliographically approved
Yamalova, D., Medvedev, A. & Zhusubaliyev, Z. (2019). Bifurcation analysis for non-local design of a hybrid observer for the impulsive Goodwin's oscillator.
Open this publication in new window or tab >>Bifurcation analysis for non-local design of a hybrid observer for the impulsive Goodwin's oscillator
2019 (English)In: Article in journal (Other academic) Submitted
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-382411 (URN)
Available from: 2019-04-25 Created: 2019-04-25 Last updated: 2019-05-07Bibliographically approved
Cubo, R., Fahlström, M., Jiltsova, E., Andersson, H. & Medvedev, A. (2019). Calculating Deep Brain Stimulation Amplitudes and Power Consumption by Constrained Optimization. Journal of Neural Engineering, 16(1), Article ID 016020.
Open this publication in new window or tab >>Calculating Deep Brain Stimulation Amplitudes and Power Consumption by Constrained Optimization
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2019 (English)In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 16, no 1, article id 016020Article in journal (Refereed) Published
Abstract [en]

Objective: Deep brain stimulation (DBS) consists of delivering electrical stimuli to a brain target via an implanted lead to treat neurological and psychiatric conditions. Individualized stimulation is vital to ensure therapeutic results, since DBS may otherwise become ineffective or cause undesirable side effects. Since the DBS pulse generator is battery-driven, power consumption incurred by the stimulation is important. In this study, target coverage and power consumption are compared over a patient population for clinical and model-based patient-specific settings calculated by constrained optimization.

Approach: Brain models for five patients undergoing bilateral DBS were built. Mathematical optimization of activated tissue volume was utilized to calculate stimuli amplitudes, with and without specifying the volumes, where stimulation was not allowed to avoid side effects. Power consumption was estimated using measured impedance values and battery life under both clinical and optimized settings.

Results: It was observed that clinical settings were generally less aggressive than the ones suggested by unconstrained model-based optimization, especially under asymmetrical stimulation. The DBS settings satisfying the constraints were close to the clinical values.

Significance: The use of mathematical models to suggest optimal patient-specific DBS settings that observe technological and safety constraints can save time in clinical practice. It appears though that the considered safety constraints based on brain anatomy depend on the patient and further research into it is needed. This work highlights the need of specifying the brain volumes to be avoided by stimulation while optimizing the DBS amplitude, in contrast to minimizing general stimuli overspill, and applies the technique to a cohort of patients. It also stresses the importance of considering power consumption in DBS optimization, since it increases with the square of the stimuli amplitude and also critically affects battery life through pulse frequency and duty cycle.

Keywords
neuromodulation, deep brain stimulation, inverse problems
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-368330 (URN)10.1088/1741-2552/aaeeb7 (DOI)000455843600002 ()30524006 (PubMedID)
Available from: 2018-12-04 Created: 2018-12-04 Last updated: 2019-02-05Bibliographically approved
Yamalova, D. & Medvedev, A. (2019). Hybrid observer with finite-memory output error correction for linear systems under intrinsic impulsive feedback. Automatica
Open this publication in new window or tab >>Hybrid observer with finite-memory output error correction for linear systems under intrinsic impulsive feedback
2019 (English)In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836Article in journal (Other academic) Submitted
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-382412 (URN)
Available from: 2019-04-25 Created: 2019-04-25 Last updated: 2019-05-07Bibliographically approved
Bro, V. & Medvedev, A. (2019). Identification of continuous Volterra models with explicit time delay through series of Laguerre functions. In: : .
Open this publication in new window or tab >>Identification of continuous Volterra models with explicit time delay through series of Laguerre functions
2019 (English)Conference paper, Published paper (Other academic)
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-385943 (URN)
Note

submitted

Available from: 2019-06-18 Created: 2019-06-18 Last updated: 2019-06-18Bibliographically approved
Taghvafard, H., Medvedev, A., Proskurnikov, A. V. & Cao, M. (2019). Impulsive model of endocrine regulation with a local continuous feedback. Mathematical Biosciences, 310, 128-135
Open this publication in new window or tab >>Impulsive model of endocrine regulation with a local continuous feedback
2019 (English)In: Mathematical Biosciences, ISSN 0025-5564, E-ISSN 1879-3134, Vol. 310, p. 128-135Article in journal (Refereed) Published
National Category
Endocrinology and Diabetes Control Engineering
Identifiers
urn:nbn:se:uu:diva-382991 (URN)10.1016/j.mbs.2019.02.006 (DOI)000464483500011 ()30822407 (PubMedID)
Available from: 2019-02-26 Created: 2019-05-13 Last updated: 2019-06-14Bibliographically approved
Bro, V. & Medvedev, A. (2019). Modeling of human smooth pursuit by sparse Volterra models with functionally dependent parameters.
Open this publication in new window or tab >>Modeling of human smooth pursuit by sparse Volterra models with functionally dependent parameters
2019 (English)In: Article in journal (Other academic) Submitted
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-385940 (URN)
Available from: 2019-06-18 Created: 2019-06-18 Last updated: 2019-06-18Bibliographically approved
Medvedev, A., Zhusubaliyev, Z. T., Rosén, O. & Martins da Silva, M. (2019). Oscillations-free PID control of anesthetic drug delivery in neuromuscular blockade. Computer Methods and Programs in Biomedicine, 171, 119-131
Open this publication in new window or tab >>Oscillations-free PID control of anesthetic drug delivery in neuromuscular blockade
2019 (English)In: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 171, p. 119-131Article in journal (Refereed) Published
Abstract [en]

