Tomasz Przybyła

An application of detection function for the eye blinking detection

The electrooculogram represents the electrical activity of muscles which steering of movements of an eye. The eye blinking is a natural protection system which defends the eye from environmental exposure. The spontaneous eye blink is considered to be a suitable indicator for fatigue diagnostics during many, different tasks of human being activity. The detection function is used to detect the spontaneous eye blink action. On this base the position of an eye blink is estimated. The results demonstrate that the measurement of an eye blink parameter provides reliable information for eye-controlled systems from human-machine interface.

A new method of saccadic eye movement detection for optokinetic nystagmus analysis

The analysis of eye movements is valuable in both clinical work and research. One of the characteristic type of eye movements is saccade. The accurate detection of saccadic eye movements is the base for further processing of saccade parameters such as velocity, amplitude and duration. This paper concerns an accurate saccade detection method that is based on pre-processing signal and then the proposed non-linear detection function can be applied. The described method characterizes less sensitivity for any kind of noise due to an application of the robust myriad filter which is used to eliminate baseline drifts and impulsive artifacts. The congenital nystagmus is one of the field where our method can be applied to detect saccades. The proposed detection function is computationally efficient and precisely determines the time position of saccadic eye movements even when the signal-to-noise ratio is low. The presented method may have potential application in automatic ENG signal processing systems for determining visual acuity.

Telemedical application for centralized home care of high-risk pregnancy based on control sharing approach

The paper presents a fetal telemonitoring system, where the signals are acquired remotely at patient’s home using portable antepartum fetal monitor, and wirelessly transmitted to the central computer through the GSM network. The external telemedical channels were developed as a part of the centralized fetal monitoring system, whose architecture was extended by set of mobile instrumentation. While within a classical centralized fetal surveillance system all control functions are carried out from the central station, for remote monitoring the functions have to be shared between the hospital and the patient’s side. Some aspects of the system design allowing for optimal usage of existing structure and service procedures, and for being more patient-friendly and cost-effective, are discussed.

The Adaptive Fuzzy Meridian and Its Appliction to Fuzzy Clustering

The fuzzy clustering methods are useful in the data mining field of applications. In this paper a new clustering method that deals with data described by the meridian distribution is presented. The fuzzy meridian is used as the cluster prototype. Simple computation method for the fuzzy meridian is given as well as the meridian medianity parameter. A numerical example illustrates the performance of the proposed method.

Fuzzy Approach to Saccades Detection in Optokinetic Nystagmus

The electronystagmography (ENG) based analysis of the nystagmus provides valuable information about condition of the human vision system. The typical ENG signal corresponding to nystagmus has a form of a saw tooth waveform with slow and fast (saccade) components. The slow component is related to the stimulus while the saccade refers to a rapid reset of eye position. The accurate detection of saccadic eye movements is inevitable when determining the nystagmus characteristic. The paper presents saccades detection method that is based on fuzzy clustering. The proposed procedure is computationally efficient and allows for precise determination of the saccade position in the time domain.

An automatic saccadic eye movement detection in an optokinetic nystagmus signal.

Abstract A saccade is one of the characteristic types of eye movements. The accurate detection and location of saccades in the signal representing the movement activity of the eyes are essential in medical applications. The main purpose of this paper is to present a new, robust approach to the detection of saccadic eye movements. The procedure is based on a so-called detection function, which is the result of the electronystagmographic (ENG) myriad signal filtering, nonlinear operation, and fuzzy median clustering. Smooth peaks of the detection function waveform correspond to the location of saccades in the ENG signal. The median fuzzy clustering-based method allows for calculating the amplitude threshold of the detection function, which improves the accurate saccade recognition. Both of these robust methods provide a two-step protection against outliers. The proposed algorithm was tested using artificial as well as real optokinetic nystagmus signals under different noise conditions. The results show the usefulness of the procedure when the precise detection and location of saccades are necessary.

Hybrid QRS detection circuit based on dynamic reconfigurable field programmable analog array.

Abstract In many medical applications it is important to detect the QRS complex in the electrocardiogram (ECG) waveform with possibly low time delay. Traditional software detectors of the QRS complex implement algorithms usually based on cascades of digital filters introduce delays up to parts of a second. Hardware QRS detectors fulfill the low delay requirements, but have worse adaptive features for the changing ECG shape. In this paper a new approach to QRS detection is presented. The proposed detector is based on a Field Programmable Analog Array (FPAA). The most interesting feature of the FPAA is the dynamic reconfigurability. This solution makes it possible to modify the parameters of particular blocks of the detector or even the whole structure during runtime, without any changes in hardware and disturbance of the system functionality. The prototype QRS detector was built using AN221E04 circuit from the Anadigm company. The reconfiguration data are calculated by the AD7020 microcontroller and downloaded to the FPAA after each QRS detection.

An approach to the EOG signal segmentation based on fuzzy reasoning

In this paper we presented an approach to segmentation of an electrooculography (EOG) signal. For segmentation we have used the elements of the fuzzy set theory. Results obtained in our numerical experiments show usefulness of proposed approach. Our method can be also used for the generating of a learning set necessary for the neural networks or the fuzzy-neural systems training.

A Recovery of FHR Signal in the Embedded Space

In the paper we present a proposition of a recovery method for fetal heart rate signals (FHR). Recorded FHR signal often contains interruptions. The interruptions of the signal are caused among others by fetal movements. In such cases, the instantaneous heart rate determination is difficult because parts of the signal are missing. For the reconstruction of missing parts of the FHR signal, an approximation in an embedded space is proposed. The embedded space is created by applying the Taken’s theory. Next, the vicinity is determined for the missing samples (missing features in the embedded space). For the vicinity computation, two strategies are chosen: the nearest surrounding of the approximated sample or K nearest neighborhoods. The missing value is computed as a mean or a median. Numerical experiments performed for test (simulated) signals and the real FHR signal show advantages of proposed approach.

Robust fuzzy clustering using adaptive fuzzy meridians

The fuzzy clustering methods are useful in the data mining applications. This paper describes a new fuzzy clustering method in which each cluster prototype is calculated as a fuzzy meridian. The meridian is the maximum likelihood estimator of the location for the meridian distribution. The value of the meridian depends on the data samples and also depends on the medianity parameter. The sample meridian is extended to fuzzy sets to define a fuzzy meridian. For the estimation of medianity parameter value, the classical Parzen window method by real non-negative weights has been generalized. An example illustrating the robustness of the proposed method was given.