Agnieszka Pręgowska, Ph.D., Eng.

Department of Biosystems and Soft Matter (ZBiMM)
Division of Complex Fluids (PFPZ)
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 417
room: 442
e-mail: aprego

Doctoral thesis
2013-06-05Półaktywne sterowanie układami mechanicznymi drgającymi skrętnie 
supervisor -- Tomasz Szolc, Ph.D., Dr. Habil., Eng., IPPT PAN
661
 
Recent publications
1.Proniewska K., Pręgowska A., Malinowski K.P., Sleep-related breathing biomarkers as a predictor of vital functions, Bio-Algorithms and Med-Systems, ISSN: 1895-9091, DOI: 10.1515/bams-2017-0003, Vol.13, No.1, pp.43-49, 2017
Abstract:

Because an average human spends one third of his life asleep, it is apparent that the quality of sleep has an important impact on the overall quality of life. To properly understand the influence of sleep, it is important to know how to detect its disorders such as snoring, wheezing, or sleep apnea. The aim of this study is to investigate the predictive capability of a dual-modality analysis scheme for methods of sleep-related breathing disorders (SRBDs) using biosignals captured during sleep. Two logistic regressions constructed using backward stepwise regression to minimize the Akaike information criterion were extensively considered. To evaluate classification correctness, receiver operating characteristic (ROC) curves were used. The proposed classification methodology was validated with constructed Random Forests methodology. Breathing sounds and electrocardiograms of 15 study subjects with different degrees of SRBD were captured and analyzed. Our results show that the proposed classification model based on selected parameters for both logistic regressions determine the different types of acoustic events during sleep. The ROC curve indicates that selected parameters can distinguish normal versus abnormal events during sleep with high sensitivity and specificity. The percentage of prediction for defined SRBDs is very high. The initial assumption was that the quality of result is growing with the number of parameters included in the model. The best recognition reached is more than 89% of good predictions. Thus, sleep monitoring of breath leads to the diagnosis of vital function disorders. The proposed methodology helps find a way of snoring rehabilitation, makes decisions concerning future treatment, and has an influence on the sleep quality.

Keywords:

patient monitoring, sleep-related breathing disorders, vital functions

Affiliations:
Proniewska K.-other affiliation
Pręgowska A.-IPPT PAN
Malinowski K.P.-other affiliation
2.Konowrocki R., Szolc T., Pochanke A., Pręgowska A., An influence of the stepping motor control and friction models on precise positioning of the complex mechanical system, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2015.09.030, Vol.70-71, pp.397-413, 2016
Abstract:

This paper aims to investigate, both experimentally and theoretically, the electromechanical dynamic interaction between a driving stepping motor and a driven laboratory belt-transporter system. A test-rig imitates the operation of a robotic device in the form of a working tool-carrier under translational motion. The object under consideration is equipped with measurement systems, which enable the registration of electrical and mechanical quantities. Analytical considerations are performed by means of a circuit model of the electric motor and a discrete, non-linear model of the mechanical system. Various scenarios of the working tool-carrier motion and positioning by the belt-transporter are measured and simulated; in all cases the electric current control of the driving motor has been applied. The main goal of this study is to investigate the influence of the stepping motor control parameters along with various mechanical friction models on the precise positioning of a laboratory robotic device.

Keywords:

Belt transporter system, Precise positioning, Stepping motor, Current control, Experimental verification

Affiliations:
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
Pochanke A.-other affiliation
Pręgowska A.-IPPT PAN
3.Pręgowska A., Szczepański J., Wajnryb E., Temporal code versus rate code for binary Information Sources, NEUROCOMPUTING, ISSN: 0925-2312, DOI: 10.1016/j.neucom.2016.08.034, Vol.216, pp.756-762, 2016
Abstract:

Neuroscientists formulate very different hypotheses about the nature of neural coding. At one extreme, it has been argued that neurons encode information through relatively slow changes in the arrival rates of individual spikes (rate codes) and that the irregularity in the spike trains reflects the noise in the system. At the other extreme, this irregularity is the code itself (temporal codes) so that the precise timing of every spike carries additional information about the input. It is well known that in the estimation of Shannon Information Transmission Rate, the patterns and temporal structures are taken into account, while the “rate code” is already determined by the firing rate, i.e. by the spike frequency. In this paper we compare these two types of codes for binary Information Sources, which model encoded spike trains. Assuming that the information transmitted by a neuron is governed by an uncorrelated stochastic process or by a process with a memory, we compare the Information Transmission Rates carried by such spike trains with their firing rates. Here we show that a crucial role in the relation between information transmission and firing rates is played by a factor that we call the “jumping” parameter. This parameter corresponds to the probability of transitions from the no-spike-state to the spike-state and vice versa. For low jumping parameter values, the quotient of information and firing rates is a monotonically decreasing function of the firing rate, and there therefore a straightforward, one-to-one, relation between temporal and rate codes. However, it turns out that for large enough values of the jumping parameter this quotient is a non-monotonic function of the firing rate and it exhibits a global maximum, so that in this case there is an optimal firing rate. Moreover, there is no one-to-one relation between information and firing rates, so the temporal and rate codes differ qualitatively. This leads to the observation that the behavior of the quotient of information and firing rates for a large jumping parameter value is especially important in the context of bursting phenomena.

