Aprendizaje no supervisado: aplicación en epilepsia

Epilepsy is a neurological disorder characterized by recurrent seizures. The primary objective is to present an analysis of the results shown in the training data simulation charts. Data were collected by means of the 10-20 system. The “10–20” system is an internationally recognized method to describe and apply the location of scalp electrodes in the context of an EEG exam. It shows the differences obtained between the tests generated and the anomalies of the test data based on training data. Finally, the results are interpreted and the efficacy of the procedure is discussed.La epilepsia es uno de los trastornos neurológicos comunes caracterizado por convulsiones recurrentes. El objetivo principal de este artículo es dar a conocer el análisis de los resultados presentados en las gráficas de simulación de los datos de entrenamiento. Los datos fueron recolectados mediante el sistema 10-20. El sistema "10-20" es un método reconocido internacionalmente, este describe la ubicación de electrodos en la cabeza para una prueba de EEG. Se muestran las diferencias obtenidas entre las pruebas generadas con las anomalías de los datos de prueba a partir de los datos de entrenamiento. Finalmente, se interpretan los resultados y se discute sobre la eficacia del procedimiento

sEMG-based natural control interface for a variable stiffness transradial hand prosthesis

We propose, implement, and evaluate a natural human-machine control interface for a variable stiffness transradial hand prosthesis that achieves tele-impedance control through surface electromyography (sEMG) signals. This interface, together with variable stiffness actuation (VSA), enables an amputee to modulate the impedance of the prosthetic limb to properly match the requirements of a task while performing activities of daily living (ADL). Both the desired position and stiffness references are estimated through sEMG signals and used to control the VSA hand prosthesis. In particular, regulation of hand impedance is managed through the impedance measurements of the intact upper arm; this control takes place naturally and automatically as the amputee interacts with the environment, while the position of the hand prosthesis is regulated intentionally by the amputee through the estimated position of the shoulder. The proposed approach is advantageous since the impedance regulation takes place naturally without requiring amputees' attention and diminishing their functional capability. Consequently, the proposed interface is easy to use, does not require long training periods or interferes with the control of intact body segments. This control approach is evaluated through human subject experiments conducted over able volunteers where adequate estimation of references and independent control of position and stiffness are demonstrated.Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) ; 219M58

Predicting Humans’ Identity and Mental Load from EEG: Performed by AI

EEG-based brain machine/computer interfaces (BMIs/BCIs) have a wide range of clinical and non-clinical applications. Mental workload (MW) classification, emotion recognition, motor imagery, seizure detection, and sleep stage scoring are among the active BCI research areas. One of the relatively new BCI area is EEG-based human subject recognition (i.e., EEG biometric). There still exist several challenges that need to be addressed to design a successful EEG-based biometric model applicable for real-world environments. First, there is a need for a protocol that can elicit the individual dependent EEG responses in a short period of time. A classification algorithm with high generalization power is also required to deal with the EEG signals classification task. The latter is a common challenge for all EEG-based BCI paradigms; given the non-stationary nature of the EEG signals and the small size of the EEG datasets. In addition, to building a stable EEG biometric model, the effects of human mental states (e.g., emotion, mental load) on the model performance needs to be carefully examined. In this thesis, a new protocol for the area of the EEG biometric has been proposed. The proposed protocol called “(the) N-back task” is based on the human working memory and the experimental results obtained in this thesis prove that the EEG signals elicited by the N-back task contain subject specific features, even for very short time intervals. It has also been shown that three load levels of the typical N-back task are all capable of evoking subject specific EEG features. As a result, the N-back task can be used as a protocol having more than one mode (i.e, cancelable protocol) that comes with added security benefits. The EEG signals evoked by the N-back task have been used to train a compact convolutional neural network called the EEGNet. A configuration of the EEGNet having 16 temporal and 2 spatial filters has reached an identification accuracy of approximately 97% using data instances as short as 1.1s for a pool of 26 subjects. To further improve the accuracy, a novel ensemble classifier has been designed in this thesis. The principle underlying the proposed ensemble is the “division and exclusion” of the EEG channels guided by scalp locations. The ensemble classifier has (statistically significantly) improved the subject recognition rate from 97% to 99%. Performance of the proposed ensemble model has also been assessed in the EEG-based MW classification paradigm. The ensemble classifier outperformed the single EEGNet as well as a state-of-the-art classifier called WLnet in the challenging scenario of the subject-independent (cross-subject) MW classification. The results suggest that the ensemble structure proposed in this thesis can generalize to different BCI paradigms. Finally, effects of the mental workload on the performance of the EEG-based subject authentication models have been thoroughly explored in this thesis. The obtained results affirm that MW of the genuine and impostor subjects at the train and test phases have significant effects on both false negative rate (FNR) and false positive rate (FPR) of an authentication system. Different subjects have also shown different clusters of authentication behaviors when affected by the MW changes. This finding establishes the importance of the human’s mental load in the design of real-world EEG authentication systems and introduces a new investigation line for the EEG biometric community

Znajdywanie odpowiedniości punktów charakterystycznych na obrazach stereowizyjnych

Doctoral Theses: 1. Dedicated Methods of Analysis and Processing of Stereovision Images Enable to Improve a Quality of Stereo Correspondence Results. 2. Introduction of New Attributes of Feature Points Allows to Improve the Efficiency of the Stereo Correspondence Algorithms. The aim of the dissertation is to develop a method that allows to find matches between feature points on stereo vision images. Proposed method is dedicated to medical applications. Achieving the goal of the dissertation required several partial goals. 1. Developing of medical images segmentation method. 2. Developing of matching method. 3. Evaluation of matching quality. 4. Evaluation of influence of the selected feature points attributes on stereo correspondence quality. 5. Final optimization of algorithms to work on subcutaneous vessels images. Results presented in the thesis. • Three image segmentation methods BGOM, SSSB and BLG. • Three matching methods MED, MED-NDD and MED-RGB. • First method (MED) is based on the assumption that the correct disparity is the minimal distance between given feature point on the left image and all feature points on the right image in the given row. • Second method (MED-NDD) improves the results obtained with the first method by 30% for selected images. • Third method (MED-RGB) improves the results obtained with the first method by 30% for selected images. • Quality evaluation of the created disparity map accordingly to three accuracy criteria and reference ground true disparity map. • Evaluation of influence of the new feature point attributes to stereo correspondence results. Attributes were properly selected improving an average results by 12%. However, to clearly state the values of error-minimizing attributes would have to be carried out further research on properly prepared image database. • Dedicated algorithms to cope with medical images of subcutaneous vessels that present much better effectiveness in comparison to existing widely used methods. • Proposed in dissertation algorithms are the quickest what follows from the presented comparisons. The methods were tested on three groups of test images namely solids, subcutaneous vessels and real images from the Middlebury College Stereo Vision library.. Based on the above, it must be stated that the conducted research confirms the correctness of the theses formulated at the beginning of the work