Background and Objectives: The PID-control of drug delivery or the neuromuscular blockade (NMB) in closed-loop anesthesia is considered. The NMB system dynamics portrayed by a Wiener model can exhibit sustained nonlinear oscillations under realistic PID gains and for physiologically feasible values of the model parameters. Such oscillations, also repeatedly observed in clinical trials, lead to under- and overdosing of the administered drug and undermine patient safety. This paper proposes a tuning policy for the proportional PID gain that via bifurcation analysis ensures oscillations-free performance of the control loop. Online estimates of the Wiener model parameters are needed for the controller implementation and monitoring of the closed-loop proximity to oscillation.

Methods: The nonlinear dynamics of the PID-controlled NMB system are studied by bifurcation analysis. A database of patient models estimated under PID-controlled neuromuscular blockade during general anesthesia is utilized, along with the corresponding clinical measurements. The performance of three recursive algorithms is compared in the application at hand: an extended Kalman filter, a conventional particle filter (PF), and a PF making use of an orthonormal basis to estimate the probability density function from the particle set.

Results: It is shown that with a time-varying proportional PID gain, the type of equilibria of the closed-loop system remains the same as in the case of constant controller gains. The recovery time and frequency of oscillations are also evaluated in simulation over the database of patient models. Nonlinear identification techniques based on model linearization yield biased parameter estimates and thus introduce superfluous uncertainty. The bias and variance of the estimated models are related to the computational complexity of the identification algorithms, highlighting the superiority of the PFs in this safety-critical application.

Conclusions: The study demonstrates feasibility of the proposed oscillation-free control strategy combining bifurcation theory based design and online parameter estimation by PF.

Place, publisher, year, edition, pages
ELSEVIER IRELAND LTD, 2019
Keywords
Closed-loop drug delivery, Nonlinear systems, Oscillations, Parameter estimation, Particle, Filters Wiener models
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-381115 (URN)10.1016/j.cmpb.2016.07.025 (DOI)000461654700013 ()27481776 (PubMedID)
Funder
Swedish Research Council, 201505256
Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-04-05Bibliographically approved
Medvedev, A., Proskurnikov, A. V. & Zhusubaliyev, Z. T. (2018). Entrainment in harmonically forced continuous and impulsive Goodwin's oscillators: a comparison study. In: Proc. 16th European Control Conference: . Paper presented at ECC 2018, June 12–15, Limassol, Cyprus (pp. 2046-2051). IEEE
Open this publication in new window or tab >>Entrainment in harmonically forced continuous and impulsive Goodwin's oscillators: a comparison study
2018 (English)In: Proc. 16th European Control Conference, IEEE, 2018, p. 2046-2051Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
IEEE, 2018
National Category
Control Engineering
Identifiers
urn:nbn:se:uu:diva-386388 (URN)10.23919/ECC.2018.8550447 (DOI)000467725302013 ()978-3-9524-2698-2 (ISBN)
Conference
ECC 2018, June 12–15, Limassol, Cyprus
Available from: 2019-06-19 Created: 2019-06-19 Last updated: 2019-06-19Bibliographically approved
Johansson, D., Ericsson, A., Johansson, A., Medvedev, A., Nyholm, D., Ohlsson, F., . . . Bergquist, F. (2018). Individualization of levodopa treatment using a microtablet dispenser and ambulatory accelerometry. CNS Neuroscience & Therapeutics, 24(5), 439-447
Open this publication in new window or tab >>Individualization of levodopa treatment using a microtablet dispenser and ambulatory accelerometry
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2018 (English)In: CNS Neuroscience & Therapeutics, ISSN 1755-5930, E-ISSN 1755-5949, Vol. 24, no 5, p. 439-447Article in journal (Refereed) Published
National Category
Neurology Control Engineering
Identifiers
urn:nbn:se:uu:diva-354110 (URN)10.1111/cns.12807 (DOI)000430058800008 ()29652438 (PubMedID)
Available from: 2018-01-25 Created: 2018-06-19 Last updated: 2018-06-20Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6608-250x

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