Keywords:

Information Theory, Information Source, Stochastic process, Information transmission rate, Firing rate

Affiliations:
Pręgowska A.-IPPT PAN
Szczepański J.-IPPT PAN
Wajnryb E.-IPPT PAN
4.Konowrocki R., Pręgowska A., Szolc T., Experimental and numerical investigations for the controlled rotary damper dynamically interacting with the electromechanical rotating system, SOLID STATE PHENOMENA, ISSN: 1012-0394, DOI: 10.4028/www.scientific.net/SSP.240.198, Vol.240, pp.198-205, 2016
Abstract:

In the paper dynamic electromechanical coupling between the structural model of the rotating machine drive system and the circuit model of the asynchronous motor has been investigated. By means of the computer model of the rotating machine drive system the results of experimental testing have been confirmed. From the obtained results of computations and measurements it follows that the coupling between the considered rotating system and the installed rotary dampers with the magneto-rheological fluid (MRF) results in effective energy dissipation leading to significant reduction of undesired torsional vibrations.

Keywords:

Electromechanical Coupling, Machine Drive Systems, Rotary MRF Actuator, Torsional Vibrations, Wavelet Transform (WT)

Affiliations:
Konowrocki R.-IPPT PAN
Pręgowska A.-IPPT PAN
Szolc T.-IPPT PAN
5.Pręgowska A., Szczepański J., Wajnryb E., Mutual information against correlations in binary communication channels, BMC NEUROSCIENCE, ISSN: 1471-2202, DOI: 10.1186/s12868-015-0168-0, Vol.16, No.32, pp.1-7, 2015
Abstract:

Background
Explaining how the brain processing is so fast remains an open problem (van Hemmen JL, Sejnowski T., 2004). Thus, the analysis of neural transmission (Shannon CE, Weaver W., 1963) processes basically focuses on searching for effective encoding and decoding schemes. According to the Shannon fundamental theorem, mutual information plays a crucial role in characterizing the efficiency of communication channels. It is well known that this efficiency is determined by the channel capacity that is already the maximal mutual information between input and output signals. On the other hand, intuitively speaking, when input and output signals are more correlated, the transmission should be more efficient. A natural question arises about the relation between mutual information and correlation. We analyze the relation between these quantities using the binary representation of signals, which is the most common approach taken in studying neuronal processes of the brain.

Results
We present binary communication channels for which mutual information and correlation coefficients behave differently both quantitatively and qualitatively. Despite this difference in behavior, we show that the noncorrelation of binary signals implies their independence, in contrast to the case for general types of signals.

Conclusions
Our research shows that the mutual information cannot be replaced by sheer correlations. Our results indicate that neuronal encoding has more complicated nature which cannot be captured by straightforward correlations between input and output signals once the mutual information takes into account the structure and patterns of the signals.

Keywords:

Shannon information, Communication channel, Entropy, Mutual information, Correlation, Neuronal encoding

Affiliations:
Pręgowska A.-IPPT PAN
Szczepański J.-IPPT PAN
Wajnryb E.-IPPT PAN
6.Dyniewicz B., Pręgowska A., Bajer C.I., Adaptive control of a rotating system, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2013.09.006, Vol.43, pp.90-102, 2014
Abstract:

In the present paper, an adaptive control of structural vibrations is presented. Based on earlier research, we claim that the periodical switching on of magneto-rheological controlled dampers results in the reduction of the amplitudes of vibrations more than does their permanent actuation. This statement, when applied to a moving load problem, was mathematically proved in earlier papers. In the present paper we determine the efficiency of such a control applied to a rotating shaft. The earlier mathematical analysis allows us to propose a control strategy. A finite element simulation together with the solution of the control problem shows that the dampers should act only during a short period of the highest displacements of the structure. The same conclusion is found in experimental tests. Although high frequency control with MR dampers is less efficient than in the theoretical investigations, we have found an amplitude reduction in the range of 10–20%.

