Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/11

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Institution Author: search.filters.institutionAuthor.Onay, Fatih

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  • Article
    Citation - WoS: 6
    Citation - Scopus: 10
    Using Chemosensory-Induced Eeg Signals To Identify Patients With <i>de Novo</I> Parkinson's Disease
    (Elsevier Sci Ltd, 2024) Olcay, Orkan; Onay, Fatih; Ozturk, Guliz Akin; Oniz, Adile; Ozgoren, Murat; Hummel, Thomas; Guducu, Cagdas
    Objective: Parkinson's disease (PD) patients generally exhibit an olfactory loss. Hence, psychophysical or electrophysiological tests are used for diagnosis. However, these tests are susceptible to the subjects' behavioral response bias and require advanced techniques for an accurate analysis. Proposed Approach: Using well-known feature extraction methods, we characterized chemosensory-induced EEG responses of the participants to classify whether they have PD. The classification was performed for different time intervals after chemosensory stimulation to see which temporal segment better separates healthy controls and subjects with de novo PD. Results: The performances show that entropy and connectivity features discriminate effectively PD and HC participants when olfactory-induced EEG signals were used. For these methods, discrimination is over 80% for segments 100-700 and 200-800 milliseconds after stimulus onset. Comparison with Existing Methods: We compared the performance of our framework with linear predictive coding, bispectrum, wavelet entropy-based methods, and TDI score-based classification. While the entropy- and connectivity-based methods elicited the highest classification performances for olfactory stimuli, the linear predictive coding-based method elicited slightly higher performance than our framework when the trigeminal stimuli were used. Conclusion: This is one of the first studies that use chemosensory-induced EEG signals along with different feature extraction methods to classify healthy subjects and subjects with de novo PD. Our results show that entropy and functional connectivity methods unravel the chemosensory-induced neural dynamics encapsulating critical information about the subjects' olfactory performance. Furthermore, time- and frequency-resolved feature analysis is beneficial for capturing disease-affected neural patterns.
  • Conference Object
    Ampute Elektromiyografi Sinyallerinin Evrişimli Sinir Ağları Kullanılarak Sınıflandırılması
    (IEEE, 2020) Onay, Fatih; Mert, Ahmet
    The classification of EMG signals for the amputees is important to develop a powered-prosthetic that is capable of replacing with lost limbs. The EMG signals collected from residual limbs reduce the classification accuracy due to muscle movements that cannot be realized properly. In this study, classification performance is aimed to be increased by combining CNN with root mean square (RMS) and waveform length (WL) that are used in analysis of EMG signals successfully. The features such as RMS and WL extracted from EMG signals for the classification of six hand movements at the low, medium, and high force levels were applied to CNN input, and classification results were compared with nearest neighbour and linear discriminant analysis.
  • Article
    Değişken Kuvvetli Emg Sinyallerinin Çok Değişkenli Görgül Kip Ayrışımı ile Analizi ve Sınıflandırılması
    (Marmara Üniversitesi, 2020) Onay, Fatih; Mert, Ahmet
    Elektromiyografi (EMG) sinyalleri, insan-makine etkileşimli akıllı el protezlerinin kontrolünde önemli bir rol oynamaktadır. Kas aktivesinin bir sonucu olarak ortaya çıkan EMG sinyalleri, yapılan aktiviteye dair özel bilgileri kendi içerisinde ihtiva etmektedir. Dolayısıyla akıllı el protezlerinin işlevselliğinin arttırılması, kas bölgesinden toplanan EMG sinyalinin doğru bir şekilde analiz edilip yorumlanmasına önemli ölçüde bağlıdır. Bu konsepte uygun olarak, akıllı el protezi hareketlerinin karar verme sürecinde, EMG sinyallerinin güvenilir bir şekilde kullanılabilmesi için, var olan yöntemlerin geliştirilmesi ya da bu yöntemlere üstünlük sağlayacak yeni yöntemler önerilmesi gerekmektedir. Bu çalışma kapsamında, çok kanallı EMG sinyallerinin analizinin geliştirilmesi amacıyla, çok değişkenli görgül kip ayrışımı (ÇDGKA) tabanlı öznitelik çıkarma yöntemi, geleneksel metotlara alternatif olarak sunulmuştur. Sinyali adaptif olarak salınım modlarına ayıran ÇDGKA yöntemi kullanılarak, EMG sinyalinden daha anlamlı bilgi edinilmesi amaçlanmıştır. ÇDGKA tabanlı özniteliklerin farklı el ve parmak hareketlerini ayırt etme performansı ve farklı kuvvet seviyelerine karşı gösterdiği performans incelenmiştir. Bu amaçla ampute katılımcıların artık uzuvlarından toplanan düşük, orta ve yüksek kuvvet seviyelerine ait EMG sinyalleri üzerinde ÇDGKA yöntemi uygulanarak özgül kip fonksiyonları (ÖKF) elde edilmiştir. Elde edilen ÖKF’lerden çıkarılan öznitelikler kullanılarak altı farklı el ve parmak hareketi, en yakın komşu (k-NN), doğrusal ayrım analizi (LDA) ve destek vektör makinesi (SVM) sınıflandırıcıları kullanılarak sınıflandırılmıştır. Aynı kuvvet seviyesinde eğitilip test edilerek (Senaryo 1) ve tüm kuvvet seviyelerinde eğitilip tek bir kuvvet seviyesinde test edilerek (Senaryo 2) gerçekleştirilen sınıflandırmalar neticesinde, önerilen ÇDGKA tabanlı özniteliklerin ham sinyal tabanlı özniteliklere göre, senaryo 1 için %10 - %15, senaryo 2 için %18’e kadar üstünlük sağladığı belirlenmiştir.
  • Article
    Citation - WoS: 22
    Citation - Scopus: 26
    Phasor Represented Emg Feature Extraction Against Varying Contraction Level of Prosthetic Control
    (Elsevier, 2020) Onay, Fatih; Mert, Ahmet
    This paper introduces phasor representation of electromyography (EMG) feature extraction (PRE). The well-known EMG signal analysis methods, namely root mean square (RMS), and waveform length (WL) are adopted into phasor form depending electrode placement. The values of these methods are computed from 8-channel EMG signals, and their magnitudes with respect to origin are used to construct phasor represented features in this study. The class separability of the PRE is strengthened by adding difference EMG and Euclidean distanced phasor in order to obtain improved feature set against force and electrode variations. The simulations (three schemes) are performed on publicly available EMG dataset on transradial amputees, and the results are presented in terms of accuracy and processing time considering the control strategies of a prosthetic hand. Linear (LDA), and quadratic (QDA) discriminant analysis, and knearest neighbor (k-NN) classifiers are trained, and tested by the PRE features. Our method outperforms previous accuracy rates in some cases, and reaches to accuracy results of the first study using this dataset without using any reduction method. In our simulations, accuracy rates up to 71.17% (PRE with QDA) for six classes hand movements with three force levels are obtained decreasing processing time by 81.83%. (C) 2020 Elsevier Ltd. All rights reserved.