Keywords:

Adaptive control, Semi-active control, Vibration control, Shaft vibrations, Torsional vibrations, Magneto-rheological dampers

Affiliations:
Dyniewicz B.-IPPT PAN
Pręgowska A.-IPPT PAN
Bajer C.I.-IPPT PAN
7.Szolc T., Konowrocki R., Michajłow M., Pręgowska A., An investigation of the dynamic electromechanical coupling effects in machine drive systems driven by asynchronous motors, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2014.04.004, Vol.49, pp.118-134, 2014
Abstract:

In the paper dynamic electromechanical interaction between the rotating machine drive system and the electric driving motor is considered. The investigations are performed by means of the circuit model of the asynchronous motor as well as using an advanced structural hybrid model of the drive system. Using the analytical solutions applied for the electrical and the mechanical systems the electromagnetic stiffness and coefficient of damping, both generated by the electric motor rotationally interacting with the mechanical system of the given dynamic properties, were determined. By means of experimentally validated computational responses obtained for torsional harmonic excitation induced by the driven machine working tool, a modification of dynamic properties of the mechanical system by the electromagnetic flux between the stator and the rotor has been studied.

Keywords:

Machine drive system, Asynchronous motor, Electromechanical coupling

Affiliations:
Szolc T.-IPPT PAN
Konowrocki R.-IPPT PAN
Michajłow M.-IPPT PAN
Pręgowska A.-IPPT PAN
8.Pręgowska A., Konowrocki R., Szolc T., Analysis of rotating systems using actuators with magnetorheological fluid to vibration minimization – theoretical and experimental investigation, Symulacja w Badaniach i Rozwoju, ISSN: 2081-6154, Vol.5, No.3, pp.191-198, 2014
Abstract:

The analysis of damped rotating systems using actuators with magnetorheological fluid is the subject of interest. The main purpose of this research is minimization of vibration amplitudes in order to increase fatigue durability of the most responsible machine elements. Here, control damping torques are generated by magnetorheological fluid of adjustable viscosity.
The theoretical investigations are based on a hybrid and finite element structural model (FEM) of the mechanical structure as well as on sensitivity analysis of the response with respect to the actuators damping characteristics. The analysis performed in the paper combines experimental verification using the laboratory test rig with theoretical computations.

Keywords:

rotating systems, torsional vibrations, actuators with a magnetorheological fluid, rotary actuators

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
9.Pręgowska A., Konowrocki R., Szolc T., On the semi-active control method for torsional vibrations in electro-mechanical systems by means of rotary actuators with a magneto-rheological fluid, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, ISSN: 1429-2955, Vol.51, No.4, pp.979-992, 2013
Abstract:

The aim of this paper is to present a method of the semi-active control of torsional vibrations in a working machine drive system by means of rotary actuators with a magneto-rheological fluid. The simple open-loop control strategy is proposed for a mechanical system vibrating in steady-state operating conditions. This semi-active control approach is based on the principle of optimum viscous damping and frictional properties realized by the magneto-rheological fluid, where its respective parameters are determined by the applied control electric currents. The analysis is performed theoretically by means of structural electro-mechanical models of the considered drive system as well as experimentally using a laboratory test rig in the form of a rotor-shaft system co-operating with two asynchronous motors generating properly programmed driving and retarding electro-magnetic torques

Keywords:

semi-active control, torsional vibrations, magneto-rheological rotary dampers

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
10.Pręgowska A., Konowrocki R., Szolc T., Semi-active vibration control using a rotary magnetorheological damper – experimental verification, POMIARY - AUTOMATYKA - ROBOTYKA. PAR, ISSN: 1427-9126, Vol.2, pp.487-491, 2013
Abstract:

From all kinds of vibrations, torsional ones are very important as naturally associated with fundamental rotational drive system motion. The aim of this paper is to present semi-active control of torsional vibrations of the working machine drive systems, which is performed using a rotary damper with the magnetorheological fluid. The main purpose of this research is vibration amplitudes minimization in order to increase fatigue durability of the most responsible machine elements. The special control strategies are proposed for steady-state torsional vibrations suppression. The semi-active control method is based on a principle of determinational optimum current damping coefficient values, which is realized by the magneto-rheological fluid application. The analysis performed in the paper combines experimental verification using the laboratory test rig with theoretical computations. This experiment was designed in the form of the laboratory drive system co-operating with two asynchronous motors generating properly programmed driving and retarding electromagnetic torques.

Keywords:

semi-active control, torsional vibrations, rotary dampers, magnetorheological fluid, electromechanical drive system

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
11.Pręgowska A., Konowrocki R., Szolc T., Experimental verification of the semi-active control concepts for torsional vibrations of the electro-mechanical system using rotary magneto-rheological actuators, VIBRATIONS IN PHYSICAL SYSTEMS, ISSN: 0860-6897, Vol.25, pp.329-334, 2012
Abstract:

In the paper semi-active control of torsional vibrations of the rotating machine drive system driven by an electric motor is performed by means of rotary actuators with the magneto-rheological fluid. The main purpose of these studies is a minimisation of vibration amplitudes in order to increase the fatigue durability of the most responsible elements, assure possibly precise motion of the driven machine working tool as well as to reduce a generated noise level. For suppression of steady-state torsional vibrations excited by dynamic external torques generated by the motor and by the driven object there are proposed control strategies based on a principle of optimum current damping coefficient values realized by the magneto-rheological fluid. The theoretical control concepts are experimentally verified using the laboratory test rig in the form of drive system co-operating with two asynchronous motors generating properly programmed driving and retarding electromagnetic torques.

Keywords:

semi-active control, torsional vibrations, rotary actuators, magneto-rheological fluid

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
12.Pręgowska A., Konowrocki R., Szolc T., Optimal segmentation of beam and disk structures, Structural optimization, ISSN: 0934-4373, DOI: 10.1007/BF01197041, Vol.11, No.3, pp.252-259, 1996
Abstract:

Large structures are usually composed of elements by properly designed connections. The optimal design solution in such cases should provide optimal size and number of elements together with optimal connection stiffness. The problem is formulated by assuming the element cost to be a nonlinear function of its size and the cost of connection to depend on its stiffness or transmitted forces. The number of elements and the connection stiffness now constitute the design parameters to be determined. A two-level procedure is proposed for determination of the optimal segmentation for beam and plate structures. Several illustrative examples are presented.

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN

List of chapters in recent monographs
1.
438
Pręgowska A., Szolc T., Pochanke A., Konowrocki R., Recent Advances in Automation, Robotics and Measuring Techniques, rozdział: Modeling and dynamic analysis of the precise electromechanical systems driven by the stepping motors, Springer International Publishing, Series: Advances in Intelligent Systems and Computing, 267, Part I, pp.205-215, 2014

Conference papers
1.Konowrocki R., Pochanke A., Pręgowska A., Szolc T., An analysis of precise positioning scenarios of the electromechanical rotating system driven by a stepping motor, SIRM 2015, 11th International Conference on Vibrations in Rotating Machines, 2015-02-23/02-25, Magdeburg (DE), No.ID-40, pp.1-10, 2015
Abstract:

In the paper there is investigated experimentally and theoretically electromechanical dynamic interaction between the driving stepping motor and the driven laboratory belt-transporter system imitating an operation of the robotic device in the form of working tool-carrier under translational motion. The considered object is properly equipped with measurement systems enabling us a registration of studied electrical and mechanical quantities. The analytical considerations are performed by means of the circuit model of the electric motor and of the discrete, non-linear model of the mechanical system. In the investigated examples various scenarios of the working tool-carrier motion and positioning by the belt-transporter are measured and simulated, where in the all cases the electric current control of the driving motor has been applied.

Keywords:

Belt transporter system, Precise positioning, Stepping motor, Current control, Experimental verification

Affiliations:
Konowrocki R.-IPPT PAN
Pochanke A.-other affiliation
Pręgowska A.-IPPT PAN
Szolc T.-IPPT PAN

Conference abstracts
1.Paprocki B., Pręgowska A., Szczepański J., Information Processing in Brain-Inspired Networks: Size and Density Effects, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P192, pp.1-2, 2016
2.Proniewska K., Pręgowska A., Adaptive design approach to tele-Health trials based on Biostatical and Information Theory methods, Telemedicine and eHealth, 2016-09-02/09-03, Warszawa (PL), pp.1, 2016
Keywords:

adaptive design, biostatistic, information Theory

Affiliations:
Proniewska K.-other affiliation
Pręgowska A.-IPPT PAN
3.Proniewska K., Pręgowska A., New approach to quantify breathing pattern changes using a monitoring scoring system, Telemedicine and eHealth, 2016-09-02/09-03, Warszawa (PL), pp.1, 2016
Keywords:

quantify breathing pattern, patient monitoring

Affiliations:
Proniewska K.-other affiliation
Pręgowska A.-IPPT PAN
4.Szczepański J., Sanchez-Vives M.V., Arnold M.M., Montejo N., Paprocki B., Pręgowska A., Amigó J.M., Wajnryb E., Analyzing Neuroscience Signals using Information Theory and Complexity Shannon Communication Approach, 12th INCF, 12th INCF Workshop on Node Communication and Collaborative Neuroinformatics, 2015-04-16/04-17, Warszawa (PL), pp.1-32, 2015

Patents
Numer/data zgłoszenia patentowego
Ogłoszenie o zgłoszeniu patentowym
Twórca / twórcy
Tytuł
Kraj i Nazwa uprawnionego z patentu
Numer patentu
Ogłoszenie o udzieleniu patentu
pdf
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2017-05-24
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Frąś L., Kołbuk-Konieczny D., Pręgowska A.
Uchwyt pomiarowy do Dzielonego Pręta Hopkinsona oraz sposób pomiaru zachowania materiału, w którym stosuje się Dzielony Pręt Hopkinsona
PL, Instytut Podstawowych Problemów Techniki PAN
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